A 32 kb nucleotide sequence from the region of the lincomycin-resistance gene (22°-25°) of the Bacillus subtilis chromosome and identification of the site of the lin-2 mutation

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Abstract
Summary: A 32 kb nucleotide sequence in the region of the lincomycin-resistance gene, located from 22° to 25° on the Bacillus subtilis chromosome, was determined. Among 32 putative ORFs identified, four [lipA for lipase, natA, natB and yzaE (renamed yccK)] have already been reported, although the functions of NatA, NatB and YccK remain to be characterized. Six putative products were found to exhibit significant similarity to known proteins in the databases, namely L-asparaginase precursor, protein aspartate phosphatase, x-glucosidase, two tellurite-resistance proteins and a hypothetical protein from B. subtilis. The region of the tellurite-resistance gene, consisting of seven ORFs, seems to correspond to an operon. The products of 14 ORFs exhibited considerable or limited similarity to known proteins. The sequenced region seems to be rich in membrane proteins, since at least 16 gene products appeared to contain membrane-spanning domains. The site of the lin-2 mutation (two nucleotide replacements) was mapped and identified by sequencing. This site is located between a putative promoter and the SD sequence of ImrA (yccB)[a putative repressor of the Imr operon, which consists of ImrA and ImrB (yccA)]. LmrB is a homologue of proteins involved in drug-export systems and seems likely to be the protein responsible for resistance to lincomycin.