1MR9

Crystal structure of Streptogramin A Acetyltransferase with acetyl-CoA bound

Summary for 1MR9

• Entry DOI: 10.2210/pdb1mr9/pdb
• Related: 1MR7 1MRL
• Descriptor: Streptogramin A Acetyltransferase, ACETYL COENZYME *A (2 entities in total)
• Functional Keywords: left-handed parallel-beta helix domain, transferase
• Biological source: Enterococcus faecium
• Total number of polymer chains: 6
• Total formula weight: 149160.34

Authors

Kehoe, L.E.,Snidwongse, J.,Courvalin, P.,Rafferty, J.B.,Murray, I.A. (deposition date: 2002-09-18, release date: 2003-08-26, Last modification date: 2023-11-15)

Primary citation

Kehoe, L.E.,Snidwongse, J.,Courvalin, P.,Rafferty, J.B.,Murray, I.A.
Structural Basis of Synercid (Quinupristin-Dalfopristin) Resistance in Gram-positive Bacterial Pathogens
J.Biol.Chem., 278:29963-29970, 2003

PubMed Abstract: 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.

PubMed: 12771141
DOI: 10.1074/jbc.M303766200

Experimental method

X-RAY DIFFRACTION (3 Å)