کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1958419 1057911 2007 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Mutation of a Conserved Glycine in the SH1-SH2 Helix Affects the Load-Dependent Kinetics of Myosin
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی زیست شیمی
پیش نمایش صفحه اول مقاله
Mutation of a Conserved Glycine in the SH1-SH2 Helix Affects the Load-Dependent Kinetics of Myosin
چکیده انگلیسی

The ATP hydrolysis rate and shortening velocity of muscle are load-dependent. At the molecular level, myosin generates force and motion by coupling ATP hydrolysis to lever arm rotation. When a laser trap was used to apply load to single heads of expressed smooth muscle myosin (S1), the ADP release kinetics accelerated with an assistive load and slowed with a resistive load; however, ATP binding was mostly unaffected. To investigate how load is communicated within the motor, a glycine located at the putative fulcrum of the lever arm was mutated to valine (G709V). In the absence of load, stopped-flow and laser trap studies showed that the mutation significantly slowed the rates of ADP release and ATP binding, accounting for the ∼270-fold decrease in actin sliding velocity. The load dependence of the mutant’s ADP release rate was the same as that of wild-type S1 (WT) despite the slower rate. In contrast, load accelerated ATP binding by ∼20-fold, irrespective of loading direction. Imparting mechanical energy to the mutant motor partially reversed the slowed ATP binding by overcoming the elevated activation energy barrier. These results imply that conformational changes near the conserved G709 are critical for the transmission of mechanochemical information between myosin’s active site and lever arm.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: - Volume 92, Issue 5, 1 March 2007, Pages 1623–1631
نویسندگان
, , , , ,