pTAR-Encoded Proteins in Plasmid Partitioning

Kalnin, Kirill; Stegalkina, Svetlana; Yarmolinsky, Michael B.

doi:10.1128/jb.182.7.1889-1894.2000

Cited by 38 publications

(44 citation statements)

References 40 publications

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“…These five ParG analogs provide a useful and malleable suite of proteins with which to dissect further the protein-protein and protein-DNA interactions that direct the segregation of parF type plasmids. The ParG, ParB TAR , and ParB B171 proteins are necessary for the activity of their cognate partition systems (8,18,23). In the case of pTAR, the system is functional in its native host but not in E. coli (23); the latter result was replicated here (Table 2).…”

Section: Resultssupporting

confidence: 76%

“…For example, the partition regions of plasmids pTAR and pB171 include homologs of parF, but the downstream genes are homologous neither to parB, to parG, nor to each other (Fig. 1A) (18,23,40). Similarly, the putative partition cassette of plasmid pVT745 contains a parF-like gene whose 3Ј end overlaps the 5Ј end of yet another novel downstream gene (11).…”

mentioning

confidence: 99%

“…These regions harbor characteristic repeat motifs (Fig. 1B) that comprise partition and transcriptional regulatory sites (4,23; Carmelo et al, submitted). To assess whether the additional proteins under analysis here were also DNA-binding factors, the proteins were tested in gel retardation assays with the equivalent DNA regions from their cognate partition loci.…”

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confidence: 99%

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Protein Diversity Confers Specificity in Plasmid Segregation

2005

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The ParG segregation protein (8.6 kDa) of multidrug resistance plasmid TP228 is a homodimeric DNAbinding factor. The ParG dimer consists of intertwined C-terminal domains that adopt a ribbon-helix-helix architecture and a pair of flexible, unstructured N-terminal tails. A variety of plasmids possess partition loci with similar organizations to that of TP228, but instead of ParG homologs, these plasmids specify a diversity of unrelated, but similarly sized, partition proteins. These include the proteobacterial pTAR, pVT745, and pB171 plasmids. The ParG analogs of these plasmids were characterized in parallel with the ParG homolog encoded by the pseudomonal plasmid pVS1. Like ParG, the four proteins are dimeric. No heterodimerization was detectable in vivo among the proteins nor with the prototypical ParG protein, suggesting that monomermonomer interactions are specific among the five proteins. Nevertheless, as with ParG, the ParG analogs all possess significant amounts of unordered amino acid residues, potentially highlighting a common structural link among the proteins. Furthermore, the ParG analogs bind specifically to the DNA regions located upstream of their homologous parF-like genes. These nucleoprotein interactions are largely restricted to cognate protein-DNA pairs. The results reveal that the partition complexes of these and related plasmids have recruited disparate DNA-binding factors that provide a layer of specificity to the macromolecular interactions that mediate plasmid segregation.Protein machines for DNA transactions, including transcription, replication, recombination. and segregation, involve highly specific protein-protein and protein-nucleic acid contacts. These interactions are crucial for the precise assembly of the requisite multiprotein complexes and for the biological processes that these complexes mediate (1). A broad, but defined, spectrum of protein-protein and protein-DNA interactions have evolved that determine exactly the architecture of nucleoprotein complexes (5, 30, 43 [and other references therein]).The segregation of plasmids in bacteria also involves specific protein-protein and protein-DNA interactions. Plasmid partition most commonly involves a pair of plasmid-encoded proteins, often denoted ParA and ParB, that assemble on a cisacting partition site, sometimes known as parS (39). The ParA protein does not directly contact the partition site DNA but is instead recruited into the partition nucleoprotein complex through interactions with the ParB protein (4, 6). ParA possesses weak intrinsic ATPase activity which is stimulated by the ParB factor. The assembly of the partition nucleoprotein complex is required for the proper movement of plasmid pairs in opposite poleward directions prior to cell division (9,15,26,27). This movement is likely to occur as a result of extensive ATP-mediated polymerization and/or depolymerization of the ParA component (D. Barillà et al., EMBO J., in press).The partition cassette of the multidrug resistance plasmid TP228 specifies a ParA homolog, P...

