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1.
MMWR Morb Mortal Wkly Rep ; 73(19): 435-440, 2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38753567

RESUMO

Clade I monkeypox virus (MPXV), which can cause severe illness in more people than clade II MPXVs, is endemic in the Democratic Republic of the Congo (DRC), but the country has experienced an increase in suspected cases during 2023-2024. In light of the 2022 global outbreak of clade II mpox, the increase in suspected clade I cases in DRC raises concerns that the virus could spread to other countries and underscores the importance of coordinated, urgent global action to support DRC's efforts to contain the virus. To date, no cases of clade I mpox have been detected outside of countries in Central Africa where the virus is endemic. CDC and other partners are working to support DRC's response. In addition, CDC is enhancing U.S. preparedness by raising awareness, strengthening surveillance, expanding diagnostic testing capacity for clade I MPXV, ensuring appropriate specimen handling and waste management, emphasizing the importance of appropriate medical treatment, and communicating guidance on the recommended contact tracing, containment, behavior modification, and vaccination strategies.


Assuntos
Surtos de Doenças , Mpox , República Democrática do Congo/epidemiologia , Humanos , Estados Unidos/epidemiologia , Mpox/epidemiologia , Surtos de Doenças/prevenção & controle , Centers for Disease Control and Prevention, U.S. , Monkeypox virus/isolamento & purificação
3.
Nature ; 625(7993): 195-203, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38123684

RESUMO

Progression through the cell cycle is controlled by regulated and abrupt changes in phosphorylation1. Mitotic entry is initiated by increased phosphorylation of mitotic proteins, a process driven by kinases2, whereas mitotic exit is achieved by counteracting dephosphorylation, a process driven by phosphatases, especially PP2A:B553. Although the role of kinases in mitotic entry is well established, recent data have shown that mitosis is only successfully initiated when the counterbalancing phosphatases are also inhibited4. Inhibition of PP2A:B55 is achieved by the intrinsically disordered proteins ARPP195,6 and FAM122A7. Despite their critical roles in mitosis, the mechanisms by which they achieve PP2A:B55 inhibition is unknown. Here, we report the single-particle cryo-electron microscopy structures of PP2A:B55 bound to phosphorylated ARPP19 and FAM122A. Consistent with our complementary NMR spectroscopy studies, both intrinsically disordered proteins bind PP2A:B55, but do so in highly distinct manners, leveraging multiple distinct binding sites on B55. Our extensive structural, biophysical and biochemical data explain how substrates and inhibitors are recruited to PP2A:B55 and provide a molecular roadmap for the development of therapeutic interventions for PP2A:B55-related diseases.


Assuntos
Microscopia Crioeletrônica , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas Intrinsicamente Desordenadas , Fosfoproteínas , Proteína Fosfatase 2 , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/química , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Intrinsicamente Desordenadas/química , Proteínas Intrinsicamente Desordenadas/metabolismo , Proteínas Intrinsicamente Desordenadas/ultraestrutura , Mitose , Ressonância Magnética Nuclear Biomolecular , Fosfoproteínas/química , Fosfoproteínas/metabolismo , Fosfoproteínas/ultraestrutura , Fosforilação , Proteína Fosfatase 2/química , Proteína Fosfatase 2/metabolismo , Proteína Fosfatase 2/ultraestrutura
4.
MMWR Morb Mortal Wkly Rep ; 72(43): 1162-1167, 2023 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-37883327

