Conformational Changes of the β Chain of the Outer-Arm Dynein from Sea Urchin Sperm Flagella Coupled with ATP Hydrolysis1

Abstract

Conformational changes of the β chain of the outer-arm dynein from sea urchin sperm flagella in relation to ATP hydrolysis was examined by tryptic digestion. Tryptic digestion of the β chain in the presence of 2 mM ATP (ADP) and 100 μM vanadate (V₁) or in the presence of 4 mM ATPγS produced different polypeptides from in the case of no addition. The difference was similar to the result previously reported for 21S outer-arm dynein heavy chains [Inaba, K. & Mohri, H. (1989) J. Biol. Chem. 264, 8384–8388]. Unlike the tryptic digestion pattern of 21S dynein heavy chains, however, the 135-kDa polypeptide was consistently produced from the β chain, even in the presence of ATP (ADP) and V₁. The tryptic digestion pattern of the 21S particle reconstituted from the separated α chain, the β/ IC1 complex and the IC2/IC3 complex [Tang, W.-J.Y., Bell, C.W., Sale, W.S., & Gibbons, I.R. (1982) J. Biol. Chem. 257, 508–515] was similar to that of intact 21S dynein; the 135-kDa polypeptide was only slightly produced in the presence of ATP and V₁. The digestion rate constant of the 135-kDa polypeptide from the β chain in the presence of ATP and V₁ was significantly decreased as compared with in the case of 21S dynein or that of the reconstituted 21S particle. These results suggest that the trypsin sensitivity of the 135-kDa region of the β chain changes with the association of the β/IC1 complex with the α chain and the IC2/ IC3 complex in the presence of ATP and V₁.