Nucleotide sequence of the staphylokinase gene from Staphylococcus aureus

We have determined the entire nucleotide sequence of a 1,4-kilobase segment containing the staphylokinase gene, sak, molecularly cloned from the bacteriophage S phi-C genome of Staphylococcus aureus. The probable coding region is 489 base pairs long and these base pairs are translated into a polypeptide of 163 amino acid residues (Mr = 18,490) with a presumed signal sequence of 27 amino acid residues at the NH2-terminal end. In regions adjacent to the sak structural gene a possible promoter sequence and three possible terminator sequences for transcription were found about 100 base pairs upstream from the initiation codon and about 300, 400, and 500 base pairs downstream from the termination codon, respectively; they are active in an in vitro transcription system using Escherichia coli RNA polymerase. The immunoactive 18,500-dalton and 15,500-dalton proteins corresponding to a precursor form before secretion and a mature form after secretion of the sak gene products, respectively, were identified by the E. coli maxicell system.