1
|
A Bifunctional UDP-Sugar 4-Epimerase Supports Biosynthesis of Multiple Cell Surface Polysaccharides in Sinorhizobium meliloti. J Bacteriol 2019; 201:JB.00801-18. [PMID: 30833352 DOI: 10.1128/jb.00801-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 02/25/2019] [Indexed: 01/19/2023] Open
Abstract
Sinorhizobium meliloti produces multiple extracellular glycans, including among others, lipopolysaccharides (LPS), and the exopolysaccharides (EPS) succinoglycan (SG) and galactoglucan (GG). These polysaccharides serve cell protective roles. Furthermore, SG and GG promote the interaction of S. meliloti with its host Medicago sativa in root nodule symbiosis. ExoB has been suggested to be the sole enzyme catalyzing synthesis of UDP-galactose in S. meliloti (A. M. Buendia, B. Enenkel, R. Köplin, K. Niehaus, et al. Mol Microbiol 5:1519-1530, 1991, https://doi.org/10.1111/j.1365-2958.1991.tb00799.x). Accordingly, exoB mutants were previously found to be affected in the synthesis of the galactose-containing glycans LPS, SG, and GG and consequently, in symbiosis. Here, we report that the S. meliloti Rm2011 uxs1-uxe-apsS-apsH1-apsE-apsH2 (SMb20458-63) gene cluster directs biosynthesis of an arabinose-containing polysaccharide (APS), which contributes to biofilm formation, and is solely or mainly composed of arabinose. Uxe has previously been identified as UDP-xylose 4-epimerase. Collectively, our data from mutational and overexpression analyses of the APS biosynthesis genes and in vitro enzymatic assays indicate that Uxe functions as UDP-xylose 4- and UDP-glucose 4-epimerase catalyzing UDP-xylose/UDP-arabinose and UDP-glucose/UDP-galactose interconversions, respectively. Overexpression of uxe suppressed the phenotypes of an exoB mutant, evidencing that Uxe can functionally replace ExoB. We suggest that under conditions stimulating expression of the APS biosynthesis operon, Uxe contributes to the synthesis of multiple glycans and thereby to cell protection, biofilm formation, and symbiosis. Furthermore, we show that the C2H2 zinc finger transcriptional regulator MucR counteracts the previously reported CuxR-c-di-GMP-mediated activation of the APS biosynthesis operon. This integrates the c-di-GMP-dependent control of APS production into the opposing regulation of EPS biosynthesis and swimming motility in S. meliloti IMPORTANCE Bacterial extracellular polysaccharides serve important cell protective, structural, and signaling roles. They have particularly attracted attention as adhesives and matrix components promoting biofilm formation, which significantly contributes to resistance against antibiotics. In the root nodule symbiosis between rhizobia and leguminous plants, extracellular polysaccharides have a signaling function. UDP-sugar 4-epimerases are important enzymes in the synthesis of the activated sugar substrates, which are frequently shared between multiple polysaccharide biosynthesis pathways. Thus, these enzymes are potential targets to interfere with these pathways. Our finding of a bifunctional UDP-sugar 4-epimerase in Sinorhizobium meliloti generally advances the knowledge of substrate promiscuity of such enzymes and specifically of the biosynthesis of extracellular polysaccharides involved in biofilm formation and symbiosis in this alphaproteobacterium.
Collapse
|
2
|
Fingermann M, Hozbor D. Acid tolerance response of Bordetella bronchiseptica in avirulent phase. Microbiol Res 2015; 181:52-60. [DOI: 10.1016/j.micres.2015.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 08/26/2015] [Accepted: 09/01/2015] [Indexed: 01/06/2023]
|
3
|
Müller MG, Forsberg LS, Keating DH. The rkp-1 cluster is required for secretion of Kdo homopolymeric capsular polysaccharide in Sinorhizobium meliloti strain Rm1021. J Bacteriol 2009; 191:6988-7000. [PMID: 19734304 PMCID: PMC2772494 DOI: 10.1128/jb.00466-09] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Accepted: 08/31/2009] [Indexed: 11/20/2022] Open
Abstract
Under conditions of nitrogen stress, leguminous plants form symbioses with soil bacteria called rhizobia. This partnership results in the development of structures called root nodules, in which differentiated endosymbiotic bacteria reduce molecular dinitrogen for the host. The establishment of rhizobium-legume symbioses requires the bacterial synthesis of oligosaccharides, exopolysaccharides, and capsular polysaccharides. Previous studies suggested that the 3-deoxy-D-manno-oct-2-ulopyranosonic acid (Kdo) homopolymeric capsular polysaccharide produced by strain Sinorhizobium meliloti Rm1021 contributes to symbiosis with Medicago sativa under some conditions. However, a conclusive symbiotic role for this polysaccharide could not be determined due to a lack of mutants affecting its synthesis. In this study, we have further characterized the synthesis, secretion, and symbiotic function of the Kdo homopolymeric capsule. We showed that mutants lacking the enigmatic rkp-1 gene cluster fail to display the Kdo capsule on the cell surface but accumulate an intracellular polysaccharide of unusually high M(r). In addition, we have demonstrated that mutations in kdsB2, smb20804, and smb20805 affect the polymerization of the Kdo homopolymeric capsule. Our studies also suggest a role for the capsular polysaccharide in symbiosis. Previous reports have shown that the overexpression of rkpZ from strain Rm41 allows for the symbiosis of exoY mutants of Rm1021 that are unable to produce the exopolysaccharide succinoglycan. Our results demonstrate that mutations in the rkp-1 cluster prevent this phenotypic suppression of exoY mutants, although mutations in kdsB2, smb20804, and smb20805 have no effect.
