Takahito Kashiwabara and Tomoya Kemmochi
Math. Comp. 89 (2020), 1647-1679.
Abstract, references and article information

As 1 in 6 UK adults struggle with their mental health, is the rise in remote working making employees happier or creating a workforce racked by loneliness?

Burt Totaro
Trans. Amer. Math. Soc. 373 (2020), 3609-3626.
Abstract, references and article information

Cătălin I. Cârstea, Gen Nakamura and Lauri Oksanen
Trans. Amer. Math. Soc. 373 (2020), 3423-3443.
Abstract, references and article information

dlberek posted a photo:

dlberek posted a photo:

dlberek posted a photo:

dlberek posted a photo:

S. S. Lohvinenko and K. V. Ralchenko
Theor. Probability and Math. Statist. 99 (2020), 149-168.
Abstract, references and article information

D. V. Gusak and E. V. Karnaukh
Theor. Probability and Math. Statist. 99 (2020), 77-89.
Abstract, references and article information

I. Arab and P. E. Oliveira
Theor. Probability and Math. Statist. 99 (2020), 19-37.
Abstract, references and article information

Weimin Chen
Proc. Amer. Math. Soc. 148 (2020), 2707-2716.
Abstract, references and article information

Mahmoud Benkhalifa
Proc. Amer. Math. Soc. 148 (2020), 2695-2706.
Abstract, references and article information

James Walsh
Proc. Amer. Math. Soc. 148 (2020), 2645-2654.
Abstract, references and article information

Qingying Bu
Proc. Amer. Math. Soc. 148 (2020), 2459-2467.
Abstract, references and article information

To counter our adverse economic conditions, I have unveiled four sets of relief measures since last August. Totalling some $25 billion, the funds are focused on supporting businesses and lightening the burden weighing on the people of Hong Kong.

Meanwhile, we will continue to reach out to the community. Through wide-ranging dialogue communication and the pursuit of policies that address the deep-seated issues at the heart of our divide, I am hopeful that together we will find a path to peace and prosperity.

From an economic perspective, there is reason for optimism. I am heartened by the confidence private equity investors have shown in us. In the third quarter of 2019, some 560 private equity companies here managed US$153 billion.

We have nearly 50 more private equity (PE) firms based here when compared with the previous quarter. Among the world's top 10 PE fund managers, nine have a presence here in Hong Kong. That, ladies and gentlemen, underlines Hong Kong's formidable strengths in the Asian PE market. In that we trail only Mainland.

By channelling capital into corporations and startups in the innovation and technology field, PE and VC (venture capital) funds may well become as important as banks and IPO markets one day.

This Government is determined to help unlock the vast potential of the asset and wealth management business, because we believe you are critical to ensuring Hong Kong's status as one of the world's leading financial centres.

Fund-service centre 

That is why we have been stepping up efforts to sharpen Hong Kong's competitive edge on asset and wealth management through a multi-pronged approach including: (a) diversifying our fund structures and streamlining the licensing process to encourage fund formation; (b) adopting a more user-friendly approach to attract family offices; (c) providing a more facilitative tax environment for funds; and (d) expanding our fund distribution network through deepening our mutual access arrangements with other major financial markets.

On fund structure, the long-awaited, limited-partnership fund regime is close to reality, thanks in part to your favourable feedback. Indeed, we are now developing the necessary legislation. Because of the current filibustering at the Legislative Council, the tabling of the legislation got a little delayed, but it remains our top policy priority for the rest of this year to put this forward.

We are confident that the new regime will attract PE and VC funds, and we count on your support for that. With the new regime in place, we aim to bring in as many offshore funds as possible onshore to Hong Kong. We are well positioned to capture the opportunity arising from what happened on the international front over tax base erosion. This is mutually beneficial to Hong Kong as a fund hub and also the PE industry at large as you search for a new home for the funds you manage.

