12 November 2014 , Volume 90, Number 6

27 January 2015

23 February 2015

12 March 2015 , Volume 91, Number 2

Members Event

Event participants

Professor Joseph S Nye, University Distinguished Service Professor, Harvard Kennedy School of Government
Chair: Gideon Rachman, Chief Foreign Affairs Commentator, Financial Times

Research Event

Event participants

Charlie Parton, Counsellor, Political Section, Beijing Delegation, European External Action Service
Chair: Roderic Wye, Assciate Fellow, Asia Programme, Chatham House

Members Event

Event participants

Professor Kerry Brown, Director, Lau China Institute, King's College London; Associate Fellow, Asia Programme, Chatham House
Chair: Isabel Hilton OBE, Founder and Editor, Chinadialogue

Members Event

Event participants

Parag Khanna, Author, Connectography: Mapping the Global Network Revolution

4 July 2016

Invitation Only Research Event

Event participants

Professor Philippe Sands QC, Barrister, Matrix Chambers
Chris Whomersley, Deputy Legal Adviser, Foreign and Commonwealth Office (2002-14)
Professor Julia Xue, Academy Senior Fellow, International Law Programme, Chatham House
Chair: Elizabeth Wilmshurst, Distinguished Fellow, International Law Programme, Chatham House

geoffiths posted a photo:

Challenge #17 the inspiration for today’s photo is to come from the VERY next thing you audibly hear. I heard someone say "Welcome" so my interpretation was a future of getting close again would be welcome.

Hidden in the flash. posted a photo:

With a lockdown in place it is against the rules for me to go to places I like to shoot, so I though I would try to create a series called Isolated creativity. The series is not intended to be a diary but a way of documenting thoughts and emotions via photography.

I've felt a bit like Pink Rabbit over the passed few day. I'm not fed up and depressed by the lockdown but by the people who think that it's okay to break the rules. By the tabloid media that run stories that convince people it's okay to go out and about, when it Isn't. By the political points scoring that has started to appear in all forms of media.Lastly I fed up with second home owners that have turned up during lockdown and appear to be going out and about most days.

Just like Pink Rabbit I have the blues.

Reiterlied posted a photo:

A tribute to Pirates I made last year when winter was coming to an end.

(You can find the blog post I wrote last year at Stuck in Plastic: www.stuckinplastic.com/2019/04/week-17-ching-shih/)

The investigation into the fatal shooting in Brunswick, Georgia, will also look at a neighbor of suspects Gregory and Travis McMichael who recorded video of the incident, authorities said.

Ousted vaccine expert Rick Bright said he is "frustrated at our inability to be heard as scientists."

Elizabeth Spiers wrote about an incident where Jared Kushner used the memorial of an employee to congratulate himself for success.