Collapse
Affiliation(s)
- Maike G. Müller
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois 60153, Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - Lennart S. Forsberg
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois 60153, Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - David H. Keating
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois 60153, Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| |
Collapse
|
4
|
Jofré E, Fischer S, Príncipe A, Castro M, Ferrari W, Lagares A, Mori G. Mutation in a D-alanine-D-alanine ligase of Azospirillum brasilense Cd results in an overproduction of exopolysaccharides and a decreased tolerance to saline stress. FEMS Microbiol Lett 2008; 290:236-46. [PMID: 19025567 DOI: 10.1111/j.1574-6968.2008.01421.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Bacteria of the genus Azospirillum are free-living nitrogen-fixing, rhizobacteria that are found in close association with plant roots, where they exert beneficial effects on plant growth and yield in many crops of agronomic importance. Unlike other bacteria, little is known about the genetics and biochemistry of exopolysaccharides in Azospirillum brasilense. In an attempt to characterize genes associated with exopolysaccharides production, we generated an A. brasilense Cd Tn5 mutant that showed exopolysaccharides overproduction, decreased tolerance to saline conditions, altered cell morphology, and increased sensitivity to detergents. Genetic characterization showed that the Tn5 was inserted within a ddlB gene encoding for a d-alanine-d-alanine ligase, and located upstream of the ftsQAZ gene cluster responsible for cell division in different bacteria. Heterologous complementation of the ddlB Tn5 mutant restored the exopolysaccharides production to wild-type levels and the ability to grow in the presence of detergents, but not the morphology and growth characteristics of the wild-type bacteria, suggesting a polar effect of Tn5 on the fts genes. This result and the construction of a nonpolar ddlB mutant provide solid evidence of the presence of transcriptional coupling between a gene associated with peptidoglycan biosynthesis and the fts genes required to control cell division.
Collapse
Affiliation(s)
- Edgardo Jofré
- Departamento de Ciencias Naturales, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
| | | | | | | | | | | | | |
Collapse
|
5
|
Ormeño-Orrillo E, Rosenblueth M, Luyten E, Vanderleyden J, Martínez-Romero E. Mutations in lipopolysaccharide biosynthetic genes impair maize rhizosphere and root colonization of Rhizobium tropici CIAT899. Environ Microbiol 2008; 10:1271-84. [PMID: 18312393 DOI: 10.1111/j.1462-2920.2007.01541.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Three transposon mutants of Rhizobium tropici CIAT899 affected in lipopolysaccharide (LPS) biosynthesis were characterized and their maize rhizosphere and endophytic root colonization abilities were evaluated. The disrupted genes coded for the following putative products: the ATPase component of an O antigen ABC-2 type transporter (wzt), a nucleotide-sugar dehydratase (lpsbeta2) and a bifunctional enzyme producing GDP-mannose (noeJ). Electrophoretic analysis of affinity purified LPS showed that all mutants lacked the smooth LPS bands indicating an O antigen minus phenotype. In the noeJ mutant, the rough LPS band migrated faster than the parental band, suggesting a truncated LPS core. When inoculated individually, the wzt and noeJ mutants colonize the rhizosphere and root to a lower extent than the parental strain while no differences were observed between the lpsbeta2 mutant and the parental strain. All mutants were impaired in competitive rhizosphere and root colonization. Pleiotropic effects of the mutations on known colonization traits such as motility and growth rate were observed, but they were not sufficient to explain the colonization behaviours. It was found that the LPS mutants were sensitive to the maize antimicrobial 6-methoxy-2-benzoxazolinone (MBOA). Only the combined effects of altered growth rate and susceptibility to maize antimicrobials could account for all the observed colonization phenotypes. The results suggest an involvement of the LPS in protecting R. tropici against maize defence response during rhizosphere and root colonization.