RESUMO

Early detection of emerging SARS-CoV-2 variants is critical to guiding rapid risk assessments, providing clear and timely communication messages, and coordinating public health action. CDC identifies and monitors novel SARS-CoV-2 variants through diverse surveillance approaches, including genomic, wastewater, traveler-based, and digital public health surveillance (e.g., global data repositories, news, and social media). The SARS-CoV-2 variant BA.2.86 was first sequenced in Israel and reported on August 13, 2023. The first U.S. COVID-19 case caused by this variant was reported on August 17, 2023, after a patient received testing for SARS-CoV-2 at a health care facility on August 3. In the following month, eight additional U.S. states detected BA.2.86 across various surveillance systems, including specimens from health care settings, wastewater surveillance, and traveler-based genomic surveillance. As of October 23, 2023, sequences have been reported from at least 32 countries. Continued variant tracking and further evidence are needed to evaluate the full public health impact of BA.2.86. Timely genomic sequence submissions to global public databases aided early detection of BA.2.86 despite the decline in the number of specimens being sequenced during the past year. This report describes how multicomponent surveillance and genomic sequencing were used in real time to track the emergence and transmission of the BA.2.86 variant. This surveillance approach provides valuable information regarding implementing and sustaining comprehensive surveillance not only for novel SARS-CoV-2 variants but also for future pathogen threats.


Assuntos
COVID-19 , Humanos , SARS-CoV-2/genética , Águas Residuárias , Vigilância Epidemiológica Baseada em Águas Residuárias
5.
bioRxiv ; 2023 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-37693408

RESUMO

Progression through the cell cycle is controlled by regulated and abrupt changes in phosphorylation.1 Mitotic entry is initiated by increased phosphorylation of mitotic proteins, a process driven by kinases,2 while mitotic exit is achieved by counteracting dephosphorylation, a process driven by phosphatases, especially PP2A:B55.3 While the role of kinases in mitotic entry is well-established, recent data have shown that mitosis is only successfully initiated when the counterbalancing phosphatases are also inhibited.4 For PP2A:B55, inhibition is achieved by the two intrinsically disordered proteins (IDPs), ARPP19 (phosphorylation-dependent)6,7 and FAM122A5 (inhibition is phosphorylation-independent). Despite their critical roles in mitosis, the mechanisms by which they achieve PP2A:B55 inhibition is unknown. Here, we report the cryo-electron microscopy structures of PP2A:B55 bound to phosphorylated ARPP19 and FAM122A. Consistent with our complementary NMR spectroscopy studies both IDPs bind PP2A:B55, but do so in highly distinct manners, unexpectedly leveraging multiple distinct binding sites on B55. Our extensive structural, biophysical and biochemical data explain how substrates and inhibitors are recruited to PP2A:B55 and provides a molecular roadmap for the development of therapeutic interventions for PP2A:B55 related diseases.

6.
Clin Exp Dermatol ; 48(12): 1361-1363, 2023 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-37665965

RESUMO

Rosacea is a common chronic inflammatory skin disease with a complex aetiology and major psychological impact, rendering patients susceptible to misinformation. We aimed to assess the content of rosacea-related misinformation online. A formal review of PubMed was performed, using the terms 'rosacea' AND 'misinformation' OR 'disinformation' OR 'conspiracy theory', along with informal Google searches using combinations of these terms, and further targeted searches on Twitter, Facebook, Instagram and TikTok. Key areas of misinformation identified in the search included mislabelling of rosacea as adult acne; falsehoods about rosacea only occurring in older adults or in individuals with lightly pigmented skin; incorrect causes of rosacea such as makeup or diet; and misleading 'cures', some of which may lead to exacerbation of the underlying rosacea. Dermatologists must be aware of the large amount of rosacea misinformation trending online and be prepared to counteract them with evidence to optimize patient care.


Assuntos
Acne Vulgar , Rosácea , Humanos , Idoso , Comunicação , Pele
7.
J Pharmacol Exp Ther ; 387(2): 214-225, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37643795