PE and VC funds, whether onshore or offshore, have enjoyed a profits tax exemption since last April. A tax-exempt fund can invest in local and overseas private companies. Hong Kong, by now, has a tax regime at fund level that is competitive and caters to the needs of the PE industry. I fully understand that resolving the tax issues at fund level is not enough in itself. It is of even greater importance to tackle head-on the tax arrangement for investment managers. This is a hard nut to crack, but one that I am determined to look into and come up with solutions that will strengthen Hong Kong's position as a leading fund hub with one of the most competitive tax arrangements for investment managers in the PE industry.

The significance of the limited partnership fund regime in completing Hong Kong's fund manufacturing infrastructure is underpinned by its precursor - the open-ended fund company regime. Since its operation in July 2018, a number of open-ended fund companies have sprouted. The SFC (Securities & Futures Commission) is also looking into how to make the regime more business-friendly to facilitate the take-up.

In short, the Government and our regulators are committed to developing Hong Kong into a full-fledged fund-service centre.

We are equally intent on expanding our fund-distribution network. We continue to expand our Mutual Recognition of Funds arrangements. Last year, Luxembourg and the Netherlands joined existing partners, the Mainland, Switzerland, France and the United Kingdom. More international partnerships will follow.

Family offices
Hong Kong is also an ideal location for the establishment of family offices, and we are boosting our promotional efforts in this regard.

The Hong Kong Monetary Authority and InvestHK will provide comprehensive services to attract family offices to Hong Kong. The SFC has also recently issued licensing guidance for PE firms and family offices. This will enhance clarity and would help address the industry's concerns.

Without a steady flow of talented professionals, of course, we will not be able to cash in on all the opportunities there for us. That is why the Government's Pilot Programme to Enhance Talent Training for the Asset & Wealth Management Sector has been supporting the industry since 2016.

I encourage you to offer exposure, opportunity and jobs for our youth. To give them a stake in the society through the programme.

Business bridge 

Zooming out a bit, the Government will continue to boost Hong Kong's singular advantage as the business and financial bridge between international markets and investors and their counterparts on the Mainland.

To that end, we continue to emphasise the established channels - our Stock Connects, Bond Connect and the Mutual Recognition of Funds arrangements. We will also strengthen our position as the global offshore Renminbi business hub.

Then there is the Guangdong-Hong Kong-Macao Greater Bay Area Development, and the extraordinary opportunity that it presents to Hong Kong.

With a GDP in excess of US$1.6 trillion and more than 70 million prosperous consumers, the Greater Bay Area presents vast potential for the asset and wealth management sector. For each and every one of you. The establishment of a Greater Bay Area wealth-management connect scheme, which was, as you know, recently announced, will go a long way towards realising that promise.

Our regulators are working out the details with their counterparts on the Mainland, and we will keep you posted and we are determined to push that forward as soon as possible. 

Financial Secretary Paul Chan gave these remarks at the Asia Private Equity Forum 2020 on January 15.

Hong Kong has, for the first time, held the Willem C Vis (East) International Commercial Arbitration Moot (VEM) through an online platform amidst the COVID-19 pandemic. While most of the competitions in other jurisdictions have been cancelled or postponed due to challenges posed by the pandemic, the 17th VEM was the only international mooting which went ahead as scheduled through an online dispute resolution (ODR) platform.

Though the outbreak of COVID-19 has changed our travel patterns and presented many challenges, advance in modern technology has helped us to address them. For the first time in the moot’s history, the mooting competition was conducted completely online with the support of Electronic Business Related Arbitration & Mediation (eBRAM). The platform supported by eBRAM accommodated 71 teams from 21 jurisdictions and about 250 arbitrators from 52 jurisdictions to take part in the moot which started on March 22. This exemplifies the importance of technological developments in the legal field.

The audience, with the latest lawtech support by eBRAM, watched the lively and intensive oral arguments online with participants of the finalists showing considerable flair and aptitude in trying their best to present their case to an international panel of distinguished arbitrators. The Chinese University of Hong Kong won the competition after rounds of rigorous and remarkable oral submissions before the panel.

