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Related Concept Videos

Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
The Replisome03:01

The Replisome

DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
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 Replisome03:01

The Replisome

DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
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 DNA Replication Fork01:02

The DNA Replication Fork

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...
The DNA Replication Fork01:02

The DNA Replication Fork

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...

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Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase
07:27

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Published on: April 29, 2010

RecA acts as a switch to regulate polymerase occupancy in a moving replication fork.

Chiara Indiani1, Meghna Patel, Myron F Goodman

  • 1Manhattan College, Riverdale, NY 10471, USA.

Proceedings of the National Academy of Sciences of the United States of America
|March 20, 2013
PubMed
Summary

Escherichia coli RecA protein regulates DNA polymerases at the replication fork. RecA activates translesion synthesis polymerases but inhibits the main DNA Polymerase III, acting as a switch.

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Area of Science:

  • Molecular Biology
  • DNA Replication
  • Enzymology

Background:

  • DNA replication is crucial for cell division, involving a complex replisome machinery.
  • Escherichia coli possesses multiple DNA polymerases, including the primary DNA Polymerase III and translesion synthesis (TLS) polymerases (Pols II, IV, V).
  • The RecA protein is a key cellular recombinase involved in DNA repair and recombination.

Purpose of the Study:

  • To investigate the role of Escherichia coli RecA in directing DNA polymerase activity at the replication fork.
  • To determine how RecA influences the function of different DNA polymerases within the replisome.

Main Methods:

  • Analysis of replisome activity in vitro and in vivo.
  • Biochemical assays to measure DNA polymerase kinetics and interactions.
  • Genetic manipulation of RecA and DNA polymerase expression in E. coli.

Main Results:

  • RecA specifically activates replisomes containing translesion synthesis (TLS) polymerases (Pols II, IV, V).
  • RecA significantly inhibits the activity of the primary replication machinery, the DNA Polymerase III replisome.
  • Differential regulation of polymerase activity by RecA at the replication fork.

Conclusions:

  • RecA acts as a regulatory switch, controlling which DNA polymerases are active during replication.
  • This regulation likely ensures efficient and accurate DNA replication, especially in the presence of DNA damage.
  • RecA's dual role in recombination and polymerase regulation highlights its central importance in genome maintenance.