Single-molecule studies contrast ordered DNA replication with stochastic translesion synthesis

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Abstract

High fidelity replicative DNA polymerases are unable to synthesize past DNA adducts that result from diverse chemicals, reactive oxygen species or UV light. To bypass these replication blocks, cells utilize specialized translesion DNA polymerases that are intrinsically error prone and associated with mutagenesis, drug resistance, and cancer. How untimely access of translesion polymerases to DNA is prevented is poorly understood. Here we use co-localization single-molecule spectroscopy (CoSMoS) to follow the exchange of the E. coli replicative DNA polymerase Pol IIIcore with the translesion polymerases Pol II and Pol IV. We find that in contrast to the toolbelt model, the replicative and translesion polymerases do not form a stable complex on one clamp but alternate their binding. Furthermore, while the loading of clamp and Pol IIIcore is highly organized, the exchange with the translesion polymerases is stochastic and is not determined by lesion-recognition but instead a concentration-dependent competition between the polymerases.

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Gengjing Zhao

MRC Laboratory of Molecular Biology, Medical Research Council, Cambridge, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Emma S Gleave

MRC Laboratory of Molecular Biology, Medical Research Council, Cambridge, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Meindert Hugo Lamers

MRC Laboratory of Molecular Biology, Medical Research Council, Cambridge, United Kingdom

For correspondence
m.h.lamers@lumc.nl

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-4205-1338

Funding

Medical Research Council (U105197143)

Gengjing Zhao
Emma S Gleave

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.