1xpk

CRYSTAL STRUCTURE OF STAPHYLOCOCCUS AUREUS HMG-COA SYNTHASE WITH HMG-CoA AND WITH ACETOACETYL-COA AND ACETYLATED CYSTEINE

spinqualitylabelsall models 1xpk, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1xpk is a 4 chain structure with sequence from Staphylococcus aureus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Ligands: CAA, HMG, SCY, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A0A0H3K1U2_STAAW Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The formation of carbon-carbon bonds via an acyl-enzyme intermediate plays a central role in fatty acid, polyketide, and isoprenoid biosynthesis. Uniquely among condensing enzymes, 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase (HMGS) catalyzes the formation of a carbon-carbon bond by activating the methyl group of an acetylated cysteine. This reaction is essential in Gram-positive bacteria, and represents the first committed step in human cholesterol biosynthesis. Reaction kinetics, isotope exchange, and mass spectroscopy suggest surprisingly that HMGS is able to catalyze the "backwards" reaction in solution, where HMG-CoA is cleaved to form acetoacetyl-CoA (AcAc-CoA) and acetate. Here, we trap a complex of acetylated HMGS from Staphylococcus aureus and bound acetoacetyl-CoA by cryo-cooling enzyme crystals at three different times during the course of its back-reaction with its physiological product (HMG-CoA). This nonphysiological "backwards" reaction is used to understand the details of the physiological reaction with regards to individual residues involved in catalysis and substrate/product binding. The structures suggest that an active-site glutamic acid (Glu-79) acts as a general base both in the condensation between acetoacetyl-CoA and the acetylated enzyme, and the hydrolytic release of HMG-CoA from the enzyme. The ability to trap this enzyme-intermediate complex may suggest a role for protein dynamics and the interplay between protomers during the normal course of catalysis. 3-hydroxy-3-methylglutaryl-CoA synthase intermediate complex observed in "real-time".,Theisen MJ, Misra I, Saadat D, Campobasso N, Miziorko HM, Harrison DH Proc Natl Acad Sci U S A. 2004 Nov 23;101(47):16442-7. Epub 2004 Oct 21. PMID:15498869 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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