A DNA REGION THAT COMPLEMENTS ON ESCHERICHIA-COLI CYSG MUTATION IN THIOBACILLUS-FERROOXIDANS

Thiobacillus ferrooxidans AP19-3 has a novel NADH-dependent sulfite re ductase in the periplasmic space, The gene responsible for the appeara nce of NADH-dependent sulfite reductase activity was cloned into a vec tor plasmid pBR322 to give a 5.7-kb hybrid plasmid, pTHS1, which conta ins a 1.3-kb DNA fragment of T. ferrooxidans AP19-3, When pTHS1 was us ed to transform sulfite reductase deficient E. coli mutants, strain AT 2455 (cysG), JM246 (cysI), and AT2427 (cysJ), it complemented only the E, coli cysG mutation, Since cysG codes for S-adenosyl-L-methionine : uroporphyrinogen III methyltransferase, the enzyme involved in sirohe me synthesis, the results indicate that the DNA region that codes for S-adenosyl-L-methionine: uroporphyrinogen In methyltransferase is pres ent in a T. ferrooxidans 1.3 kb DNA fragment on pTHS1.