Periplasmic glucans of Pseudomonas syringae pv. syringae

Talaga, Philippe; Fournet, Bernard; Bohin, Jean-Pierre

doi:10.1128/jb.176.21.6538-6544.1994

Cited by 56 publications

(44 citation statements)

References 39 publications

(39 reference statements)

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“…In Escherichia coli, the backbone, containing 7 to 13 glucose units, is substituted with phosphoglycerol, phosphoethanolamine, and succinyl residues (19). In Erwinia chrysanthemi, the backbone contains 5 to 12 glucose units substituted with succinyl and acetyl residues (9), and in Pseudomonas syringae, the backbone, consisting of 6 to 13 glucose units, is not substituted (38). In E. coli, the OPG backbone is synthesized by the products of the mdoGH operon located in the vicinity of pyrC, a gene involved in the biosynthesis of uracil (6).…”

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Osmoregulated Periplasmic Glucan Synthesis Is Required for Erwinia chrysanthemi Pathogenicity

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Hugouvieux‐Cotte‐Pattat

et al. 2001

J Bacteriol

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Erwinia chrysanthemi is a phytopathogenic enterobacterium causing soft rot disease in a wide range of plants. Osmoregulated periplasmic glucans (OPGs) are intrinsic components of the gram-negative bacterial envelope. We cloned the opgGH operon of E. chrysanthemi, encoding proteins involved in the glucose backbone synthesis of OPGs, by complementation of the homologous locus mdoGH of Escherichia coli. OpgG and OpgH show a high level of similarity with MdoG and MdoH, respectively, and mutations in the opgG or opgH gene abolish OPG synthesis. The opg mutants exhibit a pleiotropic phenotype, including overproduction of exopolysaccharides, reduced motility, bile salt hypersensitivity, reduced protease, cellulase, and pectate lyase production, and complete loss of virulence. Coinoculation experiments support the conclusion that OPGs present in the periplasmic space of the bacteria are necessary for growth in the plant host.Osmoregulated periplasmic glucans (OPGs) are a family of oligosaccharides found in the periplasmic space of gram-negative bacteria. Their two common features are the presence of glucose as the sole constituent sugar and their increased level in media of low osmolarity (5).Members of the family Enterobacteriaceae and related bacteria synthesize a family of linear and branched OPGs that are variously substituted. The linear backbone is constituted by glucose units joined by ␤,1-2 linkages, and the branches are made of one glucose unit linked to the main chain by a ␤,1-6 linkage. In Escherichia coli, the backbone, containing 7 to 13 glucose units, is substituted with phosphoglycerol, phosphoethanolamine, and succinyl residues (19). In Erwinia chrysanthemi, the backbone contains 5 to 12 glucose units substituted with succinyl and acetyl residues (9), and in Pseudomonas syringae, the backbone, consisting of 6 to 13 glucose units, is not substituted (38). In E. coli, the OPG backbone is synthesized by the products of the mdoGH operon located in the vicinity of pyrC, a gene involved in the biosynthesis of uracil (6). In this bacterium, the defect in OPG synthesis does not confer an easily selectable phenotype in laboratory conditions. Thus, the mdoGH locus was cloned using the linked selectable genetic marker pyrC (23).Many factors are involved in the virulence of pathogenic bacteria, and OPGs appear to be among them. In P. syringae pv. syringae, the causal agent of brown spot disease of the common bean (Phaseolus vulgaris), the hrpM mutant, obtained after transposon mutagenesis, was isolated because it failed to incite disease on the host plant and to cause the hypersensitive reaction on a non-host plant such as tobacco (29). The hrpM mutant does not synthesize OPGs, and the hrpM locus complements the OPG synthesis defect of the mdoH200::Tn10 mutant of E. coli. The amino acid sequences of HrpM and MdoH are 75.5% identical and 87.5% similar (25). More recently, a transposon insertion in a gene similar to hrpM/mdoH was isolated because it severely reduces the virulence in Pseudomonas aeruginosa PA14, an opp...