Representative Michael McCaul, who has harshly criticized China in his position as the ranking member on the House Foreign Affairs Committee, disclosed that his family owns stock in a Chinese tech company he described as a threat to national security.An April 20 periodic transaction report showed that McCaul disclosed a February purchase of between $50,000 and $100,000 in shares of the Chinese firm Tencent Holdings, Politico reported.In November, several months before the shares were purchased, the Texas congressman said that Tencent Holdings is among the "Chinese companies that threaten America’s economic and national security."The tech conglomerate is "heavily involved" in the "social credit system, a dystopian system China has implemented to score its citizens’ behavior," McCaul said at the time, as well as an "integral part" of the Chinese Communist Party’s industrial policies and "one of four national champions for artificial intelligence."McCaul's lawyer, Elliot Berke, said that the shares are not owned personally by McCaul but by his wife, and the decision to invest in Tencent was made by a third party.“Congressman McCaul did not purchase any shares in China’s Tencent Holdings or any other Chinese company,” the attorney said. “Congressman McCaul’s wife has assets she solely owns and a third party manager made the purchase without her direction.”Rachel Walker, a spokeswoman for McCaul, emphasized that the revelation of the Tencent shares “highlights that many Americans unwittingly invest their money in Chinese owned companies."Federal employees are often unaware they own such investments because the federal government’s thrift savings plan program creates portfolios that include Tencent and other Chinese companies, Walker said. McCaul has argued that such retirement investment plans should not invest American dollars in such "shady" Chinese companies, often without the knowledge of the investor."Congressman McCaul has been a fierce critic of the brutal behavior of the Chinese Communist Party and will continue to fight to hold them accountable as the Chair of the China Task Force," Walker said. "This should be a wake-up call to us all that the CCP’s involvement in the U.S. economy is far more reaching than many Americans realize and that we need to change the way we do business with China, including our investments."Tencent owns the Chinese social media platform WeChat, which has more than one billion users and is suspected of monitoring the activities of users both inside and outside of China. Tencent is also associated with Chinese tech firm Huawei, which U.S. officials said can secretly access American cellular phone networks, giving it access to sensitive information.McCaul has taken a leading role in criticizing China's handling of the coronavirus pandemic as well, accusing Beijing of launching perhaps the "worst cover-up in human history."He was tapped on Thursday by House Minority Leader Kevin McCarthy as chairman of the China Task Force, the aim of which is to develop "legislative solutions to address the Chinese Communist Party’s malign global agenda."The task force will "develop new and enduring policy solutions that, among others, enhance our economic strength and create jobs, protect our national security, rethink our supply chains and grow our competitive edge in technology," McCaul said in a statement on his appointment.

South Dakota Governor Kristi Noem sent letters to two Sioux tribes demanding they remove COVID-19 checkpoints because they interfere with traffic.

Nepal protested India's inauguration of a new road to China that passes through territory claimed by Kathmandu on Saturday, with police arresting dozens demonstrating close to India's embassy. Indian defence minister Rajnath Singh on Friday inaugurated via video link the 80-kilometre (50 miles) long road from Ghatiabagarh in northern Uttarakhand state to the Lipu Lekh pass high in the Himalaya. The pass is claimed by Nepal based on an 1816 treaty that defines its western border with India.

The former Senate staffer, who is accusing Joe Biden of sexually assaulting her 27 years ago, is being represented by a lawyer who is also a donor to President Trump.

"I think it's always important to think about suicide as individual vulnerabilities and context," Eric Caine said.

The government said it's distributing the promising coronavirus drug, remdesivir, to some hard-hit states. Eventually, all 50 states should get it.

Travel blogger and photographer Andy Luten drove 4,200 miles across six states to see the grounded jets, detailing the shocking state of aviation.