Collapse
Affiliation(s)
- Ernesto Ormeño-Orrillo
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, Mexico
| | | | | | | | | |
Collapse
|
6
|
Pereira SIA, Lima AIG, Figueira EMDAP. Screening possible mechanisms mediating cadmium resistance in Rhizobium leguminosarum bv. viciae isolated from contaminated Portuguese soils. MICROBIAL ECOLOGY 2006; 52:176-86. [PMID: 16897308 DOI: 10.1007/s00248-006-9057-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2005] [Accepted: 10/17/2005] [Indexed: 05/11/2023]
Abstract
Environment heavy-metal contamination is now widespread. Soils may become contaminated from a variety of anthropogenic sources, such as smelters, mining, industry, and application of metal-containing pesticides and fertilizers. Soil microorganisms are very sensitive to moderate heavy-metal concentrations. Therefore, the present work was designed to screen possible mechanisms involved in Rhizobium's Cd resistance; with this purpose, we determined the tolerance levels of several isolates originated from sites with different heavy-metal contamination. Whole-cell-soluble proteins and plasmid profiles were analyzed. We also determined Cd cell concentrations and lipopolysaccharide (LPS) amounts. Results showed different tolerances among Rhizobium isolates; according to their maximum resistance level, isolates were divided in four groups: sensitive (0-125 microM CdCl(2)), moderately tolerant (125-210 microM CdCl(2)), tolerant (250-500 microM CdCl(2)), and extremely tolerant (> or =750 microM CdCl(2)). Intracellular Cd concentrations were lower when compared to wall-bound Cd. Unexpectedly, extremely tolerant isolates accumulated higher levels of metal, suggesting the presence of intracellular agents that prevent metal interfering with important metabolic pathways. The electrophoretic patterns of whole-cell-soluble proteins evidenced cadmium as an inducer of protein metabolism alterations, which were more evident in some polypeptides. Plasmid profiles also showed differences; most tolerant isolates presented two plasmids with molecular weights of 485 and 415 kb, indicating that extrachromosomal DNA may be involved in cadmium resistance. LPS showed to be a common mechanism of resistance. However, the degree of tolerance conferred by LPS is not enough to support tolerance to the higher levels of stress imposed. Presence of other resistance mechanisms is currently being investigated.
Collapse
Affiliation(s)
- Sofia Isabel Almeida Pereira
- Centro de Biologia Celular, Departamento de Biologia, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
| | | | | |
Collapse
|
7
|
Bosch A, Serra D, Prieto C, Schmitt J, Naumann D, Yantorno O. Characterization of Bordetella pertussis growing as biofilm by chemical analysis and FT-IR spectroscopy. Appl Microbiol Biotechnol 2005; 71:736-47. [PMID: 16292646 DOI: 10.1007/s00253-005-0202-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 09/17/2005] [Accepted: 09/23/2005] [Indexed: 11/28/2022]
Abstract
Although Bordetella pertussis, the etiologic agent of whooping cough, adheres and grows on the ciliated epithelium of the respiratory tract, it has been extensively studied only in liquid cultures. In this work, the phenotypic expression of B. pertussis in biofilm growth is described as a first approximation of events that may occur in the colonization of the host. The biofilm developed on polypropylene beads was monitored by chemical methods and Fourier transform infrared (FT-IR) spectroscopy. Analysis of cell envelopes revealed minimal differences in outer membrane protein (OMP) pattern and no variation of lipopolysaccharide (LPS) expression in biofilm compared with planktonically grown cells. Sessile cells exhibited a 2.4- to 3.0-fold higher carbohydrate/protein ratio compared with different types of planktonic cells. A 1.8-fold increased polysaccharide content with significantly increased hydrophilic characteristics was observed. FT-IR spectra of the biofilm cells showed higher intensity in the absorption bands assigned to polysaccharides (1,200-900 cm(-1) region) and vibrational modes of carboxylate groups (1,627, 1,405, and 1,373 cm(-1)) compared with the spectra of planktonic cells. In the biofilm matrix, uronic-acid-containing polysaccharides, proteins, and LPS were detected. The production of extracellular carbohydrates during biofilm growth was not associated with changes in the specific growth rate, growth phase, or oxygen limitation. It could represent an additional virulence factor that may help B. pertussis to evade host defenses.
Collapse
Affiliation(s)
- A Bosch
- Centro de Investigación y Desarrollo en Fermentaciones Industriales (CINDEFI), Facultad de Ciencias Exactas, UNLP, calle 50 y 115, 1900 La Plata, Argentina
| | | | | | | | | | | |
Collapse
|
8
|
Hozbor DF, Pich Otero AJL, Lodeiro AR, Del Papa MF, Pistorio M, Lagares A. The symbiotic defect in a Sinorhizobium meliloti lipopolysaccharide mutant can be overcome by expression of other surface polysaccharides. Res Microbiol 2005; 155:855-60. [PMID: 15567281 DOI: 10.1016/j.resmic.2004.06.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Accepted: 06/29/2004] [Indexed: 11/23/2022]
Abstract
In this work we have examined the extent of functional complementation in symbiosis among different Sinorhizobium meliloti surface polysaccharides including lipopolysaccharide (LPS). We show that a symbiotic deficiency associated with an LPS defect can be reversed by appropriate expression of other surface polysaccharides such as galactoglucan (EPSII) and a particular form of capsular polysaccharide (KdoPS). It is noteworthy that, while succinoglycan EPSI and LPS cannot functionally substitute for each other, they can both be replaced by the same common set of polysaccharides (i.e., EPSII/KdoPS). The complex pattern of functional complementation in symbiosis among S. meliloti surface polysaccharides was shown to be different in Medicago truncatula compared to that previously reported for M. sativa.
