Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1999 Jan;181(1):225-30.
doi: 10.1128/JB.181.1.225-230.1999.

Lactobacillus casei 64H contains a phosphoenolpyruvate-dependent phosphotransferase system for uptake of galactose, as confirmed by analysis of ptsH and different gal mutants

K Bettenbrock  1 , U Siebers, P Ehrenreich, C A Alpert
Affiliations
Free PMC article

Lactobacillus casei 64H contains a phosphoenolpyruvate-dependent phosphotransferase system for uptake of galactose, as confirmed by analysis of ptsH and different gal mutants

K Bettenbrock et al. J Bacteriol. 1999 Jan.
Free PMC article

Abstract

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 phosphoenolpyruvate-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.

PubMed Disclaimer

Figures

FIG. 1
FIG. 1
Induction of the galactose-PTS, detetmined for growth on either galactose or lactose. (A) Growth curves. The arrow indicates the time of addition of the carbohydrates. (B) Curves of specific activity. ▴, uninduced; ■, induced by galactose; formula image, induced by lactose.
FIG. 2
FIG. 2
Analysis of intermediates of galactose metabolism in different mutants. The autoradiogram shows extracts of [14C]galactose-metabolizing cells which were separated by thin-layer chromatography. Lane 1, KB6419; lane 2, KB6417; lane 3, 64H; lane 4, PG4; lane 5, STZB1; lane 6, PG41; lane 7, PG45. Positions of reference substances are indicated at the right. GAP, glyceraldehyde 3-phosphate; Fru, fructose; Tag, tagatose.
See this image and copyright information in PMC

References

    1. Alpert C-A, Siebers U. The lac operon of Lactobacillus casei contains lacT, a gene coding for a protein of the BglG family of transcriptional antiterminators. J Bacteriol. 1997;179:1555–1562. - PMC - PubMed
    1. Alpert C-A, Chassy B M. Molecular organization of the plasmid encoded lactose-PTS of Lactobacillus casei. FEMS Microbiol Rev. 1989;63:157–166. - PubMed
    1. Bettenbrock K, Alpert C-A. The gal genes for the Leloir pathway of Lactobacillus casei64H. Appl Environ Microbiol. 1998;64:2013–2019. - PMC - PubMed
    1. Bettenbrock, K., and C.-A. Alpert. Unpublished data.
    1. Bisset D L, Anderson R L. Lactose and d-galactose metabolism in Staphylococcus aureus: pathway of d-galactose 6-phosphate degradation. Biochem Biophys Res Commun. 1973;52:641–647. - PubMed

Publication types

MeSH terms

LinkOut - more resources