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Abstract
Among all the systems developed by enterobacteria to face osmotic stress, only osmoregulated periplasmic glucans (OPGs) were found to be modulated during osmotic fluxes. First detected in 1973 by E.P. Kennedy's group in a study of phospholipid turnover in Escherichia coli, OPGs have been shown across alpha, beta, and gamma subdivisions of the proteobacteria. Discovery of OPG-like compounds in the epsilon subdivision strongly suggested that the presence of periplasmic glucans is essential for almost all proteobacteria. This article offers an overview of the different classes of OPGs. Then, the biosynthesis of OPGs and their regulation in E. coli and other species are discussed. Finally, the biological role of OPGs is developed. Beyond structural function, OPGs are involved in pathogenicity, in particular, by playing a role in signal transduction pathways. Recently, OPG synthesis proteins have been suggested to control cell division and growth rate.
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Affiliation(s)
- Sébastien Bontemps-Gallo
- Univ. Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F 59000 Lille, France
| | - Jean-Pierre Bohin
- Univ. Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F 59000 Lille, France
| | - Jean-Marie Lacroix
- Univ. Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F 59000 Lille, France
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Bontemps-Gallo S, Madec E, Dondeyne J, Delrue B, Robbe-Masselot C, Vidal O, Prouvost AF, Boussemart G, Bohin JP, Lacroix JM. Concentration of osmoregulated periplasmic glucans (OPGs) modulates the activation level of the RcsCD RcsB phosphorelay in the phytopathogen bacteria Dickeya dadantii. Environ Microbiol 2012; 15:881-94. [PMID: 23253096 DOI: 10.1111/1462-2920.12054] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 11/14/2012] [Indexed: 11/26/2022]
Abstract
Osmoregulated periplasmic glucans (OPGs) are general constituents of many Proteobacteria. Synthesis of these oligosaccharides is repressed by increased osmolarity of the medium. OPGs are important factors required for full virulence in many zoo- or phytopathogens including Dickeya dadantii. The phytopathogen enterobacterium D. dadantii causes soft-rot disease on a wide range of plant species. The total loss of virulence of opg-negative strains of D. dadantii is linked to the constitutive activation of the RcsCD RcsB phosphorelay highlighting relationship between this phosphorelay and OPGs. Here we show that OPGs control the RcsCD RcsB activation in a concentration-dependent manner, are required for proper activation of this phosphorelay by medium osmolarity, and a high concentration of OPGs in planta is maintained to achieve the low level of activation of the RcsCD RcsB phosphorelay required for full virulence in D. dadantii.
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Affiliation(s)
- Sébastien Bontemps-Gallo
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, IFR 147, Université des Sciences et Technologies de Lille, 59655, Villeneuve d'Ascq, France
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Bouchart F, Boussemart G, Prouvost AF, Cogez V, Madec E, Vidal O, Delrue B, Bohin JP, Lacroix JM. The virulence of a Dickeya dadantii 3937 mutant devoid of osmoregulated periplasmic glucans is restored by inactivation of the RcsCD-RcsB phosphorelay. J Bacteriol 2010; 192:3484-90. [PMID: 20418397 PMCID: PMC2897653 DOI: 10.1128/jb.00143-10] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 04/14/2010] [Indexed: 11/20/2022] Open
Abstract
Dickeya dadantii is a pectinolytic phytopathogen enterobacterium that causes soft rot disease on a wide range of plant species. The virulence of D. dadantii involves several factors, including the osmoregulated periplasmic glucans (OPGs) that are general constituents of the envelope of proteobacteria. In addition to the loss of virulence, opg-negative mutants display a pleiotropic phenotype, including decreased motility and increased exopolysaccharide synthesis. A nitrosoguanidine-induced mutagenesis was performed on the opgG strain, and restoration of motility was used as a screen. The phenotype of the opg mutant echoes that of the Rcs system: high level activation of the RcsCD-RcsB phosphorelay is needed to activate exopolysaccharide synthesis and to repress motility, while low level activation is required for virulence in enterobacteria. Here, we show that mutations in the RcsCDB phosphorelay system restored virulence and motility in a D. dadantii opg-negative strain, indicating a relationship between the Rcs phosphorelay and OPGs.
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Affiliation(s)
- Franck Bouchart
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Gilles Boussemart
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Anne-France Prouvost
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Virginie Cogez
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Edwige Madec
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Olivier Vidal
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Brigitte Delrue
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Jean-Pierre Bohin
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
| | - Jean-Marie Lacroix
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
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Lequette Y, Lanfroy E, Cogez V, Bohin JP, Lacroix JM. Biosynthesis of osmoregulated periplasmic glucans in Escherichia coli: the membrane-bound and the soluble periplasmic phosphoglycerol transferases are encoded by the same gene. Microbiology (Reading) 2008; 154:476-483. [DOI: 10.1099/mic.0.2007/013169-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Yannick Lequette
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL/CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, Cedex, France
| | - Eric Lanfroy
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL/CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, Cedex, France
| | - Virginie Cogez
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL/CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, Cedex, France
| | - Jean-Pierre Bohin
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL/CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, Cedex, France
| | - Jean-Marie Lacroix
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL/CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, Cedex, France
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Delangle A, Prouvost AF, Cogez V, Bohin JP, Lacroix JM, Cotte-Pattat NH. Characterization of the Erwinia chrysanthemi Gan locus, involved in galactan catabolism. J Bacteriol 2007; 189:7053-61. [PMID: 17644603 PMCID: PMC2045229 DOI: 10.1128/jb.00845-07] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Accepted: 07/12/2007] [Indexed: 11/20/2022] Open
Abstract
beta-1,4-Galactan is a major component of the ramified regions of pectin. Analysis of the genome of the plant pathogenic bacteria Erwinia chrysanthemi revealed the presence of a cluster of eight genes encoding proteins potentially involved in galactan utilization. The predicted transport system would comprise a specific porin GanL and an ABC transporter made of four proteins, GanFGK(2). Degradation of galactans would be catalyzed by the periplasmic 1,4-beta-endogalactanase GanA, which released oligogalactans from trimer to hexamer. After their transport through the inner membrane, oligogalactans would be degraded into galactose by the cytoplasmic 1,4-beta-exogalactanase GanB. Mutants affected for the porin or endogalactanase were unable to grow on galactans, but they grew on galactose and on a mixture of galactotriose, galactotetraose, galactopentaose, and galactohexaose. Mutants affected for the periplasmic galactan binding protein, the transporter ATPase, or the exogalactanase were only able to grow on galactose. Thus, the phenotypes of these mutants confirmed the functionality of the gan locus in transport and catabolism of galactans. These mutations did not affect the virulence of E. chrysanthemi on chicory leaves, potato tubers, or Saintpaulia ionantha, suggesting an accessory role of galactan utilization in the bacterial pathogeny.
