February 27 , 2008
3pm in Howey Physics Lecture Room 5
Eli Rothenberg
Department of Physics
University of Illinois, Urbana
"Exploring the mechanisms of DNA replication and repair proteins through single-molecule analysis"
DNA Replication is one of the most basic processes in cell metabolism, ensuring the heredity of the genetic material, and enabling cell proliferation. In the course of chromosomal replication and remodeling, DNA undergoes strenuous interactions and alterations which might result in damage. DNA damage, such as double strand break (DSB), activates a DNA repair pathway. While DNA repair is mandatory for genomic permanence and replication fidelity, repair dysfunction may lead to deregulation of chromosome replication, malignant transformations, and tumorigenesis.
Single molecule (sm) microscopy and spectroscopy are powerful techniques that allow probing of specific features of biomolecules otherwise masked in ensemble measurements. Fluorescence techniques such as fluorescence-resonance-energy-transfer (FRET) can resolve kinetic and dynamic behaviors with resolution of several nanometers. Many of the fundamental questions regarding the exact behavior and function of proteins taking part in DNA replication and repair can be addressed effectively using sm-spectroscopy techniques, such as smFRET.
In my talk I will discuss our recent findings, obtained through smFRET, of two key players in DNA repair and replication processes:
- The Human Rad52 (hRad52) protein has critical functions in distinct pathways of DNA repair, one of which promotes the annealing of complementary strands of DNA. I will describe the detailed mechanism by which hRad52 mediates the annealing of ssDNA resulting in duplex DNA formation.
- The archaeal minichromosome maintenance protein (MCM) forms a homohexameric complex that functions as the DNA replicative helicase and serves as a model system for its eukaryotic counterpart. The DNA substrate specificity and binding mechanism of MCM will be discussed.
