Nucleic Acids Research, 1989, Vol. 17, No. 16 6531-6543
© 1989
MOLECULAR BIOLOGY |
Bacillus subtilis gene coding for constitutive O6-methylguanine-DNA alkyttransferase
Radiobiology Division, National Cancer Center Research Institute Tsukiji, 5-1-1 Chuo-ku, Tokyo 104, Japan 1Oncogene Division, National Cancer Center Research Institute Tsukiji, 5-1-1 Chuo-ku, Tokyo 104, Japan
Received June 5, 1989. Accepted July 17, 1989.
We have cloned a Bacillus subtilis DNA fragment that could correct the defect in a constitutive O6-methylguanine-DNA alkyltransferase (Dat1). This fragment also corrected the hypersensitivity of the strain TKJ6951(ada-7 dat-1) to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). In the fragment, the gene activity resides in a region of about 850 bp which contains an open reading frame capable of coding for a protein of 165 amino acid residues. The amino acid sequence of this protein exhibits striking similarity to those of E. coli O6-methylguanine-DNA alkyltransferases (Ogt and Ada proteins). We conclude that this is a structural gene for the Datl protein, which is distinct from inducible DNA alkyltransferases involved in the adaptive response. The dat-1 mutation was shown to be caused by a structural rearrangement affecting the coding region, and the 0.8 kb transcripts of this gene were detected in dat+ cells but not in dot mutant cells.