SEQUENCE OF THE PUTATIVE ALANINE RACEMASE OPERON IN STAPHYLOCOCCUS-AUREUS - INSERTIONAL INTERRUPTION OF THIS OPERON REDUCES D-ALANINE SUBSTITUTION OF LIPOTEICHOIC ACID AND AUTOLYSIS

A gene cluster comprising the alanine racemase gene air was identified 5' to the sigB operon in Staphylococcus aureus. It is flanked upstrea m by four ORFs of which one shows similarity to the dpj gene of Escher ichia coil, and downstream by two ORFs of which the last shows similar ity to the E. coil pemK gene. Preliminary data suggest that the seven ORFs orf1-orf2-orf3-dpj-alr-orf6-pemK may form an operon. Disruption o f the proposed operon by insertional mutagenesis leads to a drastic lo ss in the D-alanine (D-Ala) substitution of lipoteichoic acid and to d elayed autolysis, without affecting the D-Ala substitution of the wall teichoic acid. (C) 1998 Elsevier Science B.V. All rights reserved.