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Structural insight into the DNA-binding mode of the primosomal proteins PriA, PriB, and DnaT.

Huang YH, Huang CY - Biomed Res Int (2014)

Bottom Line: The assembly of the protein complexes within the forked DNA responsible for reloading the replicative DnaB helicase anywhere on the chromosome for genome duplication requires the coordination of transient biomolecular interactions.Over the last decade, investigations on the structure and mechanism of these nucleoproteins have provided considerable insight into primosome assembly.In this review, we summarize and discuss our current knowledge and recent advances on the DNA-binding mode of the primosomal proteins PriA, PriB, and DnaT.

View Article: PubMed Central - PubMed

Affiliation: School of Biomedical Sciences, Chung Shan Medical University, No. 110, Section 1, Chien-Kuo N. Road, Taichung City 40201, Taiwan.

ABSTRACT
Replication restart primosome is a complex dynamic system that is essential for bacterial survival. This system uses various proteins to reinitiate chromosomal DNA replication to maintain genetic integrity after DNA damage. The replication restart primosome in Escherichia coli is composed of PriA helicase, PriB, PriC, DnaT, DnaC, DnaB helicase, and DnaG primase. The assembly of the protein complexes within the forked DNA responsible for reloading the replicative DnaB helicase anywhere on the chromosome for genome duplication requires the coordination of transient biomolecular interactions. Over the last decade, investigations on the structure and mechanism of these nucleoproteins have provided considerable insight into primosome assembly. In this review, we summarize and discuss our current knowledge and recent advances on the DNA-binding mode of the primosomal proteins PriA, PriB, and DnaT.

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Two DnaB helicase-recruiting pathways for DNA replication restart at the stalled replication fork in vitro. The PriA-directed pathway (i.e., PriA-PriB-DnaT-DnaC-dependent reaction) preferentially uses fork structures without gaps in the leading strand, whereas the PriC-directed pathway (i.e., PriC-DnaC-dependent system) preferentially uses fork structures containing large gaps (>5 nucleotides) in the leading strand.
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fig1: Two DnaB helicase-recruiting pathways for DNA replication restart at the stalled replication fork in vitro. The PriA-directed pathway (i.e., PriA-PriB-DnaT-DnaC-dependent reaction) preferentially uses fork structures without gaps in the leading strand, whereas the PriC-directed pathway (i.e., PriC-DnaC-dependent system) preferentially uses fork structures containing large gaps (>5 nucleotides) in the leading strand.

Mentions: Genome integrity should be maintained from generation to generation to ensure proper cell function and survival [1–3]. In bacteria, some exogenous and endogenous sources of DNA damage can inactivate a large proportion of replication forks [4, 5]. When DNA is damaged, the replication machinery, originally initiated at oriC, can be arrested and disassembled anywhere along the DNA, leading to replication failure [5, 6]. To reload DnaB helicase for oriC-independent DNA replication, collapsed DNA replication forks must be reactivated by the replication restart primosome [7, 8]. Primosome is the protein complex responsible for the conversion of single-stranded circular DNA to the replicative-form DNA in the replication cycle of ϕX174 phage [9, 10]. After DNA repair, the replication restart primosome [11–13], a formidable enzymatic machine, can translocate along the single-stranded DNA-binding protein (SSB), unwind the duplex DNA, and prime the Okazaki fragments required for the progression of replication forks [14]. In Escherichia coli, the replication restart primosome is composed of PriA helicase, PriB, PriC, DnaB helicase, DnaC, DnaT, and DnaG primase [3]. To date, two DnaB helicase-recruiting pathways are known: PriA-PriB-DnaT-DnaC-dependent and PriC-DnaC-dependent systems; the former system uses fork structures without gaps in the leading strand, whereas the latter system preferentially uses fork structures with large gaps (>5 nucleotides) in the leading strand [3]. As shown in Figure 1, PriA can bind directly and assemble a primosome on the template without gaps in the leading strand, and PriC initiates the assembly of a primosome on a fork containing gaps in the leading strand.


