Binding and Spreading of ParB on DNA Determine Its Biological Function in Pseudomonas aeruginosa

Kusiak, Magdalena; Gapczyńska, Anna; Płochocka, Danuta; Thomas, Christopher M.; Jagura-Burdzy, Grażyna

doi:10.1128/jb.00328-11

Cited by 61 publications

(80 citation statements)

References 55 publications

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“…The N-terminal domain of ParB has been suggested to be essential for ParB spreading and DNA condensation during chromosome segregation (20,35). Yamaichi et al (4) identified two conserved motifs, boxes I and II, in the N-terminal domain of BsSpo0J.…”

Section: Resultsmentioning

confidence: 99%

Insights into ParB spreading from the complex structure of Spo0J and parS

Chen

Lin

Chu

et al. 2015

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

110

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Spo0J (stage 0 sporulation protein J, a member of the ParB superfamily) is an essential component of the ParABS (partition system of ParA, ParB, and parS)-related bacterial chromosome segregation system. ParB (partition protein B) and its regulatory protein, ParA, act cooperatively through parS (partition S) DNA to facilitate chromosome segregation. ParB binds to chromosomal DNA at specific parS sites as well as the neighboring nonspecific DNA sites. Various ParB molecules can associate together and spread along the chromosomal DNA. ParB oligomer and parS DNA interact together to form a high-order nucleoprotein that is required for the loading of the structural maintenance of chromosomes proteins onto the chromosome for chromosomal DNA condensation. In this report, we characterized the binding of parS and Spo0J from Helicobacter pylori (HpSpo0J) and solved the crystal structure of the C-terminal domain truncated protein (Ct-HpSpo0J)-parS complex. Ct-HpSpo0J folds into an elongated structure that includes a flexible N-terminal domain for protein-protein interaction and a conserved DNA-binding domain for parS binding. Two Ct-HpSpo0J molecules bind with one parS. Ct-HpSpo0J interacts vertically and horizontally with its neighbors through the N-terminal domain to form an oligomer. These adjacent and transverse interactions are accomplished via a highly conserved arginine patch: RRLR. These interactions might be needed for molecular assembly of a highorder nucleoprotein complex and for ParB spreading. A structural model for ParB spreading and chromosomal DNA condensation that lead to chromosome segregation is proposed.arginine patch | chromosome segregation | ParABS | ParB spreading | parS T he integrity of chromosomes and plasmids relies on precise DNA replication and segregation (1, 2). The initiation of DNA replication has to synchronize with the cell cycle to ensure precise chromosome segregation (3). In bacteria, the chromosomeencoded plasmid-partitioning system (Par) (4) and the structural maintenance of chromosomes (SMC) condensation complex (5) are two highly conserved systems associate with chromosome segregation and organization. SMC contributes to the overall stability and organization of genome (6-8). The partition system denoted ParABS is comprised of two proteins (ParA and ParB) and a centromere-like DNA element (parS) (9). ParB binds specifically to parS to form a complex. After binding ATP, ParA can interact with the ParB-parS complex to form a nucleoidadaptor complex. ParB promotes the ATP hydrolysis activity of the complex to separate the chromosomes (9-13).In the bacterial chromosomal ParABS system, ParB has two functions: one is to regulate chromosome replication and sporulation (8,12,14) and the other is to participate in chromosome segregation (5,(15)(16)(17). ParB spreads along the chromosomal DNA by binding at specific parS and nonspecific DNA sites to form a high-order partition complex (18)(19)(20). This partition complex is required for the loading of SMC onto the chromosomal DNA (5). In ad...