On Thursday, the Professional Beauty Federation of California published a press release to the “Hot Topics” section of their website. It was titled: “Time to Sue Governor Newsom.” The release came in response to Gov. Gavin Newsom’s announcement that the following morning, California would officially enter “Phase Two” of the “Safer at Home” order. Select businesses, from florists to clothing retailers to toy stores, would be able to resume operations in a limited capacity. But absent from the list of acceptable businesses: beauty salons. Newsom placed businesses like nail salons and barbershops in “Phase Three”—a stage he believes to be “months, not weeks” away. “This whole thing spread in the state of California—the first community spread—was in a nail salon,” Newsom said in a press conference last week, without providing details about the date or location of the case. “Many of the practices that you would otherwise expect of a modification were already in play in many of these salons, with people that had procedure masks on, were using gloves, and were advancing higher levels of sanitation.”The news has thrust nail salons onto the frontline of a growing coronavirus revolt in California, a battle being waged in many more American cities, like Dallas, where hairdresser Shelley Luther became a star of the anti-lockdown movement when she opted to go to jail rather than comply with an order to close her hair salon. Anti-Lockdown Protesters Are Now Facing Down Cops Outside of BarsOn Monday morning, the Professional Beauty Federation of California will file a lawsuit in federal court demanding a regulated reopening process of their salons. “We were 100 percent behind the lockdown, so that we would not overwhelm our hospitals,” the group’s legal counsel Fred Jones said in an interview with The Daily Beast. “However, after two months of the lockdown, in which, by Gov. Newsom’s own admission, we have succeeded—we have checked the mark, we have flattened the curve—we were anticipating that the governor would allow for gradual reopenings of our beauty salons under strict new guidelines.”Their argument, Jones said, hinges on the fact that, without regulated reopening, stylists will be forced underground to meet financial ends, resulting in a potentially more dangerous risk.“A lot of our stylists are on the brink of starvation in order to make their leases and make ends meet,” Jones said. “So you have a volatile combination of desperate clients and desperate stylists. We know that will lead to thousands of our stylists going underground and moving kitchen to kitchen and house to house. That’s reality. Nobody can argue that. So the real question is: how do you stop that from happening if you’re the governor? You can’t.”He suggested a gradual and controlled reopening would be safer than “stylists going house to house and spreading more than beauty.”Unmasked Protesters Storm Huntington Beach After California Governor’s ClosureSome salons statewide have already opened, defying the statewide order, like an Orange County nail spa owner who has vowed to stay open despite being handed a citation by local police, who ordered her to appear in court in July. “I have to do what I have to do. I’m fighting to provide for my children and myself and my family,” another salon owner, Breann Curtis, of The Clip Cage barbershop in Auburn, California, told Fox40 about her decision to reopen. “It’s very hard. I’m pregnant. I have children.”“Just going into debt every single day,” added Tisha Fernhoff, who owns The Beauty Bar Salon in the same Auburn shopping center. “How much longer am I supposed to just go down the rabbit hole before I just throw in the towel and go back to work?”According to Jones, the California State Board of Barbering and Cosmetology—which issues all 623,442 beauty licenses in the state—has already drafted a protocol for how salons could reopen under the current conditions. He claimed Newsom had blocked the plan from distribution, to avoid mixed messaging. (Newsom’s office didn’t respond to a request for comment and a spokesperson for the Board of Barbering and Cosmetology said their draft protocols “haven't been published because they are not finished.”)“We want him to release the plan so that our professionals can start stocking up,” Jones said. “We know we’ll need masks. Will shields be required for these services? They probably will.”If such a plan was to go into effect, Jones said, salons would use personal protective equipment widely. They would stagger appointments to avoid crowded waiting rooms, spread out work stations and shift schedules, implement a touchless pay system, and remove anything in the waiting rooms that could carry contagion. “So, sorry no more magazines and newspapers for our clientele,” Jones said. But the Centers for Disease Control and Prevention (CDC) recommends maintaining a distance of six feet from other people—a practice that would be all but impossible in salon settings. Dr. Birx Says What Trump Would Not About ProtestersThere are 53,694 licensed beauty salons in California, representing 313,734 stylists or cosmetologists, 34,093 barbers, 90,392 estheticians, 1,679 electrologists, and 129,802 manicurists, according to the State Board of Barbering and Cosmetology. All of these workers, Jones said, have to complete between 350 and 1600 hours of formal education before acquiring their license, including training in sanitization. Jones emphasized that the lawsuit stemmed from financial desperation, a sentiment shared across the country. The Labor Department announced Friday that the economy lost over 20.5 million jobs in April alone, putting the national unemployment rate at its highest since the Great Depression: 14.7 percent. But the devastation has hit the beauty sector differently than many industries. Over 80 percent of salon workers are independent contractors, meaning each stylist represents their own business. By extension, many salon owners are basically landlords, “whose income relies on those booth owners,” Jones said. As a result, most salon workers qualify for unemployment benefits under the Coronavirus Aid, Relief and Economic Security Act, signed by Trump in March—although the program is riddled with loopholes, has frequently run out of money, and may not cover their entire income, which heavily relies on tips. It is salon owners who stand to gain the most from the lawsuit. “Freelance workers do benefit on unemployment benefits,” Jones said. “But most of those Paycheck Protection Program reimbursements are based on your payments. If you’re a salon owner, you don’t have a payroll. Those stylists are their own proprietors.”On Friday, Senators Bernie Sanders (I-VT), Ed Markey (D-MA), and Kamala Harris (D-CA) introduced legislation to give a majority of Americans $2,000 a month throughout the pandemic. Asked whether the bill could provide financial relief to salon workers, while allowing them to maintain social distancing, Jones seemed doubtful that it would pass. “It’s the proverbial ‘check is in the mail’ promise,” he said. “When you’re dealing with true economic devastation, let me tell you, most of our licensees will not be banking on a divided Congress and a White House that is also divided. While Washington fiddles, our stylists are burning.” Read more at The Daily Beast.Get our top stories in your inbox every day. Sign up now!Daily Beast Membership: Beast Inside goes deeper on the stories that matter to you. Learn more.

