Giuseppe
Emeritus
Structural insights into phosphoinositide 3-kinase activation by the influenza A virus NS1 protein. (Proc Natl Acad Sci USA, abstract, edited)
10. Proc Natl Acad Sci U S A. 2010 Feb 2;107(5):1954-9. Epub 2010 Jan 19.
Structural insights into phosphoinositide 3-kinase activation by the influenza A virus NS1 protein.
Hale BG, Kerry PS, Jackson D, Precious BL, Gray A, Killip MJ, Randall RE, Russell RJ. - Biomedical Science Research Complex, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9ST, United Kingdom.
Seasonal epidemics and periodic worldwide pandemics caused by influenza A viruses are of continuous concern. The viral nonstructural (NS1) protein is a multifunctional virulence factor that antagonizes several host innate immune defenses during infection. NS1 also directly stimulates class IA phosphoinositide 3-kinase (PI3K) signaling, an essential cell survival pathway commonly mutated in human cancers. Here, we present a 2.3-A resolution crystal structure of the NS1 effector domain in complex with the inter-SH2 (coiled-coil) domain of p85beta, a regulatory subunit of PI3K. Our data emphasize the remarkable isoform specificity of this interaction, and provide insights into the mechanism by which NS1 activates the PI3K (p85beta
110) holoenzyme. A model of the NS1I3K heterotrimeric complex reveals that NS1 uses the coiled-coil as a structural tether to sterically prevent normal inhibitory contacts between the N-terminal SH2 domain of p85beta and the p110 catalytic subunit. Furthermore, in this model, NS1 makes extensive contacts with the C2/kinase domains of p110, and a small acidic alpha-helix of NS1 sits adjacent to the highly basic activation loop of the enzyme. During infection, a recombinant influenza A virus expressing NS1 with charge-disruption mutations in this acidic alpha-helix is unable to stimulate the production of phosphatidylinositol 3,4,5-trisphosphate or the phosphorylation of Akt. Despite this, the charge-disruption mutations in NS1 do not affect its ability to interact with the p85beta inter-SH2 domain in vitro. Overall, these data suggest that both direct binding of NS1 to p85beta (resulting in repositioning of the N-terminal SH2 domain) and possible NS1110 contacts contribute to PI3K activation.
PMID: 20133840 [PubMed - in process]
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10. Proc Natl Acad Sci U S A. 2010 Feb 2;107(5):1954-9. Epub 2010 Jan 19.
Structural insights into phosphoinositide 3-kinase activation by the influenza A virus NS1 protein.
Hale BG, Kerry PS, Jackson D, Precious BL, Gray A, Killip MJ, Randall RE, Russell RJ. - Biomedical Science Research Complex, University of St. Andrews, North Haugh, St. Andrews, Fife, KY16 9ST, United Kingdom.
Seasonal epidemics and periodic worldwide pandemics caused by influenza A viruses are of continuous concern. The viral nonstructural (NS1) protein is a multifunctional virulence factor that antagonizes several host innate immune defenses during infection. NS1 also directly stimulates class IA phosphoinositide 3-kinase (PI3K) signaling, an essential cell survival pathway commonly mutated in human cancers. Here, we present a 2.3-A resolution crystal structure of the NS1 effector domain in complex with the inter-SH2 (coiled-coil) domain of p85beta, a regulatory subunit of PI3K. Our data emphasize the remarkable isoform specificity of this interaction, and provide insights into the mechanism by which NS1 activates the PI3K (p85beta
110) holoenzyme. A model of the NS1I3K heterotrimeric complex reveals that NS1 uses the coiled-coil as a structural tether to sterically prevent normal inhibitory contacts between the N-terminal SH2 domain of p85beta and the p110 catalytic subunit. Furthermore, in this model, NS1 makes extensive contacts with the C2/kinase domains of p110, and a small acidic alpha-helix of NS1 sits adjacent to the highly basic activation loop of the enzyme. During infection, a recombinant influenza A virus expressing NS1 with charge-disruption mutations in this acidic alpha-helix is unable to stimulate the production of phosphatidylinositol 3,4,5-trisphosphate or the phosphorylation of Akt. Despite this, the charge-disruption mutations in NS1 do not affect its ability to interact with the p85beta inter-SH2 domain in vitro. Overall, these data suggest that both direct binding of NS1 to p85beta (resulting in repositioning of the N-terminal SH2 domain) and possible NS1110 contacts contribute to PI3K activation.PMID: 20133840 [PubMed - in process]
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