CLONING AND SEQUENCING OF SOME GENES RESPONSIBLE FOR PORPHYRIN BIOSYNTHESIS FROM THE ANAEROBIC BACTERIUM CLOSTRIDIUM-JOSUI

The 6.2-kbp DNA fragment encoding the enzymes in the porphyrin synthes is pathway of a cellulolytic anaerobe, Clostridium josui, was cloned i nto Escherichia coli and sequenced. This fragment contained four hem g enes, hemA, hemC, hemD, and hemB, in order, which were homologous to t he corresponding genes from E. coli and Bacillus subtilis. A typical p romoter sequence was found only upstream of hemA, suggesting that thes e four genes were under the control of this promoter as an operon. The hemA and hemD genes cloned from C. josui were able to complement the hemA and hemD mutations, respectively, of. coli. The COOH-terminal reg ion of C. josui HemA and the NH2-terminal region of C. josui HemD were homologous to E. coli CysG (Met-1 to Leu-151) and to E. coli CysG (As p-213 to Phe-454) and Pseudomonas denitrificans CobA, respectively. Fu rthermore, the cloned 6.2-kbp DNA fragment complemented E. coli cysG m utants. These results suggested that both C. josui hemA and hemD encod e bifunctional enzymes.