Collapse
Affiliation(s)
- Daniela F Hozbor
- Instituto de Bioquímica y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115, 1900 La Plata, Argentina.
| | | | | | | | | | | |
Collapse
|
9
|
Laus MC, Logman TJ, Van Brussel AAN, Carlson RW, Azadi P, Gao MY, Kijne JW. Involvement of exo5 in production of surface polysaccharides in Rhizobium leguminosarum and its role in nodulation of Vicia sativa subsp. nigra. J Bacteriol 2004; 186:6617-25. [PMID: 15375143 PMCID: PMC516619 DOI: 10.1128/jb.186.19.6617-6625.2004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Analysis of two exopolysaccharide-deficient mutants of Rhizobium leguminosarum, RBL5808 and RBL5812, revealed independent Tn5 transposon integrations in a single gene, designated exo5. As judged from structural and functional homology, this gene encodes a UDP-glucose dehydrogenase responsible for the oxidation of UDP-glucose to UDP-glucuronic acid. A mutation in exo5 affects all glucuronic acid-containing polysaccharides and, consequently, all galacturonic acid-containing polysaccharides. Exo5-deficient rhizobia do not produce extracellular polysaccharide (EPS) or capsular polysaccharide (CPS), both of which contain glucuronic acid. Carbohydrate composition analysis and nuclear magnetic resonance studies demonstrated that EPS and CPS from the parent strain have very similar structures. Lipopolysaccharide (LPS) molecules produced by the mutant strains are deficient in galacturonic acid, which is normally present in the core and lipid A portions of the LPS. The sensitivity of exo5 mutant rhizobia to hydrophobic compounds shows the involvement of the galacturonic acid residues in the outer membrane structure. Nodulation studies with Vicia sativa subsp. nigra showed that exo5 mutant rhizobia are impaired in successful infection thread colonization. This is caused by strong agglutination of EPS-deficient bacteria in the root hair curl. Root infection could be restored by simultaneous inoculation with a Nod factor-defective strain which retained the ability to produce EPS and CPS. However, in this case colonization of the nodule tissue was impaired.
Collapse
Affiliation(s)
- Marc C Laus
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
10
|
Jofré E, Lagares A, Mori G. Disruption of dTDP-rhamnose biosynthesis modifies lipopolysaccharide core, exopolysaccharide production, and root colonization in Azospirillum brasilense. FEMS Microbiol Lett 2004; 231:267-75. [PMID: 14987774 DOI: 10.1016/s0378-1097(04)00003-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2003] [Revised: 12/23/2003] [Accepted: 12/24/2003] [Indexed: 10/26/2022] Open
Abstract
The interaction between Azospirillum brasilense and plants is not fully understood, although several bacterial surface components like exopolysaccharides (EPS), flagella, and capsular polysaccharides are required for attachment and colonization. While in other plant-bacteria associations (Rhizobium-legume, Pseudomonas-potato), lipopolysaccharides (LPS) play a key role in the establishment of an effective association, their role in the root colonization by Azospirillum had not been determined. In this study, we isolated a Tn5 mutant of A. brasilense Cd (EJ1) with an apparently modified LPS core structure, non-mucoid colony morphology, increased EPS production, and affected in maize root colonization. A 3790-bp region revealed the presence of three complete open reading frames designated rmlC, rmlB and rmlD. The beginning of a fourth open reading frame was found and designated rmlA. These genes are organized in a cluster which shows homology to the cluster involved in the synthesis of dTDP-rhamnose in other bacteria. Additionally, the analysis of the monosaccharide composition of LPSs showed a diminution of rhamnose compared to the wild-type strain.
Collapse
Affiliation(s)
- Edgardo Jofré
- Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta 36-Km 601, 5800 Río Cuarto, Córdoba, Argentina.