RESUMO

Hereditary angioedema (HAE) is a rare autosomal dominant disorder caused by a deficiency in functional C1 esterase inhibitor, a serpin family protein that blocks the activity of plasma kallikrein. Insufficient inhibition of plasma kallikrein results in the overproduction of bradykinin, a vasoactive inflammatory mediator that produces both pain and unpredictable swelling during HAE attacks, with potentially life-threatening consequences. We describe the generation of STAR-0215, a humanized IgG1 antibody with a long circulating half-life (t1/2) that potently inhibits plasma kallikrein activity, with a >1000-fold lower affinity for prekallikrein and no measurable inhibitory activity against other serine proteases. The high specificity and inhibitory effect of STAR-0215 is demonstrated through a unique allosteric mechanism involving N-terminal catalytic domain binding, destabilization of the activation domain, and reversion of the active site to the inactive zymogen state. The YTE (M252Y/S254T/T256E) modified fragment crystallizable (Fc) domain of STAR-0215 enhances pH-dependent neonatal Fc receptor binding, resulting in a prolonged t1/2 in vivo (∼34 days in cynomolgus monkeys) compared with antibodies without this modification. A single subcutaneous dose of STAR-0215 (≥100 mg) was predicted to be active in patients for 3 months or longer, based on simulations using a minimal physiologically based pharmacokinetic model. These data indicate that STAR-0215, a highly potent and specific antibody against plasma kallikrein with extended t1/2, is a potential agent for long-term preventative HAE therapy administered every 3 months or less frequently. SIGNIFICANCE STATEMENT: STAR-0215 is a YTE-modified immunoglobulin G1 monoclonal antibody with a novel binding mechanism that specifically and potently inhibits the enzymatic activity of plasma kallikrein and prevents the generation of bradykinin. It has been designed to be a long-lasting prophylactic treatment to prevent attacks of HAE and to decrease the burden of disease and the burden of treatment for people with HAE.

8.
Nat Commun ; 14(1): 4069, 2023 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-37429846

RESUMO

Vocalizations differ substantially between the sexes in many primates, and low-frequency male vocalizations may be favored by sexual selection because they intimidate rivals and/or attract mates. Sexual dimorphism in fundamental frequency may be more pronounced in species with more intense male mating competition and in those with large group size, where social knowledge is limited and efficient judgment of potential mates and competitors is crucial. These non-mutually exclusive explanations have not been tested simultaneously across primate species. In a sample of vocalizations (n = 1914 recordings) across 37 anthropoid species, we investigated whether fundamental frequency dimorphism evolved in association with increased intensity of mating competition (H1), large group size (H2), multilevel social organization (H3), a trade-off against the intensity of sperm competition (H4), and/or poor acoustic habitats (H5), controlling for phylogeny and body size dimorphism. We show that fundamental frequency dimorphism increased in evolutionary transitions towards larger group size and polygyny. Findings suggest that low-frequency male vocalizations in primates may have been driven by selection to win mating opportunities by avoiding costly fights and may be more important in larger groups, where limited social knowledge affords advantages to rapid assessment of status and threat potential via conspicuous secondary sexual characteristics.


Assuntos
Sêmen , Caracteres Sexuais , Masculino , Feminino , Animais , Reprodução , Primatas , Haplorrinos
9.
Nature ; 620(7972): 61-66, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37468630

RESUMO

White dwarfs, the extremely dense remnants left behind by most stars after their death, are characterized by a mass comparable to that of the Sun compressed into the size of an Earth-like planet. In the resulting strong gravity, heavy elements sink towards the centre and the upper layer of the atmosphere contains only the lightest element present, usually hydrogen or helium1,2. Several mechanisms compete with gravitational settling to change a white dwarf's surface composition as it cools3, and the fraction of white dwarfs with helium atmospheres is known to increase by a factor of about 2.5 below a temperature of about 30,000 kelvin4-8; therefore, some white dwarfs that appear to have hydrogen-dominated atmospheres above 30,000 kelvin are bound to transition to be helium-dominated as they cool below it. Here we report observations of ZTF J203349.8+322901.1, a transitioning white dwarf with two faces: one side of its atmosphere is dominated by hydrogen and the other one by helium. This peculiar nature is probably caused by the presence of a small magnetic field, which creates an inhomogeneity in temperature, pressure or mixing strength over the surface9-11. ZTF J203349.8+322901.1 might be the most extreme member of a class of magnetic, transitioning white dwarfs-together with GD 323 (ref. 12), a white dwarf that shows similar but much more subtle variations. This class of white dwarfs could help shed light on the physical mechanisms behind the spectral evolution of white dwarfs.