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Osmoregulated Periplasmic Glucan Synthesis Is Required for Erwinia chrysanthemi Pathogenicity

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Hugouvieux‐Cotte‐Pattat

et al. 2001

J Bacteriol

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“…However, beyond this functional homology, the OPGs synthesized by these different bacteria are very different in structure. The OPGs of S. meliloti and A. tumefaciens are cyclic structures of family II that may be modified with anionic substituents such as phosphoglycerol and/or succinyl moieties (5), the OPGs of B. japonicum are cyclic structures of family III that may be modified by substitution with phosphocholine (18), while the OPGs of P. syringae are linear and highly branched and devoid of any substituents (24).…”

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Osmoregulated Periplasmic Glucans of Erwinia chrysanthemi

et al. 2001

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OPGs were isolated by trichloracetic acid treatment and gel permeation chromatography. The synthesis of these compounds appeared to be osmoregulated, since lower amounts of OPGs were produced when bacteria were grown in media of higher osmolarities. However, a large fraction of these OPGs were recovered in the culture medium. Then, these compounds were characterized by compositional analysis, high-performance anion-exchange chromatography, matrix-assisted laser desorption mass spectrometry, and 1 H and 13 C nuclear magnetic resonance analyses. OPGs produced by E. chrysanthemi are very heterogeneous at the level of both backbone structure and substitution of these structures. The degree of polymerization of the glucose units ranges from 5 to 12. The structures are branched, with a linear backbone consisting of ␤-1,2-linked glucose units to which a variable number of branches, composed of one glucose residue, are attached by ␤-1,6 linkages in a random way. This glucan backbone may be substituted by O-acetyl and O-succinyl ester-linked residues.Osmoregulated periplasmic glucans (OPGs) are general constituents of the envelopes of gram-negative bacteria (4). Glucose is the sole constitutive sugar, and their abundance in the periplasmic compartment is osmoregulated, with the highest levels synthesized during growth at very low osmolarity. Four families of OPGs have been described on the basis of structural features of the polyglucose backbone. In family I, OPGs appear to range from 5 to 12 glucose residues, with the principal species containing 8 or 9 glucose residues. The structure is highly branched, the backbone consisting of ␤-1,2-linked glucose units to which the branches are attached by ␤-1,6 linkages. In family II, OPGs are composed of a cyclic ␤-1,2-glucan backbone containing 17 to 25 glucose residues. In family III, OPGs are ␤-1,6 and ␤-1,3 cyclic glucans containing 10 to 13 glucose units per ring. In family IV, OPGs are cyclic and have a unique degree of polymerization (DP, ϭ 13, 16, or 18). One linkage is ␣-1,6 whereas all the other glucose residues are linked by ␤-1,2 linkages. Depending on the species considered, OPGs can be modified to various extents by a variety of substituents. Mutations at the loci ndvA and ndvB in Sinorhizobium meliloti (8), ndvB and ndvC in Bradyrhizobium japonicum (3), chvA and chvB in Agrobacterium tumefaciens (17), and hrpM in Pseudomonas syringae (11, 13) impair OPG biosynthesis, and these mutants fail to interact properly with a host plant as a symbiont or a pathogen. However, beyond this functional homology, the OPGs synthesized by these different bacteria are very different in structure. The OPGs of S. meliloti and A. tumefaciens are cyclic structures of family II that may be modified with anionic substituents such as phosphoglycerol and/or succinyl moieties (5), the OPGs of B. japonicum are cyclic structures of family III that may be modified by substitution with phosphocholine (18), while the OPGs of P. syringae are linear and highly branched and devoid of any substituents...

