Adhesin–receptor interactions in Pasteurellaceae

Jacques, Mario

doi:10.1016/s0168-6445(98)00007-2

Cited by 34 publications

(34 citation statements)

References 107 publications

(108 reference statements)

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“…Analogous interactions with animal cell receptors have been proposed as part of the activity of LPS in certain bacterial pathogens (21). In developing nodules these interactions might direct the targeting of machinery for membrane growth to the sites at which the bacteria impinge directly on the plant plasma membrane, including the site at which the infection thread is initiated (5) and, later, the tip of the infection thread (30).…”

Section: Discussionmentioning

confidence: 99%

Varying the Abundance of O Antigen in Rhizobium etli and Its Effect on Symbiosis with Phaseolus vulgaris

2000

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Judged by migration of its lipopolysaccharide (LPS) in gel electrophoresis, the O antigen of Rhizobium etli mutant strain CE166 was apparently of normal size. However, its LPS sugar composition and staining of the LPS bands after electrophoresis indicated that the proportion of its LPS molecules that possessed O antigen was only 40% of the wild-type value. Its LPS also differed from the wild type by lacking quinovosamine (2-amino-2,6-dideoxyglucose). Both of these defects were due to a single genetic locus carrying a Tn5 insertion. The deficiency in O-antigen amount, but not the absence of quinovosamine, was suppressed by transferring into this strain recombinant plasmids that shared a 7.8-kb stretch of the R. etli CE3 lps genetic region ␣, even though this suppressing DNA did not carry the genetic region mutated in strain CE166. Strain CE166 gave rise to pseudonodules on legume host Phaseolus vulgaris, whereas the mutant suppressed by DNA from lps region ␣ elicited nitrogen-fixing nodules. However, the nodules in the latter case developed slowly and were widely dispersed. Two other R. etli mutants that had one-half or less of the normal amount of O antigen also gave rise to pseudonodules on P. vulgaris. The latter strains were mutated in lps region ␣ and could be restored to normal LPS content and normal symbiosis by complementation with wild-type DNA from this region. Hence, the symbiotic role of LPS requires near-normal abundance of O antigen and may require a structural feature conferred by quinovosamine.Rhizobium etli bacteria induce bean plants to form root nodules in which they fix nitrogen. As nodules develop, the bacteria penetrate to interior plant cell layers by means of an infection thread, in which a linear bacterial colony is surrounded by a tubular wall and plant plasma membrane that separates the bacteria from plant cytoplasm (24).Mutants of R. etli that lack the O-antigen portion of the lipopolysaccharide (LPS) are defective in infection (6,10,30,35). Fewer nodules are elicited by such mutants per region of susceptible root, and in the nodules that are formed, very few bacteria can be recovered. Microscopic examination reveals that the infection threads in these nodules are distended and cease development within the root hair or the subjacent cell layer (35). Closely resembling the development of nodules elicited by mutants that do not infect at all (46), the resulting nodule structure lacks most features of a normal mature nodule and has been described as a pseudonodule (27,35). Oantigen-deficient mutants of Rhizobium leguminosarum and Bradyrhizobium japonicum also exhibit defects in infection and cause aberrant development of nodules on their respective host legumes (4,12,22,23,37,38,39,44).Although these studies demonstrate that the presence of O antigen is important in the symbiosis, the specific structural features that are required are still not established (30). However, there is evidence that addresses the question of how much O antigen each bacterium must possess in order to be symbioti...

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Section: Discussionmentioning

confidence: 99%

Varying the Abundance of O Antigen in Rhizobium etli and Its Effect on Symbiosis with Phaseolus vulgaris

2000

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“…LPS is referred to as an endotoxin and is associated with virulence. In particular, the O-antigen polysaccharide is important for host virulence since it is known to play roles in host cell adhesion (Jacques 1996;Jacques and Paradis 1998;Edwards et al 2000), resistance to phagocytes (Liang-Takasaki et al 1982), and resistance to host immune responses and surveillance (Liang-Takasaki et al 1983;Jimenez-Lucho et al 1987;Moran et al 1996;Rietschel et al 1996). Both R. insecticola strains possess similar gene sets with respect to biosynthesis of Lipid A and the core polysaccharide.…”

Section: Endotoxinsmentioning

confidence: 99%

Genomic basis of endosymbiont-conferred protection against an insect parasitoid

Hansen¹,

Vorburger²,

Moran³

2011

Genome Res.

