当前位置： SCI文献检索 > BIOCHEMISTRY期刊下所有文献 > Conformation of myosin interdomain interactions during contraction: deductions from muscle fibers using polarized fluorescence.

Conformation of myosin interdomain interactions during contraction: deductions from muscle fibers using polarized fluorescence.

Abstract：

:Myosin cross-bridge subfragment 1 (S1) is the ATP catalyzing motor protein in muscle. It consists of three domains that catalyze ATP and bind actin (catalytic), conduct energy transduction (converter), and transport the load (lever arm). Force development during contraction is thought to result from rotary lever arm movement with the cross-bridge attached to actin. To elucidate cross-bridge structure during force development, two crystal structures of S1 were extrapolated to working "in solution" or oriented "in tissue" forms, using structure-sensitive optical spectroscopic signals from two extrinsic probes. The probes were located at two interfaces containing the catalytic, converter, and lever arm domains of S1. Observed signals included circular dichroism (CD) and absorption originating from S1 in solution in the presence and absence of actin and fluorescence polarization from cross-bridges in muscle fibers. Theoretical signals were calculated from S1 crystal structure models perturbed with lever arm movement from swiveling at three conserved glycines, 699, 703, and 710 (chicken skeletal myosin numbering). Best agreement between the computed and observed signals gave structures showing that actin binding to S1 causes movement of the lever arm. A three-state model of S1 conformation during contraction consists of three actin-bound cross-bridge states observed from muscle fibers in isometric contraction, in the presence of MgADP, and in rigor. Structures best representing these states show that most of the lever arm rotation occurs between isometric contraction and the MgADP states, i.e., during phosphate release. Smaller but significant lever arm rotation occurs with ADP dissociation. Structural changes within the S1 interfaces studied are discussed in the accompanying paper [Burghardt et al. (2001) Biochemistry 40, 4834-4843].

journal_name

Biochemistry

journal_title

Biochemistry

authors

Burghardt TP,Cruz-Walker AR,Park S,Ajtai K

doi

10.1021/bi002387o

subject

Has Abstract

pub_date

2001-04-17 00:00:00

pages

4821-33

issue

eissn

0006-2960

issn

1520-4995

pii

bi002387o

journal_volume

pub_type

杂志文章

在线工具

Conformation of myosin interdomain interactions during contraction: deductions from muscle fibers using polarized fluorescence.