Contribution of the phosphoenolpyruvate:mannose phosphotransferase system to carbon catabolite repression in Lactobacillus pentosus.
The role of the Lactobacillus pentosus phosphoenolpyruvate:mannose phosphotransferase system (mannose PTS) in sugar transport and control of sugar utilization was investigated. Growth experiments and measurements of PEP-dependent phosphorylation of sugars, of sugar transport and of catabolic enzyme activity were performed, to compare a wild-type strain with an EIIB(Man) mutant, LPE6, and a ccpA mutant, LPE4. Fructose uptake in wild-type bacteria demonstrated the presence of two fructose-specific PTSs: a high-affinity system, EII(Fru) (K:(m)=52 microM) which is inducible by fructose, and a low-affinity system (K:(m)=300 microM). The latter system was lacking in LPE6 and therefore corresponds to EII(Man). LPE6 was unable to phosphorylate glucose, mannose, N:-acetylglucosamine and 2-deoxyglucose in a PEP-dependent reaction, indicating that these sugars are substrates of EII(Man). Transport and phosphorylation of these compounds was the same in LPE4 and in wild-type bacteria, although growth of LPE4 on these sugars was impaired. In wild-type bacteria and in LPE4 the activity of EII(Fru) was lowered by the presence of EII(Man) substrates in the growth medium, but this decrease was not observed in LPE6. These results indicate that EII(Man) but not CcpA regulates the synthesis of EII(Fru). Mutations in EII(Man) or CcpA resulted in a relief of catabolite repression exerted by EII(Man) substrates on the activity of beta-galactosidase and beta-glucosidase, indicating that EII(Man) and CcpA are important components in catabolite repression in L. pentosus. Fructose-mediated repression of these two enzymes appeared to be correlated with the activity of EII(Fru).
Chaillou
Stéphane
S
TNO Voeding, Department of Applied Microbiology and Gene Technology, PO box 360 3700 AJ Zeist, The Netherlands2.|EC Slater Institute, BioCentrum, University of Amsterdam, Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands1.
Postma
Pieter W
PW
EC Slater Institute, BioCentrum, University of Amsterdam, Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands1.
Pouwels
Peter H
PH
TNO Voeding, Department of Applied Microbiology and Gene Technology, PO box 360 3700 AJ Zeist, The Netherlands2.|EC Slater Institute, BioCentrum, University of Amsterdam, Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands1.
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002250:Carbon Radioisotopes / Q000378:metabolism; D002463:Cell Membrane Permeability; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D007778:Lactobacillus / Q000201:enzymology* / Q000254:growth & development; D009154:Mutation; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism*; D010766:Phosphorylation; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D002250:Carbon Radioisotopes; D004268:DNA-Binding Proteins; D012097:Repressor Proteins; C069286:catabolite control proteins, bacteria; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C037992:phosphoenolpyruvate-mannose phosphotransferase