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Affiliation(s)
- Aurélie Delangle
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR147, Université des Sciences et Technologies de Lille, Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
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Lequette Y, Rollet E, Delangle A, Greenberg EP, Bohin JP. Linear osmoregulated periplasmic glucans are encoded by the opgGH locus of Pseudomonas aeruginosa. Microbiology (Reading) 2007; 153:3255-3263. [PMID: 17906125 DOI: 10.1099/mic.0.2007/008953-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Osmoregulated periplasmic glucans (OPGs) are produced by many proteobacteria and are important for bacterial-host interactions. The opgG and opgH genes involved in the synthesis of OPGs are the most widely distributed genes in proteobacterial genomes. Two other non-homologous genes, both named ndvB, are also involved in OPG biosynthesis in several species. The Pseudomonas aeruginosa genome possesses two ORFs, PA5077 and PA5078, that show similarity to opgH and opgG of Pseudomonas syringae, respectively, and one ORF, PA1163, similar to ndvB of Sinorhizobium meliloti. Here, we report that the opgGH locus of P. aeruginosa PA14 is involved in the synthesis of linear polymers with beta-1,2-linked glucosyl residues branched with a few beta-1,6 glucosyl residues. Succinyl residues also substitute this glucose backbone. Transcription of opgGH is repressed by high osmolarity. Low osmolarity promotes the formation of highly structured biofilms, but biofilm development is slower and the area of biomass is reduced under high osmolarity. Biofilm development of an opgGH mutant grown under low osmolarity presents a similar phenotype to the wild-type biofilm grown under high osmolarity. These results suggest that OPGs are important for biofilm formation under conditions of low osmolarity. A previous study suggested that the P. aeruginosa ndvB gene is involved in the resistance of biofilms to antibiotics. We have shown that ndvB is not involved in the biosynthesis of the OPG described here, and opgGH do not appear to be involved in the resistance of P. aeruginosa PA14 biofilms to antibiotics.
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Affiliation(s)
- Yannick Lequette
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Eglantine Rollet
- Unité de Glycobiologie Structurale et Fonctionnelle CNRS UMR 8576, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
| | - Aurélie Delangle
- Unité de Glycobiologie Structurale et Fonctionnelle CNRS UMR 8576, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
| | - E Peter Greenberg
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
| | - Jean-Pierre Bohin
- Unité de Glycobiologie Structurale et Fonctionnelle CNRS UMR 8576, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
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Bouchart F, Delangle A, Lemoine J, Bohin JP, Lacroix JM. Proteomic analysis of a non-virulent mutant of the phytopathogenic bacterium Erwinia chrysanthemi deficient in osmoregulated periplasmic glucans: change in protein expression is not restricted to the envelope, but affects general metabolism. Microbiology (Reading) 2007; 153:760-767. [PMID: 17322196 DOI: 10.1099/mic.0.2006/000372-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Osmoregulated periplasmic glucans (OPGs) are general constituents of the envelope of Gram-negative bacteria. They are required for full virulence of bacterial phytopathogens such as Pseudomonas syringae, Xanthomonas campestris and Erwinia chrysanthemi. E. chrysanthemi is a pectinolytic gamma-proteobacterium that causes soft rot disease on a wide range of plant species. In addition to the loss of virulence, opg mutants exhibit a pleiotropic phenotype that affects motility, bile-salt resistance, exoenzyme secretion, exopolysaccharide synthesis and membrane lipid composition. This is believed to be the first proteomic analysis of an OPG-defective mutant of E. chrysanthemi and it revealed that, in addition to the effects described, catabolic enzyme synthesis was enhanced and there was a greater abundance of some proteins catalysing the folding and degradation of proteins needed for various stress responses. Thus, in the opg mutant strain, loss of virulence was the result of a combination of envelope structure changes and cellular metabolism modifications.
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Affiliation(s)
- Franck Bouchart
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR 118, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
| | - Aurélie Delangle
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR 118, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
| | - Jérôme Lemoine
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR 118, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
| | - Jean-Pierre Bohin
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR 118, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
| | - Jean-Marie Lacroix
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576 IFR 118, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
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Rivière G, Michaud A, Corradi HR, Sturrock ED, Ravi Acharya K, Cogez V, Bohin JP, Vieau D, Corvol P. Characterization of the first angiotensin-converting like enzyme in bacteria: Ancestor ACE is already active. Gene 2007; 399:81-90. [PMID: 17597310 PMCID: PMC7127174 DOI: 10.1016/j.gene.2007.05.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 05/04/2007] [Accepted: 05/04/2007] [Indexed: 12/02/2022]
Abstract
Angiotensin-converting enzyme (ACE) is a metallopeptidase that converts angiotensin I into angiotensin II. ACE is crucial in the control of cardiovascular and renal homeostasis and fertility in mammals. In vertebrates, both transmembrane and soluble ACE, containing one or two active sites, have been characterized. So far, only soluble, single domain ACEs from invertebrates have been cloned, and these have been implicated in reproduction in insects. Furthermore, an ACE-related carboxypeptidase was recently characterized in Leishmania, a unicellular eukaryote, suggesting the existence of ACE in more distant organisms. Interestingly, in silico databank analysis revealed that bacterial DNA sequences could encode putative ACE-like proteins, strikingly similar to vertebrates' enzymes. To gain more insight into the bacterial enzymes, we cloned the putative ACE from the phytopathogenic bacterium, Xanthomonas axonopodis pv. citri, named XcACE. The 2 kb open reading frame encodes a 672-amino-acid soluble protein containing a single active site. In vitro expression and biochemical characterization revealed that XcACE is a functional 72 kDa dipeptidyl-carboxypeptidase. As in mammals, this metalloprotease hydrolyses angiotensin I into angiotensin II. XcACE is sensitive to ACE inhibitors and chloride ions concentration. Variations in the active site residues, highlighted by structural modelling, can account for the different substrate selectivity and inhibition profile compared to human ACE. XcACE characterization demonstrates that ACE is an ancestral enzyme, provoking questions about its appearance and structure/activity specialisation during the course of evolution.