| | | | | |
Collapse
|
11
|
Lerouge I, Verreth C, Michiels J, Carlson RW, Datta A, Gao MY, Vanderleyden J. Three genes encoding for putative methyl- and acetyltransferases map adjacent to the wzm and wzt genes and are essential for O-antigen biosynthesis in Rhizobium etli CE3. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2003; 16:1085-1093. [PMID: 14651342 DOI: 10.1094/mpmi.2003.16.12.1085] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The elucidation of the structure of the O-antigen of Rhizobium etli CE3 predicts that the R. etli CE3 genome must contain genes encoding acetyl- and methyltransferases to confer the corresponding modifications to the O-antigen. We identified three open reading frames (ORFs) upstream of wzm, encoding the membrane component of the O-antigen transporter and located in the lps alpha-region of R. etli CE3. The ORFs encode two putative acetyltransferases with similarity to the CysE-LacA-LpxA-NodL family of acetyltransferases and one putative methyltransferase with sequence motifs common to a wide range of S-adenosyl-L-methionine-dependent methyltransferases. Mutational analysis of the ORFs encoding the putative acetyltransferases and methyltransferase revealed that the acetyl and methyl decorations mediated by these specific enzymes are essential for O-antigen synthesis. Composition analysis and high performance anion exchange chromatography analysis of the lipopolysaccharides (LPSs) of the mutants show that all of these LPSs contain an intact core region and lack the O-antigen polysaccharide. The possible role of these transferases in the decoration of the O-antigen of R. etli is discussed.
Collapse
|
12
|
Sharypova LA, Niehaus K, Scheidle H, Holst O, Becker A. Sinorhizobium meliloti acpXL mutant lacks the C28 hydroxylated fatty acid moiety of lipid A and does not express a slow migrating form of lipopolysaccharide. J Biol Chem 2003; 278:12946-54. [PMID: 12566460 DOI: 10.1074/jbc.m209389200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipid A is the hydrophobic anchor of lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria. Lipid A of all Rhizobiaceae is acylated with a long fatty acid chain, 27-hydroxyoctacosanoic acid. Biosynthesis of this long acyl substitution requires a special acyl carrier protein, AcpXL, which serves as a donor of C28 (omega-1)-hydroxylated fatty acid for acylation of rhizobial lipid A (Brozek, K.A., Carlson, R.W., and Raetz, C. R. (1996) J. Biol. Chem. 271, 32126-32136). To determine the biological function of the C28 acylation of lipid A, we constructed an acpXL mutant of Sinorhizobium meliloti strain 1021. Gas-liquid chromatography and mass spectrometry analysis of the fatty acid composition showed that the acpXL mutation indeed blocked C28 acylation of lipid A. SDS-PAGE analysis of acpXL mutant LPS revealed only a fast migrating band, rough LPS, whereas the parental strain 1021 manifested both rough and smooth LPS. Regardless of this, the LPS of parental and mutant strains had a similar sugar composition and exposed the same antigenic epitopes, implying that different electrophoretic profiles might account for different aggregation properties of LPS molecules with and without a long acyl chain. The acpXL mutant of strain 1021 displayed sensitivity to deoxycholate, delayed nodulation of Medicago sativa, and a reduced competitive ability. However, nodules elicited by this mutant on roots of M. sativa and Medicago truncatula had a normal morphology and fixed nitrogen. Thus, the C28 fatty acid moiety of lipid A is not crucial, but it is beneficial for establishing an effective symbiosis with host plants. acpXL lies upstream from a cluster of five genes, including msbB (lpxXL), which might be also involved in biosynthesis and transfer of the C28 fatty acid to the lipid A precursor.
Collapse
Affiliation(s)
- Larissa A Sharypova
- Institute of Genetics, Biology VI, University of Bielefeld, Postfach 100131, Bielefeld D-33501, Germany.
| | | | | | | | | |
Collapse
|
13
|
Vedam V, Kannenberg EL, Haynes JG, Sherrier DJ, Datta A, Carlson RW. A Rhizobium leguminosarum AcpXL mutant produces lipopolysaccharide lacking 27-hydroxyoctacosanoic acid. J Bacteriol 2003; 185:1841-50. [PMID: 12618448 PMCID: PMC150140 DOI: 10.1128/jb.185.6.1841-1850.2003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2002] [Accepted: 12/16/2002] [Indexed: 11/20/2022] Open
Abstract
The structure of the lipid A from Rhizobium etli and Rhizobium leguminosarum lipopolysaccharides (LPSs) lacks phosphate and contains a galacturonosyl residue at its 4' position, an acylated 2-aminogluconate in place of the proximal glucosamine, and a very long chain omega-1 hydroxy fatty acid, 27-hydroxyoctacosanoic acid (27OHC28:0). The 27OHC28:0 moiety is common in lipid A's among members of the Rhizobiaceae and also among a number of the facultative intracellular pathogens that form chronic infections, e.g., Brucella abortus, Bartonella henselae, and Legionella pneumophila. In this paper, a mutant of R. leguminosarum was created by placing a kanamycin resistance cassette within acpXL, the gene which encodes the acyl carrier protein for 27OHC28:0. The result was an LPS containing a tetraacylated lipid A lacking 27OHC28:0. A small amount of the mutant lipid A may contain an added palmitic acid residue. The mutant is sensitive to changes in osmolarity and an increase in acidity, growth conditions that likely occur in the nodule microenvironment. In spite of the probably hostile microenvironment of the nodule, the acpXL mutant is still able to form nitrogen-fixing root nodules even though the appearance and development of nodules are delayed. Therefore, it is possible that the acpXL mutant has a host-inducible mechanism which enables it to adapt to these physiological changes.
