Unraveling DMA Condensation with Optical Tweezers

摘要

Since the invention of optical tweezers by Ashkin, Chu, and co-workers almost 20 years ago (I), this technique has been applied to a variety of biological systems. It has yielded a wealth of information, such as how biopolymers behave under stress (2), how DNA-inter acting enzymes decode or digest DNA (3-6), how motor proteins walk along molecular tracks (7, 8), and how RNA and protein molecules fold and unfold (9-11). By allowing the manipulation of individual molecules, optical tweezers reveal howthese biological systems work at the molecular level. On page 222 of this issue, Case et al. (12) demonstrate yet another elegant application of this technique: unraveling the mystery of how proteins called con-densins make DNA take on a compact form.