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Affiliation(s)
- Guillaume Rivière
- Unité Neurosciences et Physiologie Adaptative, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cédex, France.
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Bohin A, Bouchart F, Richet C, Kol O, Leroy Y, Timmerman P, Huet G, Bohin JP, Zanetta JP. GC/MS identification and quantification of constituents of bacterial lipids and glycoconjugates obtained after methanolysis as heptafluorobutyrate derivatives. Anal Biochem 2005; 340:231-44. [PMID: 15840496 DOI: 10.1016/j.ab.2005.02.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2004] [Indexed: 10/25/2022]
Abstract
In previous articles [Anal. Biochem. 284 (2000) 201; J. Lipid Res. 43 (2002) 794], we reported that the GC/MS identification and quantification of nearly all constituents of glycolipids could be obtained on the same sample in a single GC/MS analysis as heptafluorobutyrate derivatives of the products liberated using acid-catalyzed methanolysis. The same type of data could be obtained on glycoproteins and proteoglycans [Biochemistry 42 (2003) 8342]. These experiments were performed on material from higher organisms, and there was no evidence that bacteria-specific constituents could also be identified and quantified. The current article reports that the GC/MS analysis of compounds liberated by acid-catalyzed methanolysis as heptafluorobutyrate derivatives allows the simultaneous qualitative and quantitative determinations of pentoses, deoxyhexoses, hexoses, hexosamines, uronic acids, Kdo, Mur, heptose, Kdn, and neuraminic acid as well as of most fatty acids (including hydroxylated fatty acids). This approach provides a way of obtaining fingerprints of bacterial constituents and quantification of the overall effect of gene inactivation or of culture conditions.
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Affiliation(s)
- Anne Bohin
- CNRS Unité Mixte de Recherche 8576, Unité de Glycobiologie Structurale et Fonctionnelle, Université des Sciences et Technologies de Lille Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France
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Hanoulle X, Rollet E, Clantin B, Landrieu I, Odberg-Ferragut C, Lippens G, Bohin JP, Villeret V. Structural analysis of Escherichia coli OpgG, a protein required for the biosynthesis of osmoregulated periplasmic glucans. J Mol Biol 2004; 342:195-205. [PMID: 15313617 DOI: 10.1016/j.jmb.2004.07.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Revised: 07/06/2004] [Accepted: 07/06/2004] [Indexed: 11/17/2022]
Abstract
Osmoregulated periplasmic glucans (OPGs) G protein (OpgG) is required for OPGs biosynthesis. OPGs from Escherichia coli are branched glucans, with a backbone of beta-1,2 glucose units and with branches attached by beta-1,6 linkages. In Proteobacteria, OPGs are involved in osmoprotection, biofilm formation, virulence and resistance to antibiotics. Despite their important biological implications, enzymes synthesizing OPGs are poorly characterized. Here, we report the 2.5 A crystal structure of OpgG from E.coli. The structure was solved using a selenemethionine derivative of OpgG and the multiple anomalous diffraction method (MAD). The protein is composed of two beta-sandwich domains connected by one turn of 3(10) helix. The N-terminal domain (residues 22-388) displays a 25-stranded beta-sandwich fold found in several carbohydrate-related proteins. It exhibits a large cleft comprising many aromatic and acidic residues. This putative binding site shares some similarities with enzymes such as galactose mutarotase and glucodextranase, suggesting a potential catalytic role for this domain in OPG synthesis. On the other hand, the C-terminal domain (residues 401-512) has a seven-stranded immunoglobulin-like beta-sandwich fold, found in many proteins where it is mainly implicated in interactions with other molecules. The structural data suggest that OpgG is an OPG branching enzyme in which the catalytic activity is located in the large N-terminal domain and controlled via the smaller C-terminal domain.
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Affiliation(s)
- Xavier Hanoulle
- UMR 8525 CNRS, Institut de Biologie de Lille, Université de Lille II, 1 rue du Professeur Calmette, BP447, 59021, France.
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Lequette Y, Odberg-Ferragut C, Bohin JP, Lacroix JM. Identification of mdoD, an mdoG paralog which encodes a twin-arginine-dependent periplasmic protein that controls osmoregulated periplasmic glucan backbone structures. J Bacteriol 2004; 186:3695-702. [PMID: 15175282 PMCID: PMC419940 DOI: 10.1128/jb.186.12.3695-3702.2004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Osmoregulated periplasmic glucans (OPGs) of Escherichia coli are anionic and highly branched oligosaccharides that accumulate in the periplasmic space in response to low osmolarity of the medium. The glucan length, ranging from 5 to 12 glucose residues, is under strict control. Two genes that form an operon, mdoGH, govern glucose backbone synthesis. The new gene mdoD, which appears to be a paralog of mdoG, was characterized in this study. Cassette inactivation of mdoD resulted in production of OPGs with a higher degree of polymerization, indicating that OpgD, the mdoD product (according to the new nomenclature), controls the glucose backbone structures. OpgD secretion depends on the Tat secretory pathway. Orthologs of the mdoG and mdoD genes are found in various proteobacteria. Most of the OpgD orthologs exhibit a Tat-dependent secretion signal, while most of the OpgG orthologs are Sec dependent.
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Zanetta JP, Pons A, Richet C, Huet G, Timmerman P, Leroy Y, Bohin A, Bohin JP, Trinel PA, Poulain D, Hofsteenge J. Quantitative gas chromatography/mass spectrometry determination of C-mannosylation of tryptophan residues in glycoproteins. Anal Biochem 2004; 329:199-206. [PMID: 15158478 DOI: 10.1016/j.ab.2004.02.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2003] [Indexed: 11/30/2022]
Abstract
C-mannosylation of Trp residue is one of the most recently discovered types of glycosylation, but the identification of these mannosylated residues in proteins is rather tedious. In a previous paper, it was reported that the complete analysis of all constituents of glycoproteins (sialic acids, monosaccharides, and amino acids) could be determined on the same sample in three different steps of gas chromatography/mass spectrometry of heptafluorobutyrate derivatives. It was observed that during the acid-catalyzed methanolysis step used for liberation of monosaccharide from classical O- and N-glycans, Trp and His were quantitatively transformed by the addition of a methanol molecule on their indole and imidazole groups, respectively. These derivatives were stable to acid hydrolysis used for the liberation of amino acids. Since monosaccharide derivatives were also stabilized as heptafluorobutyrate derivatives of O-methyl-glycosides, it was suggested that C-mannosides of Trp residues could quantitatively be recovered. Based on the analyses of standard compounds, peptides and RNase 2 from human urine, we report that C((2))-mannosylated Trp could be quantitatively recovered and identified during the step of amino acid analysis. Analyses of different samples indicated that this type of glycosylation is absent in bacteria and yeasts.
