Structural elucidation of the viscous exopolysaccharide produced by Lactobacillus helveticus Lb161

Staaf, Mikael; Yang, Zhennai; Huttunen, Eine; Widmalm, Göran

doi:10.1016/s0008-6215(00)00027-6

Cited by 46 publications

(19 citation statements)

References 22 publications

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“…It is not unreasonable to assume that this enzyme has functions other than galactose metabolism and that the other functions are essential for cell viability. In different L. helveticus strains extracellular polysaccharides composed of D-glucose and D-galactose have been found (21,26). Thus, in L. helveticus, as in other organ- on May 12, 2018 by guest http://aem.asm.org/ isms, the galE product could be involved in preparation of carbohydrate residues for incorporation into complex polymers, such as exopolysaccharides.…”

Section: Resultsmentioning

confidence: 99%

Unusual Organization for Lactose and Galactose Gene Clusters in Lactobacillus helveticus

Fortina

Ricci

Mora

et al. 2003

Appl Environ Microbiol

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The nucleotide sequences of the Lactobacillus helveticus lactose utilization genes were determined, and these genes were located and oriented relative to one another. The lacLM genes (encoding the ␤-galactosidase protein) were in a divergent orientation compared to lacR (regulatory gene) and lacS (lactose transporter). Downstream from lacM was an open reading frame (galE) encoding a UDP-galactose 4 epimerase, and the open reading frame had the same orientation as lacM. The lacR gene was separated from the downstream lacS gene by 2.0 kb of DNA containing several open reading frames that were derived from fragmentation of another permease gene (lacS). Northern blot analysis revealed that lacL, lacM, and galE made up an operon that was transcribed in the presence of lactose from an upstream lacL promoter. The inducible genes lacL and lacM were regulated at the transcriptional level by the LacR repressor. In the presence of glucose and galactose galE was transcribed from its promoter, suggesting that the corresponding enzyme can be expressed constitutively. Lactose transport was inducible by addition of lactose to the growth medium.The bioconversion of lactose into lactic acid is one of the principal metabolic events for which lactic acid bacteria (LAB) are employed in the dairy industry. During growth in milk good starter cultures produce lactic acid rapidly and reliably; thus, LAB viability depends on the ability of LAB to metabolize lactose. Today, due to recent developments in molecular biology applications, it is possible to improve existing fermentation processes by enhancing specific metabolic fluxes. Needless to say, doing this requires detailed metabolic and/or genetic knowledge.Genetic studies of the metabolic pathways for lactose utilization in the gram-positive LAB have revealed a variety of lac operons. In lactococci and some Lactobacillus casei strains (11,22,28) lactose transport and hydrolysis depend on a phosphoenolpyruvate-dependent phosphotransferase system combined with phospho-␤-galactosidase, and the relevant genes are plasmid encoded. A lactose permease system in which a ␤-galactosidase catalyzes sugar cleavage is the characteristic system of lactose uptake and hydrolysis found in Streptococcus thermophilus (10,19), Lactobacillus bulgaricus (14), and Leuconostoc lactis (5, 33). The lac genes of S. thermophilus and L. bulgaricus are located chromosomally, whereas in Leuconostoc lactis a plasmid codes for ␤-galactosidase. Moreover, it is possible to find within a species (e.g., Lactococcus lactis or L. bulgaricus) some strains that have both ␤-galactosidase and phospho-␤-galactosidase activities (11).Also, the genomic organization of lac clusters and the gene order can vary. In S. thermophilus and L. bulgaricus the lactose transport genes (lacS) are organized like an operon, and the ␤-galactosidase genes (lacZ) are downstream (14). In Leuconostoc lactis (5) and Lactobacillus sake (17) the ␤-galactosidase is encoded by two partially overlapping genes, lacL and lacM, and no operon-like organizatio...

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Section: Resultsmentioning

confidence: 99%

Unusual Organization for Lactose and Galactose Gene Clusters in Lactobacillus helveticus

Fortina

Ricci

Mora

et al. 2003

Appl Environ Microbiol

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“…We found evidence for partial acetylation of both EPS-1 (at multiple sites) and EPS-2 (at a single site), although we did not establish the precise location of the substituents. O -Acetylation of bacterial EPS is frequently reported in both lactic acid bacteria (37–40) and others, including Klebsiella aerogenes , E. coli O8:K27, and the plant pathogen Pseudomonas flavescens (41–43). Acetylation can alter the physical properties of the EPS, giving, for example, increased viscosity in solution.…”

Section: Discussionmentioning

confidence: 99%

Structure and Biosynthesis of Two Exopolysaccharides Produced by Lactobacillus johnsonii FI9785

Dertli

Colquhoun²,

Gunning

et al. 2013

Journal of Biological Chemistry

106

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Background: Bacterial cell surface polysaccharides are important in pathogenesis, cell adhesion, and protection against harsh environments.Results: Two novel exopolysaccharide (EPS) structures were identified in Lactobacillus johnsonii.Conclusion: The eps cluster is essential for production of both EPS, but epsE is required only for the heteropolymer.Significance: This study will guide functional analysis of EPS in survival and colonization of gut commensals.

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“…Bacterial exopolysaccharides have been used as thickeners, stabilizers, and gelling agents. 3 To improve these properties, attention has been paid to the engineering of polysaccharide structures via chemical 4 or enzymatic derivatizations [5][6][7] and by genetic modification of source micro-organisms. 8,9 Recently, a family of glucansucrases was discovered in Lactobacillus reuteri, which converts sucrose into large, heavily branched R-D-glucans.…”

Section: Introductionmentioning

confidence: 99%

Structural Analysis of Bioengineered α-d-Glucan Produced by a Triple Mutant of the Glucansucrase GTF180 Enzyme from Lactobacillus reuteri Strain 180: Generation of (α1→4) Linkages in a Native (1→3)(1→6)-α-d-Glucan

et al. 2008

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Site-directed mutagenesis of the glucansucrase gtf180 gene from Lactobacillus reuteri strain 180 was used to transform the active site region. The R-D-glucan (mEPS-PNNS) produced by the triple mutant V1027P:S1137N: A1139S differed in structure from that of the wild-type R-D-glucan (EPS180). Besides (R1f3) and (R1f6) linkages, as present in EPS180, mEPS-PNNS also contained (R1f4) linkages. Linkage analysis, periodate oxidation, and 1D/2D 1 H NMR spectroscopy of the intact mEPS-PNNS, as well as MS and NMR analysis of oligosaccharides obtained by partial acid hydrolysis of mEPS-PNNS afforded a composite model, which includes all identified structural features.

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Structural elucidation of the viscous exopolysaccharide produced by Lactobacillus helveticus Lb161

Cited by 46 publications

References 22 publications

Unusual Organization for Lactose and Galactose Gene Clusters in Lactobacillus helveticus

Unusual Organization for Lactose and Galactose Gene Clusters in Lactobacillus helveticus

Structure and Biosynthesis of Two Exopolysaccharides Produced by Lactobacillus johnsonii FI9785

Structural Analysis of Bioengineered α-d-Glucan Produced by a Triple Mutant of the Glucansucrase GTF180 Enzyme from Lactobacillus reuteri Strain 180: Generation of (α1→4) Linkages in a Native (1→3)(1→6)-α-d-Glucan

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