10.
MMWR Morb Mortal Wkly Rep ; 72(5): 113-118, 2023 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-36730046

RESUMO

After the emergence of SARS-CoV-2 in late 2019, transmission expanded globally, and on January 30, 2020, COVID-19 was declared a public health emergency of international concern.* Analysis of the early Wuhan, China outbreak (1), subsequently confirmed by multiple other studies (2,3), found that 80% of deaths occurred among persons aged ≥60 years. In anticipation of the time needed for the global vaccine supply to meet all needs, the World Health Organization (WHO) published the Strategic Advisory Group of Experts on Immunization (SAGE) Values Framework and a roadmap for prioritizing use of COVID-19 vaccines in late 2020 (4,5), followed by a strategy brief to outline urgent actions in October 2021.† WHO described the general principles, objectives, and priorities needed to support country planning of vaccine rollout to minimize severe disease and death. A July 2022 update to the strategy brief§ prioritized vaccination of populations at increased risk, including older adults,¶ with the goal of 100% coverage with a complete COVID-19 vaccination series** for at-risk populations. Using available public data on COVID-19 mortality (reported deaths and model estimates) for 2020 and 2021 and the most recent reported COVID-19 vaccination coverage data from WHO, investigators performed descriptive analyses to examine age-specific mortality and global vaccination rollout among older adults (as defined by each country), stratified by country World Bank income status. Data quality and COVID-19 death reporting frequency varied by data source; however, persons aged ≥60 years accounted for >80% of the overall COVID-19 mortality across all income groups, with upper- and lower-middle-income countries accounting for 80% of the overall estimated excess mortality. Effective COVID-19 vaccines were authorized for use in December 2020, with global supply scaled up sufficiently to meet country needs by late 2021 (6). COVID-19 vaccines are safe and highly effective in reducing severe COVID-19, hospitalizations, and mortality (7,8); nevertheless, country-reported median completed primary series coverage among adults aged ≥60 years only reached 76% by the end of 2022, substantially below the WHO goal, especially in middle- and low-income countries. Increased efforts are needed to increase primary series and booster dose coverage among all older adults as recommended by WHO and national health authorities.


Assuntos
COVID-19 , Vacinas , Humanos , Idoso , COVID-19/epidemiologia , COVID-19/prevenção & controle , Vacinas contra COVID-19 , SARS-CoV-2 , Vacinação , Organização Mundial da Saúde
11.
Nucleic Acids Res ; 51(3): 1001-1018, 2023 02 22.
Artigo em Inglês | MEDLINE | ID: mdl-36100255

RESUMO

Site-specific DNA recombinases play a variety of biological roles, often related to the dissemination of antibiotic resistance, and are also useful synthetic biology tools. The simplest site-specific recombination systems will recombine any two cognate sites regardless of context. Other systems have evolved elaborate mechanisms, often sensing DNA topology, to ensure that only one of multiple possible recombination products is produced. The closely related resolvases from the Tn3 and γδ transposons have historically served as paradigms for the regulation of recombinase activity by DNA topology. However, despite many proposals, models of the multi-subunit protein-DNA complex (termed the synaptosome) that enforces this regulation have been unsatisfying due to a lack of experimental constraints and incomplete concordance with experimental data. Here, we present new structural and biochemical data that lead to a new, detailed model of the Tn3 synaptosome, and discuss how it harnesses DNA topology to regulate the enzymatic activity of the recombinase.


Site-specific DNA recombinases alter the connectivity of DNA by recognizing specific DNA sequences, then cutting the DNA strands and pasting them together in a new configuration. Such enzymes play a variety of biological roles, often related to the dissemination of antibiotic resistance, and are also useful biotechnology tools. The simplest site-specific recombination systems will recombine any two cognate sites regardless of context. However, others have evolved elaborate mechanisms to ensure that only one of multiple possible recombination products is produced. Tn3 resolvase has long been known to be regulated by DNA topology­that is, it will cut and reconnect two target sequences only if they lie on the same DNA molecule, and if they are in the proper relative orientation. This study presents new structural and biochemical data that lead to a new, detailed model of the large protein­DNA complex formed by Tn3 resolvase and its cognate sites. This 3D model illustrates how DNA topology can be harnessed to regulate the activity of a recombinase and provides a basis for engineering Tn3 resolvase and related recombination systems as genome editing tools.


