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  • 1
    Publication Date: 2013-04-26
    Description: Cell-surface-receptor binding by influenza viruses is a key determinant of their transmissibility, both from avian and animal species to humans as well as from human to human. Highly pathogenic avian H5N1 viruses that are a threat to public health have been observed to acquire affinity for human receptors, and transmissible-mutant-selection experiments have identified a virus that is transmissible in ferrets, the generally accepted experimental model for influenza in humans. Here, our quantitative biophysical measurements of the receptor-binding properties of haemagglutinin (HA) from the transmissible mutant indicate a small increase in affinity for human receptor and a marked decrease in affinity for avian receptor. From analysis of virus and HA binding data we have derived an algorithm that predicts virus avidity from the affinity of individual HA-receptor interactions. It reveals that the transmissible-mutant virus has a 200-fold preference for binding human over avian receptors. The crystal structure of the transmissible-mutant HA in complex with receptor analogues shows that it has acquired the ability to bind human receptor in the same folded-back conformation as seen for HA from the 1918, 1957 (ref. 4), 1968 (ref. 5) and 2009 (ref. 6) pandemic viruses. This binding mode is substantially different from that by which non-transmissible wild-type H5 virus HA binds human receptor. The structure of the complex also explains how the change in preference from avian to human receptors arises from the Gln226Leu substitution, which facilitates binding to human receptor but restricts binding to avian receptor. Both features probably contribute to the acquisition of transmissibility by this mutant virus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xiong, Xiaoli -- Coombs, Peter J -- Martin, Stephen R -- Liu, Junfeng -- Xiao, Haixia -- McCauley, John W -- Locher, Kathrin -- Walker, Philip A -- Collins, Patrick J -- Kawaoka, Yoshihiro -- Skehel, John J -- Gamblin, Steven J -- BB/E010806/Biotechnology and Biological Sciences Research Council/United Kingdom -- MC_U117512723/Medical Research Council/United Kingdom -- MC_U117584222/Medical Research Council/United Kingdom -- U117512723/Medical Research Council/United Kingdom -- U117570592/Medical Research Council/United Kingdom -- U117584222/Medical Research Council/United Kingdom -- England -- Nature. 2013 May 16;497(7449):392-6. doi: 10.1038/nature12144. Epub 2013 Apr 24.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23615615" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Birds/metabolism/virology ; Chick Embryo ; Crystallography, X-Ray ; Ferrets/*virology ; Hemagglutinin Glycoproteins, Influenza Virus/*chemistry/genetics/*metabolism ; *Host Specificity ; Humans ; Influenza A Virus, H5N1 Subtype/chemistry/*genetics/*metabolism/pathogenicity ; Models, Biological ; Models, Molecular ; Mutation ; Orthomyxoviridae Infections/*transmission/*virology ; Protein Conformation ; Receptors, Virus/*metabolism ; Species Specificity
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2013-12-18
    Description: Lentiviruses contain accessory genes that have evolved to counteract the effects of host cellular defence proteins that inhibit productive infection. One such restriction factor, SAMHD1, inhibits human immunodeficiency virus (HIV)-1 infection of myeloid-lineage cells as well as resting CD4(+) T cells by reducing the cellular deoxynucleoside 5'-triphosphate (dNTP) concentration to a level at which the viral reverse transcriptase cannot function. In other lentiviruses, including HIV-2 and related simian immunodeficiency viruses (SIVs), SAMHD1 restriction is overcome by the action of viral accessory protein x (Vpx) or the related viral protein r (Vpr) that target and recruit SAMHD1 for proteasomal degradation. The molecular mechanism by which these viral proteins are able to usurp the host cell's ubiquitination machinery to destroy the cell's protection against these viruses has not been defined. Here we present the crystal structure of a ternary complex of Vpx with the human E3 ligase substrate adaptor DCAF1 and the carboxy-terminal region of human SAMHD1. Vpx is made up of a three-helical bundle stabilized by a zinc finger motif, and wraps tightly around the disc-shaped DCAF1 molecule to present a new molecular surface. This adapted surface is then able to recruit SAMHD1 via its C terminus, making it a competent substrate for the E3 ligase to mark for proteasomal degradation. The structure reported here provides a molecular description of how a lentiviral accessory protein is able to subvert the cell's normal protein degradation pathway to inactivate the cellular viral defence system.