Attorney General Bill Barr explained that the FBI did not conduct “a bonafide counterintelligence investigation” in the case that led former Trump national security adviser Michael Flynn to plead guilty to federal investigators in 2017.Barr, speaking in an exclusive interview with CBS News after the Justice Department dropped its case against Flynn on Thursday, said that his review of the case found Bureau investigators laid “a perjury trap” for Flynn in a January 2017 White House interview.“They didn’t warn him, the way that would usually be required by the Department, they bypassed the Justice Department, they bypassed the protocols at the White House, and so forth,” Barr stated. “These were things that persuaded me that there was not a legitimate counterintelligence investigation.”Former FBI director James Comey admitted in a December 2018 interview that he “sent” the agents to interview Flynn, adding that it was “something I probably wouldn’t have done or maybe gotten away with in a more organized administration.”In its Thursday court filing, the Justice Department explained that it was “not persuaded” that Flynn’s interview, which led to his guilty plea for lying to FBI agents Peter Strzok and Joe Pientka, had proper predication and was materially relevant.Comey tweeted his disappointment, following the decision, saying "the DOJ has lost its way."> The DOJ has lost its way. But, career people: please stay because America needs you. The country is hungry for honest, competent leadership.> > -- James Comey (@Comey) May 7, 2020Barr pointed to recently-released information that showed the FBI moved to close its surveillance of Flynn after finding “no derogatory information” about the retired general’s contacts with Russians, only for Strzok to keep the case open, leading to the eventual interview.“They were closing the investigation, in December [2016], they started that process and on January 4, they were closing it. When they heard about the phone call, which the FBI had the transcripts to — there was no question as to what was discussed, the FBI knew exactly what was discussed — and General Flynn, being the former director of the DIA, said to them, ‘you listen to everything, you know what was said,’” Barr explained.“So there’s no mystery about the call, but they initially tried some theories of how could open another investigation, which didn’t fly, and then they found out that they had not technically closed the earlier investigation, and they kept it open for the expressed purpose of trying to catch — lay a perjury trap — for General Flynn,” he added. A different filing released last week showed handwritten notes from an FBI official that questioned if the goal of Flynn’s White House interview was “to get him to lie, so we can prosecute him or get him fired.”Barr also did not comment on whether those that sought to entrap Flynn would face criminal charges, pointing to U.S. Attorney John Durham’s probe into the origins of the Trump-Russia investigation and saying his team was “in the middle” of “looking at the whole pattern of conduct.”“I’m going to wait until all the evidence is [in], and I get their recommendations as to what they found and how serious it is. But, if we were to find wrongdoing, in the sense of any criminal act, obviously we would follow through on that,” Barr said. “But again, just because something may even stink to high heaven, and appear to everyone to be bad, we still have to apply the right standard and be convinced that there is a violation of a criminal statute and that we can prove it beyond a reasonable doubt. The same standard applies to everybody.”

