1aaf
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NUCLEOCAPSID ZINC FINGERS DETECTED IN RETROVIRUSES: EXAFS STUDIES ON INTACT VIRUSES AND THE SOLUTION-STATE STRUCTURE OF THE NUCLEOCAPSID PROTEIN FROM HIV-1
OverviewOverview
All retroviral nucleocapsid (NC) proteins contain one or two copies of an, invariant 3Cys-1His array (CCHC = C-X2-C-X4-H-X4-C; C = Cys, H = His, X =, variable amino acid) that are essential for RNA genome packaging and, infectivity and have been proposed to function as zinc-binding domains., Although the arrays are capable of binding zinc in vitro, the, physiological relevance of zinc coordination has not been firmly, established. We have obtained zinc-edge extended X-ray absorption fine, structure (EXAFS) spectra for intact retroviruses in order to determine if, virus-bound zinc, which is present in quantities nearly stoichiometric, with the CCHC arrays (Bess, J.W., Jr., Powell, P.J., Issaq, H.J., Schumack, L.J., Grimes, M.K., Henderson, L.E., & Arthur, L.O., 1992, J., Virol. 66, 840-847), exists in a unique coordination environment. The, viral EXAFS spectra obtained are remarkably similar to the spectrum of a, model CCHC zinc finger peptide with known 3Cys-1His zinc coordination, structure. This finding, combined with other biochemical results, indicates that the majority of the viral zinc is coordinated to the NC, CCHC arrays in mature retroviruses. Based on these findings, we have, extended our NMR studies of the HIV-1 NC protein and have determined its, three-dimensional solution-state structure. The CCHC arrays of HIV-1 NC, exist as independently folded, noninteracting domains on a flexible, polypeptide chain, with conservatively substituted aromatic residues, forming hydrophobic patches on the zinc finger surfaces. These residues, are essential for RNA genome recognition, and fluorescence measurements, indicate that at least one residue (Trp37) participates directly in, binding to nucleic acids in vitro. The NC is only the third HIV-1 protein, to be structurally characterized, and the combined EXAFS, structural, and, nucleic acid-binding results provide a basis for the rational design of, new NC-targeted antiviral agents and vaccines for the control of AIDS.
About this StructureAbout this Structure
1AAF is a Single protein structure of sequence from Human immunodeficiency virus type 1 (isolate mn) with ZN as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Nucleocapsid zinc fingers detected in retroviruses: EXAFS studies of intact viruses and the solution-state structure of the nucleocapsid protein from HIV-1., Summers MF, Henderson LE, Chance MR, Bess JW Jr, South TL, Blake PR, Sagi I, Perez-Alvarado G, Sowder RC 3rd, Hare DR, et al., Protein Sci. 1992 May;1(5):563-74. PMID:1304355
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