Nucleotide-induced movements in the myosin head near the converter region

Structural changes in subfragment 1 of skeletal muscle myosin were investig ated by cross-linking trypsin-cleaved S1 with 1-ethyl-3-(3-dimethylaminopro pyl)carbodiimide. In the absence of nucleotide the alkali light chains are cross-linked to the 27 kDa heavy chain fragment; the presence of MgATP redu ces the efficiency of this reaction. On the other hand, MgATP promotes the cross-link formation between the N-terminal 27 kDa and C-terminal 20 kDa fr agments of the heavy chain. The chemical cleavage of the cross-linked heavy chains fragments with N-chlorosuccinimide and hydroxylamine indicates that the cross-links are formed between the regions spanning residues 131-204 a nd 699-809. These results indicate that the two regions of the heavy chain that are relatively distant in nucleotide-free skeletal S1 [Rayment et al. (1993) Science 261, 50-58] can potentially interact upon addition of nucleo tide. (C) 2000 Elsevier Science B.V. All rights reserved.