Assuntos
DNA , Complexos Multiproteicos , Transposon Resolvases , Elementos de DNA Transponíveis , Recombinases/genética , Transposases/genética , Transposon Resolvases/genética , Transposon Resolvases/metabolismo , Complexos Multiproteicos/química
12.
Emerg Infect Dis ; 28(13): S85-S92, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36502409

RESUMO

Viral genomic surveillance has been a critical source of information during the COVID-19 pandemic, but publicly available data can be sparse, concentrated in wealthy countries, and often made public weeks or months after collection. We used publicly available viral genomic surveillance data submitted to GISAID and GenBank to examine sequencing coverage and lag time to submission during 2020-2021. We compared publicly submitted sequences by country with reported infection rates and population and also examined data based on country-level World Bank income status and World Health Organization region. We found that as global capacity for viral genomic surveillance increased, international disparities in sequencing capacity and timeliness persisted along economic lines. Our analysis suggests that increasing viral genomic surveillance coverage worldwide and decreasing turnaround times could improve timely availability of sequencing data to inform public health action.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , SARS-CoV-2/genética , Pandemias , COVID-19/epidemiologia , Genoma Viral , Genômica
13.
Emerg Infect Dis ; 28(13): S8-S16, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36502410

RESUMO

Early warning and response surveillance (EWARS) systems were widely used during the early COVID-19 response. Evaluating the effectiveness of EWARS systems is critical to ensuring global health security. We describe the Centers for Disease Control and Prevention (CDC) global COVID-19 EWARS (CDC EWARS) system and the resources CDC used to gather, manage, and analyze publicly available data during the prepandemic period. We evaluated data quality and validity by measuring reporting completeness and compared these with data from Johns Hopkins University, the European Centre for Disease Prevention and Control, and indicator-based data from the World Health Organization. CDC EWARS was integral in guiding CDC's early COVID-19 response but was labor-intensive and became less informative as case-level data decreased and the pandemic evolved. However, CDC EWARS data were similar to those reported by other organizations, confirming the validity of each system and suggesting collaboration could improve EWARS systems during future pandemics.


Assuntos
COVID-19 , Estados Unidos/epidemiologia , Humanos , COVID-19/epidemiologia , COVID-19/prevenção & controle , Pandemias/prevenção & controle , Centers for Disease Control and Prevention, U.S. , Organização Mundial da Saúde , Saúde Global
14.
Health Soc Care Community ; 30(6): e6194-e6205, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36205443

RESUMO

There are long-standing concerns that people experiencing homelessness may not recover well if left unsupported after a hospital stay. This study reports on a study investigating the cost-effectiveness of three different 'in patient care coordination and discharge planning' configurations for adults experiencing homelessness who are discharged from hospitals in England. The first configuration provided a clinical and housing in-reach service during acute care and discharge coordination but with no 'step-down' care. The second configuration provided clinical and housing in-reach, discharge coordination and 'step-down' intermediate care. The third configuration consisted of housing support workers providing in-reach and discharge coordination as well as step-down care. These three configurations were each compared with 'standard care' (control, defined as one visit by the homelessness health nurse before discharge during which patients received an information leaflet on local services). Multiple sources of data and multi-outcome measures were adopted to assess the cost utility of hospital discharge service delivery for the NHS and broader public perspective. Details of 354 participants were collated on service delivery costs (salary, on-costs, capital, overheads and 'hotel' costs, advertising and other indirect costs), the economic consequences for different public services (e.g. NHS, social care, criminal justice, housing, etc.) and health utilities (quality-adjusted-life-years, QALYs). Findings were complex across the configurations, but, on the whole, there was promising evidence suggesting that, with delivery costs similar to those reported for bed-based intermediate care, step-down care secured better health outcomes and improved cost-effectiveness (compared with usual care) within NICE cost-effectiveness recommendations.


