Published November 11, 2013
With a focus on the bacterium Escherichia coli, Mark Sutton, PhD, associate professor of biochemistry, will build on a decade of research to further study the complex coordination of molecular mechanisms that contribute to mutations caused by errors made during DNA replication and repair.
The results could aid efforts to develop novel therapies to fight a host of diseases, including cancers, as well as bacterial antibiotic resistance.
Sutton has received a $1.4 million, four-year grant from the National Institute of General Medical Sciences for the project, “Coordination of DNA Replication, Repair and Translesion DNA Synthesis.”
Failure to efficiently coordinate DNA replication with other cellular processes results in mutations that contribute to disease and complicate treatment of infections by conferring antibiotic resistance, Sutton explains.
His long-term goal is to develop an integrated, mechanistic understanding of how organisms coordinate the actions of their DNA replication machinery with those of other cellular factors that act in DNA repair and damage tolerance, he says.
He hopes to identify critical steps in molecular control networks that may be able to be targeted for therapeutic gain.
Through their current project, Sutton and his team will be the first to study certain mechanisms at work in the E. coli bacterium, seeking new clues into how DNA replication, repair and damage tolerance processes are regulated and coordinated.
Most disease-related mutations stem from errors made by various DNA polymerases — enzymes involved in copying and repairing cellular DNA.
The researchers will study the role of the E. coli’s beta sliding clamp proteins, which, in part, manage the actions of the polymerases.
Previously, Sutton’s team found that specific E. coli beta-clamp-DNA interactions are required for mutagenesis induced by DNA damage.
They now plan to define mechanisms by which low-fidelity bacterial DNA polymerases catalyze mutations by gaining access to the DNA replication fork.
First, they will determine how the different beta-clamp-DNA interactions contribute to both DNA replication fidelity and a damage control process known as translesion synthesis (TLS).
Through TLS, specialized DNA polymerases replicate across from DNA lesions, or areas of damaged DNA. Although this process helps cells tolerate DNA damage, it also introduces the risk of mutations.
In addition, the research team will structurally define complexes consisting of five different E. coli polymerase, clamp and DNA.
They will then seek to identify how the beta sliding clamp protein mediates switches between high fidelity and error-prone lesion bypass DNA polymerases.
Throughout the project, the researchers will use a combination of approaches, including:
They will also use techniques including:
The results may lead to targeted therapies that work by controlling replication fidelity and mutagenesis.
Moreover, this research “will serve as a framework for understanding similar molecular control networks in humans, contributing to our understanding of mechanisms underlying human diseases, including cancer, as well as aging,” Sutton says.