In a tweet Saturday morning, Tesla's chief executive said it would file a lawsuit against county officials over not being able to run its factory.

(University of Stirling) A new University of Stirling study is seeking to understand how the easing of COVID-19 pandemic restrictions on licensed premises can be effectively managed to protect emergency services.

Lethal infections by strains of the highly-pathogenic avian influenza virus (HPAIV) H5N1 pose serious threats to both the poultry industry and public health worldwide. A lack of confirmed HPAIV epitopes recognized by cytotoxic T lymphocytes (CTLs) has hindered the utilization of CD8+ T-cell–mediated immunity and has precluded the development of effectively diversified epitope-based vaccination approaches. In particular, an HPAIV H5N1 CTL-recognized epitope based on the peptide MHC-I–β2m (pMHC-I) complex has not yet been designed. Here, screening a collection of selected peptides of several HPAIV strains against a specific pathogen-free pMHC-I (pBF2*1501), we identified a highly-conserved HPAIV H5N1 CTL epitope, named HPAIV–PA123–130. We determined the structure of the BF2*1501–PA123–130 complex at 2.1 Å resolution to elucidate the molecular mechanisms of a preferential presentation of the highly-conserved PA123–130 epitope in the chicken B15 lineage. Conformational characteristics of the PA123–130 epitope with a protruding Tyr-7 residue indicated that this epitope has great potential to be recognized by specific TCRs. Moreover, significantly increased numbers of CD8+ T cells specific for the HPAIV–PA123–130 epitope in peptide-immunized chickens indicated that a repertoire of CD8+ T cells can specifically respond to this epitope. We anticipate that the identification and structural characterization of the PA123–130 epitope reported here could enable further studies of CTL immunity against HPAIV H5N1. Such studies may aid in the development of vaccine development strategies using well-conserved internal viral antigens in chickens.

Although a robust inflammatory response is needed to combat infection, this response must ultimately be terminated to prevent chronic inflammation. One mechanism that terminates inflammatory signaling is the production of alternative mRNA splice forms in the Toll-like receptor (TLR) signaling pathway. Whereas most genes in the TLR pathway encode positive mediators of inflammatory signaling, several, including that encoding the MyD88 signaling adaptor, also produce alternative spliced mRNA isoforms that encode dominant-negative inhibitors of the response. Production of these negatively acting alternatively spliced isoforms is induced by stimulation with the TLR4 agonist lipopolysaccharide (LPS); thus, this alternative pre-mRNA splicing represents a negative feedback loop that terminates TLR signaling and prevents chronic inflammation. In the current study, we investigated the mechanisms regulating the LPS-induced alternative pre-mRNA splicing of the MyD88 transcript in murine macrophages. We found that 1) the induction of the alternatively spliced MyD88 form is due to alternative pre-mRNA splicing and not caused by another RNA regulatory mechanism, 2) MyD88 splicing is regulated by both the MyD88- and TRIF-dependent arms of the TLR signaling pathway, 3) MyD88 splicing is regulated by the NF-κB transcription factor, and 4) NF-κB likely regulates MyD88 alternative pre-mRNA splicing per se rather than regulating splicing indirectly by altering MyD88 transcription. We conclude that alternative splicing of MyD88 may provide a sensitive mechanism that ensures robust termination of inflammation for tissue repair and restoration of normal tissue homeostasis once an infection is controlled.

