title: Structural and biochemical studies of inhibitor binding to human cytomegalovirus protease.
abstract: Herpesvirus protease is required for the life cycle of the virus and is an attractive target for the design and development of new anti-herpes agents. The protease belongs to a new class of serine proteases, with a novel backbone fold and a unique Ser-His-His catalytic triad. Here we report the crystal structures of human cytomegalovirus protease in complex with two peptidomimetic inhibitors. The structures reveal a new hydrogen-bonding interaction between the main chain carbonyl of the P(5) residue and the main chain amide of amino acid 137 of the protease, which is important for the binding affinity of the inhibitor. Conformational flexibility was observed in the S(3) pocket of the enzyme, and this is supported by our characterization of several mutants in this pocket. One of the structures is at 2.5 A resolution, allowing us for the first time to locate ordered solvent molecules in the inhibitor complex. The presence of two solvent molecules in the active site may have implications for the design of new inhibitors against this enzyme. Favorable and stereospecific interactions have been established in the S(1)' pocket for one of these inhibitors.
authors.affiliation: Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
authors.forename: Reza
authors.initials: R
authors.lastname: Khayat
authors.forename: Renu
authors.initials: R
authors.lastname: Batra
authors.forename: Chungeng
authors.initials: C
authors.lastname: Qian
authors.forename: Teddy
authors.initials: T
authors.lastname: Halmos
authors.forename: Murray
authors.initials: M
authors.lastname: Bailey
authors.forename: Liang
authors.initials: L
authors.lastname: Tong
mesh_terms: D000409:Alanine / Q000235:genetics; D001120:Arginine / Q000235:genetics; D001667:Binding, Competitive / Q000235:genetics; D003460:Crystallization; D018360:Crystallography, X-Ray; D003587:Cytomegalovirus / Q000201:enzymology* / Q000235:genetics; D018698:Glutamic Acid / Q000235:genetics; D005973:Glutamine / Q000235:genetics; D006801:Humans; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding / Q000235:genetics; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014867:Water / Q000737:chemistry
chemical_list: D015842:Serine Proteinase Inhibitors; D014867:Water; D005973:Glutamine; D018698:Glutamic Acid; D001120:Arginine; D012697:Serine Endopeptidases; C071910:assemblin; D000409:Alanine