Interactions of HIV-1 Gag with Assembly Cofactors

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• 作者：Nick Shkriabai ; Siddhartha A. K. Datta ; Zhuojun Zhao ; Sonja Hess ; Alan Rein ; and Mamuka Kvaratskhelia
• 刊名：Biochemistry
• 出版年：2006
• 出版时间：April 4, 2006
• 年：2006
• 卷：45
• 期：13
• 页码：4077 - 4083
• 全文大小：177K
• 年卷期：v.45,no.13(April 4, 2006)
• ISSN：1520-4995

文摘

HIV-1 Gag is the only protein required for retroviral particle assembly. There is evidencesuggesting that phosphatidylinositol phosphate and nucleic acid are essential for viruslike particle assembly.To elucidate structural foundations of interactions of HIV-1 Gag with the assembly cofactors PI(4,5)P₂and RNA, we employed mass spectrometric protein footprinting. In particular, the NHS-biotin modificationapproach was used to identify the lysine residues that are exposed to the solvent in free Gag and areprotected from biotinylation by direct protein-ligand or protein-protein contacts in Gag complexes withPI(4,5)P₂ and/or RNA. Of 21 surface lysines readily modified in free Gag, only K30 and K32, located inthe matrix domain, were strongly protected in the Gag-PI(4,5)P₂ complex. Nucleic acid also protectedthese lysines, but only at significantly higher concentrations. In contrast, nucleic acids and not PI(4,5)P₂exhibited strong protection of two nucleocapsid domain residues: K391 and K424. In addition, K314,located in the capsid domain, was specifically protected only in the presence of both PI(4,5)P₂ and nucleicacid. We suggest that concerted binding of PI(4,5)P₂ and nucleic acid to the matrix and nucleocapsiddomains, respectively, promotes protein-protein interactions involving capsid domains. These protein-protein interactions must be involved in virus particle assembly.