The Government has always been supportive of the development of lawtech spearheaded by, amongst others, eBRAM, which is expected to be launched this year to resolve cross-boundary disputes online. If funding is approved by the Legislative Council Finance Committee on time, eBRAM would be able to provide an efficient, cost-effective and safe online platform for deal-making and resolution of cross-boundary commercial and investment disputes. We understand that eBRAM also plans to develop an online dispute resolution platform to support cross-boundary business-to-business transactions in the Asia-Pacific Economic Cooperation region.

We would continue to offer our support to the VEM as part of our legal education campaign. However, the VEM would not have been held smoothly without the technical support provided by eBRAM and also the tenacity and determination displayed by the Vis East Moot Foundation. The successful conclusion of the moot proved that Hong Kong has the capability of developing lawtech.

Changes are inevitable, including technological changes. The COVID-19 pandemic posed new challenges to Hong Kong, but it also provides an opportunity for us to explore lawtech in the provision of legal services. We all should join hands to make the best use of the technologies to develop ODR to assist all parties in resolving disputes in an efficient, effective and fair manner with a view to bringing rule of law and justice for all.

Secretary for Justice Teresa Cheng wrote this article and posted it on her blog on March 31.

Screw lemonade. If life gives you lemons, find someone who got vodka and make a martini. I have been teaching college classes online since March 21. Do I enjoy it? Not particularly. Is it a lot more work? God, yes. … Continue reading →

We as mathematicians seem practically hell-bent on removing the phrase “I’m just not a math person” from students’ vocabularies. Maybe that’s why they scream it so loudly and defiantly? Math has so many tactical advantages over sports and the arts. … Continue reading →

Janine Freeman
Jul 1, 2004; 17:137-140
Nutrition FYI

All the details on Uber's biggest announcements as well as updates on the controversial company's trials and tribulations

Hong Kong Exchanges & Clearing Limited (HKEx) today announced that Charles Li will not seek reappointment as Chief Executive at the end of his current contract in October 2021.

The Government said it respected Mr Li's decision and expressed deep appreciation for his exemplary contribution to the development of the financial market during his tenure as HKEx Chief Executive in the past decade.

Since taking the helm in January 2010, he has led HKEx and Hong Kong’s capital market in achieving important breakthroughs one after another.

The vibrancy and growth that Mr Li has brought to Hong Kong in the capital market helps reinforce the status of Hong Kong as a leading international financial centre.

Financial Secretary Paul Chan said: "Thanks to his vision and leadership, Mr Li has laid a solid and strong foundation for our stock market, rendering Hong Kong the largest IPO market in the world for seven times in the past 11 years.

"He has been instrumental in the successful launch of mutual market access programmes between Hong Kong and the Mainland, notably the Shanghai-Hong Kong Stock Connect in 2014, which was expanded to include Shenzhen-Hong Kong Stock Connect in 2016 and Bond Connect in 2017.

"He also played a pivotal role in the launch of new listing regime in Hong Kong, the enhanced internationalisation of HKEx and its international visibility. These are all important achievements of HKEx in the past few years under Mr Li’s able leadership."

Mr Chan added that the Government is confident the HKEx board will continue to ensure the success of HKEx in the years to come.

updated April 1, 2020

In response to current challenges that colleges and universities face as a result of the spread of COVID-19, the American Mathematical Society is offering libraries and institutions additional support, in line with recommendations in the ICOLC Statement on the Global COVID-19 Pandemic and Its Impact on Library Services and Resources.

The AMS is also participating in the Copyright Clearance Center Education Continuity License program, providing access to our content for distance learning and other educational uses at no cost to the user.

We are extending grace access for content hosted on our platforms (including MathSciNet) through the end of May for our existing customers. We will re-evaluate this timing as needed.

As courses transition to online, we can provide instructors with complimentary electronic “reserve” copies of our textbooks for cases in which students do not have access to their print copies.

E-books purchased through the perpetual access model on the AMS platform are always available DRM-free with unlimited simultaneous use. In addition, we are partnering with ProQuest to allow multi-user access through mid-June to all e-books purchased on their platforms. Read ProQuest’s statement.