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Affiliation(s)
- Jean-Pierre Zanetta
- CNRS Unité Mixte de Recherche 8576, Glycobiologie Structurale et Fonctionnelle, Université des Sciences et Technologies de Lille Bâtiment C9, 59655 Villeneuve d'Ascq Cedex, France.
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Cogez V, Gak E, Puskas A, Kaplan S, Bohin JP. The opgGIH and opgC genes of Rhodobacter sphaeroides form an operon that controls backbone synthesis and succinylation of osmoregulated periplasmic glucans. Eur J Biochem 2002; 269:2473-84. [PMID: 12027885 DOI: 10.1046/j.1432-1033.2002.02907.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Osmoregulated periplasmic glucans (OPGs) of Rhodobacter sphaeroides are anionic cyclic molecules that accumulate in large amounts in the periplasmic space in response to low osmolarity of the medium. Their anionic character is provided by the substitution of the glucosidic backbone by succinyl residues. A wild-type strain was subject to transposon mutagenesis, and putative mutant clones were screened for changes in OPGs by thin layer chromatography. One mutant deficient in succinyl substitution of the OPGs was obtained and the gene inactivated in this mutant was characterized and named opgC. opgC is located downstream of three ORFs, opgGIH, two of which are similar to the Escherichia coli operon, mdoGH, governing OPG backbone synthesis. Inactivation of opgG, opgI or opgH abolished OPG production and complementation analysis indicated that the three genes are necessary for backbone synthesis. In contrast, inactivation of a gene similar to ndvB, encoding the OPG-glucosyl transferase in Sinorhizobium meliloti, had no consequence on OPG synthesis in Rhodobacter sphaeroides. Cassette insertions in opgH had a polar effect on glucan substitution, indicating that opgC is in the same transcription unit. Expression of opgIHC in E. coli mdoB/mdoC and mdoH mutants allowed the production of slightly anionic and abnormally long linear glucans.
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Affiliation(s)
- Virginie Cogez
- Unité de Glycobiologie Structurale et Fonctionnelle, CNRS UMR8576, Université des Sciences et Technologies de Lille, France
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Talaga P, Cogez V, Wieruszeski JM, Stahl B, Lemoine J, Lippens G, Bohin JP. Osmoregulated periplasmic glucans of the free-living photosynthetic bacterium Rhodobacter sphaeroides. Eur J Biochem 2002; 269:2464-72. [PMID: 12027884 DOI: 10.1046/j.1432-1033.2002.02906.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The osmoregulated periplasmic glucans (OPGs) produced by Rhodobacter sphaeroides, a free-living organism, were isolated by trichloracetic acid treatment and gel permeation chromatography. Compounds obtained were characterized by compositional analysis, matrix-assisted laser desorption ionization mass spectrometry and nuclear magnetic resonance. R. sphaeroides predominantly synthesizes a cyclic glucan containing 18 glucose residues that can be substituted by one to seven succinyl esters residues at the C6 position of some of the glucose residues, and by one or two acetyl residues. The glucans were subjected to a mild alkaline treatment in order to remove the succinyl and acetyl substituents, analyzed by MALDI mass spectrometry and purified by high-performance anion-exchange chromatography. Methylation analysis revealed that this glucan is linked by 17 1,2 glycosidic bonds and one 1,6 glycosidic bond. Homonuclear and (1)H/(13)C heteronuclear NMR experiments revealed the presence of a single alpha-1,6 glycosidic linkage, whereas all other glucose residues are beta-1,2 linked. The different anomeric proton signals allowed a complete sequence-specific assignment of the glucan. The structural characteristics of this glucan are very similar to the previously described OPGs of Ralstonia solanacearum and Xanthomonas campestris, except for its different size and the presence of substituents. Therefore, similar OPGs are synthesized by phytopathogenic as well as free-living bacteria, suggesting these compounds are intrinsic components of the Gram-negative bacterial envelope.
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Affiliation(s)
- Philippe Talaga
- Unité de Glycobiologie Structurale et Fonctionnelle, CNRS UMR8576, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France
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Wieruszeski JM, Bohin A, Bohin JP, Lippens G. In vivo detection of the cyclic osmoregulated periplasmic glucan of Ralstonia solanacearum by high-resolution magic angle spinning NMR. J Magn Reson 2001; 151:118-123. [PMID: 11444945 DOI: 10.1006/jmre.2001.2348] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We investigate the mobility of the osmoregulated periplasmic glucans of Ralstonia solanacearum in the bacterial periplasm through the use of high-resolution (HR) NMR spectroscopy under static and magic angle spinning (MAS) conditions. Because the nature of periplasm is far from an isotropic aqueous solution, the molecules could be freely diffusing or rather associated to a periplasmic protein, a membrane protein, a lipid, or the peptidoglycan. HR MAS NMR spectroscopy leads to more reproducible results and allows the in vivo detection and characterization of the complex molecule.
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Affiliation(s)
- J M Wieruszeski
- CNRS UMR 8525, Institut de Biologie de Lille/Institut Pasteur de Lille, 1 rue du Professeur Calmette, Lille Cedex, 59021, France
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16
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Abstract
We report the initial characterization of the osmoregulated periplasmic glucans (OPGs) of Erwinia chrysanthemi. OPGs are intrinsic components of the bacterial envelope necessary to the pathogenicity of this phytopathogenic enterobacterium (F. Page, S. Altabe, N. Hugouvieux-Cotte-Pattat, J.-M. Lacroix, J. Robert-Baudouy and J.-P. Bohin, J. Bacteriol. 183:0000-0000, 2001 [companion in this issue]). 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 beta-1,2-linked glucose units to which a variable number of branches, composed of one glucose residue, are attached by beta-1,6 linkages in a random way. This glucan backbone may be substituted by O-acetyl and O-succinyl ester-linked residues.