Collapse
Affiliation(s)
- Vinata Vedam
- Carbohydrate Research Center, University of Georgia Complex, Athens, Georgia 30602, USA
| | | | | | | | | | | |
Collapse
|
14
|
Tzeng YL, Datta A, Strole C, Kolli VSK, Birck MR, Taylor WP, Carlson RW, Woodard RW, Stephens DS. KpsF is the arabinose-5-phosphate isomerase required for 3-deoxy-D-manno-octulosonic acid biosynthesis and for both lipooligosaccharide assembly and capsular polysaccharide expression in Neisseria meningitidis. J Biol Chem 2002; 277:24103-13. [PMID: 11956197 DOI: 10.1074/jbc.m200931200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have identified and defined the function of kpsF of Neisseria meningitidis and the homologues of kpsF in encapsulated K1 and K5 Escherichia coli. KpsF was shown to be the arabinose-5-phosphate isomerase, an enzyme not previously identified in prokaryotes, that mediates the interconversion of ribulose 5-phosphate and arabinose 5-phosphate. KpsF is required for 3-deoxy-d-manno-octulosonic acid (Kdo) biosynthesis in N. meningitidis. Mutation of kpsF or the gene encoding the CMP-Kdo synthetase (kpsU/kdsB) in N. meningitidis resulted in expression of a lipooligosaccharide (LOS) structure that contained only lipid A and reduced capsule expression in the five invasive disease-associated meningococcal serogroups (A, B, C, Y, and W-135). The step linking meningococcal capsule and LOS biosynthesis was shown to be Kdo production as the expression of capsule was wild type in a Kdo transferase (kdtA) mutant. Thus, in addition to lipooligosaccharide assembly, Kdo is required for meningococcal capsular polysaccharide expression. Furthermore, N. meningitidis, unlike enteric Gram-negative bacteria, can survive and synthesize only unglycosylated lipid A.
Collapse
Affiliation(s)
- Yih-Ling Tzeng
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, the Department of Veterans Affairs Medical Center, Atlanta, Georgia 30033, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Sisti F, Fernández J, Rodríguez ME, Lagares A, Guiso N, Hozbor DF. In vitro and in vivo characterization of a Bordetella bronchiseptica mutant strain with a deep rough lipopolysaccharide structure. Infect Immun 2002; 70:1791-8. [PMID: 11895940 PMCID: PMC127836 DOI: 10.1128/iai.70.4.1791-1798.2002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella bronchiseptica is closely related to Bordetella pertussis, which produces respiratory disease primarily in mammals other than humans. However, its importance as a human pathogen is being increasingly recognized. Although a large amount of research on Bordetella has been generated regarding protein virulence factors, the participation of the surface lipopolysaccharide (LPS) during B. bronchiseptica infection is less understood. To get a better insight into this matter, we constructed and characterized the behavior of an LPS mutant with the deepest possible rough phenotype. We generated the defective mutant B. bronchiseptica LP39 on the waaC gene, which codes for a heptosyl transferase involved in the biosynthesis of the core region of the LPS molecule. Although in B. bronchiseptica LP39 the production of the principal virulence determinants adenylate cyclase-hemolysin, filamentous hemagglutinin, and pertactin persisted, the quantity of the two latter factors was diminished, with the levels of pertactin being the most greatly affected. Furthermore, the LPS of B. bronchiseptica LP39 did not react with sera obtained from mice that had been infected with the parental strain, indicating that this defective LPS is immunologically different from the wild-type LPS. In vivo experiments demonstrated that the ability to colonize the respiratory tract is reduced in the mutant, being effectively cleared from lungs within 5 days, whereas the parental strain survived at least for 30 days. In vitro experiments have demonstrated that, although B. bronchiseptica LP39 was impaired for adhesion to human epithelial cells, it is still able to survive within the host cells as efficiently as the parental strain. These results seem to indicate that the deep rough form of B. bronchiseptica LPS cannot represent a dominant phenotype at the first stage of colonization. Since isolates with deep rough LPS phenotype have already been obtained from human B. bronchiseptica chronic infections, the possibility that this phenotype arises as a consequence of selection pressure within the host at a late stage of the infection process is discussed.
