Actin-binding cleft closure in myosin II probed by site-directed spin labeling and pulsed EPR.

ABSTRACT: We present a structurally dynamic model for nucleotide- and actin-induced closure of the actin-binding cleft of myosin, based on site-directed spin labeling and electron paramagnetic resonance (EPR) in Dictyostelium myosin II. The actin-binding cleft is a solvent-filled cavity that extends to the nucleotide-binding pocket and has been predicted to close upon strong actin binding. Single-cysteine labeling sites were engineered to probe mobility and accessibility within the cleft. Addition of ADP and vanadate, which traps the posthydrolysis biochemical state, influenced probe mobility and accessibility slightly, whereas actin binding caused more dramatic changes in accessibility, consistent with cleft closure. We engineered five pairs of cysteine labeling sites to straddle the cleft, each pa

SUBMITTER: Klein JC 

PROVIDER: S-EPMC2529091 | biostudies-literature | 2008 Sep

REPOSITORIES: biostudies-literature