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Structure of HIV-1 Capsid Protein by Cryo-EM
Structural highlights
FunctionQ79791_9HIV1 Capsid protein p24 forms the conical core of the virus that encapsulates the genomic RNA-nucleocapsid complex (By similarity).[SAAS:SAAS000071_004_008806] Nucleocapsid protein p7 encapsulates and protects viral dimeric unspliced (genomic) RNA. Binds these RNAs through its zinc fingers (By similarity).[SAAS:SAAS000071_004_011858] Publication Abstract from PubMedRetroviral capsid proteins are conserved structurally but assemble into different morphologies. The mature human immunodeficiency virus-1 (HIV-1) capsid is best described by a 'fullerene cone' model, in which hexamers of the capsid protein are linked to form a hexagonal surface lattice that is closed by incorporating 12 capsid-protein pentamers. HIV-1 capsid protein contains an amino-terminal domain (NTD) comprising seven alpha-helices and a beta-hairpin, a carboxy-terminal domain (CTD) comprising four alpha-helices, and a flexible linker with a 310-helix connecting the two structural domains. Structures of the capsid-protein assembly units have been determined by X-ray crystallography; however, structural information regarding the assembled capsid and the contacts between the assembly units is incomplete. Here we report the cryo-electron microscopy structure of a tubular HIV-1 capsid-protein assembly at 8 A resolution and the three-dimensional structure of a native HIV-1 core by cryo-electron tomography. The structure of the tubular assembly shows, at the three-fold interface, a three-helix bundle with critical hydrophobic interactions. Mutagenesis studies confirm that hydrophobic residues in the centre of the three-helix bundle are crucial for capsid assembly and stability, and for viral infectivity. The cryo-electron-microscopy structures enable modelling by large-scale molecular dynamics simulation, resulting in all-atom models for the hexamer-of-hexamer and pentamer-of-hexamer elements as well as for the entire capsid. Incorporation of pentamers results in closer trimer contacts and induces acute surface curvature. The complete atomic HIV-1 capsid model provides a platform for further studies of capsid function and for targeted pharmacological intervention. Mature HIV-1 capsid structure by cryo-electron microscopy and all-atom molecular dynamics.,Zhao G, Perilla JR, Yufenyuy EL, Meng X, Chen B, Ning J, Ahn J, Gronenborn AM, Schulten K, Aiken C, Zhang P Nature. 2013 May 30;497(7451):643-6. doi: 10.1038/nature12162. PMID:23719463[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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