ATP-DEPENDENT CONFORMATIONAL-CHANGES OF DYNEIN - EVIDENCE FOR CHANGES IN THE INTERACTION OF DYNEIN HEAVY-CHAIN WITH THE INTERMEDIATE CHAIN-1

Conformational changes of the dynein beta heavy chain/intermediate chain 1 (IC1) complex from outer arm dynein of sea urchin sperm flagella were examined by means of crosslinking experiments using a bifunctional cross-linker, dimethylsuberimidate. Crosslinking of the beta/IC1 complex in the absence of ATP and vanadate (V-i) produced five cross-linked products. Immunoblotting of the products with anti-beta chain and anti-IC1 antibodies revealed that all of them were cross-linked between beta chain and IC1, Crosslinking of the complex in the presence of ATP and V-i produced four cross-linked products, but their electrophoretic mobilities were different from those of the cross-linked products obtained in the absence of ATP and V-i. Immunoblotting showed that only one cross-linked product was formed by cross-linking between beta and IC1 and others were formed by intramolecular cross-linking of the beta chain. Quantitative analysis indicated that crosslinking between beta and IC1 decreased in the presence of ATP and V-i. These results suggest that conformational changes of the beta heavy chain occur and the interaction between beta chain and IC1 changes during ATP hydrolysis.