The Unstructured N-terminal Tail of ParG Modulates Assembly of a Quaternary Nucleoprotein Complex in Transcription Repression

Carmelo, Emma; Barillà, Daniela; Golovanov, Alexander P.; Lian, Lu‐Yun; Derome, Andrew; Hayes, Finbarr

doi:10.1074/jbc.m501173200

Cited by 26 publications

(51 citation statements)

References 47 publications

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“…For example, the recently studied plasmids from gram-negative bacteria, including plasmid TP228 (1,4,5,15,17), pVS1 (20), pTAR (21), pB171 (10), pVT745 (13), and pRA2 (24), all contain type Ib partition cassettes (14). However, the partitioning mechanisms utilized by this new type of cassette are unclear.…”

Section: Resultsmentioning

confidence: 99%

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A Type Ib ParB Protein Involved in Plasmid Partitioning in a Gram-Positive Bacterium

Yin

Xie

et al. 2006

J Bacteriol

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Our current understanding of segregation of prokaryotic plasmids has been derived mainly from the study of the gram-negative bacterial plasmids. We previously reported a replicon of the cryptic plasmid from a gram-positive bacterium, Leifsonia xyli subsp. cynodontis. The replicon contains a putative plasmid partition cassette including a Walker-type ATPase followed by open reading frame 4 without sequence homologue. Here we reported that the orf4 gene was essential for maintaining the plasmid stability in L. xyli subsp. cynodontis. Furthermore, the purified orf4 protein specifically and cooperatively bound to direct repeat sequences located upstream of the parA gene in vitro, indicating that orf4 is a parB gene and that the direct repeat DNA sequences constitute a partition site, parS. The location of parS and the features of ParA and ParB proteins suggest that this plasmid partition cassette belongs to type Ib, representing the first type Ib cassette identified from a gram-positive bacterial plasmid.

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Section: Resultsmentioning

confidence: 99%

“…Several type Ib ParB-like proteins have recently been identified in plasmids TP228 (1,4,5,15,17), pVS1 (20), pTAR (21), pB171 (10), pVT745 (13), and pRA2 (24). However, these plasmids are exclusively from gram-negative bacteria (11).…”

mentioning

confidence: 99%

A Type Ib ParB Protein Involved in Plasmid Partitioning in a Gram-Positive Bacterium

Yin

Xie

et al. 2006

J Bacteriol

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“…His-tagged ParF, ParG, ⌬ParG, ParGR19K, and ParGR19A proteins were purified as described (4,7). Histagged ParF and ParG are as proficient as wild-type proteins in supporting plasmid partition in vivo (4).…”

Section: Methodsmentioning

confidence: 99%

“…Assays were performed as described (4). ⌬9parG, ⌬19parG, and ⌬30parG were cloned in pT25 (35) as described (7).…”

Section: Methodsmentioning

confidence: 99%

“…ParG is dimeric, with symmetric C-terminal domains that interleave into a ribbon-helixhelix fold that is crucial for DNA binding, and unstructured N-terminal tails (4,6). Additional to its role as a centromerebinding protein, ParG is a transcriptional repressor of the parFG genes: transient associations between the flexible and folded domains in complex with target DNA modulate organization of a higher-order complex critical for transcriptional repression (7).…”

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The tail of the ParG DNA segregation protein remodels ParF polymers and enhances ATP hydrolysis via an arginine finger-like motif

Barillà

Carmelo²,

Hayes

2007

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

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115

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ParA superfamily ͉ polymerization ͉ plasmid partition ͉ ATPase T he precise distribution of newly replicated genomes to progeny cells is imperative for stable transmission of genetic information. In bacteria, the most well characterized segregation mechanisms are specified by low-copy-number plasmids. These systems most frequently comprise two plasmid-encoded proteins, often termed ParA and ParB, that assemble on a cis-acting centromeric site. ParB directly binds the centromere, whereas ParA is recruited by interactions with ParB. The resulting segrosome complex is a positioning apparatus that localizes the attached plasmids to specific subcellular addresses (1, 2).The segregation locus of multidrug-resistance plasmid TP228 in Escherichia coli consists of the parF and parG genes and nearby parH centromere (3). ParG (8.6 kDa) is the prototype of a class of small proteins involved in accurate segregation that are unrelated phylogenetically to ParB, but that fulfil analogous functions as centromere-binding factors (1,4,5). ParG is dimeric, with symmetric C-terminal domains that interleave into a ribbon-helixhelix fold that is crucial for DNA binding, and unstructured N-terminal tails (4, 6). Additional to its role as a centromerebinding protein, ParG is a transcriptional repressor of the parFG genes: transient associations between the flexible and folded domains in complex with target DNA modulate organization of a higher-order complex critical for transcriptional repression (7).The ParA superfamily of ATPases, widely encoded by both chromosomes and plasmids, is characterized by a variant Walkertype ATP-binding motif (8). ParF (22.0 kDa) epitomizes one clade of the superfamily (3). In common with other ParA proteins, ParF is a weak ATPase whose nucleotide hydrolysis is enhanced Ϸ30-fold by ParG (9). ATP binding and/or hydrolysis by ParA proteins has long been recognized as a crucial facet of the segregation process, although its mechanistic purpose was uncertain (10-12). We have recently shown that ATP binding stimulates the polymerization of ParF into extensive multistranded filaments, whereas ADP antagonizes filamentation. ParG is another key modulator of polymerization (9). Mutagenesis of the ATP-binding site in Parf perturbed DNA segregation in vivo, ATP hydrolysis, and polymerization. We envisage that segrosome formation is initiated by site-specific binding of ParG to parH, generating paired complexes of specific topology. ParF is then recruited. ParF polymerization within the complex is controlled by nucleotide binding, by ParG-mediated stimulation of ATP hydrolysis, by remodeling effects of ParG, and, more speculatively, by cell cycle signals. Polymerization, or depolymerization, invokes separation of paired plasmids and their segregation in opposite poleward directions (1, 9).Arginine fingers stimulate nucleotide hydrolysis by NTPases through the action of an arginine side chain inserted into the catalytic niche (13,14). The arginine stabilizes the transition state through neutralization of negative charge...

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Survey of the year 2005 commercial optical biosensor literature

2006

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We identified 1113 articles (103 reviews, 1010 primary research articles) published in 2005 that describe experiments performed using commercially available optical biosensors. While this number of publications is impressive, we find that the quality of the biosensor work in these articles is often pretty poor. It is a little disappointing that there appears to be only a small set of researchers who know how to properly perform, analyze, and present biosensor data. To help focus the field, we spotlight work published by 10 research groups that exemplify the quality of data one should expect to see from a biosensor experiment. Also, in an effort to raise awareness of the common problems in the biosensor field, we provide side-by-side examples of good and bad data sets from the 2005 literature.

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The Unstructured N-terminal Tail of ParG Modulates Assembly of a Quaternary Nucleoprotein Complex in Transcription Repression

Abstract: ParG is the prototype of a group of small (<10 kDa) proteins involved in accurate plasmid segregation. The protein is a dimeric DNA binding factor, which consists of symmetric paired C-terminal domains that interleave into a ribbon-helix-helix fold that is crucial for the inter-

Cited by 26 publications

References 47 publications

A Type Ib ParB Protein Involved in Plasmid Partitioning in a Gram-Positive Bacterium

A Type Ib ParB Protein Involved in Plasmid Partitioning in a Gram-Positive Bacterium

The tail of the ParG DNA segregation protein remodels ParF polymers and enhances ATP hydrolysis via an arginine finger-like motif

Survey of the year 2005 commercial optical biosensor literature

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