Revyakin Andrey, Liu Chenyu, Ebright Richard H, Strick Terence R
Howard Hughes Medical Institute, Waksman Institute, and Department of Chemistry, Rutgers University, Piscataway, NJ 08854, USA.
Science. 2006 Nov 17;314(5802):1139-43. doi: 10.1126/science.1131398.
Using single-molecule DNA nanomanipulation, we show that abortive initiation involves DNA "scrunching"--in which RNA polymerase (RNAP) remains stationary and unwinds and pulls downstream DNA into itself--and that scrunching requires RNA synthesis and depends on RNA length. We show further that promoter escape involves scrunching, and that scrunching occurs in most or all instances of promoter escape. Our results support the existence of an obligatory stressed intermediate, with approximately one turn of additional DNA unwinding, in escape and are consistent with the proposal that stress in this intermediate provides the driving force to break RNAP-promoter and RNAP-initiation-factor interactions in escape.
通过单分子DNA纳米操纵技术,我们发现流产起始涉及DNA“挤压”——即RNA聚合酶(RNAP)保持静止,解旋并将下游DNA拉入自身——并且这种挤压需要RNA合成且依赖于RNA长度。我们进一步表明启动子逃逸涉及挤压,并且挤压发生在大多数或所有启动子逃逸的情况中。我们的结果支持在逃逸过程中存在一种强制性应激中间体,其额外解开约一圈DNA,并且与该中间体中的应激提供打破RNAP-启动子和RNAP-起始因子相互作用以实现逃逸的驱动力这一观点一致。