THE STAPHYLOCOCCUS-AUREUS ILES GENE, ENCODING ISOLEUCYL-TRANSFER-RNA SYNTHETASE, IS A MEMBER OF THE T-BOX FAMILY

The Staphylococcus aureus ileS gene, encoding isoleucyl-tRNA synthetas e (IleRS), contains a long mRNA leader region. This region exhibits ma ny of the features of the gram-positive synthetase gene family, includ ing the T box and leader region terminator and antiterminator. The ter minator was shown to be functional in vivo, and readthrough increased during growth in the presence of mupirocin, an inhibitor of IleRS acti vity. The S. nm eus ileS leader structure includes several critical di fferences from the other members of the T-box family, suggesting that regulation of this gene in S. aureus may exhibit unique features.