title: 3'-processing and strand transfer catalysed by retroviral integrase in crystallo.
abstract: Retroviral integrase (IN) is responsible for two consecutive reactions, which lead to insertion of a viral DNA copy into a host cell chromosome. Initially, the enzyme removes di- or trinucleotides from viral DNA ends to expose 3'-hydroxyls attached to the invariant CA dinucleotides (3'-processing reaction). Second, it inserts the processed 3'-viral DNA ends into host chromosomal DNA (strand transfer). Herein, we report a crystal structure of prototype foamy virus IN bound to viral DNA prior to 3'-processing. Furthermore, taking advantage of its dependence on divalent metal ion cofactors, we were able to freeze trap the viral enzyme in its ground states containing all the components necessary for 3'-processing or strand transfer. Our results shed light on the mechanics of retroviral DNA integration and explain why HIV IN strand transfer inhibitors are ineffective against the 3'-processing step of integration. The ground state structures moreover highlight a striking substrate mimicry utilized by the inhibitors in their binding to the IN active site and suggest ways to improve upon this clinically relevant class of small molecules.
authors.affiliation: Division of Infectious Diseases, Imperial College London, London, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Hare
authors.forename: Goedele N
authors.initials: GN
authors.lastname: Maertens
authors.forename: Peter
authors.initials: P
authors.lastname: Cherepanov
mesh_terms: D002384:Catalysis; D020134:Catalytic Domain; D002413:Cations, Divalent / Q000737:chemistry; D004279:DNA, Viral / Q000378:metabolism; D006678:HIV / Q000201:enzymology; D019426:Integrases / Q000737:chemistry*; D016092:Spumavirus / Q000201:enzymology*; D016662:Virus Integration; D014961:X-Ray Diffraction
chemical_list: D002413:Cations, Divalent; D004279:DNA, Viral; D019426:Integrases