Appl. Environ. Microbiol., Jun 1997, 2111-2116, Vol 63, No. 6
R Stentz, R Lauret, SD Ehrlich, F Morel-Deville and M Zagorec
The ptsH and ptsI genes of Lactobacillus sake, encoding the general enzymes
of the phosphoenolpyruvate: carbohydrate phosphotransferase system (PTS),
were cloned and sequenced. HPr (88 amino acids), encoded by ptsH, and
enzyme I (574 amino acids), encoded by ptsI, are homologous to the
corresponding known enzymes of other bacteria. Nucleotide sequence and mRNA
analysis showed that the two genes are cotranscribed in a large transcript
encoding both HPr and enzyme I. The transcription of ptsHI was shown to be
independent of the carbon source. Four ptsI mutants were constructed by
single-crossover recombination. For all mutants, growth on PTS
carbohydrates was abolished. Surprisingly, the growth rates of mutants on
ribose and arabinose, two carbohydrates which are not transported by the
PTS, were accelerated. This unexpected phenotype suggests that the PTS
negatively controls ribose and arabinose utilization in L. sake by a
mechanism different from the regulation involving HPr described for other
gram- positive bacteria.
Copyright © 1997, American Society for Microbiology
Molecular cloning and analysis of the ptsHI operon in Lactobacillus sake
Laboratoire de Recherches sur la Viande, INRA, Jouy-en-Josas, France.
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