Assuntos
Pessoas Mal Alojadas , Alta do Paciente , Adulto , Humanos , Problemas Sociais , Habitação , Hospitais
15.
J Public Health Manag Pract ; 28(5): 491-495, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35834786

RESUMO

Trends in the percentages of the US population covered by state-issued nonpharmaceutical interventions (NPIs), including restaurant and bar restrictions, stay-at-home orders, gathering limits, and mask mandates, were examined by using county-specific data sets on state-issued orders for NPIs from March 1, 2020, to August 15, 2021. Most of the population was covered by multiple NPIs early in the pandemic. Most state-issued orders were lifted or relaxed as COVID-19 cases decreased during summer 2020. Few states reimplemented strict NPIs during later surges in US COVID-19 cases over the winter of 2020-2021. The exceptions were mask mandates, which covered about 80% of the population between August 2020 and February 2021, and the most restrictive gathering limits, which covered a maximum of 66% of the population in early 2020 and 68% of the population in winter 2020-2021. Most NPIs were lifted by the end of the analysis period.


Assuntos
COVID-19 , COVID-19/epidemiologia , COVID-19/prevenção & controle , Humanos , Pandemias/prevenção & controle
16.
Nature ; 609(7926): 408-415, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35831509

RESUMO

Receptor tyrosine kinase (RTK)-RAS signalling through the downstream mitogen-activated protein kinase (MAPK) cascade regulates cell proliferation and survival. The SHOC2-MRAS-PP1C holophosphatase complex functions as a key regulator of RTK-RAS signalling by removing an inhibitory phosphorylation event on the RAF family of proteins to potentiate MAPK signalling1. SHOC2 forms a ternary complex with MRAS and PP1C, and human germline gain-of-function mutations in this complex result in congenital RASopathy syndromes2-5. However, the structure and assembly of this complex are poorly understood. Here we use cryo-electron microscopy to resolve the structure of the SHOC2-MRAS-PP1C complex. We define the biophysical principles of holoenzyme interactions, elucidate the assembly order of the complex, and systematically interrogate the functional consequence of nearly all of the possible missense variants of SHOC2 through deep mutational scanning. We show that SHOC2 binds PP1C and MRAS through the concave surface of the leucine-rich repeat region and further engages PP1C through the N-terminal disordered region that contains a cryptic RVXF motif. Complex formation is initially mediated by interactions between SHOC2 and PP1C and is stabilized by the binding of GTP-loaded MRAS. These observations explain how mutant versions of SHOC2 in RASopathies and cancer stabilize the interactions of complex members to enhance holophosphatase activity. Together, this integrative structure-function model comprehensively defines key binding interactions within the SHOC2-MRAS-PP1C holophosphatase complex and will inform therapeutic development .


Assuntos
Microscopia Crioeletrônica , Peptídeos e Proteínas de Sinalização Intracelular , Complexos Multiproteicos , Proteína Fosfatase 1 , Proteínas ras , Motivos de Aminoácidos , Sítios de Ligação , Guanosina Trifosfato/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/química , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Sistema de Sinalização das MAP Quinases , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Complexos Multiproteicos/ultraestrutura , Mutação de Sentido Incorreto , Fosforilação , Ligação Proteica , Proteína Fosfatase 1/química , Proteína Fosfatase 1/metabolismo , Proteína Fosfatase 1/ultraestrutura , Estabilidade Proteica , Quinases raf , Proteínas ras/química , Proteínas ras/metabolismo , Proteínas ras/ultraestrutura
17.
J Biol Chem ; 298(8): 102182, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35752362

RESUMO

The ion-pumping NQR complex is an essential respiratory enzyme in the physiology of many pathogenic bacteria. This enzyme transfers electrons from NADH to ubiquinone through several cofactors, including riboflavin (vitamin B2). NQR is the only enzyme reported that is able to use riboflavin as a cofactor. Moreover, the riboflavin molecule is found as a stable neutral semiquinone radical. The otherwise highly reactive unpaired electron is stabilized via an unknown mechanism. Crystallographic data suggested that riboflavin might be found in a superficially located site in the interface of NQR subunits B and E. However, this location is highly problematic, as the site does not have the expected physiochemical properties. In this work, we have located the riboflavin-binding site in an amphipathic pocket in subunit B, previously proposed to be the entry site of sodium. Here, we show that this site contains absolutely conserved residues, including N200, N203, and D346. Mutations of these residues decrease enzymatic activity and specifically block the ability of NQR to bind riboflavin. Docking analysis and molecular dynamics simulations indicate that these residues participate directly in riboflavin binding, establishing hydrogen bonds that stabilize the cofactor in the site. We conclude that riboflavin is likely bound in the proposed pocket, which is consistent with enzymatic characterizations, thermodynamic studies, and distance between cofactors.


