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Phosphorothioate analogs of ATP as the substrates of dynein and ciliary or flagellar movement.

The phosphorothioate analog of ATP has a sulfur atom replacing a non-bridging oxygen atom of the triphosphate moiety of ATP. Due to the tetrahedral nature of the phosphorus atom, stereoisomers are known to exist, designated as the Sp and Rp isomers. We have reported [Shimizu & Furusawa (1986) Biochemistry 25, 5787] on the hydrolytic activity of the 22S dynein from Tetrahymena cilia towards the phosphorothioate analogs of ATP. In this paper, we extend our study and report on the microtubule-dynein dissociation by these analogs and on their ability to support sea urchin flagellar dynein enzymatic activity as well as ciliary or flagellar motility. It has been shown that the microtubule--22S-dynein complex is dissociated by the binding of ATP to the dynein enzymatic sites [Porter & Johnson (1983) J. Biol. Chem. 258, 6575]. We studied the dissociation by adenosine 5'-[alpha-thio]triphosphate (ATP[alpha S]), Sp or Rp, by light-scattering stopped-flow methods. The dissociation by (Sp)ATP[alpha S] was rapid and the rate of the light-scattering change by (Sp)ATP[alpha S] was a hyperbolic function of the nucleotide concentration, indicating that dissociation was a two-step process. On the other hand, (Rp)ATP[alpha S] up to 2 mM induced only slow and partial dissociation of the complex, while, in the presence of vanadate, it induced complete dissociation with a slightly higher rate (0.5 s-1). The adenosine 5'-[beta-thio]triphosphate (ATP[beta S]) isomers did not induce dissociation. The hydrolytic activity of the outer arm dynein from sea urchin sperm flagella towards these analogs was similar to that of 22S dynein. The ratios of Vmax (nmol.mg protein-1.min-1)/apparent Km (microM) of this dynein were 400-720, 53, 9.7, 0.62 and 0.028 for ATP, ATP[alpha S] (Sp or Rp), ATP[beta S] (Sp or Rp), respectively, in the presence of Mg2+ as the supporting cation. This dynein exhibited the same stereospecificity at beta phosphate as the 22S dynein or myosin. The detergent models of Tetrahymena or sea urchin spermatozoa were reactivated only by ATP or (Sp)ATP[alpha S] while other analogs were ineffective. The maximal beat frequency of the cilia or flagella reactivated by (Sp)ATP[alpha S] was one-quarter to one-half of that produced by ATP reactivation.