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ASV INTEGRASE CORE DOMAIN WITH CD(II) COFACTORS
Structural highlights
FunctionPOL_RSVSB Capsid protein p27: Self-associates to form the irregular polyhedron core composed of hexamers and pentamers, that encapsulates the genomic RNA-nucleocapsid complex. Assembles as a tube in vitro. Binds to inositol hexakisphosphate (IP6), which allows the assembly of the polyhedral capsid.[UniProtKB:P03322] Plays a role in the oligomerization of the Gag polyprotein and in the stabilization of the immature particle. Essential layering element during tube assembly. Allows the cooperative binging of Gag to the host plasma membrane.[UniProtKB:P03322] Binds strongly to viral nucleic acids and promotes their packaging (By similarity). Plays a role in the maturation-stabilization of the viral dimeric RNA via highly structured zinc-binding motifs (By similarity).[UniProtKB:P03322][UniProtKB:P0C776] The aspartyl protease mediates proteolytic cleavages of Gag and Gag-Pol polyproteins during or shortly after the release of the virion from the plasma membrane. Cleavages take place as an ordered, step-wise cascade to yield mature proteins. This process is called maturation. Displays maximal activity during the budding process just prior to particle release from the cell.[PROSITE-ProRule:PRU00275] Catalyzes viral DNA integration into the host chromosome, by performing a series of DNA cutting and joining reactions (PubMed:9218451). This recombination event is an essential step in the viral replication cycle. Has a strong preference for using the 3'-OH at the viral DNA end as a nucleophile.[UniProtKB:P03354][1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedRetroviral integrases (INs) contain two known metal binding domains. The N-terminal domain includes a zinc finger motif and has been shown to bind Zn2+, whereas the central catalytic core domain includes a triad of acidic amino acids that bind Mn2+ or Mg2+, the metal cofactors required for enzymatic activity. The integration reaction occurs in two distinct steps; the first is a specific endonucleolytic cleavage step called "processing," and the second is a polynucleotide transfer or "joining" step. Our previous results showed that the metal preference for in vitro activity of avian sarcoma virus IN is Mn2+ > Mg2+ and that a single cation of either metal is coordinated by two of the three critical active site residues (Asp-64 and Asp-121) in crystals of the isolated catalytic domain. Here, we report that Ca2+, Zn2+, and Cd2+ can also bind in the active site of the catalytic domain. Furthermore, two zinc and cadmium cations are bound at the active site, with all three residues of the active site triad (Asp-64, Asp-121, and Glu-157) contributing to their coordination. These results are consistent with a two-metal mechanism for catalysis by retroviral integrases. We also show that Zn2+ can serve as a cofactor for the endonucleolytic reactions catalyzed by either the full-length protein, a derivative lacking the N-terminal domain, or the isolated catalytic domain of avian sarcoma virus IN. However, polynucleotidyl transferase activities are severely impaired or undetectable in the presence of Zn2+. Thus, although the processing and joining steps of integrase employ a similar mechanism and the same active site triad, they can be clearly distinguished by their metal preferences. Binding of different divalent cations to the active site of avian sarcoma virus integrase and their effects on enzymatic activity.,Bujacz G, Alexandratos J, Wlodawer A, Merkel G, Andrake M, Katz RA, Skalka AM J Biol Chem. 1997 Jul 18;272(29):18161-8. PMID:9218451[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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