The Region in Myosin S-1 that may be Involved in Energy Transduction

Abstract

Newly-reported structural information about certain proximities between points on bound nucleotide and points on the heavy chain of myosin S-1 are incorporated into a previously-reported [Botts, J. Thomason, J.F. & Morales, M.F. Proc. Nat. Acad. Sci. USA,86, 2204-2208 (1989)] structure of S-l. The resulting, enhanced structure is then used to identify some functionalities (e.g., the ATP-perturbable tryptophans), and to explain certain observations (e.g., some concerning the role of bound Mg²⁺ in the spectral response of TNBS-labelled Lys-83, and some concerning the response of the S-1 CD signal to nucleotide binding and to temperature change). These considerations lead to the suggestion that a strand of the 50 kDa “domain” (residues 510 to 540), and a strand of the 20 kDa ‘domain” (residues 697–719) are involved in transmitting the effects of nucleotide binding and hydrolysis to the loop (constituted from the same “domains”) that reaches a major (S-l)-actin interface.