The specific aims of this project are to determine the physicochemical and enzymatic properties of the multiple isoenzymic forms of dynein ATPase present in cilia and sperm flagella, to elucidate the steps in the mechanochemical cycle by which the binding and hydrolysis of molecules of ATP at sites on the outer and inner dynein arms generate mechanical shear stresses between adjacent doublet tubules of the axoneme, to clarify the function of two distinct ATPase sites present in the dynein-1 outer arm, and possibly also in the dynein-2 inner arm, and to investigate the extent to which the interaction of the dynein isoenzymes with micromolar concentrations of Ca2+ are involved in the Ca2+-regulation of the form and direction of bending in cilia and sperm flagella. We shall look for partial functional activity in subsets of heavy and light polypeptide chains in the 21S outer arm particle in sea urchin sperm flagella and for a significant interaction with calcium and an intrinsic calmodulin-type regulatory subunit. Efforts will be made to solubilize dynein-2 in a form that retains functional capability as a preliminary to determining its function. Photocleavage of the dynein heavy chains in the presence of vanadate and ATP will be used in conjunction with photoaffinity labelling and monoclonal antibodies to map the functional domains to specific regions of the polypeptides. The interaction of the various dynein isoenzymes with native tubulin and with other axonemal proteins will be studied in order to obtain information about the function of the isoenzymes in flagellar motility. The long-term objective of the project is to elucidate the functional role of the dynein isoenzymes in ciliary and flagellar motility, as well as in the forms of cytoplasmic movement involving cytoplasmic microtubules. This work is of direct relevance to problems of male infertility resulting from sperm immotility as in Kartageners syndrome and to the severe respiratory problems associated with the recently defined """"""""immotile-cilia syndrome"""""""".
Showing the most recent 10 out of 27 publications
