SEQUENCE OF A STAPHYLOCOCCAL GENE, VAT, ENCODING AN ACETYLTRANSFERASEINACTIVATING THE A-TYPE COMPOUNDS OF VIRGINIAMYCIN-LIKE ANTIBIOTICS

The Staphylococcus aureus plasmids, pIP680 and pIP1156, which confer r esistance to A-type compounds of virginiamycin-like antibiotics (Vml: streptogramin A, pristinamycin IIA, virginiamycin M) and to synergisti c mixtures of the A and B compounds of Vml antibiotics, were shown to direct the modification of A-type compounds by acetylation. The vat ge ne, encoding the acetyltransferase modifying A-type compounds, was iso lated from plasmid pIP680 and sequenced. This gene potentially encodes a 219-amino-acid (aa) protein, VAT, of 24 330 Da showing at least 38% aa identity with two chloramphenicol acetyltransferases encoded by ca t genes isolated from Escherichia coli and Agrobacterium tumefaciens. Resistance to A-type compounds of Vml antibiotics conferred to S. aure us by vat was not expressed in E. coli, although a protein having a M( r) similar to that encoded by this gene was detected in E. coli minice lls. The vat gene was detected by the polymerase chain reaction in two chromosomally located staphylococcal conjugative elements and in the conjugative plasmid, pIP1156, conferring resistance to A-type compound s.