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Affiliation(s)
- V Cogez
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
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Page F, Altabe S, Hugouvieux-Cotte-Pattat N, Lacroix JM, Robert-Baudouy J, Bohin JP. Osmoregulated periplasmic glucan synthesis is required for Erwinia chrysanthemi pathogenicity. J Bacteriol 2001; 183:3134-41. [PMID: 11325942 PMCID: PMC95214 DOI: 10.1128/jb.183.10.3134-3141.2001] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2000] [Accepted: 03/06/2001] [Indexed: 11/20/2022] Open
Abstract
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.
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Affiliation(s)
- F Page
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR USTL-CNRS 8576, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq Cedex, France
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18
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Abstract
Large amounts of osmoregulated periplasmic glucans (OPGs) are found in the periplasmic space of Proteobacteria. Four families of OPGs are described on the basis of structural features of the polyglucose backbone. Depending on the species considered, OPGs can be modified to various extent by a variety of substituents. Genes governing the backbone synthesis are identified in a limited number of species. They belong to three unrelated families. OPG synthesis is subject to osmoregulation and feedback control. Osmoregulation can occur at the level of gene expression and/or at the level of enzyme activity. Mutants defective in OPG synthesis have a highly pleiotropic phenotype, indicative of an overall alteration of their envelope properties. Mutants of this kind were obtained as attenuated or avirulent derivatives of plant or animals pathogen. Thus, OPGs appear to be important intrinsic components of the Gram-negative bacterial envelope, which can be essential in extreme conditions found in nature, and especially when bacteria must interact with an eukaryotic host.
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Affiliation(s)
- J P Bohin
- Laboratoire de Chimie Biologique, CNRS UMR 8576, Université des Sciences et Technologies de Lille, 59655, Villeneuve d'Ascq, France.
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Lacroix JM, Lanfroy E, Cogez V, Lequette Y, Bohin A, Bohin JP. The mdoC gene of Escherichia coli encodes a membrane protein that is required for succinylation of osmoregulated periplasmic glucans. J Bacteriol 1999; 181:3626-31. [PMID: 10368134 PMCID: PMC93837 DOI: 10.1128/jb.181.12.3626-3631.1999] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Osmoregulated periplasmic glucans (OPGs) of Escherichia coli are anionic oligosaccharides that accumulate in the periplasmic space in response to low osmolarity of the medium. Their anionic character is provided by the substitution of the glucosidic backbone by phosphoglycerol originating from the membrane phospholipids and by succinyl residues from unknown origin. A phosphoglycerol-transferase-deficient mdoB mutant was subjected to Tn5 transposon mutagenesis, and putative mutant clones were screened for changes in the anionic character of OPGs by thin-layer chromatography. One mutant deficient in succinylation of OPGs was obtained, and the gene inactivated in this mutant was characterized and named mdoC. mdoC, which encodes a membrane-bound protein, is closely linked to the mdoGH operon necessary for the synthesis of the OPG backbone.
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Affiliation(s)
- J M Lacroix
- Laboratoire de Chimie Biologique, UMR111 du CNRS, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, Cedex, France
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Debarbieux L, Bohin A, Bohin JP. Topological analysis of the membrane-bound glucosyltransferase, MdoH, required for osmoregulated periplasmic glucan synthesis in Escherichia coli. J Bacteriol 1997; 179:6692-8. [PMID: 9352918 PMCID: PMC179597 DOI: 10.1128/jb.179.21.6692-6698.1997] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The MdoH protein is essential for synthesis of the osmoregulated periplasmic glucans, known as membrane-derived oligosaccharides (MDOs), in Escherichia coli. Mutants lacking MdoH are deficient in a glucosyltransferase activity assayed in vitro. The MdoH protein is the product of the second gene of an operon, and it has been shown to span the cytoplasmic membrane. The MdoH protein comprises 847 amino acids and is poorly expressed as observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. We have experimentally measured the topological organization of MdoH within the membrane by construction of fusions to beta-lactamase as a reporter. Analysis of 51 different MdoH-beta-lactamase fusions suggested that the MdoH protein crosses the cytoplasmic membrane eight times, with the N and C termini in the cytoplasm. Moreover, a 310-amino-acid domain is present in the cytoplasm between the second and third transmembrane segments. It was deduced from the measurement of the MDO biosynthetic activity of truncated or fused MdoH proteins that almost all the C-terminal residues are necessary for this activity. The model of the MdoH protein in the membrane suggests that this protein could be directly involved in the translocation of nascent polyglucose chains to the periplasmic space.
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Affiliation(s)
- L Debarbieux
- Laboratoire de Chimie Biologique, UMR111 du CNRS, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France
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21
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Lippens G, Wieruszeski JM, Talaga P, Bohin JP. Measurement of three-bond coupling constants in the osmoregulated periplasmic glucan of Burkholderia solanacearum. J Biomol NMR 1996; 8:311-318. [PMID: 8953219 DOI: 10.1007/bf00410329] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The cyclic osmoregulated periplasmic glucan produced by Burkholderia solanacearum contains 13 glucose units, all beta-(1-2) linked except for one alpha-(1-6) linkage. We report here the measurement of the 3J(C1-H2') and 3J(H1-C2') coupling constants, characterizing the glycosidic linkages, through the use of a 13C/12C double half-filtered NOESY experiments. The values obtained give information about the (phi, psi) angles of the different linkages. The results presented from an important step towards a detailed experimental model of the cyclic glucan, which might allow us to clarify its biological role and establish whether the cavity of these molecules is compatible with the capability of complexing host molecular signals.
