MECHANOCHEMICAL COUPLING IN CILIA

This chapter describes the mechanochemical coupling (the conversion of chemical energy to mechanical energy) in cilia and flagella. It examines the cytoskeletal core of the simple eukaryotic cilia and flagella, called the “axoneme.” The “9 + 2” microtubular structure of the axoneme, the cytoskeletal core of eukaryotic cilia and flagella, is found widely among eukaryotes. The structural complexity of the axoneme is matched by the corresponding biochemical complexity. Vanadate is a potent inhibitor of dynein ATPase and axonemal motion, which inhibits dynein by acting as a phosphate analog in the dynein-product complex. The two aspects of axonemal motion which are sensitive to mechanical influence are bend propagation and beat frequency. Different types of mechanical perturbations have been used to study the mechanical influence on axonemal motion. The type of perturbation affects the axoneme differently and may be interpreted to have significantly different effects on the axoneme. Bend propagation is the process by which a bend is formed, typically at the base of the axoneme and is propagated distally. This normally occurs with relatively little change in shape or size of the propagating bend. Once a bend is produced, whether naturally or by external mechanical stimuli, that bend will propagate given sufficient MgATP concentration. © 1991, Elsevier Science & Technology. All rights reserved.