Invited Speakers

Haruo SUGI (Teikyo University)

TEM showed “Myosin Head Power Stroke producing Muscle Contraction”

Title: Electron microscopic recording of Myosin head power stroke producing muscle contraction using the gas environmental chamber
Author: Haruo Sugi
Affiliation: Professor emeritus, Medical School, Teikyo University
Email: sugi[at]kyf.biglobe.ne.jp

Fig. 1

Fig. 2
A TEM with a gas environmental chamber containing muscle actin and myosin filaments revealed how myosin heads extending from myosin filaments change their structure during isometric force generation. (Fig.1a) Diagram of a myosin head consisting of catalytic (CAD), converter (CD) and lever arm (LD) domains. Distal (1) or proximal (2) region of myosin head is position-marked with a gold particle via two different antibodies. (Fig.1b,c) Diagrams showing averaged position changes of myosin head distal (1) and proximal (2) regions during power stroke in response to ATP at standard (b) and low (c) ionic strength. (Fig.2A-F) Examples of imaging plate records showing sequential changes in position of pixels where the center of mass position of each gold particle is located. In each frame, pixel positions were recorded before (red), during (blue) and after (yellow) ATP application. Myosin heads were position-marked at distal (A,C,D) or proximal (B,E,F) region of myosin head. (pixel size: 2.5 nm x 2.5 nm)
As early as late 1980s, we have started to use the gas environmental chamber (EC), which enables us to record ATP-induced structural changes of hydrated, living muscle myofilaments. Here we report a number of novel features of ATP-induced power and recovery strokes in individual myosin heads producing muscle contraction. We emphasize that the EC is an extremely powerful tool for studying dynamic structural changes of biomolecules directly related to their physiological function.
Biographical Sketch: Haruo Sugi finished postgraduate School in the University of Tokyo with the degree of Ph.D, and appointed to be instructor in Physiology in the University of Tokyo Medical School in 1961. From 1965 to 1967, he worked in Columbia University as a research associate, and in National Institutes of Health as a visiting scientist. Sugi was Professor and Chairman in the Department of Physiology, Teikyo University from 1973 to 2004, when he bacame Emeritus Professor.