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Section: Resultssupporting

confidence: 76%

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confidence: 99%

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confidence: 99%

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Protein Diversity Confers Specificity in Plasmid Segregation

2005

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“…Almost all replicons encode two unique proteins that have been associated with maintenance: a ParA/SopA homolog and BpaB, leading to speculation that BpaB may function in a manner analogous to the ParB/SopB proteins of other bacterial replicons (5,11,20,30,54,55). In addition to their roles in plasmid maintenance, some ParB/ SopB proteins directly regulate the expression of plasmid genes (4,19,31,46,47). This and previous studies indicate that cp32-encoded BpaB proteins are also regulatory factors (30).…”

Section: Discussionmentioning

confidence: 99%

Borrelia burgdorferi cp32 BpaB Modulates Expression of the Prophage NucP Nuclease and SsbP Single-Stranded DNA-Binding Protein

Chenail¹,

Jutras²,

Adams³

et al. 2012

Journal of Bacteriology

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“…Our main contribution is the finding that the P1 centromere analog, parS, can play an important, possibly catalytic role in that regulation. The P1 par operon is one of several partition operons that are regulated by the concerted action of both the proteins that they encode (24,29,30,32,33,35,47,55). Regulation of the partition operon of F appears also to be affected by the F-specific centromere sopC acting to enhance SopA-mediated repression (59).…”

Section: Discussionmentioning

confidence: 99%

Effects of the P1 Plasmid Centromere on Expression of P1 Partition Genes

Hao

Yarmolinsky

2002

J Bacteriol

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The partition operon of P1 plasmid encodes two proteins, ParA and ParB, required for the faithful segregation of plasmid copies to daughter cells. The operon is followed by a centromere analog, parS, at which ParB binds. ParA, a weak ATPase, represses the par promoter most effectively in its ADP-bound form. ParB can recruit ParA to parS, stimulate its ATPase, and significantly stimulate the repression. We report here that parS also participates in the regulation of expression of the par genes. A single chromosomal parS was shown to augment repression of several copies of the par promoter by severalfold. The repression increase was sensitive to the levels of ParA and ParB and to their ratio. The increase may be attributable to a conformational change in ParA mediated by the parS-ParB complex, possibly acting catalytically. We also observed an in cis effect of parS which enhanced expression of parB, presumably due to a selective modulation of the mRNA level. Although ParB had been earlier found to spread into and silence genes flanking parS, silencing of the par operon by ParB spreading was not significant. Based upon analogies between partitioning and septum placement, we speculate that the regulatory switch controlled by the parS-ParB complex might be essential for partitioning itself.Like many plasmids and chromosomes present in low copy numbers, plasmid prophage P1 is rarely lost at cell division. Its remarkable segregational stability is achieved by the mediation of partition proteins encoded by an operon of two genes. They act in conjunction with a cis-acting cluster of sites, parS, referred to as the plasmid centromere. Like many prokaryotic operons, the partition operon of P1 is regulated in a cooperative fashion by the proteins it encodes. The first protein of the operon, ParA, acts as repressor; the second, ParB, acts as corepressor (18).ParA binds in vitro to a region of 80 to 150 bp centered on a 20-bp imperfect palindrome overlapping the promoter, P par (9,11,29) (Fig.

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pTAR-Encoded Proteins in Plasmid Partitioning

Cited by 38 publications

References 40 publications

Protein Diversity Confers Specificity in Plasmid Segregation

Protein Diversity Confers Specificity in Plasmid Segregation

Borrelia burgdorferi cp32 BpaB Modulates Expression of the Prophage NucP Nuclease and SsbP Single-Stranded DNA-Binding Protein

Effects of the P1 Plasmid Centromere on Expression of P1 Partition Genes

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