Bacterial Chromosome Segregation

Draper, G. Craig; Gober, James W.

doi:10.1146/annurev.micro.56.012302.160729

Cited by 72 publications

(57 citation statements)

References 169 publications

(260 reference statements)

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“…In contrast, prokaryotic chromosomes are either completely devoid of centromeres or carry the so-called "plasmid centromeres" which are not essential (with a few exceptions, such as Caulobacter) (57)(58)(59)(60).…”

Section: Structural Differencesmentioning

confidence: 99%

The Precarious Prokaryotic Chromosome

Kuzminov

2014

J Bacteriol

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Evolutionary selection for optimal genome preservation, replication, and expression should yield similar chromosome organizations in any type of cells. And yet, the chromosome organization is surprisingly different between eukaryotes and prokaryotes. The nuclear versus cytoplasmic accommodation of genetic material accounts for the distinct eukaryotic and prokaryotic modes of genome evolution, but it falls short of explaining the differences in the chromosome organization. I propose that the two distinct ways to organize chromosomes are driven by the differences between the global-consecutive chromosome cycle of eukaryotes and the local-concurrent chromosome cycle of prokaryotes. Specifically, progressive chromosome segregation in prokaryotes demands a single duplicon per chromosome, while other "precarious" features of the prokaryotic chromosomes can be viewed as compensations for this severe restriction.

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Section: Structural Differencesmentioning

confidence: 99%

The Precarious Prokaryotic Chromosome

Kuzminov

2014

J Bacteriol

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“…These proteins were first analyzed in low-copy-number plasmids (including prophage) of Escherichia coli, such as F and P1, and were found to be essential for accurate partitioning of the plasmids (9,17). The P1 ParA protein binds both ADP and ATP (7).…”

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confidence: 99%

“…On the other hand, like B. subtilis, ParB binds to several parS sequences in the oriC region, including a sequence downstream of the parAB operon (9,33). Both ParA and ParB showed polar localization in predivisional cells, while in B. subtilis Soj moved dynamically between cell poles or nucleoids (32,42).…”

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Increasing the Ratio of Soj to Spo0J Promotes Replication Initiation inBacillus subtilis

et al. 2003

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The ParA and ParB protein families are well conserved in bacteria. However, their functions are still unclear. In Bacillus subtilis, Soj and Spo0J are members of these two protein families, respectively. A previous report revealed that replication initiated early and asynchronously in spo0J null mutant cells, as determined by flow cytometry. In this study, we examined the cause of this promotion of replication initiation. Deletion of both the soj and spo0J genes restored the frequency of replication initiation to almost the wild-type level, suggesting that production of Soj in the absence of Spo0J leads to early and asynchronous initiation of replication. Consistent with this suggestion, overproduction of Soj in wild-type cells had the same effect on replication initiation as in the spo0J null mutant, and overproduction of both Soj and Spo0J did not. These results indicate that when the ratio of Soj to Spo0J increases, Soj interferes with tight control of replication initiation and causes early and asynchronous initiation. Whereas replication initiation also occurred significantly earlier in the two spo0J mutants, spo0J14 and spo0J17, it occurred only slightly early in the sojK16Q mutant and was delayed in the sojG12V mutant. Although Soj localized to nucleoids in the spo0J mutants, the two Soj mutant proteins were distributed throughout the cell or localized to cell poles. Thus, interestingly, the promotion of replication initiation seems to correlate with localization of Soj to nucleoids. This may suggest that Soj inhibits transcription of some cell cycle genes and leads to early and asynchronous initiation of replication. In wild-type cells Spo0J counteracts this Soj function.The ParA and ParB protein families are widely conserved in bacteria and plasmids (47). These proteins were first analyzed in low-copy-number plasmids (including prophage) of Escherichia coli, such as F and P1, and were found to be essential for accurate partitioning of the plasmids (9, 17). The P1 ParA protein binds both ADP and ATP (7). The ATP-bound form interacts with the ParB-parS complex (parS:ParB-binding DNA sequence) and plays a direct role in partitioning (4). ParB stimulates a weak ATPase activity of ParA (8) and changes the ATP form to the ADP form that cannot interact with the ParB-parS complex. Thus, ParA-ADP is released from the ParB-parS complex and acts as repressor of the parAB operon by binding to the promoter region (4). The ParB protein was detected as foci within the cell, and its localization depended on ParA and parS (11), as expected from the biochemical data. Using a green fluorescent protein (GFP)-ParB fusion, Li and Austin (28) recently showed that P1 plasmid copies are suddenly separated into two daughter cells from the cell center immediately before cell division.In the case of the F plasmid, the biochemical activities of the ParA and ParB family members (SopA and SopB) are very similar to those of the P1 proteins (17). The cis-acting sopC region including the SopB-binding sequences was required for localizat...

