title: Structural analysis of mevalonate-3-kinase provides insight into the mechanisms of isoprenoid pathway decarboxylases.
abstract: In animals, cholesterol is made from 5-carbon building blocks produced by the mevalonate pathway. Drugs that inhibit the mevalonate pathway such as atorvastatin (lipitor) have led to successful treatments for high cholesterol in humans. Another potential target for the inhibition of cholesterol synthesis is mevalonate diphosphate decarboxylase (MDD), which catalyzes the phosphorylation of (R)-mevalonate diphosphate, followed by decarboxylation to yield isopentenyl pyrophosphate. We recently discovered an MDD homolog, mevalonate-3-kinase (M3K) from Thermoplasma acidophilum, which catalyzes the identical phosphorylation of (R)-mevalonate, but without concomitant decarboxylation. Thus, M3K catalyzes half the reaction of the decarboxylase, allowing us to separate features of the active site that are required for decarboxylation from features required for phosphorylation. Here we determine the crystal structure of M3K in the apo form, and with bound substrates, and compare it to MDD structures. Structural and mutagenic analysis reveals modifications that allow M3K to bind mevalonate rather than mevalonate diphosphate. Comparison to homologous MDD structures show that both enzymes employ analogous Arg or Lys residues to catalyze phosphate transfer. However, an invariant active site Asp/Lys pair of MDD previously thought to play a role in phosphorylation is missing in M3K with no functional replacement. Thus, we suggest that the invariant Asp/Lys pair in MDD may be critical for decarboxylation rather than phosphorylation.
authors.affiliation: Department of Chemistry and Biochemistry, UCLA-DOE Institute for Genomics and Proteomics, Molecular Biology Institute, University of California, Los Angeles, California, 90095-1570.
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Vinokur
authors.forename: Tyler P
authors.initials: TP
authors.lastname: Korman
authors.forename: Michael R
authors.initials: MR
authors.lastname: Sawaya
authors.forename: Michael
authors.initials: M
authors.lastname: Collazo
authors.forename: Duillio
authors.initials: D
authors.lastname: Cascio
authors.forename: James U
authors.initials: JU
authors.lastname: Bowie
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002262:Carboxy-Lyases / Q000737:chemistry* / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D008798:Mevalonic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment; D013729:Terpenes / Q000378:metabolism*; D013822:Thermoplasma / Q000737:chemistry / Q000201:enzymology*
chemical_list: D013729:Terpenes; C046285:5-diphosphomevalonic acid; D017853:Phosphotransferases (Alcohol Group Acceptor); C021796:mevalonate kinase; D002262:Carboxy-Lyases; C022503:pyrophosphomevalonate decarboxylase; D008798:Mevalonic Acid
keywords: GHMP kinase; cholesterol; mevalonate diphosphate decarboxylase; mevalonate kinase; mevalonate pathway; mevalonate pyrophosphate decarboxylase; mevalonate-3-kinase; statin