Inhibition of tRNA-dependent ligase MurM from Streptococcus pneumoniae by phosphonate and sulfonamide inhibitors
作者:Elena Cressina、Adrian J. Lloyd、Gianfranco De Pascale、B. James Mok、Stephen Caddick、David I. Roper、Christopher G. Dowson、Timothy D.H. Bugg
DOI:10.1016/j.bmc.2009.03.028
日期:2009.5
Ligase MurM catalyses the addition of Ala from alanyl-tRNA(Ala), or Ser from seryl-tRNA(Ser), to lipid intermediate II in peptidoglycan biosynthesis in Streptococcus pneumoniae, and is a determinant of high-level penicillin resistance. Phosphorus-based transition state analogues were designed as inhibitors of the MurM-catalysed reaction. Phosphonamide analogues mimicking the attack of a lysine nucleophile upon Ala-tRNA(Ala) showed no inhibition of MurM, but adenosine 3'-phosphonate analogues showed inhibition of MurM, the most active being a 2'-deoxyadenosine analogue (IC50 100 mu M). Structure/function studies upon this analogue established that modi. cation of the amino group of the aminoalkylphosphonate resulted in loss of potency, and modi. cation of the adenosine 5'-hydroxyl group with either a t-butyl dimethyl silyl or a carbamate functional group resulted in loss of activity. A library of 48 aryl sulfonamides was also screened against MurM using a radiochemical assay, and two compounds showed sub-millimolar inhibition. These compounds are the first small molecule inhibitors of the Fem ligase family of peptidyltransferases found in Gram-positive bacteria. (C) 2009 Elsevier Ltd. All rights reserved.