Nucleotide sequence of manX (ptsL) encoding the enzyme IIIMan(II-AMan) function in the phosphotransferase system ofEscherichia coliK-12

The nucleotide sequence of the manX(ptsL) gene, encoding enzyme IIIMan function in the phosphoenolpyruvate transport system, and that of the 5′ end of the manY(pel) gene of Escherichia coli, was determined. Sequence analysis of manX revealed the presence of a large open reading frame with a coding capacity of 315 amino acids (Mr 34 299), Mapping of the mRNA 5′ end showed that transcription starts 138 nucleotides upstream from the initiation codon. Upstream from the manX-coding region a possible promoter and ribosome binding site were identified. The manX gene is closely linked to the manY(pel) gene, the genes being transcribed in the same direction probably as one transcriptional unit. No apparent sequence homology was found between manX, encoding the mannose-specific enzyme IIIMan, and crr, encoding the glucose-specific enzyme IIIGlc, suggesting a divergent origin of these functionally related proteins.