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Section: Resultsmentioning

confidence: 99%

Insights into ParB spreading from the complex structure of Spo0J and parS

Chen

Lin

Chu

et al. 2015

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

110

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“…14), the minimal density of ParB is ∼1,000/μm 2 , consistent with estimates of ParB density on P1 plasmid of approximately one dimer per 30 bp (25). This points to the critical role of the "ParB-spreading" process in which ParB binding to parS on the plasmid nucleates higher-order complex assembly involving a large number of ParBs to promote plasmid segregation (26)(27)(28)(29)(30). Conversely, if the density of ParB was too high, too many ParA-ParB bonds formed resulting in the decrease of both the persistence and the speed (Fig.…”

Section: Directed and Persistent Movement Emerges From A Mechanochemicalmentioning

confidence: 99%

Directed and persistent movement arises from mechanochemistry of the ParA/ParB system

Vecchiarelli

Mizuuchi

et al. 2015

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

108

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The segregation of DNA before cell division is essential for faithful genetic inheritance. In many bacteria, segregation of low-copy number plasmids involves an active partition system composed of a nonspecific DNA-binding ATPase, ParA, and its stimulator protein ParB. The ParA/ParB system drives directed and persistent movement of DNA cargo both in vivo and in vitro. Filament-based models akin to actin/microtubule-driven motility were proposed for plasmid segregation mediated by ParA. Recent experiments challenge this view and suggest that ParA/ParB system motility is driven by a diffusion ratchet mechanism in which ParB-coated plasmid both creates and follows a ParA gradient on the nucleoid surface. However, the detailed mechanism of ParA/ParB-mediated directed and persistent movement remains unknown. Here, we develop a theoretical model describing ParA/ParB-mediated motility. We show that the ParA/ParB system can work as a Brownian ratchet, which effectively couples the ATPase-dependent cycling of ParA-nucleoid affinity to the motion of the ParB-bound cargo. Paradoxically, this resulting processive motion relies on quenching diffusive plasmid motion through a large number of transient ParA/ParB-mediated tethers to the nucleoid surface. Our work thus sheds light on an emergent phenomenon in which nonmotor proteins work collectively via mechanochemical coupling to propel cargos-an ingenious solution shaped by evolution to cope with the lack of processive motor proteins in bacteria.ParA ATPase | Brownian ratchet | theoretical model | motility

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“…Roadblock experiments with Spo0J suggest that the formation of onedimensional filaments is required for spreading, although Spo0J does not silence genes adjacent to parS sites (Murray et al 2006;Breier and Grossman 2007). Fluorescent protein fusions to chromosomal ParBs form compact foci that colocalize with origins, suggesting that ParB may also gather the origin-proximal parS sites into a single complex (Glaser et al 1997;Lin et al 1997;Sullivan et al 2009;Shebelut et al 2010;Kusiak et al 2011). In line with its proposed role as an organizer of the origin-proximal region, ParB is required to recruit the structural maintenance of chromosomes (SMC) condensin complex adjacent to the origin in B. subtilis and Streptococcus pneumoniae (Gruber and Errington 2009;Sullivan et al 2009;Minnen et al 2011).…”

mentioning

confidence: 99%

ParB spreading requires DNA bridging

et al. 2014

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The parABS system is a widely employed mechanism for plasmid partitioning and chromosome segregation in bacteria. ParB binds to parS sites on plasmids and chromosomes and associates with broad regions of adjacent DNA, a phenomenon known as spreading. Although essential for ParB function, the mechanism of spreading remains poorly understood. Using single-molecule approaches, we discovered that Bacillus subtilis ParB (Spo0J) is able to trap DNA loops. Point mutants in Spo0J that disrupt DNA bridging are defective in spreading and recruitment of structural maintenance of chromosomes (SMC) condensin complexes in vivo. DNA bridging helps to explain how a limited number of Spo0J molecules per parS site (~20) can spread over many kilobases and suggests a mechanism by which ParB proteins could facilitate the loading of SMC complexes. We show that DNA bridging is a property of diverse ParB homologs, suggesting broad evolutionary conservation.

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Binding and Spreading of ParB on DNA Determine Its Biological Function in Pseudomonas aeruginosa

Cited by 61 publications

References 55 publications

Insights into ParB spreading from the complex structure of Spo0J and parS

Insights into ParB spreading from the complex structure of Spo0J and parS

Directed and persistent movement arises from mechanochemistry of the ParA/ParB system

ParB spreading requires DNA bridging

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