MOLECULAR-CLONING AND NUCLEOTIDE-SEQUENCE OF THE PORPHOBILINOGEN DEAMINASE GENE, HEMC, FROM CHLOROBIUM-VIBRIOFORME

We previously reported the DNA sequence and expression of the Chlorobi um vibrioforme glutamyl-tRNA reductase (hemA) gene (Majumdar et al., A rch Microbiol 156:281, 1991). The sequence downstream of the hemA gene indicated homology to Escherichia coli and Bacillus subtilis porphobi linogen deaminase (hemC) gene. The Chlorobium gene was confirmed to be the porphobilinogen deaminase gene, and complete sequence of the stru ctural gene was obtained, A 2.8-kb DNA fragment containing the 1.3-kb hemA gene of Chlorobium was cloned into a hemC auxotroph (Sz16) of Bac illus subtilis, and complementation of the auxotroph to prototrophy wa s achieved, DNA sequence data showed a single open reading frame of 84 0 bp coding a protein of 279 amino acid residues, The deduced amino ac id sequence of the Chlorobium porphobilinogen deaminase revealed 39% t o 46% homology with the corresponding prokaryotic and eukaryotic seque nces.