The Sinorhizobium meliloti chromosomal origin of replication

Sibley, Christopher D.; MacLellan, Shawn R.; Finan, Turlough M.

doi:10.1099/mic.0.28455-0

Cited by 29 publications

(34 citation statements)

References 53 publications

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“…5 A and B) (21). A previously verified DnaA-binding motif upstream of the repABC operon of pSymA was identified by this analysis, as well as a conserved CtrAbinding motif 90 bp downstream of the DnaA site (11). The presence of these binding motifs suggests a possible interplay between CtrA and DnaA in the regulation of expression of this repABC operon on pSymA during the cell cycle.…”

Section: Microarray Analysis Of Synchronized S Meliloti Cultures Idementioning

confidence: 87%

“…The results of this study suggest that the S. meliloti cell cycle transcriptional regulatory network, especially the regulon of the master regulator CtrA, has adapted specifically to fit its lifestyle both within the soil and its legume host. are essential and/or functionally conserved in S. meliloti, our understanding of the role of transcriptional regulation in the S. meliloti cell cycle and the link between the cell cycle and cellular differentiation during symbiosis has been limited (11,12,24,25).…”

Section: Significancementioning

confidence: 99%

“…For example, it has been shown that altering the expression of genes central to S. meliloti cell cycle processes (i.e., ftsZ, dnaA, minE, and ccrM) produces bacteroid-like polyploid cells (10)(11)(12)(13) and that mutation of conserved cell cycle regulators (cbrA, cpdR1, and divJ) blocks bacteroid formation and symbiosis (14)(15)(16). Furthermore, in the α-proteobacterium Caulobacter crescentus, the cellular differentiation program governing morphological and replicative asymmetry in progeny cells is genetically integrated with the cell cycle (17).…”

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confidence: 99%

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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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Section: Microarray Analysis Of Synchronized S Meliloti Cultures Idementioning

confidence: 87%

Section: Significancementioning

confidence: 99%

mentioning

confidence: 99%

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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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“…This phenotype is correlated with blocked cell division (Latch & Margolin, 1997;Wright et al, 1997;Sibley et al, 2006) and loss of normal control of DNA replication initiation (Wright et al, 1997). It remains to be established whether a blockage in cell division always leads to branching in S. meliloti; however, this possibility is of considerable interest given the cellular morphology of N 2 -fixing bacteroids.…”

Section: Discussionmentioning

confidence: 99%

A Sinorhizobium meliloti minE mutant has an altered morphology and exhibits defects in legume symbiosis

et al. 2007

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Sinorhizobium meliloti differentiates from rod-shaped, free-living cells into pleomorphic, non-dividing, N 2 -fixing bacteroids within alfalfa root nodules. Here, the role of the minCDE genes in bacteroid differentiation and in free-living cell division is examined. Disruption of the minE gene resulted in large, swollen and branched free-living cells, and in symbiosis a minE mutation resulted in a defect in nitrogen fixation with activity reduced by approximately 70 % compared to the wild-type. It has been demonstrated that the minCDE genes form an operon driven by a promoter located 173 bp upstream of minC. The minCDE genes were expressed in free-living cells and in both the infection zone and the symbiotic zone of alfalfa nodules; however, no changes in the free-living cell morphology, growth or symbiotic N 2 fixation were detected as a result of deletion of these genes. Induced production of individual or combinations of Min proteins in S. meliloti altered its rod-shaped cell morphology. Moreover, cell morphologies resulting from the overexpression of the S. meliloti Min proteins in Escherichia coli suggested similar functions for the E. coli and S. meliloti min genes. These data suggest that there is greater redundancy in the roles of cell division genes in S. meliloti compared with E. coli.

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“…Examples include those overexpressing ccrM (78), ftsZ (41), dnaA (65), and min genes (7) or undergoing treatment with DNA-damaging agents (41). Begg and Donachie (2a) have indicated that when cell division is blocked, cells continue to increase in mass by elongating into filaments many times the length of the dividing cells.…”

Section: Resultsmentioning

confidence: 99%

Involvement of the Azorhizobial Chromosome Partition Gene ( parA ) in the Onset of Bacteroid Differentiation during Sesbania rostrata Stem Nodule Development

Liu¹,

Lee²,

Wang³

et al. 2011

Appl Environ Microbiol

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A parA gene in-frame deletion mutant of Azorhizobium caulinodans ORS571 (ORS571-⌬parA) was constructed to evaluate the roles of the chromosome-partitioning gene on various bacterial traits and on the development of stem-positioned nodules. The ⌬parA mutant showed a pleiomorphic cell shape phenotype and was polyploid, with differences in nucleoid sizes due to dramatic defects in chromosome partitioning. Upon inoculation of the ⌬parA mutant onto the stem of Sesbania rostrata, three types of immature nodule-like structures with impaired nitrogen-fixing activity were generated. Most showed signs of bacteroid early senescence. Moreover, the ⌬parA cells within the nodule-like structures exhibited multiple developmental-stage phenotypes. Since the bacA gene has been considered an indicator for bacteroid formation, we applied the expression pattern of bacA as a nodule maturity index in this study. Our data indicate that the bacA gene expression is parA dependent in symbiosis. The presence of the parA gene transcript was inversely correlated with the maturity of nodule; the transcript was switched off in fully mature bacteroids. In summary, our experimental evidence demonstrates that the parA gene not only plays crucial roles in cellular development when the microbe is free-living but also negatively regulates bacteroid formation in S. rostrata stem nodules.

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The Sinorhizobium meliloti chromosomal origin of replication

Cited by 29 publications

References 53 publications

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

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

A Sinorhizobium meliloti minE mutant has an altered morphology and exhibits defects in legume symbiosis

Involvement of the Azorhizobial Chromosome Partition Gene ( parA ) in the Onset of Bacteroid Differentiation during Sesbania rostrata Stem Nodule Development

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