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3886899/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3886899/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schwefel, David -- Groom, Harriet C T -- Boucherit, Virginie C -- Christodoulou, Evangelos -- Walker, Philip A -- Stoye, Jonathan P -- Bishop, Kate N -- Taylor, Ian A -- 084955/Wellcome Trust/United Kingdom -- MC_U117512710/Medical Research Council/United Kingdom -- MC_U117565647/Medical Research Council/United Kingdom -- MC_U117592729/Medical Research Council/United Kingdom -- U117512710/Medical Research Council/United Kingdom -- U11756564/Medical Research Council/United Kingdom -- U117592729/Medical Research Council/United Kingdom -- England -- Nature. 2014 Jan 9;505(7482):234-8. doi: 10.1038/nature12815. Epub 2013 Dec 15.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Molecular Structure, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK. ; Division of Virology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24336198" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Carrier Proteins/chemistry/*metabolism ; Cercocebus atys/virology ; Crystallography, X-Ray ; HIV/*chemistry/*physiology ; Host-Pathogen Interactions ; Humans ; Models, Molecular ; Molecular Sequence Data ; Monomeric GTP-Binding Proteins/chemistry/*metabolism ; Proteasome Endopeptidase Complex/metabolism ; *Proteolysis ; Simian Immunodeficiency Virus/chemistry/physiology ; Ubiquitination ; Viral Regulatory and Accessory Proteins/*chemistry/*metabolism ; vpr Gene Products, Human Immunodeficiency Virus/chemistry/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2011-03-15
    Description: The heterotrimeric AMP-activated protein kinase (AMPK) has a key role in regulating cellular energy metabolism; in response to a fall in intracellular ATP levels it activates energy-producing pathways and inhibits energy-consuming processes. AMPK has been implicated in a number of diseases related to energy metabolism including type 2 diabetes, obesity and, most recently, cancer. AMPK is converted from an inactive form to a catalytically competent form by phosphorylation of the activation loop within the kinase domain: AMP binding to the gamma-regulatory domain promotes phosphorylation by the upstream kinase, protects the enzyme against dephosphorylation, as well as causing allosteric activation. Here we show that ADP binding to just one of the two exchangeable AXP (AMP/ADP/ATP) binding sites on the regulatory domain protects the enzyme from dephosphorylation, although it does not lead to allosteric activation. Our studies show that active mammalian AMPK displays significantly tighter binding to ADP than to Mg-ATP, explaining how the enzyme is regulated under physiological conditions where the concentration of Mg-ATP is higher than that of ADP and much higher than that of AMP. We have determined the crystal structure of an active AMPK complex. The structure shows how the activation loop of the kinase domain is stabilized by the regulatory domain and how the kinase linker region interacts with the regulatory nucleotide-binding site that mediates protection against dephosphorylation. From our biochemical and structural data we develop a model for how the energy status of a cell regulates AMPK activity.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078618/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3078618/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xiao, Bing -- Sanders, Matthew J -- Underwood, Elizabeth -- Heath, Richard -- Mayer, Faith V -- Carmena, David -- Jing, Chun -- Walker, Philip A -- Eccleston, John F -- Haire, Lesley F -- Saiu, Peter -- Howell, Steven A -- Aasland, Rein -- Martin, Stephen R -- Carling, David -- Gamblin, Steven J -- MC_U117584222/Medical Research Council/United Kingdom -- MC_U120027537/Medical Research Council/United Kingdom -- U.1175.03.004.00008(60522)/Medical Research Council/United Kingdom -- Medical Research Council/United Kingdom -- England -- Nature. 2011 Apr 14;472(7342):230-3. doi: 10.1038/nature09932. Epub 2011 Mar 13.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21399626" target="_blank"〉PubMed〈/a〉
    Keywords: AMP-Activated Protein Kinases/*chemistry/genetics/*metabolism ; Adenosine Diphosphate/*metabolism/*pharmacology ; Adenosine Monophosphate/metabolism/pharmacology ; Adenosine Triphosphate/metabolism/pharmacology ; Allosteric Regulation/drug effects/genetics ; Animals ; Binding Sites ; Crystallography, X-Ray ; Enzyme Activation/drug effects/genetics ; Kinetics ; Magnesium/metabolism ; Mammals ; Models, Molecular ; Phosphorylation/drug effects/genetics ; Protein Binding ; Protein Structure, Tertiary/drug effects/genetics ; Thermodynamics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2013-06-22