Bacterial products such as lipopolysaccharides (or endotoxin) cause systemic inflammation, resulting in a substantial global health burden. The onset, progression, and resolution of the inflammatory response to endotoxin are usually tightly controlled to avoid chronic inflammation. Members of the NF-κB family of transcription factors are key drivers of inflammation that activate sets of genes in response to inflammatory signals. Such responses are typically short-lived and can be suppressed by proteins that act post-translationally, such as the SOCS (suppressor of cytokine signaling) family. Less is known about direct transcriptional regulation of these responses, however. Here, using a combination of in vitro approaches and in vivo animal models, we show that endotoxin treatment induced expression of the well-characterized transcriptional repressor Krüppel-like factor 3 (KLF3), which, in turn, directly repressed the expression of the NF-κB family member RELA/p65. We also observed that KLF3-deficient mice were hypersensitive to endotoxin and exhibited elevated levels of circulating Ly6C+ monocytes and macrophage-derived inflammatory cytokines. These findings reveal that KLF3 is a fundamental suppressor that operates as a feedback inhibitor of RELA/p65 and may be important in facilitating the resolution of inflammation.

Prevention of aberrant cutaneous wound repair and appropriate regeneration of an intact and functional integument require the coordinated timing of fibroblast and keratinocyte migration. Here, we identified a mechanism whereby opposing cell-specific motogenic functions of a multifunctional intracellular and extracellular protein, the receptor for hyaluronan-mediated motility (RHAMM), coordinates fibroblast and keratinocyte migration speed and ensures appropriate timing of excisional wound closure. We found that, unlike in WT mice, in Rhamm-null mice, keratinocyte migration initiates prematurely in the excisional wounds, resulting in wounds that have re-surfaced before the formation of normal granulation tissue, leading to a defective epidermal architecture. We also noted aberrant keratinocyte and fibroblast migration in the Rhamm-null mice, indicating that RHAMM suppresses keratinocyte motility but increases fibroblast motility. This cell context–dependent effect resulted from cell-specific regulation of extracellular signal-regulated kinase 1/2 (ERK1/2) activation and expression of a RHAMM target gene encoding matrix metalloprotease 9 (MMP-9). In fibroblasts, RHAMM promoted ERK1/2 activation and MMP-9 expression, whereas in keratinocytes, RHAMM suppressed these activities. In keratinocytes, loss of RHAMM function or expression promoted epidermal growth factor receptor–regulated MMP-9 expression via ERK1/2, which resulted in cleavage of the ectodomain of the RHAMM partner protein CD44 and thereby increased keratinocyte motility. These results identify RHAMM as a key factor that integrates the timing of wound repair by controlling cell migration.

β-1,3-d-Glucan is a ubiquitous glucose polymer produced by plants, bacteria, and most fungi. It has been used as a diagnostic tool in patients with invasive mycoses via a highly-sensitive reagent consisting of the blood coagulation system of horseshoe crab. However, no method is currently available for measuring β-1,6-glucan, another primary β-glucan structure of fungal polysaccharides. Herein, we describe the development of an economical and highly-sensitive and specific assay for β-1,6-glucan using a modified recombinant endo-β-1,6-glucanase having diminished glucan hydrolase activity. The purified β-1,6-glucanase derivative bound to the β-1,6-glucan pustulan with a KD of 16.4 nm. We validated the specificity of this β-1,6-glucan probe by demonstrating its ability to detect cell wall β-1,6-glucan from both yeast and hyphal forms of the opportunistic fungal pathogen Candida albicans, without any detectable binding to glucan lacking the long β-1,6-glucan branch. We developed a sandwich ELISA-like assay with a low limit of quantification for pustulan (1.5 pg/ml), and we successfully employed this assay in the quantification of extracellular β-1,6-glucan released by >250 patient-derived strains of different Candida species (including Candida auris) in culture supernatant in vitro. We also used this assay to measure β-1,6-glucan in vivo in the serum and in several organs in a mouse model of systemic candidiasis. Our work describes a reliable method for β-1,6-glucan detection, which may prove useful for the diagnosis of invasive fungal infections.

