A novel cyclic beta-1,2-glucan mutant of Rhizobium meliloti

Breedveld, M.W.; Hadley, Jill A.; Miller, Karen J.

doi:10.1128/jb.177.22.6346-6351.1995

Cited by 18 publications

(27 citation statements)

References 35 publications

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“…Although other mutants of glucan substituent transferases have been described for E. coli, S. meliloti, and R. sphaeroides, those mutants contain increased levels of other substituents, such as phosphoethanolamine, succinyl, and acetyl substituents, respectively (6,14,22). B. abortus cgm mutants accumulated neutral cyclic ␤-1,2-glucans; the lack of succinyl residues did not promote any increment of other nonglycosidic substituents.…”

Section: Discussionmentioning

confidence: 99%

“…Succinyl transfer was also shown to occur in the periplasmic compartment in S. meliloti (6). In E. coli and R. sphaeroides, the genes mdoC and opgC, respectively, encode predicted membrane proteins required for wild-type succinyl modification of OPG (14,29).…”

mentioning

confidence: 99%

“…The mdoB gene encodes phosphoglycerol transferase I. In S. meliloti, the cgmB gene encodes a soluble protein required for phosphoglycerol modification of cyclic glucan (6). Nothing has been reported about the transfer of the other substituents to glucans.…”

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confidence: 99%

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The Brucella abortus Cyclic β-1,2-Glucan Virulence Factor Is Substituted with O-Ester-Linked Succinyl Residues

et al. 2006

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Brucella periplasmic cyclic ␤-1,2-glucan plays an important role during bacterium-host interaction. Nuclear magnetic resonance spectrometry analysis, thin-layer chromatography, and DEAE-Sephadex chromatography were used to characterize Brucella abortus cyclic glucan. In the present study, we report that a fraction of B. abortus cyclic ␤-1,2-glucan is substituted with succinyl residues, which confer anionic character on the cyclic ␤-1,2-glucan. The oligosaccharide backbone is substituted at C-6 positions with an average of two succinyl residues per glucan molecule. This O-ester-linked succinyl residue is the only substituent of Brucella cyclic glucan. A B. abortus open reading frame (BAB1_1718) homologous to Rhodobacter sphaeroides glucan succinyltransferase (OpgC) was identified as the gene encoding the enzyme responsible for cyclic glucan modification. This gene was named cgm for cyclic glucan modifier and is highly conserved in Brucella melitensis and Brucella suis. Nucleotide sequencing revealed that B. abortus cgm consists of a 1,182-bp open reading frame coding for a predicted membrane protein of 393 amino acid residues (42.7 kDa) 39% identical to Rhodobacter sphaeroides succinyltransferase. cgm null mutants in B. abortus strains 2308 and S19 produced neutral glucans without succinyl residues, confirming the identity of this protein as the cyclic-glucan succinyltransferase enzyme. In this study, we demonstrate that succinyl substituents of cyclic ␤-1,2-glucan of B. abortus are necessary for hypo-osmotic adaptation. On the other hand, intracellular multiplication and mouse spleen colonization are not affected in cgm mutants, indicating that cyclic-␤-1,2-glucan succinylation is not required for virulence and suggesting that no lowosmotic stress conditions must be overcome during infection.Brucella spp. are gram-negative, facultative intracellular bacteria that cause a chronic zoonotic disease known worldwide as brucellosis. Brucella abortus, the etiological agent of bovine brucellosis, causes abortion and infertility in cattle and undulant fever in humans (17). The human disease is also caused by Brucella melitensis, Brucella suis, and Brucella canis. Brucella spp. are intracellular pathogens that invade and proliferate within host cells; virulence is associated with the ability to multiply inside professional and nonprofessional phagocytic cells (40).Cyclic glucans appear to be important as intrinsic components of gram-negative bacterial cell envelopes (7). Beyond their common features, glucans show an unexpected structural diversity (4). The role of cyclic glucan in gram-negative bacterial cell envelopes is still controversial. Cyclic-glucan mutants have a highly pleiotropic phenotype, suggesting an overall alteration of their cell envelope properties. Mutants deficient in cyclic-glucan production were found to be attenuated or avirulent compared to their wild-type parent strains, suggesting that the cyclic glucan is an important virulence attribute for the bacteria in their interaction with eukaryotic host...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

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The Brucella abortus Cyclic β-1,2-Glucan Virulence Factor Is Substituted with O-Ester-Linked Succinyl Residues

et al. 2006

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“…Intriguingly, the above analysis revealed that many of the 336 cell cycle-regulated genes specific to S. meliloti are crucial for its distinctive lifestyle. For example, megaplasmid replication and segregation genes (repABC) and a putative cyclic β-1,2 glucan ABC transporter (ndvA) do not have homologs in C. crescentus and are required for symbiosis (42). Also, several cell envelope genes (lpxB, olsB, opgC, ddl, and rlpA) and the genes coding for the Min system (minCDE) had cell cycle-regulated transcripts in S. meliloti, but either did not have homologs in C. crescentus or did not demonstrate cell cycle-regulated transcription in C. crescentus, demonstrating that the cell cycle regulon is highly specialized in each species.…”

Section: Microarray Analysis Of Synchronized S Meliloti Cultures Idementioning

confidence: 99%

Global analysis of cell cycle gene expression of the legume symbiontSinorhizobium meliloti

Nisco

Abo

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

118

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In α-proteobacteria, strict regulation of cell cycle progression is necessary for the specific cellular differentiation required for adaptation to diverse environmental niches. The symbiotic lifestyle of Sinorhizobium meliloti requires a drastic cellular differentiation that includes genome amplification. To achieve polyploidy, the S. meliloti cell cycle program must be altered to uncouple DNA replication from cell division. In the α-proteobacterium Caulobacter crescentus, cell cycle-regulated transcription plays an important role in the control of cell cycle progression but this has not been demonstrated in other α-proteobacteria. Here we describe a robust method for synchronizing cell growth that enabled global analysis of S. meliloti cell cycle-regulated gene expression. This analysis identified 462 genes with cell cycle-regulated transcripts, including several key cell cycle regulators, and genes involved in motility, attachment, and cell division. Only 28% of the 462 S. meliloti cell cycle-regulated genes were also transcriptionally cell cycle-regulated in C. crescentus. Furthermore, CtrA-and DnaA-binding motif analysis revealed little overlap between the cell cycle-dependent regulons of CtrA and DnaA in S. meliloti and C. crescentus. The predicted S. meliloti cell cycle regulon of CtrA, but not that of DnaA, was strongly conserved in more closely related α-proteobacteria with similar ecological niches as S. meliloti, suggesting that the CtrA cell cycle regulatory network may control functions of central importance to the specific lifestyles of α-proteobacteria.cell cycle regulation | symbiosis | alpha-proteobacteria

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“…It is well known that the ndvB gene in S. meliloti and the chvB gene in A. tumefaciens encode a large-molecular-mass cytoplasmic membrane protein involved in the biosynthesis of the neutral cyclic β-1,2-glucan backbone from UDP-glucose (40)(41)(42). Additionally, the cgmB gene encodes a soluble protein required for phosphoglycerol modification of the PG (43). Conversely, the identity of the genes involved with the PG substitution by succinyl residues in S. meliloti and A. tumefaciens remains unclear.…”

Section: Genes Involved In Pg Biosynthesismentioning

confidence: 99%