X-ray Crystal Structures of HMG-CoA Synthase from Enterococcus faecalis and a Complex with Its Second Substrate/Inhibitor Acetoacetyl-CoA
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- 作者：C. Nicklaus Steussy ; Anthony A. Vartia ; John W. Burgner ; II ; Autumn Sutherlin ; Victor W. Rodwell ; and Cynthia V. Stauffacher
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：November 1, 2005
- 年：2005
- 卷：44
- 期：43
- 页码：14256 - 14267
- 全文大小：1003K
- 年卷期：v.44,no.43(November 1, 2005)
- ISSN：1520-4995
文摘
Biosynthesis of the isoprenoid precursor, isopentenyl diphosphate, is a critical function in allindependently living organisms. There are two major pathways for this synthesis, the non-mevalonatepathway found in most eubacteria and the mevalonate pathway found in animal cells and a number ofpathogenic bacteria. An early step in this pathway is the condensation of acetyl-CoA and acetoacetyl-CoA into HMG-CoA, catalyzed by the enzyme HMG-CoA synthase. To explore the possibility of a smallmolecule inhibitor of the enzyme functioning as a non-cell wall antibiotic, the structure of HMG-CoAsynthase from Enterococcus faecalis (MVAS) was determined by selenomethionine MAD phasing to 2.4Å and the enzyme complexed with its second substrate, acetoacetyl-CoA, to 1.9 Å. These structures showthat HMG-CoA synthase from Enterococcus is a member of the family of thiolase fold enzymes and,while similar to the recently published HMG-CoA synthase structures from Staphylococcus aureus, exhibitsignificant differences in the structure of the C-terminal domain. The acetoacetyl-CoA binary structuredemonstrates reduced coenzyme A and acetoacetate covalently bound to the active site cysteine througha thioester bond. This is consistent with the kinetics of the reaction that have shown acetoacetyl-CoA tobe a potent inhibitor of the overall reaction, and provides a starting point in the search for a small moleculeinhibitor.