Replisome assembly reveals the basis for the asymmetric function in leading and lagging strand replication

Article Abstract:

A study on the asymmetric function of Escherichia coli replicase, DNA polymerase III holoenzyme, reveals a symmetric function of its two core polymerases. The polymerases also possess characteristics that permit lagging strand replication. The lone gamma complex coordinates fairly between the two cores to gather the beta clamps to DNA. An external asymmetric function is afforded by the helicase that surrounds the lagging strand. The helicase contact then limits the actions of the major polymerase while the secondary core is left to cycle the lagging strand.

Genetic aspects

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A molecular switch in a replicating machine defined by an internal competition for protein rings

Article Abstract:

DNA replication involves the coordinated action of clamping molecules and the polymerase molecule on the DNA. The clamp is a ringlike structure that is bound to a clamp loader molecule while inactive. In the presence of DNA, the clamp loader attaches the clamp to the DNA and the polymerase molecule competes with the loader for a binding site on the clamp molecule. At the end of replication, the polymerase disengages from the clamp's binding site, which is then reattached to a free clamp loader until the next replication event.

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Trading places on DNA - a three-point switch underlies primer handoff from primase to the replicative DNA polymerase

Article Abstract:

A study was conducted to analyze the switch between primase and DNA polymerase in Escherichia coli. Surface plasmon resonance was carried out at 24 and 37 degrees C by the Biacore 1000 internal temperature control. Experimental results indicated that the switch supports a competition between primase and a gamma complex for a third protein. Findings also showed a DNA loop on a lagging strand that grows bigger as the lagging core polymerase draws DNA to it.

Analysis

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