Allostery exploits the conformational dynamics of enzymes by triggering a shift in population ensembles toward functionally distinct conformational or dynamic states. Allostery extensively regulates the activities of key enzymes within biosynthetic pathways to meet metabolic demand for their end products. Here, we have examined a critical enzyme, 3-deoxy-d-arabino-heptulosonate 7-phosphate synthase (DAH7PS), at the gateway to aromatic amino acid biosynthesis in Mycobacterium tuberculosis, which shows extremely complex dynamic allostery: three distinct aromatic amino acids jointly communicate occupancy to the active site via subtle changes in dynamics, enabling exquisite fine-tuning of delivery of these essential metabolites. Furthermore, this allosteric mechanism is co-opted by pathway branchpoint enzyme chorismate mutase upon complex formation. In this study, using statistical coupling analysis, site-directed mutagenesis, isothermal calorimetry, small-angle X-ray scattering, and X-ray crystallography analyses, we have pinpointed a critical node within the complex dynamic communication network responsible for this sophisticated allosteric machinery. Through a facile Gly to Pro substitution, we have altered backbone dynamics, completely severing the allosteric signal yet remarkably, generating a nonallosteric enzyme that retains full catalytic activity. We also identified a second residue of prime importance to the inter-enzyme communication with chorismate mutase. Our results reveal that highly complex dynamic allostery is surprisingly vulnerable and provide further insights into the intimate link between catalysis and allostery.

Background

Positive serology for cytomegalovirus (CMV) has been associated with all-cause mortality risk but its role in COPD mortality is unknown. The objective of the present study was to assess the relationship between CMV serology and COPD mortality.

Deep-subsurface hot brines in northwest Poland, extracted through boreholes reaching 1.6 and 2.6 km below the ground surface, were microbiologically investigated using culture-independent and culture-dependent methods. The high-throughput sequencing of 16S rRNA gene amplicons showed a very low diversity of bacterial communities, which were dominated by phyla Proteobacteria and Firmicutes. Bacterial genera potentially involved in sulfur oxidation and nitrate reduction (Halothiobacillus and Methylobacterium) prevailed in both waters over the sulfate reducers ("Candidatus Desulforudis" and Desulfotomaculum). Only one archaeal taxon, affiliated with the order Thermoplasmatales, was detected in analyzed samples. Bacterial isolates obtained from these deep hot brines were closely related to Bacillus paralicheniformis based on the 16S rRNA sequence similarity. However, genomic and physiological analyses made for one of the isolates, Bacillus paralicheniformis strain TS6, revealed the existence of more diverse metabolic pathways than those of its moderate-temperature counterpart. These specific traits may be associated with the ecological adaptations to the extreme habitat, which suggest that some lineages of B. paralicheniformis are halothermophilic.

IMPORTANCE Deep-subsurface aquifers, buried thousands of meters down the Earth’s crust, belong to the most underexplored microbial habitats. Although a few studies revealed the existence of microbial life at the depths, the knowledge about the microbial life in the deep hydrosphere is still scarce due to the limited access to such environments. Studying the subsurface microbiome provides unique information on microbial diversity, community structure, and geomicrobiological processes occurring under extreme conditions of the deep subsurface. Our study shows that low-diversity microbial assemblages in subsurface hot brines were dominated by the bacteria involved in biogeochemical cycles of sulfur and nitrogen. Based on genomic and physiological analyses, we found that the Bacillus paralicheniformis isolate obtained from the brine under study differed from the mesophilic species in the presence of specific adaptations to harsh environmental conditions. We indicate that some lineages of B. paralicheniformis are halothermophilic, which was not previously reported.

Increasing numbers of variants of the carbapenem-hydrolyzing class D β-lactamase OXA-48 are identified in Enterobacterales worldwide. Among them, OXA-181 and OXA-232 are of particular interest, as they differ from each other by a single amino acid substitution at position 214 (R in OXA-181 and S in OXA-232) that results in reduced carbapenem-hydrolyzing activity for OXA-232. To investigate the role of amino acid position 214 (AA214), the X-ray structure of OXA-232 was determined and AA214 of OXA-48 and of OXA-232 was replaced by G, L, D, E, S, R, and K using site-directed mutagenesis. These mutants were phenotypically characterized, and three mutants of OXA-232 were purified to study their steady-state kinetic properties. The X-ray structure of OXA-232 along with molecular modeling studies showed that the interaction via a salt bridge between R214 and D159 in OXA-48 is not possible with the G214 or S214 mutation. In contrast, with K214, which is also positively charged, the interaction with D159 is maintained. With the E214 mutant, an alternative binding conformation of imipenem that is not compatible with a nucleophilic attack by S70 was evidenced. Thus, imipenem has a very poor apparent affinity for the E214 mutant because of its nonproductive binding mode. Similarly, we could explain the lack of temocillin hydrolysis by the OXA-232-S214E mutant, which is due to the unfavorable interaction between the negatively charged R1 substituent of temocillin with the E214 residue. Overall, we demonstrate that AA214 in OXA-48-like β-lactamases is critical for the carbapenemase activity.

Background:

Limited treatment options are available for oral mucositis, a common, debilitating complication of cancer therapy. We examined the association between daily delivery time of radiotherapy and the severity of oral mucositis in patients with head and neck cancer.

