The Sinorhizobium meliloti ExpE1 protein secreted by a type I secretion system involving ExpD1 and ExpD2 is required for biosynthesis or secretion of the exopolysaccharide galactoglucan

Moreira, Leonilde M.; Becker, Jörg; Pühler, Alfred; Becker, Anke

doi:10.1099/00221287-146-9-2237

Cited by 25 publications

(8 citation statements)

References 53 publications

(57 reference statements)

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“…1, Supplementary Table S1) required for the formation of O-antigens [41]. The putative biofilm-plasmid contains, for example, the complete rhamnose operon [13] and an operon with a type I secretion polysaccharide export system (YP 006564766, YP 006564765; [24]) followed by three genes for the conversion of d-mannose-1-phosphate into GDP-l-fucose (YP 006564764 to YP 006564762). In rhizobia, where biofilm formation is essential for the efficient colonization of root surfaces and nodulation [6,11], a homolog of the Phaeobacter UDP-glucose 6-dehydrogenase (YP 006564778) is required for O-antigen lipopolysaccharide (LPS) and K-antigen capsular polysaccharide (KPS) biosynthesis, as recently shown by knock-out analyses in Rhizobium rhizogenes K84 [1].…”

Section: Resultsmentioning

confidence: 99%

Plasmid curing and the loss of grip – The 65-kb replicon of Phaeobacter inhibens DSM 17395 is required for biofilm formation, motility and the colonization of marine algae

Frank

Michael

Päuker

et al. 2015

Systematic and Applied Microbiology

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Section: Resultsmentioning

confidence: 99%

Plasmid curing and the loss of grip – The 65-kb replicon of Phaeobacter inhibens DSM 17395 is required for biofilm formation, motility and the colonization of marine algae

Frank

Michael

Päuker

et al. 2015

Systematic and Applied Microbiology

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“…Another phenotype shown by the S. meliloti tolC mutant was absence of exopolysaccharides succinoglycan and galactoglucan from the culture supernatant [15]. Absence of galactoglucan in the tolC mutant is explained by the lack of WgeA protein secretion [16], but the contribution of TolC to succinoglycan production is so far not understood. Several phenotypes displayed by the S. meliloti tolC mutant strain illustrated the wide importance of this outer membrane protein to cellular functions.…”

Section: Introductionmentioning

confidence: 99%

Absence of functional TolC protein causes increased stress response gene expression in Sinorhizobium meliloti

et al. 2010

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BackgroundThe TolC protein from Sinorhizobium meliloti has previously been demonstrated to be required for establishing successful biological nitrogen fixation symbiosis with Medicago sativa. It is also needed in protein and exopolysaccharide secretion and for protection against osmotic and oxidative stresses. Here, the transcriptional profile of free-living S. meliloti 1021 tolC mutant is described as a step toward understanding its role in the physiology of the cell.ResultsComparison of tolC mutant and wild-type strains transcriptomes showed 1177 genes with significantly increased expression while 325 had significantly decreased expression levels. The genes with an increased expression suggest the activation of a cytoplasmic and extracytoplasmic stress responses possibly mediated by the sigma factor RpoH1 and protein homologues of the CpxRA two-component regulatory system of Enterobacteria, respectively. Stress conditions are probably caused by perturbation of the cell envelope. Consistent with gene expression data, biochemical analysis indicates that the tolC mutant suffers from oxidative stress. This is illustrated by the elevated enzyme activity levels detected for catalase, superoxide dismutase and glutathione reductase. The observed increase in the expression of genes encoding products involved in central metabolism and transporters for nutrient uptake suggests a higher metabolic rate of the tolC mutant. We also demonstrated increased swarming motility in the tolC mutant strain. Absence of functional TolC caused decreased expression mainly of genes encoding products involved in nitrogen metabolism and transport.ConclusionThis work shows how a mutation in the outer membrane protein TolC, common to many bacterial transport systems, affects expression of a large number of genes that act in concert to restore cell homeostasis. This finding further underlines the fundamental role of this protein in Sinorhizobium meliloti biology.

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“…Some homologous genes occur on plasmids in several other Roseobacter clade members (Kalhoefer et al, 2011); however, some genes are P. gallaeciensis unique (Supplementary Material S7). These include a glycosyltransferase-like protein (PGA1_65p00370), putatively involved in polysaccharide biosynthesis, and two ORFs (PGA1_65p00320 and 65p00330) related to a type I secretion system, which is known to export exopolysaccharides in S. meliloti (Moreira et al, 2000). Moreover, gene clusters were found that share homology with some rkp genes of S. meliloti (Supplementary Material S9), which are required for production and export of capsular polysaccharides (Kereszt et al, 1998).…”

Section: Attachment To and Interaction With Surfacesmentioning

confidence: 99%

Phaeobacter gallaeciensis genomes from globally opposite locations reveal high similarity of adaptation to surface life

et al. 2012

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Phaeobacter gallaeciensis, a member of the abundant marine Roseobacter clade, is known to be an effective colonizer of biotic and abiotic marine surfaces. Production of the antibiotic tropodithietic acid (TDA) makes P. gallaeciensis a strong antagonist of many bacteria, including fish and mollusc pathogens. In addition to TDA, several other secondary metabolites are produced, allowing the mutualistic bacterium to also act as an opportunistic pathogen. Here we provide the manually annotated genome sequences of the P. gallaeciensis strains DSM 17395 and 2.10, isolated at the Atlantic coast of north western Spain and near Sydney, Australia, respectively. Despite their isolation sites from the two different hemispheres, the genome comparison demonstrated a surprisingly high level of synteny (only 3% nucleotide dissimilarity and 88% and 93% shared genes). Minor differences in the genomes result from horizontal gene transfer and phage infection. Comparison of the P. gallaeciensis genomes with those of other roseobacters revealed unique genomic traits, including the production of iron-scavenging siderophores. Experiments supported the predicted capacity of both strains to grow on various algal osmolytes. Transposon mutagenesis was used to expand the current knowledge on the TDA biosynthesis pathway in strain DSM 17395. This first comparative genomic analysis of finished genomes of two closely related strains belonging to one species of the Roseobacter clade revealed features that provide competitive advantages and facilitate surface attachment and interaction with eukaryotic hosts.

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The Sinorhizobium meliloti ExpE1 protein secreted by a type I secretion system involving ExpD1 and ExpD2 is required for biosynthesis or secretion of the exopolysaccharide galactoglucan

Cited by 25 publications

References 53 publications

Plasmid curing and the loss of grip – The 65-kb replicon of Phaeobacter inhibens DSM 17395 is required for biofilm formation, motility and the colonization of marine algae

Plasmid curing and the loss of grip – The 65-kb replicon of Phaeobacter inhibens DSM 17395 is required for biofilm formation, motility and the colonization of marine algae

Absence of functional TolC protein causes increased stress response gene expression in Sinorhizobium meliloti

Phaeobacter gallaeciensis genomes from globally opposite locations reveal high similarity of adaptation to surface life

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