Inter-α-inhibitor is a proteoglycan essential for mammalian reproduction and also plays a less well-characterized role in inflammation. It comprises two homologous “heavy chains” (HC1 and HC2) covalently attached to chondroitin sulfate on the bikunin core protein. Before ovulation, HCs are transferred onto the polysaccharide hyaluronan (HA) to form covalent HC·HA complexes, thereby stabilizing an extracellular matrix around the oocyte required for fertilization. Additionally, such complexes form during inflammatory processes and mediate leukocyte adhesion in the synovial fluids of arthritis patients and protect against sepsis. Here using X-ray crystallography, we show that human HC1 has a structure similar to integrin β-chains, with a von Willebrand factor A domain containing a functional metal ion-dependent adhesion site (MIDAS) and an associated hybrid domain. A comparison of the WT protein and a variant with an impaired MIDAS (but otherwise structurally identical) by small-angle X-ray scattering and analytical ultracentrifugation revealed that HC1 self-associates in a cation-dependent manner, providing a mechanism for HC·HA cross-linking and matrix stabilization. Surprisingly, unlike integrins, HC1 interacted with RGD-containing ligands, such as fibronectin, vitronectin, and the latency-associated peptides of transforming growth factor β, in a MIDAS/cation-independent manner. However, HC1 utilizes its MIDAS motif to bind to and inhibit the cleavage of complement C3, and small-angle X-ray scattering–based modeling indicates that this occurs through the inhibition of the alternative pathway C3 convertase. These findings provide detailed structural and functional insights into HC1 as a regulator of innate immunity and further elucidate the role of HC·HA complexes in inflammation and ovulation.

β-Glucocerebrosidase (GBA) hydrolyzes glucosylceramide (GlcCer) to generate ceramide. Previously, we demonstrated that lysosomal GBA1 and nonlysosomal GBA2 possess not only GlcCer hydrolase activity, but also transglucosylation activity to transfer the glucose residue from GlcCer to cholesterol to form β-cholesterylglucoside (β-GlcChol) in vitro. β-GlcChol is a member of sterylglycosides present in diverse species. How GBA1 and GBA2 mediate β-GlcChol metabolism in the brain is unknown. Here, we purified and characterized sterylglycosides from rodent and fish brains. Although glucose is thought to be the sole carbohydrate component of sterylglycosides in vertebrates, structural analysis of rat brain sterylglycosides revealed the presence of galactosylated cholesterol (β-GalChol), in addition to β-GlcChol. Analyses of brain tissues from GBA2-deficient mice and GBA1- and/or GBA2-deficient Japanese rice fish (Oryzias latipes) revealed that GBA1 and GBA2 are responsible for β-GlcChol degradation and formation, respectively, and that both GBA1 and GBA2 are responsible for β-GalChol formation. Liquid chromatography–tandem MS revealed that β-GlcChol and β-GalChol are present throughout development from embryo to adult in the mouse brain. We found that β-GalChol expression depends on galactosylceramide (GalCer), and developmental onset of β-GalChol biosynthesis appeared to be during myelination. We also found that β-GlcChol and β-GalChol are secreted from neurons and glial cells in association with exosomes. In vitro enzyme assays confirmed that GBA1 and GBA2 have transgalactosylation activity to transfer the galactose residue from GalCer to cholesterol to form β-GalChol. This is the first report of the existence of β-GalChol in vertebrates and how β-GlcChol and β-GalChol are formed in the brain.

