ISOLATION OF THE STAPHYLOCOCCUS-AUREUS HEM CDBL GENE-CLUSTER CODING FOR EARLY STEPS IN HEME-BIOSYNTHESIS

We have recently reported [Kafala, B., Sasarman, A., 1994. Can. J. Mic robiol. 40, 651-657] the cloning and sequencing of the Staphylococcus aureus hemB gene. This gene purportedly encodes the delta-aminolevulin ic acid dehydratase of the heme pathway. In this present communication , we report the sequences and identities of three putative hem genes. Two of these genes are located immediately upstream from hemB. Complem entation analysis of Escherichia coli and Salmonella typhimurium hemC and hemD mutants and the comparison of the Sa nucleotide sequences wit h those of Bacillus subtilis and Ec showed that these two open reading frames, ORF1 and ORF2, are likely to be the hemC gene coding for porp hobilinogen deaminase and the hemD gene coding for uroporphyrinogen II I synthase, respectively. The third hem gene, hemL, is located immedia tely downstream of hemB, and encodes glutamate 1-semialdehyde 2,1-amin otransferase. Sequencing of the region which extends past hemL indicat es that no further hem genes are located downstream of hemL. In Sa, he mC, hemD hemB and hemL are proposed to constitute a hem cluster encodi ng enzymes required for the synthesis of uroporphyrinogen III from glu tamate 1-semialdehyde (GSA). (C) 1997 Elsevier Science B.V.