We are providing remote access to all our content, including MathSciNet. In normal circumstances, this remote access can be set up while on campus or while connected via institution VPN (in order to validate IP-based access). We realize many students, faculty, and researchers did not have an opportunity to initiate this access before leaving campus, so we have given instructions to our library partners on how patrons can connect to our content. Please contact your librarian for assistance.

Libraries: if you have not received instructions to share with your patrons, please email us at cust-serv@ams.org or be in touch about any other of your library’s needs.

Review all AMS Resources & Updates.

(Fundação de Amparo à Pesquisa do Estado de São Paulo) Thanks to its magnetic properties, the material -- zinc-doped manganese chromite -- can be used in a range of products, from gas sensors to data storage devices.

(University of Southampton) Scientists have published highly detailed images of lab-grown neurons using Extreme Ultraviolet radiation that could aid the analysis of neurodegenerative diseases.

(University of South Florida (USF Health)) A new preclinical study by researchers at the University of South Florida Health (USF Health) Morsani College of Medicine and Johns Hopkins University School of Medicine offers promise of a specific treatment for NEC, a rare inflammatory bowel disease that is a leading cause of death in premature infants. The team found that inhibiting the inflammatory and blood-clotting molecule thrombin with targeted nanotherapy can protect against NEC-like injury in newborn mice.

Previous studies have shown that sphingosine kinase interacting protein (SKIP) inhibits sphingosine kinase (SK) function in fibroblasts. SK phosphorylates sphingosine producing the potent signaling molecule sphingosine-1-phosphate (S1P). SKIP gene (SPHKAP) expression is silenced by hypermethylation of its promoter in acute myeloid leukemia (AML). However, why SKIP activity is silenced in primary AML cells is unclear. Here, we investigated the consequences of SKIP down-regulation in AML primary cells and the effects of SKIP re-expression in leukemic cell lines. Using targeted ultra-HPLC-tandem MS (UPLC-MS/MS), we measured sphingolipids (including S1P and ceramides) in AML and control cells. Primary AML cells had significantly lower SK activity and intracellular S1P concentrations than control cells, and SKIP-transfected leukemia cell lines exhibited increased SK activity. These findings show that SKIP re-expression enhances SK activity in leukemia cells. Furthermore, other bioactive sphingolipids such as ceramide were also down-regulated in primary AML cells. Of note, SKIP re-expression in leukemia cells increased ceramide levels 2-fold, inactivated the key signaling protein extracellular signal-regulated kinase, and increased apoptosis following serum deprivation or chemotherapy. These results indicate that SKIP down-regulation in AML reduces SK activity and ceramide levels, an effect that ultimately inhibits apoptosis in leukemia cells. The findings of our study contrast with previous results indicating that SKIP inhibits SK function in fibroblasts and therefore challenge the notion that SKIP always inhibits SK activity.

Hypersecretion of glucagon from pancreatic α-cells strongly contributes to diabetic hyperglycemia. Moreover, failure of α-cells to increase glucagon secretion in response to falling blood glucose concentrations compromises the defense against hypoglycemia, a common complication in diabetes therapy. However, the mechanisms underlying glucose regulation of glucagon secretion are poorly understood and likely involve both α-cell–intrinsic and intraislet paracrine signaling. Among paracrine factors, glucose-stimulated release of the GABA metabolite γ-hydroxybutyric acid (GHB) from pancreatic β-cells might mediate glucose suppression of glucagon release via GHB receptors on α-cells. However, the direct effects of GHB on α-cell signaling and glucagon release have not been investigated. Here, we found that GHB (4–10 μm) lacked effects on the cytoplasmic concentrations of the secretion-regulating messengers Ca2+ and cAMP in mouse α-cells. Glucagon secretion from perifused mouse islets was also unaffected by GHB at both 1 and 7 mm glucose. The GHB receptor agonist 3-chloropropanoic acid and the antagonist NCS-382 had no effects on glucagon secretion and did not affect stimulation of secretion induced by a drop in glucose from 7 to 1 mm. Inhibition of endogenous GHB formation with the GABA transaminase inhibitor vigabatrin also failed to influence glucagon secretion at 1 mm glucose and did not prevent the suppressive effect of 7 mm glucose. In human islets, GHB tended to stimulate glucagon secretion at 1 mm glucose, an effect mimicked by 3-chloropropanoic acid. We conclude that GHB does not mediate the inhibitory effect of glucose on glucagon secretion.