    Description: Of the 132 people known to have been infected with H7N9 influenza viruses in China, 37 died, and many were severely ill. Infection seems to have involved contact with infected poultry. We have examined the receptor-binding properties of this H7N9 virus and compared them with those of an avian H7N3 virus. We find that the human H7 virus has significantly higher affinity for alpha-2,6-linked sialic acid analogues ('human receptor') than avian H7 while retaining the strong binding to alpha-2,3-linked sialic acid analogues ('avian receptor') characteristic of avian viruses. The human H7 virus does not, therefore, have the preference for human versus avian receptors characteristic of pandemic viruses. X-ray crystallography of the receptor-binding protein, haemagglutinin (HA), in complex with receptor analogues indicates that both human and avian receptors adopt different conformations when bound to human H7 HA than they do when bound to avian H7 HA. Human receptor bound to human H7 HA exits the binding site in a different direction to that seen in complexes formed by HAs from pandemic viruses and from an aerosol-transmissible H5 mutant. The human-receptor-binding properties of human H7 probably arise from the introduction of two bulky hydrophobic residues by the substitutions Gln226Leu and Gly186Val. The former is shared with the 1957 H2 and 1968 H3 pandemic viruses and with the aerosol-transmissible H5 mutant. We conclude that the human H7 virus has acquired some of the receptor-binding characteristics that are typical of pandemic viruses, but its retained preference for avian receptor may restrict its further evolution towards a virus that could transmit efficiently between humans, perhaps by binding to avian-receptor-rich mucins in the human respiratory tract rather than to cellular receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xiong, Xiaoli -- Martin, Stephen R -- Haire, Lesley F -- Wharton, Stephen A -- Daniels, Rodney S -- Bennett, Michael S -- McCauley, John W -- Collins, Patrick J -- Walker, Philip A -- Skehel, John J -- Gamblin, Steven J -- MC_U117584222/Medical Research Council/United Kingdom -- MC_U117585868/Medical Research Council/United Kingdom -- U117512723/PHS HHS/ -- U117570592/PHS HHS/ -- U117584222/PHS HHS/ -- U117585868/PHS HHS/ -- England -- Nature. 2013 Jul 25;499(7459):496-9. doi: 10.1038/nature12372.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW71AA, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23787694" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Birds/metabolism/virology ; Crystallography, X-Ray ; Hemagglutinin Glycoproteins, Influenza Virus/chemistry/metabolism ; Humans ; Influenza A Virus, H7N3 Subtype/metabolism ; Influenza A virus/chemistry/isolation & purification/*metabolism ; Influenza, Human/*virology ; Models, Molecular ; Mucins/chemistry/metabolism ; N-Acetylneuraminic Acid/analogs & derivatives/chemistry/*metabolism ; Protein Binding ; Protein Conformation ; Receptors, Virus/chemistry/*metabolism
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    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2014-05-30
    Description: H10N8 follows H7N9 and H5N1 as the latest in a line of avian influenza viruses that cause serious disease in humans and have become a threat to public health. Since December 2013, three human cases of H10N8 infection have been reported, two of whom are known to have died. To gather evidence relating to the epidemic potential of H10 we have determined the structure of the haemagglutinin of a previously isolated avian H10 virus and we present here results relating especially to its receptor-binding properties, as these are likely to be major determinants of virus transmissibility. Our results show, first, that the H10 virus possesses high avidity for human receptors and second, from the crystal structure of the complex formed by avian H10 haemagglutinin with human receptor, it is clear that the conformation of the bound receptor has characteristics of both the 1918 H1N1 pandemic virus and the human H7 viruses isolated from patients in 2013 (ref. 3). We conclude that avian H10N8 virus has sufficient avidity for human receptors to account for its infection of humans but that its preference for avian receptors should make avian-receptor-rich human airway mucins an effective block to widespread infection. In terms of surveillance, particular attention will be paid to the detection of mutations in the receptor-binding site of the H10 haemagglutinin that decrease its avidity for avian receptor, and could enable it to be more readily transmitted between humans.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vachieri, Sebastien G -- Xiong, Xiaoli -- Collins, Patrick J -- Walker, Philip A -- Martin, Stephen R -- Haire, Lesley F -- Zhang, Ying -- McCauley, John W -- Gamblin, Steven J -- Skehel, John J -- MC_U117512723/Medical Research Council/United Kingdom -- U117570592/Medical Research Council/United Kingdom -- U117584222/Medical Research Council/United Kingdom -- U117585868/Medical Research Council/United Kingdom -- England -- Nature. 2014 Jul 24;511(7510):475-7. doi: 10.1038/nature13443.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK [2]. ; MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24870229" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Birds/*virology ; Crystallography, X-Ray ; Hemagglutinin Glycoproteins, Influenza Virus/chemistry/metabolism ; Humans ; Influenza A Virus, H1N1 Subtype/chemistry ; Influenza A Virus, H7N9 Subtype/chemistry ; Models, Molecular ; Orthomyxoviridae/*chemistry/*metabolism ; Receptors, Virus/*chemistry/*metabolism ; Zoonoses/transmission/virology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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