New genes in the 170 region of the Bacillus subtilis genome encode DNA gyrase subunits, a thioredoxin, a xylanase and an amino acid transporter

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Abstract
A DNA contig of 26.2 kb covering the 170° region of the Bacillus subtilis strain 168 genome was isolated and sequenced. For DNA isolation, suitable restriction sites at the end of previously known genes were chosen to amplify adjacent unknown DNA regions by inverse PCR. On the basis of the DNA sequence, 26 ORFs were identified of which egIS and ccdA, as well as parts of citB and tkt have been described previously. Here we report the complete sequences of the aconitase (citB) and transketolase (tkt) genes. Of the other proteins encoded on the 26.2 kb fragment, eight revealed similarities to previously described proteins. These included a pair of newly identified DNA gyrase subunits A (grIA) and B (grIB), a sodium/proton-dependent alanine carrier (alsT), a member of the thioredoxin family (tlpA), an endo-1,4-β-xylanase (xynD) and a response regulator protein. Comparison of the physical and the genetic maps revealed several differences. According to its flanking sequences the lexA (dinR) gene which was previously mapped at 162° was found to be adjacent to yneA localized at 170°. Genes citB and egIS were located the opposite way round and closer together than expected from the genetic map (citB at 173° and egIS at 170°). The prkA gene, which was mapped at 169°, was not present on the respective fragment. Sequence comparison actually showed that prkA is located close to 70° on the B. subtilis genome.