Aldehyde oxidases (AOXs) are a small group of enzymes belonging to the larger family of molybdo-flavoenzymes, along with the well-characterized xanthine oxidoreductase. The two major types of reactions that are catalyzed by AOXs are the hydroxylation of heterocycles and the oxidation of aldehydes to their corresponding carboxylic acids. Different animal species have different complements of AOX genes. The two extremes are represented in humans and rodents; whereas the human genome contains a single active gene (AOX1), those of rodents, such as mice, are endowed with four genes (Aox1-4), clustering on the same chromosome, each encoding a functionally distinct AOX enzyme. It still remains enigmatic why some species have numerous AOX enzymes, whereas others harbor only one functional enzyme. At present, little is known about the physiological relevance of AOX enzymes in humans and their additional forms in other mammals. These enzymes are expressed in the liver and play an important role in the metabolisms of drugs and other xenobiotics. In this review, we discuss the expression, tissue-specific roles, and substrate specificities of the different mammalian AOX enzymes and highlight insights into their physiological roles.

The actin cytoskeleton is extremely dynamic and supports diverse cellular functions in many physiological and pathological processes, including tumorigenesis. However, the mechanisms that regulate the actin-related protein 2/3 (ARP2/3) complex and thereby promote actin polymerization and organization in cancer cells are not well-understood. We previously implicated the proline-rich 11 (PRR11) protein in lung cancer development. In this study, using immunofluorescence staining, actin polymerization assays, and siRNA-mediated gene silencing, we uncovered that cytoplasmic PRR11 is involved in F-actin polymerization and organization. We found that dysregulation of PRR11 expression results in F-actin rearrangement and nuclear instability in non-small cell lung cancer cells. Results from molecular mechanistic experiments indicated that PRR11 associates with and recruits the ARP2/3 complex, facilitates F-actin polymerization, and thereby disrupts the F-actin cytoskeleton, leading to abnormal nuclear lamina assembly and chromatin reorganization. Inhibition of the ARP2/3 complex activity abolished irregular F-actin polymerization, lamina assembly, and chromatin reorganization due to PRR11 overexpression. Notably, experiments with truncated PRR11 variants revealed that PRR11 regulates F-actin through different regions. We found that deletion of either the N or C terminus of PRR11 abrogates its effects on F-actin polymerization and nuclear instability and that deletion of amino acid residues 100–184 or 100–200 strongly induces an F-actin structure called the actin comet tail, not observed with WT PRR11. Our findings indicate that cytoplasmic PRR11 plays an essential role in regulating F-actin assembly and nuclear stability by recruiting the ARP2/3 complex in human non-small cell lung carcinoma cells.

The peroxisome is a subcellular organelle that functions in essential metabolic pathways, including biosynthesis of plasmalogens, fatty acid β-oxidation of very-long-chain fatty acids, and degradation of hydrogen peroxide. Peroxisome biogenesis disorders (PBDs) manifest as severe dysfunction in multiple organs, including the central nervous system (CNS), but the pathogenic mechanisms in PBDs are largely unknown. Because CNS integrity is coordinately established and maintained by neural cell interactions, we here investigated whether cell-cell communication is impaired and responsible for the neurological defects associated with PBDs. Results from a noncontact co-culture system consisting of primary hippocampal neurons with glial cells revealed that a peroxisome-deficient astrocytic cell line secretes increased levels of brain-derived neurotrophic factor (BDNF), resulting in axonal branching of the neurons. Of note, the BDNF expression in astrocytes was not affected by defects in plasmalogen biosynthesis and peroxisomal fatty acid β-oxidation in the astrocytes. Instead, we found that cytosolic reductive states caused by a mislocalized catalase in the peroxisome-deficient cells induce the elevation in BDNF secretion. Our results suggest that peroxisome deficiency dysregulates neuronal axogenesis by causing a cytosolic reductive state in astrocytes. We conclude that astrocytic peroxisomes regulate BDNF expression and thereby support neuronal integrity and function.

