Homology between a genetic locus (mdoA) involved in the osmoregulated biosynthesis of periplasmic glucans in Escherichia coli and a genetic locus (hrpM) controlling pathogenicity of Pseudomonas syringae

Loubens, Isabelle; Debarbieux, Laurent; Bohin, Anne; Lacroix, Jean-Marie; Bohin, Jean-Pierre

doi:10.1111/j.1365-2958.1993.tb01959.x

Cited by 77 publications

(79 citation statements)

References 65 publications

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“…opg (or mdo) mutants have been associated with a lack of virulence in phythopathogenic bacteria such as Pseudomonas syringae and Er. chrysanthemi (Loubens et al, 1993;Mukhopadhyay et al, 1988;Page et al, 2001). Unlike the tol-pal mutants, the opgGH mutants show a complete loss of virulence, even on potato tubers, but present some phenotypes similar to those observed for the tol-pal mutants, namely reduced motility and pectate lyase production (Page et al, 2001).…”

Section: Discussionmentioning

confidence: 95%

Tol-Pal proteins are critical cell envelope components of Erwinia chrysanthemi affecting cell morphology and virulence

Dubuisson

Vianney

Hugouvieux‐Cotte‐Pattat

et al. 2005

Microbiology

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The tol-pal genes are necessary for maintaining the outer-membrane integrity of Gram-negative bacteria. These genes were first described in Escherichia coli, and more recently in several other species. They are involved in the pathogenesis of E. coli, Haemophilus ducreyi, Vibrio cholerae and Salmonella enterica. The role of the tol-pal genes in bacterial pathogenesis was investigated in the phytopathogenic enterobacterium Erwinia chrysanthemi, assuming that this organism might be a good model for such a study. The whole Er. chrysanthemi tol-pal region was characterized. Tol-Pal proteins, except TolA, showed high identity scores with their E. coli homologues. Er. chrysanthemi mutants were constructed by introducing a uidA-kan cassette in the ybgC, tolQ, tolA, tolB, pal and ybgF genes. All the mutants were hypersensitive to bile salts. Mutations in tolQ, tolA, tolB and pal were deleterious for the bacteria, which required high concentrations of sugars or osmoprotectants for their viability. Consistent with this observation, they were greatly impaired in their cell morphology and division, which was evidenced by observations of cell filaments, spherical forms, membrane blebbing and mislocalized bacterial septa. Moreover, tol-pal mutants showed a reduced virulence in a potato tuber model and on chicory leaves. This could be explained by a combination of impaired phenotypes in the tol-pal mutants, such as reduced growth and motility and a decreased production of pectate lyases, the major virulence factor of Er. chrysanthemi. INTRODUCTIONThe Tol-Pal system of Gram-negative bacteria is required for outer-membrane stability (Lazzaroni et al., 1999). It comprises five envelope proteins, TolQ, TolR, TolA, TolB and Pal, which form two complexes. The TolQ, TolR and TolA inner-membrane proteins interact via their transmembrane domains (Derouiche et al., 1995;Lazzaroni et al., 1995). The b-propeller domain of the periplasmic protein TolB is responsible for its interaction with Pal (Ray et al., 2000). TolB also interacts with the outer-membrane peptidoglycan-associated proteins Lpp and OmpA (Cascales et al., 2002;Clavel et al., 1998). TolA undergoes a conformational change in response to changes in the protonmotive force (Germon et al., 2001), and interacts with Pal in an energy-dependent manner (Cascales et al., 2001). The Cterminal periplasmic domain of TolA also interacts with the N-terminal domain of TolB (Dubuisson et al., 2002;Walburger et al., 2002).The transcriptional organization of the E. coli tol-pal genes has been characterized. The genes ybgC (orf1), tolQ, tolR, tolA and tolB, and pal and ybgF (orf2) form two operons (Muller & Webster, 1997); a large ybgC-ybgF transcript has also been postulated (Vianney et al., 1996). ybgC and ybgF encode proteins of unknown function located in the cytoplasm and the periplasm, respectively (Clavel et al., 1996;Sun & Webster, 1987). Inactivation of these two ORFs induces no obvious phenotype in E. coli. In contrast, mutations in the tol-pal genes cause the disruption of outermembr...