As a very ugly standoff develops between legacy cinemas and legacy studios, Disney appears to be playing its cards close to its chest.

Premier League clubs are fearful that a significant number of first-team stars may refuse to return to action if the league's Project Restart plan gets the green light.

Manny teaches us 20 girls Chinese. Anna Marie plays through the best games of the past decade. Chris plays more WoW, and…oh…what’s that? Clicker Heroes...

Bhaane’s Summer 2020 collection is inspired by the ’90s community...

The post Bhaane’s Summer 2020 Collection Is Inspired By ’90s Community Clubs appeared first on Man's World India.

Announcement comes as new report from Statistics Canada shows almost two million more Canadians have lost their jobs

Congratulations to first-time mother Echo the cheetah!

Azure's still going strong, and even Xbox avoided major losses.

Follow our live coronavirus updates HERE Coronavirus: the symptoms

Britons could be limited to two or three drinks when pubs reopen, a government adviser has suggested.

Wetherspoon's is planning for a reopening of its pubs and hotels "in or around June", the company has announced.

A man was sprayed in the face with an "unknown substance" before a thief stole his bag on a London bus.

Design and technology teachers have made more than 200,000 pieces of protective equipment for frontline NHS workers, new figures reveal.

Pub visits should be avoided even after coronavirus restrictions are lifted, England's deputy chief medical officer has indicated.

EXCLUSIVE

Up to 15,000 pubs face permanent closure if they cannot reopen before October, an industry boss has warned.

The emergency wage subsidy program is being extended beyond June, in an effort to encourage more employers to rehire staff and 'help kick-start' the gradual economic reopening, says Prime Minister Justin Trudeau in light of record-high job losses.

As the NHL looks for ways to salvage its regular season that was suspended by the COVID-19 pandemic, one option on the table is for a select group of so-called hub cities to host all the games. Three Canadian cities have expressed interest in the role.

Starting Monday, “park ambassadors” will be stationed at Ottawa’s busiest parks to provide information about what's permitted under pandemic rules.

Sitcom star was diagnosed with an inoperable brain tumour last year

'He made me crack up and break character every single time we did a scene together'

Weekly meat tray giveaways, craft beer deliveries and trivia held over Zoom. As pubs stand empty, those that run them look to the internet

Across Australia, pubs stand empty because of the Covid-19 lockdowns. Some venues have shut entirely, others have pivoted to takeaway businesses, and the majority have had to make changes to their staffing.

While the future of physical pubs remains very uncertain for the coming months, the entertainers, brewers and chefs that rely on pubs for their livelihood are finding ways to recreate pub experiences in patrons’ homes.

Tributes have poured in for Scrubs actor Sam Lloyd, who has died at the age of 56.

Disick's lawyers said he had checked into rehab to work on "past traumas" in relation to the death of his parents

MTV, Nickelodeon, Paramount Network and TV Land are among the channels launching on YouTube TV in the coming months.

Phil Collins has made a 'substantial donation' to help Jimmy Greaves, according to the Tottenham legend's agent.

Clubs in the EFL will be allowed to defer a quarter of players' wages this month after the league agreed a "compromise proposal" with the PFA.

Premier League clubs have been warned they may have to wait up to 18 months before they can host capacity crowds again.

Half of Premier League's clubs will push to see the season ended by the traditional June 30 deadline at Friday's shareholders' meeting, even if all games are not completed.

Premier League clubs remain committed to finishing the 2019/20 season following an online meeting today, with a potential deadline of June 30 not discussed.

Premier League clubs will hold another online meeting again today with a proposal expected to put on the table for the 2019-20 season to be finished by June 30.

Crunch talks between league two chairmen may have knock-on effect up to Premier League

LaLiga has agreed with the Spanish Football Federation (RFEF) and the National Sports Council that Spanish clubs can return to training, subject to health recommendations.

Welcome to the Evening Standard's LIVE coverage as the coronavirus crisis continues to heavily impact sport across the globe.

National League clubs have voted in favour of ending the 2019-20 season at its current point.

Only clubs with a "death wish" would want to continue the National League season, according to one chairman, after the campaign was finally abandoned on Wednesday.

Uefa will release almost £60million in benefit payments to clubs who released players for European Qualifiers early to help ease the financial impact of coronavirus.

Premier League clubs face the prospect of paying inflated wages to keep hold of out of contract players if they press ahead with plans to complete the season.

Italian football clubs have been told they can return return to training in May following a televised speech from prime minister Giuseppe Conte.

Teams could be allowed to make as many as five substitutions during matches when football returns, as part of a new proposal put forward by Fifa.

Premier League clubs have put all players based abroad on standby as a return to training draws near.

Premier League clubs expect the transfer window to be delayed until late August at the earliest as English football remains gripped by uncertainty.

Belgian top-flight clubs have postponed a vote to ratify the cancellation of the 2019-20 season, meaning a resumption remains possible.

Premier League chiefs are expected to clash with clubs at Friday's shareholders meeting over which venues could be used to finish the campaign.

Spanish clubs have been given the green light to return to individual training next week by prime minister Pedro Sanchez.

The Premier League has reportedly advised clubs that they should consider recalling players and staff who are currently abroad as Project Restart gathers pace.