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NBC Seminar
Single-molecule Studies on DNA Mismatch Repair
Speaker: Jong-Bong Lee , Ph.D
Department of Physics, POSTECH
Real time observation of individual biomolecules and their complex going
through reactions enables us to observe transient intermediate states,
multiple pathways, and the fluctuation of the molecular properties. The
removal of ensemble averaging is capable of elucidating the salient features
of the molecular mechanism in a variety of biological processes.
It has been studied that DNA repair proteins search a target via a 1dimensional diffusion along naked DNA. Due to the absence of the target on
DNA this single-molecule tracking approach lacked of understanding the
catalytic function of the repair proteins and moreover the mechanism of the
downstream transactions for the repair of an error on the DNA. I will present
the catalytic processes of MutS, mismatch repair initiation protein, on a
mismatched DNA that bears an unpaired nucleotide. Our single-molecule
analysis reveals that MutS undergoes two distinct conformational changes
during DNA mismatch repair. MutS forms a transient clamp that scans duplex
DNA to find the unpaired nucleotide and a different sliding clamp at the
mismatch that is induced by ATP binding. Our studies propose a solution for
a highly controversial issue in DNA mismatch repair.
I will also tell a story how we use a novel single-molecule technique to study
other DNA mismatch proteins such as UvrD helicase and Exonuclease that are
involved in the removal of the single-stranded DNA after the strand incision
via the downstream signaling of MutS.
When: 4:15 PM on Oct. 13 (Thu.)
Where: Engineering Building 1, E104
Contact: Prof. HyungJoon Cho (2520) / [email protected]
School of Nano-Bioscience & Chemical Engineering
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