Assuntos
Quinona Redutases , Vibrio cholerae , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Oxirredução , Quinona Redutases/química , Riboflavina/genética , Sódio/metabolismo , Vibrio cholerae/metabolismo
18.
Sci Transl Med ; 14(643): eabf3685, 2022 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-35507671

RESUMO

Epstein-Barr virus (EBV) is the major cause of infectious mononucleosis and is associated with several human cancers and, more recently, multiple sclerosis. Despite its prevalence and health impact, there are currently no vaccines or treatments. Four viral glycoproteins (gp), gp350 and gH/gL/gp42, mediate entry into the major sites of viral replication, B cells, and epithelial cells. Here, we designed a nanoparticle vaccine displaying these proteins and showed that it elicits potent neutralizing antibodies that protect against infection in vivo. We designed single-chain gH/gL and gH/gL/gp42 proteins that were each fused to bacterial ferritin to form a self-assembling nanoparticle. Structural analysis revealed that single-chain gH/gL and gH/gL/gp42 adopted a similar conformation to the wild-type proteins, and the protein spikes were observed by electron microscopy. Single-chain gH/gL or gH/gL/gp42 nanoparticle vaccines were constructed to ensure product homogeneity needed for clinical development. These vaccines elicited neutralizing antibodies in mice, ferrets, and nonhuman primates that inhibited EBV entry into both B cells and epithelial cells. When mixed with a previously reported gp350 nanoparticle vaccine, gp350D123, no immune competition was observed. To confirm its efficacy in vivo, humanized mice were challenged with EBV after passive transfer of IgG from mice vaccinated with control, gH/gL/gp42+gp350D123, or gH/gL+gp350D123 nanoparticles. Although all control animals were infected, only one mouse in each vaccine group that received immune IgG had detectable transient viremia. Furthermore, no EBV lymphomas were detected in immune animals. This bivalent EBV nanoparticle vaccine represents a promising candidate to prevent EBV infection and EBV-related malignancies in humans.


Assuntos
Infecções por Vírus Epstein-Barr , Vacinas , Animais , Anticorpos Neutralizantes , Infecções por Vírus Epstein-Barr/prevenção & controle , Furões , Herpesvirus Humano 4 , Imunoglobulina G , Camundongos , Vacinas Combinadas
20.
Nature ; 595(7865): 39-42, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34194021

RESUMO

White dwarfs represent the last stage of evolution of stars with mass less than about eight times that of the Sun and, like other stars, are often found in binaries1,2. If the orbital period of the binary is short enough, energy losses from gravitational-wave radiation can shrink the orbit until the two white dwarfs come into contact and merge3. Depending on the component masses, the merger can lead to a supernova of type Ia or result in a massive white dwarf4. In the latter case, the white dwarf remnant is expected to be highly magnetized5,6 because of the strong magnetic dynamo that should arise during the merger, and be rapidly spinning from the conservation of the orbital angular momentum7. Here we report observations of a white dwarf, ZTF J190132.9+145808.7, that exhibits these properties, but to an extreme: a rotation period of 6.94 minutes, a magnetic field ranging between 600 megagauss and 900 megagauss over its surface, and a stellar radius of [Formula: see text] kilometres, only slightly larger than the radius of the Moon. Such a small radius implies that the star's mass is close to the maximum white dwarf mass, or Chandrasekhar mass. ZTF J190132.9+145808.7 is likely to be cooling through the Urca processes (neutrino emission from electron capture on sodium) because of the high densities reached in its core.

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