THE NITROGEN-REGULATED BACILLUS-SUBTILIS NRGAB OPERON ENCODES A MEMBRANE-PROTEIN AND A PROTEIN HIGHLY SIMILAR TO THE ESCHERICHIA-COLI GLNB-ENCODED P-II PROTEIN

Expression of beta-galactosidase encoded by the nrg-29::Tn917-lacZ ins ertion increases 4,000-fold during nitrogen-limited growth (M. R. Atki nson and S. H. Fisher, J. Bacteriol. 173:23-27, 1991). The chromosomal DNA adjacent to the nrg-29::Tn917-lacZ insertion was cloned and seque nced. Analysis of the resulting nucleotide sequence revealed that the Tn917-lacZ transposon was inserted into the first gene of a dicistroni c operon, nrgAB. The nrgA gene encodes a 43-kDa hydrophobic protein th at is likely to be an integral membrane protein. The nrgB gene encodes a 13-kDa protein that has significant sequence similarity with the Es cherichia coli glnB-encoded P-II protein. Primer extension analysis re vealed that the nrgAB operon is transcribed from a single promoter. Th e nucleotide sequence of this promoter has significant similarity with the - 10 region, but not the - 35 region, of the consensus sequence f or Bacillus subtilis sigma(A)-dependent promoters.