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Single-molecule studies reveal the function of a third polymerase in the replisome
Roxana E Georgescu1, Isabel Kurth, Mike E O'Donnell
1The Rockefeller University, Howard Hughes Medical Institute, New York, New York, USA.
Nature Structural & Molecular Biology
|December 14, 2011
Summary
The Escherichia coli replisome uses three polymerases for DNA replication, improving lagging strand synthesis and processivity. This explains the unexpected three-polymerase structure in bacterial replisomes.
Area of Science:
- Molecular Biology
- Microbiology
- Biochemistry
Background:
- The bacterial replisome is responsible for DNA replication.
- Escherichia coli replisomes possess three DNA polymerases, an apparent excess for duplicating parental strands.
Purpose of the Study:
- To investigate the functional advantages of the third polymerase in the Escherichia coli replisome.
- To elucidate the role of tripolymerase versus dipolymerase configurations in DNA synthesis.
Main Methods:
- Single-molecule studies were employed to analyze replisome dynamics.
- Comparative analysis of dipolymerase and tripolymerase replisomes.
Main Results:
- Tripolymerase replisomes efficiently synthesize lagging strands, minimizing single-strand gaps.
- Tripolymerase replisomes exhibit significantly higher processivity compared to dipolymerase replisomes.
- The third polymerase enhances overall DNA replication fidelity and efficiency.
Conclusions:
- The presence of a third polymerase provides critical advantages for bacterial DNA replication.
- Enhanced lagging strand synthesis and increased processivity by tripolymerase replisomes explain their prevalence in bacteria.
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The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
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