Preferential decay of the CF₁-ε subunit induces thylakoid uncoupling in wild watermelon under drought stress

Abstract

Photosynthetic energy conversion in plants involves the formation of proton gradient across thylakoid membranes, but the mechanisms for balancing the membrane potential has been poorly elucidated. We found that drought stress induces selective decomposition of the ε subunit in the CFoCF₁ ATP synthase. Thylakoid membranes from the stressed leaves showed reduced efficiencies in proton gradient formation and energy coupling, but addition of the recombinant ε subunit significantly suppressed their leaky property. We conclude that the selective decomposition of the ε subunit induces partial uncoupling of the thylakoid membranes under drought, and hence contributes to the excess energy dissipation in chloroplasts.