title: Crystal structures of the reverse transcriptase-associated ribonuclease H domain of xenotropic murine leukemia-virus related virus.
abstract: The ribonuclease H (RNase H) domain of retroviral reverse transcriptase (RT) plays a critical role in the life cycle by degrading the RNA strands of DNA/RNA hybrids. In addition, RNase H activity is required to precisely remove the RNA primers from nascent (-) and (+) strand DNA. We report here three crystal structures of the RNase H domain of xenotropic murine leukemia virus-related virus (XMRV) RT, namely (i) the previously identified construct from which helix C was deleted, (ii) the intact domain, and (iii) the intact domain complexed with an active site α-hydroxytropolone inhibitor. Enzymatic assays showed that the intact RNase H domain retained catalytic activity, whereas the variant lacking helix C was only marginally active, corroborating the importance of this helix for enzymatic activity. Modeling of the enzyme-substrate complex elucidated the essential role of helix C in binding a DNA/RNA hybrid and its likely mode of recognition. The crystal structure of the RNase H domain complexed with β-thujaplicinol clearly showed that coordination by two divalent cations mediates recognition of the inhibitor.
authors.affiliation: Protein Structure Section, Macromolecular Crystallography Laboratory, National Cancer Institute at Frederick, Frederick, MD 21702, USA.
authors.forename: Dongwen
authors.initials: D
authors.lastname: Zhou
authors.forename: Suhman
authors.initials: S
authors.lastname: Chung
authors.forename: Maria
authors.initials: M
authors.lastname: Miller
authors.forename: Stuart F J Le
authors.initials: SF
authors.lastname: Grice
authors.forename: Alexander
authors.initials: A
authors.lastname: Wlodawer
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods*; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*; D016914:Ribonuclease H / Q000737:chemistry* / Q000378:metabolism*; D058008:Xenotropic murine leukemia virus-related virus / Q000201:enzymology*
chemical_list: D012194:RNA-Directed DNA Polymerase; D016914:Ribonuclease H