A BACILLUS-SUBTILIS LARGE ORF CODING FOR A POLYPEPTIDE HIGHLY SIMILARTO POLYKETIDE SYNTHASES

The nucleotide (nt) sequence of 13.6 kb of the outG locus of Bacillus subtilis, which maps at approximately 155-degrees between the genetic markers nrdA and polC, was determined. One putative coding sequence wa s identified corresponding to a large polypeptide of 4427 amino acids (aa). Structural organization at the nt and aa sequence level and exte nsive similarities of the deduced product, especially to EryA, suggest that the locus is potentially responsible for the synthesis of a poly ketide molecule. The locus has been renamed pksX. Comparison of the de duced product with known fatty acid and polyketide synthases (PKS) sug gested the presence of beta-ketosynthase, dehydratase, beta-ketoreduct ase and acyl-carrier protein domains. Preliminary data obtained with d eletion mutants indicate that pksX is not an essential gene.