E. Lark et Ck. Omoto, AXONEMES PARALYZED BY THE PRESENCE OF DYNEINS UNABLE TO USE RIBOSE-MODIFIED ATP, Cell motility and the cytoskeleton, 27(2), 1994, pp. 161-168
Substrate analogs are useful for studying the structures of active sit
es and for distinguishing between similar enzyme activities. Fluoresce
nt ribose-modified ATP analogs were used to investigate the functional
differences between dynein ATPases. These analogs reactivate (support
the movement of) sea urchin sperm axonemes, yet they do not reactivat
e wild-type Chlamydomonas axonemes. Surprisingly, the analogs reactiva
te the axonemes of mutants completely missing the outer arm dyneins. C
ompetition experiments using ATP and these analogs provide strong evid
ence that the analogs bind to all dynein active sites but fail to rele
ase a subset of dyneins from rigor. We suggest that this subset of Chl
amydomonas outer arm dyneins unable to use the analogs remains in rigo
r in the presence of the analogs and paralyzes the axoneme. (C) 1994 W
iley-Liss, Inc.