4zq9 | pdb_00004zq9
X-ray structure of AAV-2 OBD bound to AAVS1 site 3:1
Structural highlights
FunctionREP68_AAV2S Plays an essential role in the initiation of viral DNA synthesis. Binds specifically to an inverted terminal repeat element (ITR) on the 3' and 5' ends of the viral DNA, where it cleaves a site specifically to generate a priming site for initiation of the synthesis of a complementary strand. Plays also a role as transcriptional regulator, DNA helicase and as key factor in site-specific integration of the viral genome. Inhibits the host cell cycle G1/S and G2/M transitions. These arrests may provide essential cellular factors for viral DNA replication.[1] Publication Abstract from PubMedAdeno-Associated virus (AAV) is the only eukaryotic virus with the property of establishing latency by integrating site-specifically into the human genome. The integration site known as AAVS1 is located in chromosome 19 and contains multiple GCTC repeats that are recognized by the AAV non-structural Rep proteins. These proteins are multifunctional, with an N-terminal origin-binding domain (OBD) and a helicase domain joined together by a short linker. As a first step to understand the process of site-specific integration, we set up to characterize the recognition and assembly of Rep68 onto the AAVS1 site. We first determined the X-ray structure of AAV-2 Rep68 OBD in complex with the AAVS1 DNA site. Specificity is achieved through the interaction of a glycine-rich loop that binds the major groove and an alpha-helix that interacts with a downstream minor groove on the same face of the DNA. Although the structure shows a complex with three OBD molecules bound to the AAVS1 site, we show using analytical centrifugation and electron microscopy that the full length Rep68 forms a heptameric complex. Moreover, we determine that a minimum of two direct repeats is required to form a stable complex and melt DNA. Finally, we show that although the individual domains bind DNA poorly, complex assembly requires oligomerization and cooperative between its OBD, helicase and the linker domains. Structural Insights into the Assembly of the Adeno-Associated Virus Type 2 Rep68 Protein on the Integration site AAVS1.,Musayev FN, Zarate-Perez F, Bishop C, Burgner JW 2nd, Escalante CR J Biol Chem. 2015 Sep 14. pii: jbc.M115.669960. PMID:26370092[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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