1mr7

Crystal Structure of Streptogramin A Acetyltransferase

spinqualitylabelsall models 1mr7, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1mr7 is a 6 chain structure with sequence from Enterococcus faecium. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 1mr9, 1mrl Resources: FirstGlance, OCA, RCSB, PDBsum 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 Synercid, a new semisynthetic streptogramin-derived antibiotic containing dalfopristin and quinupristin, is used in treatment of life-threatening infections caused by glycopeptide-resistant Enterococcus faecium and other bacterial pathogens. However, dissemination of genes encoding virginiamycin acetyltransferases, enzymes that confer resistance to streptogramins, threatens to limit the medical utility of the quinupristin-dalfopristin combination. Here we present structures of virginiamycin acetyltransferase D (VatD) determined at 1.8 A resolution in the absence of ligands, at 2.8 A resolution bound to dalfopristin, and at 3.0 A resolution in the presence of acetyl-coenzyme A. Dalfopristin is bound by VatD in a similar conformation to that described previously for the streptogramin virginiamycin M1. However, specific interactions with the substrate are altered as a consequence of a conformational change in the pyrollidine ring that is propagated to adjacent constituents of the dalfopristin macrocycle. Inactivation of dalfopristin involves acetyl transfer from acetyl-coenzyme A to the sole (O-18) hydroxy group of the antibiotic that lies close to the side chain of the strictly conserved residue, His-82. Replacement of residue 82 by alanine is accompanied by a fall in specific activity of >105-fold, indicating that the imidazole moiety of His-82 is a major determinant of catalytic rate enhancement by VatD. The structure of the VatD-dalfopristin complex can be used to predict positions where further structural modification of the drug might preclude enzyme binding and thereby circumvent Synercid resistance. Structural basis of Synercid (quinupristin-dalfopristin) resistance in Gram-positive bacterial pathogens.,Kehoe LE, Snidwongse J, Courvalin P, Rafferty JB, Murray IA J Biol Chem. 2003 Aug 8;278(32):29963-70. Epub 2003 May 27. PMID:12771141 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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