Mitochondrial H+-ATPase activation by an amine oxide detergent.

N Vázquez-Laslop,G Dreyfus

doi:10.1016/s0021-9258(19)57472-5

Abstract

Lauryl dimethylamine oxide activates ATP hydrolysis by the mitochondrial H+-ATPase. Activation is observed in systems with a high content of inhibitor protein as described by Pullman and Monroy (Pullman, M.E., and Monroy, G.C. (1963) J. Biol. Chem. 238, 3762-3769), i.e. Mg-ATP submitochondrial particles and a Triton X-100-solubilized H+-ATPase from the same particles. Detergent activation of ATP hydrolysis is also present in inhibitor-reconstituted systems, i.e. submitochondrial particles, Triton extracts, and soluble F1-ATPase. In submitochondrial particles depleted of inhibitor protein, lauryl dimethylamine oxide induced a biphasic response which is characterized by a drop-in activity induced by relatively low concentrations of LDAO; at higher concentrations the detergent activates to an extent never greater than the initial activity. In inhibitor protein-depleted oligomycin-sensitive Triton extracts, lauryl dimethylamine oxide stimulates ATP hydrolysis to very high values (30 mumol min-1 mg-1). These findings suggest that in addition to the inhibitor protein ATP hydrolysis is controlled by other subunit interactions.

Highlights

From the Departamento de Bioenergetics, Imtituto de Fisiologia Celular, Uniuersidad Nacional Autdnoma de Mexico, 04510 Mexico, D.F
Induced byrelatively low concentrations ofLDAO; at Triton X-100 extracts were prepared as follows. 0.8% Triton was higherconcentrationsthedetergent activates to an added to an equal volume of submitochondrial particles at room extent never greater thanthe initial activity
These findings suggest thatin additionto the inhibitor protein ATP hydrolysis is controlled by other subunit

Summary

Introduction

From the Departamento de Bioenergetics, Imtituto de Fisiologia Celular, Uniuersidad Nacional Autdnoma de Mexico, 04510 Mexico, D.F. Aside from a small decrease of the hydrolytic activity induced by 5 mM LDAO, detergent concentrations between 30 and 40 mM increase the ATPase activity of Mg-ATP particles by more than %fold.

Results

Conclusion