3o4q
Crystal structure of the Rous Associated Virus Integrase catalytic domain A182T in citrate buffer pH 6.2
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] Publication Abstract from PubMedIntegrase (IN) is an important therapeutic target in the search for anti-Human Immunodeficiency Virus (HIV) inhibitors. This enzyme is composed of three domains and is hard to crystallize in its full form. First structural results on IN were obtained on the catalytic core domain (CCD) of the avian Rous and Sarcoma Virus strain Schmidt-Ruppin A (RSV-A) and on the CCD of HIV-1 IN. A ribonuclease-H like motif was revealed as well as a dimeric interface stabilized by two pairs of alpha-helices (alpha1/alpha5, alpha5/alpha1). These structural features have been validated in other structures of IN CCDs. We have determined the crystal structure of the Rous-associated virus type-1 (RAV-1) IN CCD to 1.8 A resolution. RAV-1 IN shows a standard activity for integration and its CCD differs in sequence from that of RSV-A by a single accessible residue in position 182 (substitution A182T). Surprisingly, the CCD of RAV-1 IN associates itself with an unexpected dimeric interface characterized by three pairs of alpha-helices (alpha3/alpha5, alpha1/alpha1, alpha5/alpha3). A182 is not involved in this novel interface, which results from a rigid body rearrangement of the protein at its alpha1, alpha3, alpha5 surface. A new basic groove that is suitable for single-stranded nucleic acid binding is observed at the surface of the dimer. We have subsequently determined the structure of the mutant A182T of RAV-1 IN CCD and obtained a RSV-A IN CCD-like structure with two pairs of buried alpha-helices at the interface. Our results suggest that the CCD of avian INs can dimerize in more than one state. Such flexibility can further explain the multifunctionality of retroviral INs, which beside integration of dsDNA are implicated in different steps of the retroviral cycle in presence of viral ssRNA. A crystal structure of the catalytic core domain of an avian sarcoma and leukemia virus integrase suggests an alternate dimeric assembly.,Ballandras A, Moreau K, Robert X, Confort MP, Merceron R, Haser R, Ronfort C, Gouet P PLoS One. 2011;6(8):e23032. Epub 2011 Aug 9. PMID:21857987[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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