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.

Heterotrimeric G proteins are the core upstream elements that transduce and amplify the cellular signals from G protein–coupled receptors (GPCRs) to intracellular effectors. GPCRs are the largest family of membrane proteins encoded in the human genome and are the targets of about one-third of prescription medicines. However, to date, no single therapeutic agent exerts its effects via perturbing heterotrimeric G protein function, despite a plethora of evidence linking G protein malfunction to human disease. Several recent studies have brought to light that the Gq family–specific inhibitor FR900359 (FR) is unexpectedly efficacious in silencing the signaling of Gq oncoproteins, mutant Gq variants that mostly exist in the active state. These data not only raise the hope that researchers working in drug discovery may be able to potentially strike Gq oncoproteins from the list of undruggable targets, but also raise questions as to how FR achieves its therapeutic effect. Here, we place emphasis on these recent studies and explain why they expand our pharmacological armamentarium for targeting Gq protein oncogenes as well as broaden our mechanistic understanding of Gq protein oncogene function. We also highlight how this novel insight impacts the significance and utility of using G(q) proteins as targets in drug discovery efforts.

Heme-regulatory motifs (HRMs) are present in many proteins that are involved in diverse biological functions. The C-terminal tail region of human heme oxygenase-2 (HO2) contains two HRMs whose cysteine residues form a disulfide bond; when reduced, these cysteines are available to bind Fe3+-heme. Heme binding to the HRMs occurs independently of the HO2 catalytic active site in the core of the protein, where heme binds with high affinity and is degraded to biliverdin. Here, we describe the reversible, protein-mediated transfer of heme between the HRMs and the HO2 core. Using hydrogen-deuterium exchange (HDX)-MS to monitor the dynamics of HO2 with and without Fe3+-heme bound to the HRMs and to the core, we detected conformational changes in the catalytic core only in one state of the catalytic cycle—when Fe3+-heme is bound to the HRMs and the core is in the apo state. These conformational changes were consistent with transfer of heme between binding sites. Indeed, we observed that HRM-bound Fe3+-heme is transferred to the apo-core either upon independent expression of the core and of a construct spanning the HRM-containing tail or after a single turnover of heme at the core. Moreover, we observed transfer of heme from the core to the HRMs and equilibration of heme between the core and HRMs. We therefore propose an Fe3+-heme transfer model in which HRM-bound heme is readily transferred to the catalytic site for degradation to facilitate turnover but can also equilibrate between the sites to maintain heme homeostasis.

VOLUME 294 (2019) PAGES 2555–2568Due to publisher error, “150 l/mm” was changed to “150 liters/mm” in the second paragraph of the “Vibrational spectroscopy of samples” section under “Experimental Procedures.” The correct phrase should be “150 l/mm.”

Cytochrome c oxidase (CcO) reduces O2 to water, coupled with a proton-pumping process. The structure of the O2-reduction site of CcO contains two reducing equivalents, Fea32+ and CuB1+, and suggests that a peroxide-bound state (Fea33+–O−–O−–CuB2+) rather than an O2-bound state (Fea32+–O2) is the initial catalytic intermediate. Unexpectedly, however, resonance Raman spectroscopy results have shown that the initial intermediate is Fea32+–O2, whereas Fea33+–O−–O−–CuB2+ is undetectable. Based on X-ray structures of static noncatalytic CcO forms and mutation analyses for bovine CcO, a proton-pumping mechanism has been proposed. It involves a proton-conducting pathway (the H-pathway) comprising a tandem hydrogen-bond network and a water channel located between the N- and P-side surfaces. However, a system for unidirectional proton-transport has not been experimentally identified. Here, an essentially identical X-ray structure for the two catalytic intermediates (P and F) of bovine CcO was determined at 1.8 Å resolution. A 1.70 Å Fe–O distance of the ferryl center could best be described as Fea34+ = O2−, not as Fea34+–OH−. The distance suggests an ∼800-cm−1 Raman stretching band. We found an interstitial water molecule that could trigger a rapid proton-coupled electron transfer from tyrosine-OH to the slowly forming Fea33+–O−–O−–CuB2+ state, preventing its detection, consistent with the unexpected Raman results. The H-pathway structures of both intermediates indicated that during proton-pumping from the hydrogen-bond network to the P-side, a transmembrane helix closes the water channel connecting the N-side with the hydrogen-bond network, facilitating unidirectional proton-pumping during the P-to-F transition.

