Conformational Changes In Myosin V Monitored By Hydrogen-Deuterium Exchange Mass Spectrometry

Conformational changes between the apo and the BeF.ADP states of Myosin V were determined by hydrogen/deuterium exchange monitored by FT-ICR mass spectrometry.In the BeF.ADP state we have observed opening of the 50K domain cleft (actin binding cleft) (aa 566-578) as expected from the x-ray structure (Coureux et al., Nature 2003). The opening of the actin binding cleft was coupled to the closure (decreased solvent accessibility) of the active site - a stretch of aa 197-231 that includes switch 1, loop1 and B6 β-strand and an additional peptide at the entrance to the active site (aa 233-237).Unexpected changes were observed in the in the SH1 helix (aa 678-692), which was more exposed and the upper 50 kDa domain (aa 331-339 and 350-381) which was less exposed. More protection was observed in the loop coupling B3 β-strand to the SH1 helix (aa 662-676).Figure: Conformational changes in Myosin V mapped on the crystal structure. Increased solvent accessibility in BeF.ADP in blue wide cylinders. Decreased accessibility in narrow red cylinders.View Large Image | View Hi-Res Image | Download PowerPoint Slide