Actinobacillus pleuropneumoniae (App) is the etiological agent of acute porcine pneumonia and responsible for severe economic losses worldwide. The capsule polymer of App serotype 1 (App1) consists of [4)-GlcNAc-β(1,6)-Gal-α-1-(PO4-] repeating units that are O-acetylated at O-6 of the GlcNAc. It is a major virulence factor and was used in previous studies in the successful generation of an experimental glycoconjugate vaccine. However, the application of glycoconjugate vaccines in the animal health sector is limited, presumably because of the high costs associated with harvesting the polymer from pathogen culture. Consequently, here we exploited the capsule polymerase Cps1B of App1 as an in vitro synthesis tool and an alternative for capsule polymer provision. Cps1B consists of two catalytic domains, as well as a domain rich in tetratricopeptide repeats (TPRs). We compared the elongation mechanism of Cps1B with that of a ΔTPR truncation (Cps1B-ΔTPR). Interestingly, the product profiles displayed by Cps1B suggested processive elongation of the nascent polymer, whereas Cps1B-ΔTPR appeared to work in a more distributive manner. The dispersity of the synthesized products could be reduced by generating single-action transferases and immobilizing them on individual columns, separating the two catalytic activities. Furthermore, we identified the O-acetyltransferase Cps1D of App1 and used it to modify the polymers produced by Cps1B. Two-dimensional NMR analyses of the products revealed O-acetylation levels identical to those of polymer harvested from App1 culture supernatants. In conclusion, we have established a protocol for the pathogen-free in vitro synthesis of tailored, nature-identical App1 capsule polymers.

Lens proteins become increasingly cross-linked through nondisulfide linkages during aging and cataract formation. One mechanism that has been implicated in this cross-linking is glycation through formation of advanced glycation end products (AGEs). Here, we found an age-associated increase in stiffness in human lenses that was directly correlated with levels of protein–cross-linking AGEs. α-Crystallin in the lens binds to other proteins and prevents their denaturation and aggregation through its chaperone-like activity. Using a FRET-based assay, we examined the stability of the αA-crystallin–γD-crystallin complex for up to 12 days and observed that this complex is stable in PBS and upon incubation with human lens–epithelial cell lysate or lens homogenate. Addition of 2 mm ATP to the lysate or homogenate did not decrease the stability of the complex. We also generated complexes of human αA-crystallin or αB-crystallin with alcohol dehydrogenase or citrate synthase by applying thermal stress. Upon glycation under physiological conditions, the chaperone–client complexes underwent greater extents of cross-linking than did uncomplexed protein mixtures. LC-MS/MS analyses revealed that the levels of cross-linking AGEs were significantly higher in the glycated chaperone–client complexes than in glycated but uncomplexed protein mixtures. Mouse lenses subjected to thermal stress followed by glycation lost resilience more extensively than lenses subjected to thermal stress or glycation alone, and this loss was accompanied by higher protein cross-linking and higher cross-linking AGE levels. These results uncover a protein cross-linking mechanism in the lens and suggest that AGE-mediated cross-linking of α-crystallin–client complexes could contribute to lens aging and presbyopia.

The dextransucrase DSR-OK from the Gram-positive bacterium Oenococcus kitaharae DSM17330 produces a dextran of the highest molar mass reported to date (∼109 g/mol). In this study, we selected a recombinant form, DSR-OKΔ1, to identify molecular determinants involved in the sugar polymerization mechanism and that confer its ability to produce a very-high-molar-mass polymer. In domain V of DSR-OK, we identified seven putative sugar-binding pockets characteristic of glycoside hydrolase 70 (GH70) glucansucrases that are known to be involved in glucan binding. We investigated their role in polymer synthesis through several approaches, including monitoring of dextran synthesis, affinity assays, sugar binding pocket deletions, site-directed mutagenesis, and construction of chimeric enzymes. Substitution of only two stacking aromatic residues in two consecutive sugar-binding pockets (variant DSR-OKΔ1-Y1162A-F1228A) induced quasi-complete loss of very-high-molar-mass dextran synthesis, resulting in production of only 10–13 kg/mol polymers. Moreover, the double mutation completely switched the semiprocessive mode of DSR-OKΔ1 toward a distributive one, highlighting the strong influence of these pockets on enzyme processivity. Finally, the position of each pocket relative to the active site also appeared to be important for polymer elongation. We propose that sugar-binding pockets spatially closer to the catalytic domain play a major role in the control of processivity. A deep structural characterization, if possible with large-molar-mass sugar ligands, would allow confirming this hypothesis.