Structural insight into the DNA-binding mode of the primosomal proteins PriA, PriB, and DnaT.

Huang YH, Huang CY - Biomed Res Int (2014)

Two DnaB helicase-recruiting pathways for DNA replication restart at the stalled replication fork in vitro. The PriA-directed pathway (i.e., PriA-PriB-DnaT-DnaC-dependent reaction) preferentially uses fork structures without gaps in the leading strand, whereas the PriC-directed pathway (i.e., PriC-DnaC-dependent system) preferentially uses fork structures containing large gaps (>5 nucleotides) in the leading strand.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4129139&req=5

fig1: Two DnaB helicase-recruiting pathways for DNA replication restart at the stalled replication fork in vitro. The PriA-directed pathway (i.e., PriA-PriB-DnaT-DnaC-dependent reaction) preferentially uses fork structures without gaps in the leading strand, whereas the PriC-directed pathway (i.e., PriC-DnaC-dependent system) preferentially uses fork structures containing large gaps (>5 nucleotides) in the leading strand.
Mentions: Genome integrity should be maintained from generation to generation to ensure proper cell function and survival [1–3]. In bacteria, some exogenous and endogenous sources of DNA damage can inactivate a large proportion of replication forks [4, 5]. When DNA is damaged, the replication machinery, originally initiated at oriC, can be arrested and disassembled anywhere along the DNA, leading to replication failure [5, 6]. To reload DnaB helicase for oriC-independent DNA replication, collapsed DNA replication forks must be reactivated by the replication restart primosome [7, 8]. Primosome is the protein complex responsible for the conversion of single-stranded circular DNA to the replicative-form DNA in the replication cycle of ϕX174 phage [9, 10]. After DNA repair, the replication restart primosome [11–13], a formidable enzymatic machine, can translocate along the single-stranded DNA-binding protein (SSB), unwind the duplex DNA, and prime the Okazaki fragments required for the progression of replication forks [14]. In Escherichia coli, the replication restart primosome is composed of PriA helicase, PriB, PriC, DnaB helicase, DnaC, DnaT, and DnaG primase [3]. To date, two DnaB helicase-recruiting pathways are known: PriA-PriB-DnaT-DnaC-dependent and PriC-DnaC-dependent systems; the former system uses fork structures without gaps in the leading strand, whereas the latter system preferentially uses fork structures with large gaps (>5 nucleotides) in the leading strand [3]. As shown in Figure 1, PriA can bind directly and assemble a primosome on the template without gaps in the leading strand, and PriC initiates the assembly of a primosome on a fork containing gaps in the leading strand.

Bottom Line: The assembly of the protein complexes within the forked DNA responsible for reloading the replicative DnaB helicase anywhere on the chromosome for genome duplication requires the coordination of transient biomolecular interactions.Over the last decade, investigations on the structure and mechanism of these nucleoproteins have provided considerable insight into primosome assembly.In this review, we summarize and discuss our current knowledge and recent advances on the DNA-binding mode of the primosomal proteins PriA, PriB, and DnaT.

View Article: PubMed Central - PubMed

Affiliation: School of Biomedical Sciences, Chung Shan Medical University, No. 110, Section 1, Chien-Kuo N. Road, Taichung City 40201, Taiwan.

ABSTRACT
Replication restart primosome is a complex dynamic system that is essential for bacterial survival. This system uses various proteins to reinitiate chromosomal DNA replication to maintain genetic integrity after DNA damage. The replication restart primosome in Escherichia coli is composed of PriA helicase, PriB, PriC, DnaT, DnaC, DnaB helicase, and DnaG primase. The assembly of the protein complexes within the forked DNA responsible for reloading the replicative DnaB helicase anywhere on the chromosome for genome duplication requires the coordination of transient biomolecular interactions. Over the last decade, investigations on the structure and mechanism of these nucleoproteins have provided considerable insight into primosome assembly. In this review, we summarize and discuss our current knowledge and recent advances on the DNA-binding mode of the primosomal proteins PriA, PriB, and DnaT.

Show MeSH
Related in: MedlinePlus