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Affiliation(s)
- G Lippens
- CNRS URA 1309, Pasteur Institute of Lille, France
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22
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Talaga P, Stahl B, Wieruszeski JM, Hillenkamp F, Tsuyumu S, Lippens G, Bohin JP. Cell-associated glucans of Burkholderia solanacearum and Xanthomonas campestris pv. citri: a new family of periplasmic glucans. J Bacteriol 1996; 178:2263-71. [PMID: 8636027 PMCID: PMC177934 DOI: 10.1128/jb.178.8.2263-2271.1996] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The cell-associated glucans produced by Burkholderia solanacearum and Xanthomonas campestris pv. citri were isolated by trichloroacetic acid treatment and gel permeation chromatography. The compounds obtained were characterized by compositional analysis, matrix-assisted laser desorption ionization mass spectrometry, and high-performance anion-exchange chromatography. B. solanacearum synthesizes only a neutral cyclic glucan containing 13 glucose residues, and X. campestris pv. citri synthesizes a neutral cyclic glucan containing 16 glucose residues. The two glucans were further purified by high-performance anion-exchange chromatography. Methylation analysis revealed that these glucans are linked by 1,2-glycosidic bonds and one 1,6-glycosidic bond. Our 600-MHz homonuclear and 1H-13C heteronuclear nuclear magnetic resonance experiments revealed the presence of a single alpha-1,6-glycosidic linkage, whereas all other glucose residues are beta-1,2 linked. The presence of this single alpha-1,6 linkage, however, induces such structural constraints in these cyclic glucans that all individual glucose residues could be distinguished. The different anomeric proton signals allowed complete sequence-specific assignment of both glucans. The structural characteristics of these glucans contrast with those of the previously described osmoregulated periplasmic glucans.
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Affiliation(s)
- P Talaga
- Laboratoire de Chimie Biologique, Centre National de la Recherche Scientifique UMR 11, Université des Sciences et Technologies de Lille, France
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23
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Abstract
We report the initial characterization of glucans present in the periplasmic space of Pseudomonas syringae pv. syringae (strain R32). These compounds were found to be neutral, unsubstituted, and composed solely of glucose. Their size ranges from 6 to 13 glucose units/mol. Linkage studies and nuclear magnetic resonance analyses demonstrated that the glucans are linked by beta-1,2 and beta-1,6 glycosidic bonds. In contrast to the periplasmic glucans found in other plant pathogenic bacteria, the glucans of P. syringae pv. syringae are not cyclic but are highly branched structures. Acetolysis studies demonstrated that the backbone consists of beta-1,2-linked glucose units to which the branches are attached by beta-1,6 linkages. These periplasmic glucans were more abundant when the osmolarity of the growth medium was lower. Thus, P. syringae pv. syringae appears to synthesize periplasmic glucans in response to the osmolarity of the medium. The structural characteristics of these glucans are very similar to the membrane-derived oligosaccharides of Escherichia coli, apart from the neutral character, which contrasts with the highly anionic E. coli membrane-derived oligosaccharides.
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Affiliation(s)
- P Talaga
- Laboratoire de Chimie Biologique, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France
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Loubens I, Debarbieux L, Bohin A, Lacroix JM, Bohin JP. 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. Mol Microbiol 1993; 10:329-40. [PMID: 7934824 DOI: 10.1111/j.1365-2958.1993.tb01959.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Membrane-derived oligosaccharides (MDO) of Escherichia coli are representative members of a family of glucans found in the periplasmic space of Gram-negative bacteria. The two genes forming the mdoGH operon are necessary for the synthesis of MDO. The nucleotide sequence (4759 bp) and the transcriptional start of this operon were determined. Both gene products were further characterized by gene fusion analysis. MdoG is a 56 kDa periplasmic protein whose function remains to be determined. MdoH, whose presence was shown to be necessary for normal glucosyl transferase activity, is a 97 kDa protein spanning the cytoplasmic membrane. To our surprise, these proteins are not homologous to the periplasmic glucan biosynthetic enzymes previously characterized in the Rhizobiaceae family. However, a considerable homology (69% identical nucleotides out of 2816) was discovered between mdoGH and the two genes present at the hrpM locus of the phytopathogenic bacterium Pseudomonas syringae pv. syringae. Functions of these genes remain mysterious but they are known to be required for both the expression of disease symptoms on host plants and the development of the hypersensitive reaction on non-host plants (Mills and Mukhopadhyay, 1990). These results confirm the importance of periplasmic glucans for the physiological ecology of Gram-negative bacteria.
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Affiliation(s)
- I Loubens
- Laboratoire de Chimie Biologique, UMR 111 du CNRS, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France
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25
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Affiliation(s)
- E Lanfroy
- Laboratoire de Chimie Biologique, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France
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Doublet P, van Heijenoort J, Bohin JP, Mengin-Lecreulx D. The murI gene of Escherichia coli is an essential gene that encodes a glutamate racemase activity. J Bacteriol 1993; 175:2970-9. [PMID: 8098327 PMCID: PMC204615 DOI: 10.1128/jb.175.10.2970-2979.1993] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The murI gene of Escherichia coli was recently identified on the basis of its ability to complement the only mutant requiring D-glutamic acid for growth that had been described to date: strain WM335 of E. coli B/r (P. Doublet, J. van Heijenoort, and D. Mengin-Lecreulx, J. Bacteriol. 174:5772-5779, 1992). We report experiments of insertional mutagenesis of the murI gene which demonstrate that this gene is essential for the biosynthesis of D-glutamic acid, one of the specific components of cell wall peptidoglycan. A special strategy was used for the construction of strains with a disrupted copy of murI, because of a limited capability of E. coli strains grown in rich medium to internalize D-glutamic acid. The murI gene product was overproduced and identified as a glutamate racemase activity. UDP-N-acetylmuramoyl-L-alanine (UDP-MurNAc-L-Ala), which is the nucleotide substrate of the D-glutamic-acid-adding enzyme (the murD gene product) catalyzing the subsequent step in the pathway for peptidoglycan synthesis, appears to be an effector of the racemase activity.
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Affiliation(s)
- P Doublet
- URA 1131 du Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, Orsay, France
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27
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Abstract
In Escherichia coli, the 5 kb mdoA locus is involved in the osmotically controlled biosynthesis of periplasmic membrane-derived oligosaccharides (MDOs). The structure of this locus was analysed by in vitro cassette insertion, transposon mutagenesis, and gene-fusion analysis. A 'neo' cassette, derived from the neomycin phosphotransferase II region of transposon Tn5, was inserted into mdoA, borne by a multicopy plasmid. This plasmid was shown to complement two previously described mdoA mutations, depending on the orientation of the exogenous gene. Thus, the gene altered by these mutations could be expressed under the control of the exogenous promoter. Moreover, the 'neo' cassette inactivated another, uncharacterized, mdo gene, because when this insertion was transferred into the chromosome MDO synthesis was abolished. The existence of a second gene was confirmed by complementation analysis with a collection of Tn1000 insertions into mdoA. Two groups were defined, and the two genes are organized into an operon (mdoGH). This conclusion was reached because Tn1000 insertions in the first gene displayed a polar effect on the expression of the second gene. An active gene fusion was obtained on a multicopy plasmid between the beginning of mdoH and lacZ. The hybrid beta-galactosidase activity followed the same osmotically controlled response as that described for of MDO synthesis. This regulation was unaffected by the presence, or absence, of MDOs in the periplasm. Finally, the amount of mdoA-specific mRNAs, determined by dot blot hybridization, decreased when the osmolarity of the growth medium increased.
