CLONING, SEQUENCING AND REGULATION OF THIA, A THIAMIN BIOSYNTHESIS GENE FROM BACILLUS-SUBTILIS

The thiA gene is involved in the biosynthesis of the pyrimidine moiety of thiamin in Bacillus subtilis. This gene was cloned using a DNA pro be rescued from thiA::Tn917 to screen a B. subtilis genomic library. T hiA exhibits 70% identity with E. coli thiC. The proposed thiA open re ading frame complements all available thiA mutants of B. subtilis as w ell as the thiC mutant of E. coli. This suggests a similar biosyntheti c pathway to 2-methyl-4-amino-5-hydroxymethylpyrimidine in both organi sms. The expression of thiA is regulated, at least on the transcriptio nal level, and is significantly repressed by thiamin and 2-methyl-4-am ino5-hydroxymethylpyrimidine. (C) 1997 Elsevier Science B.V.