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Section: Discussionmentioning

confidence: 95%

Tol-Pal proteins are critical cell envelope components of Erwinia chrysanthemi affecting cell morphology and virulence

Dubuisson

Vianney

Hugouvieux‐Cotte‐Pattat

et al. 2005

Microbiology

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“…For example, the hrpM mutant of Pseudomonas syringae pv. syringae does not synthesize OPGs and loses its ability to cause brown spot disorder on common bean (Phaseolus vulgaris) (Loubens et al, 1993). P. aeruginosa contains gene homologues for linear and cyclic OPGs (Stover et al, 2000) and it has been shown that transcripts for (cyclic) OPG synthesis are stimulated in P. aeruginosa cells grown in biofilms (Mah et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Osmoregulated periplasmic glucans of Salmonella enterica serovar Typhimurium are required for optimal virulence in mice

et al. 2009

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We purified osmoregulated periplasmic glucans (OPGs) from Salmonella enterica serovar Typhimurium and found them to be composed of 100 % glucose with 2-linked glucose as the most abundant residue, with terminal glucose, 2,3-linked and 2,6-linked glucose also present in high quantities. The two structural genes for OPG biosynthesis, opgG and opgH, form a bicistronic operon, and insertion of a kanamycin resistance gene cassette into this operon resulted in a strain devoid of OPGs. The opgGH mutant strain was impaired in motility and growth under low osmolarity conditions. The opgGH mutation also resulted in a 2 log increase in the LD 50 in mice compared to the wild-type strain SL1344. Inability to synthesize OPGs had no significant impact on the organism's lipopolysaccharide pattern or its ability to survive antimicrobial peptides-, detergent-, pH-and nutrient-stress conditions. We observed that the opgGH-defective strain respired at a reduced rate under acidic growth conditions (pH 5.0) and had lower ATP levels compared to the wild-type strain. These data indicate that OPGs of S. Typhimurium contribute towards mouse virulence as well as growth and motility under low osmolarity growth conditions.

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“…In Enterobacteria and related bacteria, both products of the opgGH operon are required for synthesis of the glucose backbone of OPGs. opgG or opgH mutant strains are completely devoid of OPGs and exhibit a reduced or non-virulent phenotype, indicating that these glucans belong to the common virulence factors of many zoopathogens and phytopathogens (Loubens et al, 1993;Mahajan-Miklos et al, 1999;Page et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Inactivation of pecS restores the virulence of mutants devoid of osmoregulated periplasmic glucans in the phytopathogenic bacterium Dickeya dadantii

2014

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Dickeya dadantii is a phytopathogenic enterobacterium that causes soft rot disease in a wide range of plant species. Maceration, an apparent symptom of the disease, is the result of the synthesis and secretion of a set of plant cell wall-degrading enzymes (PCWDEs), but many additional factors are required for full virulence. Among these, osmoregulated periplasmic glucans (OPGs) and the PecS transcriptional regulator are essential virulence factors. Several cellular functions are controlled by both OPGs and PecS. Strains devoid of OPGs display a pleiotropic phenotype including total loss of virulence, loss of motility and severe reduction in the synthesis of PCWDEs. PecS is one of the major regulators of virulence in D. dadantii, acting mainly as a repressor of various cellular functions including virulence, motility and synthesis of PCWDEs. The present study shows that inactivation of the pecS gene restored virulence in a D. dadantii strain devoid of OPGs, indicating that PecS cannot be de-repressed in strains devoid of OPGs.

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Homology between a genetic locus (mdoA) involved in the osmoregulated biosynthesis of periplasmic glucans in Escherichia coli and a genetic locus (hrpM) controlling pathogenicity of Pseudomonas syringae

Cited by 77 publications

References 65 publications

Tol-Pal proteins are critical cell envelope components of Erwinia chrysanthemi affecting cell morphology and virulence

Tol-Pal proteins are critical cell envelope components of Erwinia chrysanthemi affecting cell morphology and virulence

Osmoregulated periplasmic glucans of Salmonella enterica serovar Typhimurium are required for optimal virulence in mice

Inactivation of pecS restores the virulence of mutants devoid of osmoregulated periplasmic glucans in the phytopathogenic bacterium Dickeya dadantii

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