Dynamic measurement of myosin light-chain-domain tilt and twist in muscle contraction

• Published in: Nature (London) 1999-07, Vol.400 (6743), p.425-430
• Main Authors: Irving, M, Corrie, J. E. T, Brandmeier, B. D, Ferguson, R. E, Trentham, D. R, Kendrick-Jones, J, Hopkins, S. C, Heide, U. A. van der, Goldman, Y. E, Sabido-David, C, Dale, R. E, Criddle, S
• Format: Article
• Language: English
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Cellular biology; Chickens; Contractile proteins; Cross-Linking Reagents; Cysteine - chemistry; Escherichia coli; Fluorescence Polarization; Fundamental and applied biological sciences. Psychology; Holoproteins; Humanities and Social Sciences; Light; Models, Molecular; multidisciplinary; Muscle Contraction; Muscle, Skeletal - chemistry; Muscle, Skeletal - physiology; Muscular system; Myosin Light Chains - chemistry; Myosin Light Chains - physiology; Physiology; Protein Conformation; Proteins; Rabbits; Recombinant Proteins - chemistry; Rhodamines; Science; Science (multidisciplinary)
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/22704

A new method is described for measuring motions of protein domains in their native environment on the physiological timescale. Pairs of cysteines are introduced into the domain at sites chosen from its static structure and are crosslinked by a bifunctional rhodamine. Domain orientation in a reconstituted macromolecular complex is determined by combining fluorescence polarization data from a small number of such labelled cysteine pairs. This approach bridges the gap between in vitro studies of protein structure and cellular studies of protein function and is used here to measure the tilt and twist of the myosin light-chain domain with respect to actin filaments in single muscle cells. The results reveal the structural basis for the lever-arm action of the light-chain domain of the myosin motor during force generation in muscle.