Collapse
Affiliation(s)
- Federico Sisti
- Instituto de Bioquímica y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1900 La Plata, República Argentina
| | | | | | | | | | | |
Collapse
|
16
|
Lerouge I, Laeremans T, Verreth C, Vanderleyden J, Van Soom C, Tobin A, Carlson RW. Identification of an ATP-binding cassette transporter for export of the O-antigen across the inner membrane in Rhizobium etli based on the genetic, functional, and structural analysis of an lps mutant deficient in O-antigen. J Biol Chem 2001; 276:17190-8. [PMID: 11279176 DOI: 10.1074/jbc.m101129200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
For O-antigen lipopolysaccharide (LPS) synthesis in bacteria, transmembrane migration of undecaprenyl pyrophosphate-bound O-antigen oligosaccharide subunits or polysaccharide occurs before ligation to the core region of the LPS molecule. In this study, we identified by mutagenesis an ATP-binding cassette transporter in Rhizobium etli CE3 that is likely responsible for the translocation of the O-antigen across the inner plasma membrane. Mutant FAJ1200 LPS lacks largely the O-antigen, as shown by SDS-polyacrylamide gel electrophoresis and confirmed by immunoblot analysis. Furthermore, LPS isolated from FAJ1200 is totally devoid of any O-chain glycosyl residues and contains only those glycosyl residues that can be expected for the inner core region. The membrane component and the cytoplasmic ATP-binding component of the ATP-binding cassette transporter are encoded by wzm and wzt, respectively. The Tn5 transposon in mutant FAJ1200 is inserted in the wzm gene. This mutation resulted in an Inf- phenotype in bean plants.
Collapse
Affiliation(s)
- I Lerouge
- Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, Heverlee B-3001, Belgium
| | | | | | | | | | | | | |
Collapse
|
17
|
Crump EM, Perry MB, Clouthier SC, Kay WW. Antigenic characterization of the fish pathogen Flavobacterium psychrophilum. Appl Environ Microbiol 2001; 67:750-9. [PMID: 11157240 PMCID: PMC92644 DOI: 10.1128/aem.67.2.750-759.2001] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flavobacteria are a poorly understood and speciated group of commensal bacteria and opportunistic pathogens. The psychrotroph Flavobacterium psychrophilum is the etiological agent of rainbow trout fry syndrome and bacterial cold water disease, septicemic diseases that heavily impact salmonids. Consequently, two verified but geographically diverse isolates were characterized phenotypically and biochemically. A facile typing system was devised which readily discriminated between closely related species and was verified against a pool of recent prospective isolates. F. psychrophilum was found to be enveloped in a loosely attached, strongly antigenic outer layer comprised of a predominant, highly immunogenic, low-molecular-mass carbohydrate antigen as well as several protein antigens. Surface-exposed antigens were visualized by a combination of immunoflourescence microscopy, immunogold transmission, and thin-section electron microscopy and were discriminated by Western blotting using rabbit antisera, by selective extraction with EDTA-polymyxin B agarose beads, and by extrinsic labeling of amines with sulfo-N-hydoxysuccinimide-biotin and glycosyl groups with biotin hydrazide. The predominant approximately 16 kDa antigen was identified as low-molecular-mass lipopolysaccharide (LPS), whereas high-molecular-mass LPS containing O antigen was not as prevalent on whole cells but was abundant in culture supernatants. Rainbow trout convalescent antisera recognized both molecular mass classes of LPS as well as a predominant approximately 20-kDa protein. This study represents the first description at the molecular level of the surface characteristics and potential vaccine targets of confirmed F. psychrophilum strains.
Collapse
Affiliation(s)
- E M Crump
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | | | | | | |
Collapse
|
18
|
Lagares A, Hozbor DF, Niehaus K, Otero AJ, Lorenzen J, Arnold W, Pühler A. Genetic characterization of a Sinorhizobium meliloti chromosomal region in lipopolysaccharide biosynthesis. J Bacteriol 2001; 183:1248-58. [PMID: 11157937 PMCID: PMC94998 DOI: 10.1128/jb.183.4.1248-1258.2001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genetic characterization of a 5.5-kb chromosomal region of Sinorhizobium meliloti 2011 that contains lpsB, a gene required for the normal development of symbiosis with Medicago spp., is presented. The nucleotide sequence of this DNA fragment revealed the presence of six genes: greA and lpsB, transcribed in the forward direction; and lpsE, lpsD, lpsC, and lrp, transcribed in the reverse direction. Except for lpsB, none of the lps genes were relevant for nodulation and nitrogen fixation. Analysis of the transcriptional organization of lpsB showed that greA and lpsB are part of separate transcriptional units, which is in agreement with the finding of a DNA stretch homologous to a "nonnitrogen" promoter consensus sequence between greA and lpsB. The opposite orientation of lpsB with respect to its first downstream coding sequence, lpsE, indicated that the altered LPS and the defective symbiosis of lpsB mutants are both consequences of a primary nonpolar defect in a single gene. Global sequence comparisons revealed that the greA-lpsB and lrp genes of S. meliloti have a genetic organization similar to that of their homologous loci in R. leguminosarum bv. viciae. In particular, high sequence similarity was found between the translation product of lpsB and a core-related biosynthetic mannosyltransferase of R. leguminosarum bv. viciae encoded by the lpcC gene. The functional relationship between these two genes was demonstrated in genetic complementation experiments in which the S. meliloti lpsB gene restored the wild-type LPS phenotype when introduced into lpcC mutants of R. leguminosarum. These results support the view that S. meliloti lpsB also encodes a mannosyltransferase that participates in the biosynthesis of the LPS core. Evidence is provided for the presence of other lpsB-homologous sequences in several members of the family Rhizobiaceae.
