Lactobacillus casei 64H contains a phosphoenolpyruvate-dependent phosphotransferase system for uptake of galactose, as confirmed by analysis of ptsH and different gal mutants
Autor(en): | Bettenbrock, K Siebers, U Ehrenreich, P Alpert, CA |
Stichwörter: | GENE-CLUSTER; LACTOSE OPERON; METABOLISM; Microbiology; MUTATIONS; NUCLEOTIDE; PROTEIN; SELECTION; STREPTOCOCCUS-LACTIS; TAGATOSE 6-PHOSPHATE PATHWAY; TRANSPORT | Erscheinungsdatum: | 1999 | Herausgeber: | AMER SOC MICROBIOLOGY | Enthalten in: | JOURNAL OF BACTERIOLOGY | Band: | 181 | Ausgabe: | 1 | Startseite: | 225 | Seitenende: | 230 | Zusammenfassung: | Galactose metabolism in Lactobacillus casei 64H was analyzed by genetic and biochemical methods. Mutants with defects in ptsH, galK, or the tagatose 6-phosphate pathway were isolated either by positive selection using 2-deoxyglucose or 2-deoxygalactose or by an enrichment procedure with streptozotocin. ptsH mutations abolish growth on lactose, cellobiose, N-acetylglucosamine, mannose, fructose, mannitol, glucitol, and ribitol, while growth on galactose continues at a reduced rate. Growth on galactose is also reduced, but not abolished, in galK mutants. A mutation in galK in combination with a mutation in the tagatose 6-phosphate pathway results in sensitivity to galactose and lactose, while a galK mutation in combination with a mutation in ptsH completely abolishes galactose metabolism. Transport assays, in vitro phosphorylation assays, and thin-layer chromatography of intermediates of galactose metabolism also indicate the functioning of a permease/Leloir pathway and a phosphoenolpyurvate-dependent phosphotransferase system (PTS)/tagatose 6-phosphate pathway. The galactose-PTS is induced by growth on either galactose or lactose, but the induction kinetics for the two substrates are different. |
ISSN: | 00219193 | DOI: | 10.1128/JB.181.1.225-230.1999 |
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geprüft am 10.06.2024