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Bacterial endosymbionts exert a variety of beneficial effects on insect hosts. In pea aphids (Acyrthosiphon pisum), several inherited endosymbiont species protect their hosts against parasitoid wasps, which are major natural enemies. However, strains of these symbiont species vary in their ability to confer protection against parasitoids, with some conferring almost complete protection and others conferring almost none. In this study, two strains of the endosymbiont Regiella insecticola (R. insecticola 5.15 and R. insecticola LSR1) were found to differ in ability to protect pea aphids attacked by the parasitoid Aphidius ervi. Parasitism trials reveal that R. insecticola 5.15, but not R. insecticola LSR1, significantly reduced parasitoid success and increased aphid survivorship. To address the potential genetic basis of protection conferred by R. insecticola 5.15 we sequenced the genome of this symbiont strain, and then compared its gene repertoire with that of the already sequenced nonprotective strain R. insecticola LSR1. We identified striking differences in gene sets related to eukaryote pathogenicity. The protective strain R. insecticola 5.15 encoded five categories of pathogenicity factors that were missing or inactivated in R. insecticola LSR1. These included genes encoding the O-antigen biosynthetic pathway, an intact Type 1 Secretion System and its secreted RTX toxins, an intact SPI-1 Type 3 Secretion System and its effectors, hemin transport, and the twocomponent system PhoPQ. These five pathogenicity factors and translocation systems are hypothesized to collectively play key roles in the endosymbiont's virulence against parasitoids, resulting in aphid protection. Mechanisms through which these factors may target parasitoids are discussed.

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“…Fifteen serotypes of A. pleuropneumoniae based on capsular antigens have been identified, and the most predominant in Quebec, Canada, are serotypes 1, 5, and 7 (4). Among the many virulence factors of A. pleuropneumoniae, namely the RTX (repeats-in-toxin) toxins (5), the capsule, and the outer membrane proteins (6 -8), the lipopolysaccharides (LPS), 2 are known to be important, because of their involvement in the adhesion to host cells (9,10), and are also known to play a role in the stimulation of the host immune system. LPS are complex molecules composed of the following three well defined regions: (i) lipid A, anchored in the outer membrane; (ii) the core oligosaccharide containing 2-keto-3-deoxyoctulosonic acid (Kdo) and heptose residues; and (iii) the O-antigen, which is a polysaccharide consisting of repeating units.…”

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confidence: 99%

Truncation of the Lipopolysaccharide Outer Core Affects Susceptibility to Antimicrobial Peptides and Virulence of Actinobacillus pleuropneumoniae Serotype 1

Ramjeet

Deslandes

Michael

et al. 2005

Journal of Biological Chemistry

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We reported previously that the core oligosaccharide region of the lipopolysaccharide (LPS) is essential for optimal adhesion of Actinobacillus pleuropneumoniae, an important swine pathogen, to respiratory tract cells. Rough LPS and core LPS mutants of A. pleuropneumoniae serotype 1 were generated by using a mini-Tn10 transposon mutagenesis system. Here we performed a structural analysis of the oligosaccharide region of three core LPS mutants that still produce the same O-antigen by using methylation analyses and mass spectrometry. We also performed a kinetic study of proinflammatory cytokines production such as interleukin (IL)-6, tumor necrosis factor-␣, IL1-␤, MCP-1, and IL8 by LPS-stimulated porcine alveolar macrophages, which showed that purified LPS of the parent strain, the rough LPS and core LPS mutants, had the same ability to stimulate the production of cytokines. Most interestingly, an in vitro susceptibility test of these LPS mutants to antimicrobial peptides showed that the three core LPS mutants were more susceptible to cationic peptides than both the rough LPS mutant and the wild type parent strain. Furthermore, experimental pig infections with these mutants revealed that the galactose (Gal I) and D,D-heptose (Hep IV) residues present in the outer core of A. pleuropneumoniae serotype 1 LPS are important for adhesion and overall virulence in the natural host, whereas deletion of the terminal GalNAc-Gal II disaccharide had no effect. Our data suggest that an intact core-lipid A region is required for optimal protection of A. pleuropneumoniae against cationic peptides and that deletion of specific residues in the outer LPS core results in the attenuation of the virulence of A. pleuropneumoniae serotype 1.

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Adhesin–receptor interactions in Pasteurellaceae

Cited by 34 publications

References 107 publications

Varying the Abundance of O Antigen in Rhizobium etli and Its Effect on Symbiosis with Phaseolus vulgaris

Varying the Abundance of O Antigen in Rhizobium etli and Its Effect on Symbiosis with Phaseolus vulgaris

Genomic basis of endosymbiont-conferred protection against an insect parasitoid

Truncation of the Lipopolysaccharide Outer Core Affects Susceptibility to Antimicrobial Peptides and Virulence of Actinobacillus pleuropneumoniae Serotype 1

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