Phosphoenolpyruvate:sugar phosphotransferase system of Bacillus subtilis: nucleotide sequence of ptsX, ptsH and the 5'-end of ptsI and evidence for a ptsHI operon.

The nucleotide sequence of a 1689bp fragment of the Bacillus subtilis locus containing ptsX (a crr-like gene), ptsH (coding for HPr), and the 5'-end of ptsI (coding for Enzyme I) was determined. The deduced amino acid sequences of ptsH and the N-terminal part of ptsI were compared to those of Streptococcus faecalis and Escherichia coli. Transcription fusion demonstrated that ptsHI constitutes an operon. An open reading frame overlapping the main part of ptsH in the opposite sense was shown to be expressed in vivo, using protein fusions with beta-galactosidase. The deduced amino acid sequence of ptsX showed significant homology with that of Salmonella typhimurium glucose-specific Enzyme III. ptsX was preceded by an open reading frame whose amino acid sequence showed strong homology with the C-terminal part of E. coli Enzyme IIGlc.