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Affiliation(s)
- J M Lacroix
- Institute de Microbiologie, URA 1354 CNRS, Université Paris-Sud, Orsay, France
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Lacroix JM, Tempête M, Menichi B, Bohin JP. Molecular cloning and expression of a locus (mdoA) implicated in the biosynthesis of membrane-derived oligosaccharides in Escherichia coli. Mol Microbiol 1989; 3:1173-82. [PMID: 2552262 DOI: 10.1111/j.1365-2958.1989.tb00267.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mutants of Escherichia coli defective in the mdoA locus are blocked at an early stage in the biosynthesis of membrane-derived oligosaccharides. The mdoA locus has now been cloned into multicopy plasmids. A 5 kb DNA fragment is necessary to complement mdoA mutations. Cells harbouring the mdoA+ plasmid produced three to four times more MDO than wild-type cells. MDO overproduction did not affect the degree of MDO substitution with sn-1-phosphoglycerol residues. The biosynthesis of MDO remained under osmotic control in overproducing strains.
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Affiliation(s)
- J M Lacroix
- Institut de Microbiologie, URA 136 CNRS, Université Paris-Sud, Orsay, France
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29
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Aufrère R, Tempête M, Bohin JP. Regulation of expression of the gene for vitamin B12 receptor cloned on a multicopy plasmid in Escherichia coli. Mol Gen Genet 1986; 205:358-65. [PMID: 3027510 DOI: 10.1007/bf00430451] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The btuB gene of Escherichia coli codes for a protein (BtuB) located in the outer membrane. BtuB is the receptor for vitamin B12 (cyanocobalamin). We have cloned the btuB gene into pUC8 using transposon Tn5 as the marker to first isolate several parts of the relevant DNA fragment from the specialized transducing phage lambda darg13. After reconstitution of the gene, Tn5 was removed by selecting for spontaneous excision. The partial nucleotide sequence and transcriptional start of the btuB gene were determined. The BtuB+ plasmid allowed a large amplification of the synthesis of BtuB, resulting in a 65-fold increased level of vitamin B12 binding. The level of vitamin B12 binding was reduced by a factor of 22 when cells were grown in the presence of high concentrations of vitamin B12. The regulation of the gene was studied in more detail by the use of a protein fusion between the extreme amino-terminus of BtuB and beta-galactosidase of E. coli. The kinetics of repression and derepression were consistent with the presence in the cells of a large amount of a regulatory molecule exhibiting an apparent Km for vitamin B12 of 3 microM.
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Abstract
Bacterial DNA is organized as a compact nucleoid whose structure is maintained by membrane--DNA, protein--DNA and RNA--DNA interactions. We investigated the effect of the transcription inhibitor rifamycin on the structure of the nucleoid in B. subtilis. Decrease of nucleoid compactness and loss of DNA superhelicity were correlated with DNA transcription arrest, both in the wild-type and in a rifamycin-resistant strain. Moreover, the phospholipid content of the nucleoid does not change upon rifamycin treatment.
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31
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Jackson BJ, Bohin JP, Kennedy EP. Biosynthesis of membrane-derived oligosaccharides: characterization of mdoB mutants defective in phosphoglycerol transferase I activity. J Bacteriol 1984; 160:976-81. [PMID: 6094515 PMCID: PMC215805 DOI: 10.1128/jb.160.3.976-981.1984] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Phosphoglycerol transferase I, an enzyme of the inner, cytoplasmic membrane of Escherichia coli, catalyzes the in vitro transfer of phosphoglycerol residues from phosphatidylglycerol to membrane-derived oligosaccharides or to the model substrate arbutin (p-hydroxyphenyl-beta-D-glucoside). The products are a phosphoglycerol diester derivative of membrane-derived oligosaccharides or arbutin, respectively, and sn-1,2-diglyceride (B. J. Jackson and E. P. Kennedy, J. Biol. Chem. 258:2394-2398, 1983). Because this enzyme has its active site on the outer aspect of the inner membrane, it also catalyzes the transfer of phosphoglycerol residues to arbutin added to the medium (J.-P. Bohin and E. P. Kennedy, J. Biol. Chem. 259:8388-8393, 1984). When strains bearing the dgk mutation, which are defective in the enzyme diglyceride kinase, are grown in medium containing arbutin, they accumulate large amounts of sn-1,2-diglyceride, a product of the phosphoglycerol transferase I reaction. Growth is inhibited under these conditions. A further mutation in such a dgk strain, leading to the loss of phosphoglycerol transferase I activity, should result in the phenotype of arbutin resistance. We have exploited this fact to obtain strains with such mutations, designated mdoB, that map near min 99. Such mutants lack detectable phosphoglycerol transferase I activity, cannot transfer phosphoglycerol residues to arbutin in vivo, and synthesize membrane-derived oligosaccharides devoid of phosphoglycerol residues. These findings offer strong genetic support for the function of phosphoglycerol transferase I in membrane-derived oligosaccharide biosynthesis.
