DRA-NUPC-PDP OPERON OF BACILLUS-SUBTILIS - NUCLEOTIDE-SEQUENCE, INDUCTION BY DEOXYRIBONUCLEOSIDES, AND TRANSCRIPTIONAL REGULATION BY THE DEOR-ENCODED DEOR REPRESSOR PROTEIN

The genes encoding deoxyriboaldolase (dra), nucleoside uptake protein (nupC), and pyrimidine nucleoside phosphorylase (pdp) from Bacillus su btilis were cloned, and their nucleotide sequences were determined, Se quence analysis showed that the genes were localized immediately downs tream of the hut operon. Insertional gene disruption studies indicated that the three genes constitute an operon with the gene order dra-nup C-pdp. A promoter mapping immediately upstream of the dra gene was ide ntified, and downstream of the pdp gene the nucleotide sequence indica ted the existence of a factor-independent transcription terminator str ucture. In wild-type cells growing in succinate minimal medium, the py rimidine nucleoside phosphorylase and deoxyriboaldolase levels were fi ve- to eightfold higher in the presence of thymidine and fourfold high er in the presence of deoxyadenosine. By the use of lacZ fusions, the regulation was found to be at the level of transcription. The operon e xpression was subject to glucose repression, Upstream of the dra gene an open reading frame of 313 amino acids was identified. Inactivation of this gene led to an approximately 10-fold increase in the levels of deoxyriboaldolase and pyrimidine nucleoside phosphorylase, and no fur ther induction was seen upon the addition of deoxyribonucleosides. The upstream gene most likely Encodes the regulator for the dra-nupC-pdp operon and Has designated deoR (stands for deoxyribonucleoside regulat or).