Inhibition by ATP and activation by ADP in the regulation of flagellar movement in sea urchin sperm

Abstract

ATP and ADP are known to play inhibitory and activating roles, respectively, in the regulation of dynein motile activity of flagella. To elucidate how these nucleotide functions are related to the regulation of normal flagellar beating, we examined their effects on the motility of reactivated sea urchin sperm flagella at low pH. At pH 7.0-7.2 which is lower than the physiological pH of 8, about 90% of reactivated flagella were motionless at 1 mM ATP, while about 60% were motile at 0.02 mM ATP. The motionless flagella at 1 mM ATP maintained a single large bend or an S-shaped bend, indicating formation of dynein crossbridges in the axoneme. The ATP-dependent inhibition of flagellar movement was released by ADP, and was absent in outer arm-depleted flagella. Similar inhibition was also observed at 0.02 mM ATP when demembranated flagella were reactivated in the presence of Li+ or pretreated with protein phosphatase 1 (PP1). ADP also released this type of ATP-inhibition. In PP1-pretreated axonemes the binding of a fluorescent analogue of ADP to dynein decreased. Under elastase-treatment at pH 8.0, the beating of demembranated flagella at 1 mM ATP and 0.02 mM ATP lasted for approximately 100 and 45 s, respectively. The duration of beating at 0.02 mM ATP was prolonged by Li+, and that at 1 mM ATP was shortened by removal of outer arms. These results indicate that the regulation of on/off switching of dynein motile activity of flagella involves ATP-induced inhibition and ADP-induced activation, probably through phosphorylation/dephosphorylation of outer arm-linked protein(s).

Mechanism of flagellar oscillation–bending-induced switching of dynein activity in elastase-treated axonemes of sea urchin sperm

“…These mechanisms are involved in the regulation of both the dynein molecules (Inoue and Shingyoji, 2007) and flagellar beating (Yoshimura et al, 2007). The inhibition and activation of dynein activity seem to be associated with binding of ATP only and both ATP and ADP, respectively, to the three noncatalytic regulatory sites of dynein (Inoue and Shingyoji, 2007).…”

“…The regulation through chemical as well as mechanical signals may also play an important role in this process. Among the chemical signals, regulation of dynein activity by protein phosphorylation and dephosphorylation seems important (Inaba, 2002;Nakajima et al, 2005;Smith and Yang, 2004) although the exact pathways of this regulation remain unclear (Yoshimura et al, 2007). The regulation through the CP/RS system is responsible at a physiological, high-ATP condition.…”

“…concentrations (less than 0.1 mM), the presence of CP/RS system is not essential (Bannai et al, 2000;Nakano et al, 2003;Yoshimura et al, 2007), suggesting that other inherent asymmetries in the axoneme are required. The role of the CP/RS system at high ATP, which, as is discussed below, is probably associated with the inhibition and activation of the dynein activity by ATP and ADP, respectively (Yoshimura et al, 2007), is similar in cilia and flagella of different species (Bannai et al, 2000).…”

“…The role of the CP/RS system at high ATP, which, as is discussed below, is probably associated with the inhibition and activation of the dynein activity by ATP and ADP, respectively (Yoshimura et al, 2007), is similar in cilia and flagella of different species (Bannai et al, 2000). The recent finding of the central pair component hydin, the gene encoding which is present broadly in organisms with the ability to assemble motile 9+2 axonemes, may indicate that switching of dynein activity through the CP/RS system is a conserved property of axonemal mechanisms for alternating bends (Lechtreck and Witman, 2007;Lechtreck et al, 2008).…”

“…1E). It is interesting that the dynein activity on doublet 7 seems to be dominant and that this property is independent of Ca 2+ concentration, and thus, under many conditions, the 'quiescence' is commoner than the 'relaxed' straight form (Sale, 1985;Yoshimura et al, 2007). This means that the oscillation may be triggered by the sliding (P-sliding) necessary for P-bend formation .…”