Publications

• Genetics of L-sorbose transport and metabolism in Lactobacillus casei.

  Yebra M.J., Veyrat A., Santos M.A., Perez-Martinez G.

  Genes encoding L-sorbose metabolism of Lactobacillus casei ATCC 393 have been identified on a 6.8-kb chromosomal DNA fragment. Sequence analysis revealed seven complete genes and a partial open reading frame transcribed as two units. The deduced amino acid sequences of the first transcriptional un ... >> More

  Genes encoding L-sorbose metabolism of Lactobacillus casei ATCC 393 have been identified on a 6.8-kb chromosomal DNA fragment. Sequence analysis revealed seven complete genes and a partial open reading frame transcribed as two units. The deduced amino acid sequences of the first transcriptional unit (sorRE) showed high similarity to the transcriptional regulator and the L-sorbose-1-phosphate reductase of the sorbose (sor) operon from Klebsiella pneumoniae. The other genes are transcribed as one unit (sorFABCDG) in opposite direction to sorRE. The deduced peptide sequence of sorF showed homology with the D-sorbitol-6-phosphate dehydrogenase encoded in the sor operon from K. pneumoniae and sorABCD to components of the mannose phosphotransferase system (PTS) family but especially to domains EIIA, EIIB, EIIC and EIID of the phosphoenolpyruvate-dependent L-sorbose PTS from K. pneumoniae. Finally, the deduced amino acid sequence of a truncated gene (sorG) located downstream of sorD presented high similarity with ketose-1,6-bisphosphate aldolases. Results of studies on enzyme activities and transcriptional analysis revealed that the two gene clusters, sorRE and sorFABCDG, are induced by L-sorbose and subject to catabolite repression by D-glucose. Data indicating that the catabolite repression is mediated by components of the PTS elements and by CcpA, are presented. Results of sugar uptake assays in L. casei wild-type and sorBC mutant strains indicated that L-sorbose is taken up by L-sorbose-specific enzyme II and that L. casei contains an inducible D-fructose-specific PTS. Results of growth analysis of those strains and a man sorBC double mutant suggested that L-sorbose is probably also transported by the D-mannose PTS. We also present evidence, from studies on a sorR mutant, suggesting that the sorR gene encodes a positive regulator of the two sor operons. Sequence alignment of SorR, SorC (K. pneumoniae), and DeoR (Bacillus subtilis) revealed that they might constitute a new group of transcriptional regulators. << Less

  J. Bacteriol. 182:155-163(2000) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• L-Sorbose metabolism in Klebsiella pneumoniae and Sor+ derivatives of Escherichia coli K-12 and chemotaxis toward sorbose.

  Sprenger G.A., Lengeler J.W.

  L-Sorbose degradation in Klebsiella pneumoniae was shown to follow the pathway L-sorbose leads to L-sorbose-1-phosphate leads to D-glucitol-6-phosphate leads to D-fructose-6-phosphate. Transport and phosphorylation of L-sorbose was catalyzed by membrane-bound enzyme IIsor of the phosphoenolpyruvat ... >> More

  L-Sorbose degradation in Klebsiella pneumoniae was shown to follow the pathway L-sorbose leads to L-sorbose-1-phosphate leads to D-glucitol-6-phosphate leads to D-fructose-6-phosphate. Transport and phosphorylation of L-sorbose was catalyzed by membrane-bound enzyme IIsor of the phosphoenolpyruvate-dependent carbohydrate:phosphotransferase system, specific for and regulated by this ketose and different from all other enzymes II described thus far. Two soluble enzymes, an L-sorbose-1-phosphate reductase and a D-glucitol-6-phosphate dehydrogenase, were involved in the conversion of L-sorbose-1-phosphate to D-fructose-6-phosphate. This dehydrogenase was temperature sensitive, preventing growth of wild-type strains of K. pneumoniae at temperatures above 35 degrees C in the presence of L-sorbose. The enzyme was distinct from a second D-glucitol-6-phosphate dehydrogenase involved in the metabolism of D-glucitol. The sor genes were transferred from the chromosome of nonmotile strains of K. pneumoniae by means of a new R'sor+ plasmid to motile strains of Escherichia coli K-12. Such derivatives not only showed the temperature-sensitive Sor+ phenotype characteristic for K. pneumoniae or Sor+ wild-type strains of E. coli, but also reacted positively to sorbose in chemotaxis tests. << Less

  J. Bacteriol. 157:39-45(1984) [PubMed] [EuropePMC]

• Molecular analysis of the phosphoenolpyruvate-dependent L-sorbose: phosphotransferase system from Klebsiella pneumoniae and of its multidomain structure.

  Wehmeier U.F., Wohrl B.M., Lengeler J.W.

  We have cloned a 3.4 kb DNA fragment from the chromosome of Klebsiella pneumoniae that codes for a phosphoenolpyruvate-dependent L-sorbose: phosphotransferase system (PTS). The cloned fragment was sequenced and four open reading frames coding for 135 (sorF), 164 (sorB), 266 (sorA) and 274 (sorM) a ... >> More

  We have cloned a 3.4 kb DNA fragment from the chromosome of Klebsiella pneumoniae that codes for a phosphoenolpyruvate-dependent L-sorbose: phosphotransferase system (PTS). The cloned fragment was sequenced and four open reading frames coding for 135 (sorF), 164 (sorB), 266 (sorA) and 274 (sorM) amino acids, respectively, were found. The corresponding proteins could be detected in a T7 overexpression system, which yielded molecular masses of about 14,000 for SorF, 19,000 for SorB, 25,000 for SorA and 27,000 for SorM. SorF and SorB have all the characteristics of soluble and intracellular proteins in accordance with their functions as EIIASor and EIIBSor domains of the L-sorbose PTS. SorA and SorM, by contrast, are strongly hydrophobic, membrane-bound proteins with two to five putative transmembrane helices that alternate with a series of hydrophilic loops. They correspond to domains EIICSor and EIIDSor. The four proteins of the L-sorbose PTS resemble closely (27%-60%) the four subunits of a D-fructose PTS (EIIALev, EIIBLev, EIICLev, and EIIDLev) from Bacillus subtilis and the three subunits of the D-mannose PTS (EIIA,BMan, EIICMan, and EIIDMan) from Escherichia coli K-12. The three systems constitute a new PTS family, and sequence comparisons revealed highly conserved structures for the membrane-bound proteins. A consensus sequence for the membrane proteins was used to postulate a model for their integration into the membrane. << Less

  Mol. Gen. Genet. 246:610-618(1995) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.