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Bohin JP, Kennedy EP. Regulation of the synthesis of membrane-derived oligosaccharides in Escherichia coli. Assay of phosphoglycerol transferase I in vivo. J Biol Chem 1984; 259:8388-93. [PMID: 6330111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Membrane-derived oligosaccharides are periplasmic constituents of Escherchia coli and other Gram-negative bacteria. Oligosaccharides in this family may be variously substituted with O-succinyl ester residues, and with sn-1-phosphoglycerol and phosphoethanolamine residues derived from membrane phospholipids. Membrane-derived oligosaccharides appear to be important in osmoregulation, because their synthesis is under strict control (Kennedy, E.P. (1982) Proc. Natl. Acad. Sci. U.S.A. 79, 1092-1095). Maximum rate of synthesis is at very low osmolarity of the medium. Phosphoglycerol residues are transferred from phosphatidylglycerol to membrane-derived oligosaccharides, or to certain beta-glucoside acceptors, in a reaction catalyzed by phosphoglycerol transferase I, an enzyme of the inner membrane (Jackson, B. J., and Kennedy, E.P. (1983) J. Biol. Chem. 258, 2394-2398). We now report that this enzyme catalyzes the transfer of phosphoglycerol residues to arbutin (p-hydroxyphenyl-beta-D-glucoside) added to the medium with Km similar to that observed with the cell-free enzyme. The active site of the enzyme must therefore be on the periplasmic face of the inner membrane. We assayed phosphoglycerol transferase I in vivo and found that it is present and completely active even in cells growing in medium of very high osmolarity, in which the synthesis of membrane-derived oligosaccharides is severely reduced. We conclude that osmotic regulation must occur at the stage of the synthesis of oligosaccharide chains. A study of the kinetics of transfer of phosphoglycerol residues to membrane-derived oligosaccharides in vivo revealed that synthesis of the polyglucose chains must stop abruptly upon transfer of cells from medium of low to high osmolarity, inconsistent with a model postulating simple dilution of some rate-limiting enzyme during growth at the higher osmolarity.
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Bohin JP, Kennedy EP. Regulation of the synthesis of membrane-derived oligosaccharides in Escherichia coli. Assay of phosphoglycerol transferase I in vivo. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)39742-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Abstract
Mutants of Escherichia coli defective in the newly discovered mdoA locus are blocked at an early stage in the biosynthesis of membrane-derived oligosaccharides. The mutation has now been mapped and found to be located near 23 min on the E. coli chromosome between putA and pyrC. The mdoA mutants are defective in the membrane-localized component of the glucosyl transferase system described by Weissborn and Kennedy (A. C. Weissborn and E. P. Kennedy, Fed. Proc. 42:2122, 1983).
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Abstract
About 80% of Bacillus subtilis cells form spores when grown in nutrient broth. In medium containing various short-chain aliphatic alcohols, the frequency of sporulation was reduced to 0.5%. Mutants sporulated in the presence of alcohols at a frequency of 30 to 40%. Sporulation in the wild-type cells was sensitive to alcohol at the beginning of sporulation (stage zero). Sensitivity to alcohol in the mutants was also at stage zero, even though the sensitivity was considerably reduced. This sensitivity of sporulation to alcohol is the phenotypic expression of a genetic locus designated ssa. Mutations at this locus lead to a decreased sensitivity of sporulation to alcohol without modifying the sensitivity of growth. Genetic analysis by transduction was bacteriophage PBS1 revealed that ssa mutations are near the previously described spo0A locus. ssa mutants also differ from wild-type cells in the composition of membrane phospholipids. The relative amount of phosphatidylglycerol increased, whereas the relative amount of phosphatidylethanolamine and lysylphosphatidylglycerol decreased relative to the proportions in the wild type. The distribution of fatty acids in membrane lipids is the same as in the wild type. No differential sensitivity of phospholipid metabolism to alcohol could be detected in the mutant. This work therefore reveals that the extensive, pleiotropic changes in the membranes of ssa mutants are the phenotypic reflection of alterations at a specific gene locus.
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Abstract
In Bacillus subtilis, the fatty acid moiety of the phospholipids was affected differently during growth in the presence of 1.1 M-methanol or 0.7 M-ethanol, though at these concentrations methanol and ethanol had the same effects on growth rate and completely inhibited sporulation. Synthesis of phosphatidylglycerol was also strongly inhibited and the amount of total cell phospholipids was reduced by 50% by both alcohols. The composition of fatty acids, especially the relative concentration of 12-methyltetradecanoic acid, was modified only by ethanol; in bacteria grown in the presence of methanol, changes in fatty acid composition were negligible. In non-sporulating mutants, synthesis of phosphatidylglycerol was much less affected than in the wild-type and synthesis of phosphatidylethanolamine was increased. In these strains, fatty acid composition was also modified by ethanol but unaffected by methanol.
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Bohin JP, Rigomier D, Schaeffer P. Ethanol sensitivity of sporulation in Bacillus subtilis: a new tool for the analysis of the sporulation process. J Bacteriol 1976; 127:934-40. [PMID: 821922 PMCID: PMC233003 DOI: 10.1128/jb.127.2.934-940.1976] [Citation(s) in RCA: 44] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The growth rate of Bacillus subtilis is lowered but the final cell yield is unchanged when certain concentrations of ethanol are present in the culture medium. At the concentration allowing growth at half-maximal rate, practically no spores are formed. Blockage of spore formation generally occurs at stage 0-I. Sensitivity to ethanol of the capacity to form spores is limited, in a nonsynchronized culture, to a period of at most 45 min around t1. Postexponential events such as excretion of certain enzymes and modification of ribonucleic acid polymerase are altered or suppressed in the presence of ethanol, possibly as the results of a physical change upon the cell membrane. In effect, ethanol is turning wild-type cells into phenocopies of spoO mutants.
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Bohin JP, Bohin A, Schaeffer P. Increased nitrate reductase A activity as a sign of membrane alteration in early blocked asporogenous mutants of Bacillus subtilis. Biochimie 1976; 58:99-108. [PMID: 821543 DOI: 10.1016/s0300-9084(76)80360-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Nitrate reductase (Nar) activity, and its regulation, have been studied in B. subtilis and Spo0 mutants derived from it. The mutants are blocked at the stage zero of sporulation. The only Nar detected was the membrane-bound Nar A, which has been solubilized and purified. The enzyme itself, and its regulation, seem to be the same in Spo+ and Spo0 strains. Under all conditions tested, however, the mutants were hyperproducers of Nar A. Whether produced by a Spo+ or a Spo0 strain, the purified enzyme has the same Km on nitrate, and the same heat inactivation kinetics. In situ in membrane vesicles of a Spo+ strain, it displays the same Km and its thermoinactivation is exponential. In mutant vesicles, however, two Km's are observed, one normal and one five times higher, and thermoinactivation follows an initial period of activation. The higher Km disappears after heat activation. The Spo0 mutation studied seems to result in a modification of the membrane, such that insertion of Nar A in the modified membrane confers to the enzyme new allotopic properties. Additional and abnormal enzyme-binding sites may be created as a result of the mutation and these may be normalized during heat activation.
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