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Nucleotide sequencing revealed the genes treP encoding a putative specific enzyme IITre upstream from treA and treR encoding a potential regulator downstream from treA of Bacillus subtilis 168. The treP gene encodes a 470-amino acid (aa) protein (50 kDa) showing high similarities to several different specific enzymes II of phosphoenolpyruvate-dependent phosphotransferase systems. treR encodes a 238-aa protein (28 kDa) with high homologies in its N-terminal part to DNA-binding proteins including a helixturn-helix motif. Homologies in its C-terminal part place it in the family of FadR-GntR transcriptional regulators. The three genes, treP-treA-treR, are probably organized in one operon expressed by a sigma A-dependent promoter 53 bp upstream from treP and a rho-independent terminator 28 bp downstream from treR.

The intracellular phospho-alpha-(1,1)-glucosidase, TreA, from Bacillus subtilis (Bs) hydrolyses trehalose 6-phosphate into glucose and glucose 6-phosphate. The enzyme is also able to cleave p-nitrophenyl alpha-D-glucopyranoside (PNPG). This enzymatic reaction can be easily monitored in a beta-galactosidase analogous enzyme assay. The vectors we have constructed can be used to study promoter activity in transcriptional treA fusions and may prove especially useful under high-salt conditions due to the halophilic character of TreA. The treA gene is useful as a reporter in either Bs or Escherichia coli (Ec). Such fusions can be integrated in the Bs amyE locus and selected on either kanamycin or chloramphenicol, or used as plasmids in Ec. As an example of the general utility, we demonstrate treA expression under xylA-operator-promoter control.