Collapse
Affiliation(s)
- A Lagares
- Instituto de Bioquímica y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1900 La Plata, Argentina.
| | | | | | | | | | | | | |
Collapse
|
19
|
Prieto CI, Aguilar OM, Yantorno OM. Analyses of lipopolysaccharides, outer membrane proteins and DNA fingerprints reveal intraspecies diversity in Moraxella bovis isolated in Argentina. Vet Microbiol 1999; 70:213-23. [PMID: 10596805 DOI: 10.1016/s0378-1135(99)00142-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Intra-specific diversity within Moraxella bovis was investigated analysing DNA fingerprints, outer membrane proteins (OMP) and lipopolysaccharides (LPS) profiles. Three collection strains and 57 isolates of M. bovis, collected during 3 years from cattle with infectious bovine keratoconjunctivitis (IBK) symptoms, from diverse geographical locations of Argentina, were examined. The LPS and OMP profiles were studied through SDS-PAGE analysis and genotype was determined by PCR-DNA fingerprinting. Genotyping identified five DNA types while analysis of LPS and OMP profiles identified three rough LPS types and three OMP types among the 60 isolates of M. bovis including the three collection strains. None of the three methods employed to assess diversity was discriminating when used alone because the degree of heterogeneity in each group of surface structures was limited, but when data of each typing method were combined, 15 distinct subgroups were determined. This subgrouping was clearly able to differentiate isolates of the same genotype. These typing methods appear to be useful to assess different aspects of the disease such as the diversity within a population of M. bovis associated to epidemic conditions, track the causal agent in an outbreak of the disease, monitoring vaccination programs and studies on virulence.
Collapse
Affiliation(s)
- C I Prieto
- Centro de Investigación y Desarrollo en Fermentaciones Industriales, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina
| | | | | |
Collapse
|
20
|
Høi L, Dalsgaard I, DePaola A, Siebeling RJ, Dalsgaard A. Heterogeneity among isolates of Vibrio vulnificus recovered from eels (Anguilla anguilla) in Denmark. Appl Environ Microbiol 1998; 64:4676-82. [PMID: 9835548 PMCID: PMC90908 DOI: 10.1128/aem.64.12.4676-4682.1998] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The findings of this study demonstrate that Vibrio vulnificus isolates recovered from diseased eels in Denmark are heterogeneous as shown by O serovars, capsule types, ribotyping, phage typing, and plasmid profiling. The study includes 85 V. vulnificus isolates isolated from the gills, intestinal contents, mucus, spleen, and kidneys of eels during five disease outbreaks on two Danish eel farms from 1995 to 1997, along with a collection of 12 V. vulnificus reference strains. The results showed that more than one serovar may be capable of causing disease in eels and that these isolates are genetically heterogenous as shown by ribotyping. Ribotyping also showed that the same isolates may persist in an eel farm and cause recurrent outbreaks. Phage typing did not correlate with ribotyping or serotyping. However, we observed that 26 of 28 isolates, which were not susceptible to any of the phages, showed the same ribotype, O serovar, and capsule type. This suggests that these isolates may possess features that make them resistant to lysis by the phages used in this study. Ninety-three of 97 isolates harbored between one and three high-molecular-weight plasmids which previously had been suggested to be associated with eel virulence. The subdivision of V. vulnificus into two biotypes based on the indole reaction can no longer be supported, since 82 of 97 isolates in this study were indole positive, and a subdivision into serovars appears to be more correct.
Collapse
Affiliation(s)
- L Høi
- Department of Veterinary Microbiology, The Royal Veterinary and Agricultural University, DK-1870 Frederiksberg C, Denmark.
| | | | | | | | | |
Collapse
|
21
|
Jofré E, Fischer S, Rivarola V, Balegno H, Mori G. Saline stress affects the attachment ofAzospirillum brasilenseCd to maize and wheat roots. Can J Microbiol 1998. [DOI: 10.1139/w98-024] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present work was designed to study the effect of saline stress on the attachment of Azospirillum brasilense to maize and wheat roots. We demonstrate that both attachment steps (adsorption and anchoring) are altered. A 100-kDa protein disappeared under these experimental conditions. Coincidently, a 100-kDa flagellum protein has been identified as the agent responsible for adsorption. However, the adhesive properties of bacteria appear to involve other factors, such as the ionic strength of the medium. The impairment of anchoring ability was correlated with alterations in exopolysaccharide, glucan, and lipopolysaccharide contents.Key words: Azospirillum brasilense, saline stress, Azospirillum-root interaction.
Collapse
|