CLONING AND CHARACTERIZATION OF AN ACCESSORY GENE REGULATOR (AGR)-LIKE LOCUS FROM STAPHYLOCOCCUS-EPIDERMIDIS

The presence of sequences related to the agr of Staphylococcus aureus was demonstrated in Staphylococcus epidermidis by agr-specific PCR, an d Southern blot. The agr-like locus of S. epidermidis A086 was cloned and sequenced. An overall homology of 68% was found between the agi lo cus from S. epidermidis and S. aureus. The agr locus from S. epidermid is was organized similar to those from S. aureus and S. lugdumensis. T he putative RNAII molecule contains four open reading frames, agi d, B , C and D. AgrA was a response regulator. AgrB showed homology with tr ansducer and translocase molecules. AgrC is expected to act as a histi dine protein kinase in which a leucine zipper is present. AgrD is pres umably processed into an autoinducer peptide. The putative RNAIII mole cule contained an open reading frame encoding a putative 26 amino acid (aa) polypeptide, which differed in 3 aa from the RNAIII encoded delt a-toxin of S. aureus. Kinetic studies showed that the production of th is RNAIII was elevated during the post-exponential phase. delta-toxin activity was demonstrated for 21 of 23 tested S. epidermidis strains. Kinetic studies of the production of delta-toxin showed that the toxin was produced during the postexponential phase. Sequencing of S. epide rmidis A097, which showed a delayed agr-response, revealed a truncated AgrC lacking the histidine kinase domain. These data indicate that an agr-like locus is active in S. epidermidis during the postexponential phase. (C) 1998 Federation of European Microbiological Societies. Pub lished by Elsevier Science B.V. All rights reserved.