Hura is the lead author of a paper describing this research in the Proceedings of the National Academy of Sciences (PNAS). The article is titled "DNA conformations in mismatch repair probed in solution by X-ray scattering from gold nanocrystals." The corresponding author is John Tainer, who holds joint appointments with Berkeley Lab's Life Sciences Division and the Scripps Research Institute. (See below for complete list of co-authors)
"It is a common belief that DNA is a passive component in protein interactions that involve DNA metabolism, but many proteins actually make use of DNA structural features, such as rigidity and conformation for important biological processes," Tainer says. "The view of DNA as a passive element is at least in part due to a paucity of robust tools for examining dynamic DNA conformational states during multistep reactions."
For this study, Tainer, Hura and their colleagues were able to capitalize on the high quality X-ray beams at ALS beamline 12.3.1, also known as SIBYLS, which stands for Structurally Integrated Biology for Life Sciences. Maintained by Berkeley Lab's Life Sciences Division under the direction of Tainer, the SIBYLS experimental station is optimized for SAXS imaging, which provides global information on the conformations adopted by a population of macromolecules in almost any solution condition.
"Because X-rays scatter predominantly from electrons, the use of gold nanocrystals provides extremely high contrast relative to organic molecules critical for biology," Tainer says. "This is important because we can follow specific biological molecules in complex reactions and along pathways to understand how their changes in shape and assembly control the biological outcomes."
The SAXS study at the SIBYLS beamline validated what has been dubbed the "beads-on-a-string" model of DNA repair, in which MutS proteins are the beads and DNA is the string. In solution
|Contact: Lynn Yarris|
DOE/Lawrence Berkeley National Laboratory