Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/121352
Title: BIOPHYSICAL STUDIES ON MECHANISMS OF HOMOLOGOUS RECOMBINATIONAL PROTEINS
Authors: LE SHIMIN
Keywords: DNA damage repair; Homologous recombination; RecA filament; SSB, RecX, force
Issue Date: 6-Jul-2015
Source: LE SHIMIN (2015-07-06). BIOPHYSICAL STUDIES ON MECHANISMS OF HOMOLOGOUS RECOMBINATIONAL PROTEINS. ScholarBank@NUS Repository.
Abstract: The bacterial RecA nucleoprotein filament formed on ssDNA at the broken DNA ends is the essential player during homologous recombinational DNA damage repair. The formation and stability of the filament have to be tightly and precisely regulated by a set of accessory proteins and environmental co-factors. However, the regulatory mechanisms remain elusive. Here, I developed a platform for single-ssDNA manipulation using magnetic tweezers and systematically investigated the dynamics and stability of RecA filament regulated by several key accessory proteins including SSB, RecX, RecO, RecR, and force. I showed that at low forces, SSB outcompetes RecA binding to ssDNA, inhibiting the nucleation of RecA filament, and de-stablizes pre-formed RecA filament; RecX promotes ATP-hydrolysis-dependent, step-wise net-depolymerization of RecA filament. Remarkably, physiological level forces antagonize the inhibitory effects of SSB and RecX, facilitating repolymerization of partially depolymerized RecA filament in a 3'-to-5' direction, in contrast to previously widely accepted 5'-to-3' unidirectional RecA polymerization.
URI: http://scholarbank.nus.edu.sg/handle/10635/121352
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