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“…Of the species of bacteria examined in this report that had active acyl carrier proteins, only P. syringae was found to have a membrane glucosyltransferase by direct assay. Indeed, the genetic and product analysis of Bohin and colleagues (20,36) had already anticipated this result. In the evolutionary grouping of Olsen et al (25), P. syringae is found in the branch most closely connected to that of E. coli (the ␥-3 subgroup).…”

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“…Membrane-derived oligosaccharides have so far been found only in members of the ␥ subgroup that are very closely related to E. coli (33,36). Are periplasmic glucans that are similar to membrane-derived oligosaccharides found in less closely related purple bacteria?…”

Section: Vol 179 1997 Acyl Carrier Protein Structure 3701mentioning

confidence: 99%

“…Periplasmic glucans that are similar in structure and also are synthesized in response to environments of low osmolarity have been identified in the enteric bacteria that are closely related to E. coli (33) and, more recently, in the plant pathogen Pseudomonas syringae (36). In P. syringae, an open reading frame of the hrpM locus that is involved in bacterial pathogenicity and the hypersensitivity response of plants (23) has a deduced protein sequence that bears a striking similarity to the deduced sequence of the protein encoded by the mdoH gene of E. coli (20).…”

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Domains of Escherichia coli acyl carrier protein important for membrane-derived-oligosaccharide biosynthesis

1997

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Acyl carrier protein participates in a number of biosynthetic pathways in Escherichia coli: fatty acid biosynthesis, phospholipid biosynthesis, lipopolysaccharide biosynthesis, activation of prohemolysin, and membrane-derived oligosaccharide biosynthesis. The first four pathways require the protein's prosthetic group, phosphopantetheine, to assemble an acyl chain or to transfer an acyl group from the thioester linkage to a specific substrate. By contrast, the phosphopantetheine prosthetic group is not required for membranederived oligosaccharide biosynthesis, and the function of acyl carrier protein in this biosynthetic scheme is currently unknown. We have combined biochemical and molecular biological approaches to investigate domains of acyl carrier protein that are important for membrane-derived oligosaccharide biosynthesis. Proteolytic removal of the first 6 amino acids from acyl carrier protein or chemical synthesis of a partial peptide encompassing residues 26 to 50 resulted in losses of secondary and tertiary structure and consequent loss of activity in the membrane glucosyltransferase reaction of membrane-derived oligosaccharide biosynthesis. These peptide fragments, however, inhibited the action of intact acyl carrier protein in the enzymatic reaction. This suggests a role for the loop regions of the E. coli acyl carrier protein and the need for at least two regions of the protein for participation in the glucosyltransferase reaction. We have purified acyl carrier protein from eight species of Proteobacteria (including representatives from all four subgroups) and characterized the proteins as active or inhibitory in the membrane glucosyltransferase reaction. The complete or partial amino acid sequences of these acyl carrier proteins were determined. The results of site-directed mutagenesis to change amino acids conserved in active, and altered in inactive, acyl carrier proteins suggest the importance of residues Glu-4, Gln-14, Glu-21, and Asp-51. The first 3 of these residues define a face of acyl carrier protein that includes the beginning of the loop region, residues 16 to 36. Additionally, screening for membrane glucosyltransferase activity in membranes from bacterial species that had acyl carrier proteins that were active with E. coli membranes revealed the presence of glucosyltransferase activity only in the species most closely related to E. coli. Thus, it seems likely that only bacteria from the Proteobacteria subgroup ␥-3 have periplasmic glucans synthesized by the mechanism found in E. coli.Acyl carrier protein of Escherichia coli is a small (77-aminoacid) acidic protein that plays an essential role in several biosynthetic pathways: fatty acid biosynthesis (reviewed in reference 39), phospholipid biosynthesis (reviewed in reference 3), lipopolysaccharide biosynthesis (reviewed in reference 28), and activation of prohemolysin (11). All of these functions require the presence of the phosphopantetheine prosthetic group on serine 36 of acyl carrier protein. The terminal thiol on this prosthetic grou...

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Periplasmic glucans of Pseudomonas syringae pv. syringae

Cited by 56 publications

References 39 publications

Osmoregulated Periplasmic Glucan Synthesis Is Required for Erwinia chrysanthemi Pathogenicity

Osmoregulated Periplasmic Glucan Synthesis Is Required for Erwinia chrysanthemi Pathogenicity

Osmoregulated Periplasmic Glucans of Erwinia chrysanthemi

Domains of Escherichia coli acyl carrier protein important for membrane-derived-oligosaccharide biosynthesis

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