Nucleotide sequence of leukocidin S-component gene (lukS) from methicillin resistant Staphylococcus aureus

The nucleotide sequence of lukS gene encoding S-component of Staphylococcal leukocidin from methicillin resistant Staphylococcus aureus (MRSA) was determined. The structural gene of lukS consisted of 857 base pairs. An open reading frame that could encode a 35,556 dalton polypeptide consisting of 315 amino acids was assigned. The molecular size of the polypeptide predicted from the amino acid composition was close to the value of pre-matured S-component determined in DNA-directed transcription/translation system. Inspection of the amino acid sequence deduced from nucleotide sequence of lukS and that from S-component of leukocidin clarified that pre-matured S-component contains a typical signal sequence at the NH2 terminus. The amino acid sequence of predicted matured S-component correlated exactly with the known N-terminal 50 amino acid sequence of S-component from MRSA and S. aureus V8. The molecular size of the predicted matured protein was also close to the value of S-component determined in both MRSA and S. aureus V8. The nucleotide sequence of the 5'-flanking region showed the presence of the consensus sequence of ribosome binding site, Pribnow box and the RNA polymerase recognition site in Escherichia coli.