The C-type lectin receptors (CLRs) form a family of pattern recognition receptors that recognize numerous pathogens, such as bacteria and fungi, and trigger innate immune responses. The extracellular carbohydrate-recognition domain (CRD) of CLRs forms a globular structure that can coordinate a Ca2+ ion, allowing receptor interactions with sugar-containing ligands. Although well-conserved, the CRD fold can also display differences that directly affect the specificity of the receptors for their ligands. Here, we report crystal structures at 1.8–2.3 Å resolutions of the CRD of murine dendritic cell-immunoactivating receptor (DCAR, or Clec4b1), the CLR that binds phosphoglycolipids such as acylated phosphatidyl-myo-inositol mannosides (AcPIMs) of mycobacteria. Using mutagenesis analysis, we identified critical residues, Ala136 and Gln198, on the surface surrounding the ligand-binding site of DCAR, as well as an atypical Ca2+-binding motif (Glu-Pro-Ser/EPS168–170). By chemically synthesizing a water-soluble ligand analog, inositol-monophosphate dimannose (IPM2), we confirmed the direct interaction of DCAR with the polar moiety of AcPIMs by biolayer interferometry and co-crystallization approaches. We also observed a hydrophobic groove extending from the ligand-binding site that is in a suitable position to interact with the lipid portion of whole AcPIMs. These results suggest that the hydroxyl group-binding ability and hydrophobic groove of DCAR mediate its specific binding to pathogen-derived phosphoglycolipids such as mycobacterial AcPIMs.

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.

Fatty acid transport protein 2 (FATP2) is highly expressed in the liver, small intestine, and kidney, where it functions in both the transport of exogenous long-chain fatty acids and the activation of very-long-chain fatty acids. Here, using a murine model, we investigated the phenotypic impacts of deleting FATP2, followed by a transcriptomic analysis using unbiased RNA-Seq to identify concomitant changes in the liver transcriptome. WT and FATP2-null (Fatp2−/−) mice (5 weeks) were maintained on a standard chow diet for 6 weeks. The Fatp2−/− mice had reduced weight gain, lowered serum triglyceride, and increased serum cholesterol levels and attenuated dietary fatty acid absorption. Transcriptomic analysis of the liver revealed 258 differentially expressed genes in male Fatp2−/− mice and a total of 91 in female Fatp2−/− mice. These genes mapped to the following gene ontology categories: fatty acid degradation, peroxisome biogenesis, fatty acid synthesis, and retinol and arachidonic acid metabolism. Targeted RT-quantitative PCR verified the altered expression of selected genes. Of note, most of the genes with increased expression were known to be regulated by peroxisome proliferator–activated receptor α (PPARα), suggesting that FATP2 activity is linked to a PPARα-specific proximal ligand. Targeted metabolomic experiments in the Fatp2−/− liver revealed increases of total C16:0, C16:1, and C18:1 fatty acids; increases in lipoxin A4 and prostaglandin J2; and a decrease in 20-hydroxyeicosatetraenoic acid. We conclude that the expression of FATP2 in the liver broadly affects the metabolic landscape through PPARα, indicating that FATP2 provides an important role in liver lipid metabolism through its transport or activation activities.