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“…One central function of Spo0AϳP is to activate the transcription of essential stage II operons, including spoIIA, spoIIE, and spoIIG (2,9,10,24,(26)(27)(28). The spoIIA and spoIIG operons encode sporulation-specific sigma factors that direct early developmental transcription in the forespore and mother cell compartments, respectively (11,15,16,19).The spo0J operon is a dicistronic unit encoding proteins that belong to the ParA and ParB families, whose members are widely dispersed throughout the bacteria (1,7,17). Spo0J is a sequence-specific DNA binding protein in the ParB family that binds in vitro and in vivo to several origin-proximal DNA sites, termed parS (18).…”

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confidence: 99%

“…The spo0J operon is a dicistronic unit encoding proteins that belong to the ParA and ParB families, whose members are widely dispersed throughout the bacteria (1,7,17). Spo0J is a sequence-specific DNA binding protein in the ParB family that binds in vitro and in vivo to several origin-proximal DNA sites, termed parS (18).…”

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Soj Antagonizes Spo0A Activation of Transcription in Bacillus subtilis

McLeod

Spiegelman

2005

J Bacteriol

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The ParA family protein Soj appears to negatively regulate sporulation in Bacillus subtilis by inhibiting transcription from promoters that are activated by phosphorylated Spo0A. We tested in vitro Soj inhibition of Spo0A-independent variants of a promoter that Soj inhibited (PspoIIG). Transcription from the variants was less sensitive to Soj inhibition, suggesting that inhibition of wild-type PspoIIG was linked to transcription activation by Spo0A.Bacillus subtilis responds to nutrient deprivation and high population densities by initiating a pattern of morphological development resulting in the release of a dormant endospore (9,10,12,26). The decision to sporulate is governed by the levels of phosphorylated Spo0A (Spo0AϳP) (9,10,12,26). One central function of Spo0AϳP is to activate the transcription of essential stage II operons, including spoIIA, spoIIE, and spoIIG (2,9,10,24,(26)(27)(28). The spoIIA and spoIIG operons encode sporulation-specific sigma factors that direct early developmental transcription in the forespore and mother cell compartments, respectively (11,15,16,19).The spo0J operon is a dicistronic unit encoding proteins that belong to the ParA and ParB families, whose members are widely dispersed throughout the bacteria (1,7,17). Spo0J is a sequence-specific DNA binding protein in the ParB family that binds in vitro and in vivo to several origin-proximal DNA sites, termed parS (18). Deletion of spo0J results in a phenotype with a low frequency of anucleate cells accumulating during growth and a block to sporulation before stage II (14, 21). The sporulation block is relieved by the deletion of the parA homologue, soj (14). Transcription from spoIIA, spoIIE, and spoIIG promoters is severely reduced in a ⌬spo0J mutant and restored close to wild-type levels in a ⌬soj spo0J double mutant (14,22). Soj associates with the spo0A, spoIIA, spoIIE, and spoIIG promoters in vivo, and these associations are more pronounced in the absence of Spo0J (22,23). In vitro Soj inhibits transcription from the spoIIG promoter (PspoIIG) activated by either Spo0AϳP or the constitutively active C-terminal domain of Spo0A (Spo0AC) (3). These results imply that Soj acts as a negative regulator of sporulation by inhibiting transcription that is activated by phosphorylated Spo0A.In vitro, Soj dissociates complexes formed by incubating a DNA fragment containing PspoIIG, Spo0AC, and RNA polymerase (RNAP) (3). The Soj-induced dissociation of the promoter-Spo0A-RNAP is unusual, and it was suggested that Soj might act at a step in initiation that follows the action of Spo0A (3). To further explore the mechanism of Soj action, we first needed to distinguish whether or not Soj specifically blocked an activity of Spo0A. We reasoned that if Soj targeted a step in transcription that was independent of Spo0A, then Soj inhibition of a PspoIIG variant that had been mutated so it no longer required Spo0A for high activity would be the same as its inhibition of wild-type PspoIIG. To test this idea, we constructed a set of mutated spoIIG pro...

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Bacterial Chromosome Segregation

Cited by 72 publications

References 169 publications

The Precarious Prokaryotic Chromosome

The Precarious Prokaryotic Chromosome

Increasing the Ratio of Soj to Spo0J Promotes Replication Initiation inBacillus subtilis

Soj Antagonizes Spo0A Activation of Transcription in Bacillus subtilis

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