Structural basis of redox modulation on chloroplast ATP synthase.

ABSTRACT: In higher plants, chloroplast ATP synthase has a unique redox switch on its ? subunit that modulates enzyme activity to limit ATP hydrolysis at night. To understand the molecular details of the redox modulation, we used single-particle cryo-EM to determine the structures of spinach chloroplast ATP synthase in both reduced and oxidized states. The disulfide linkage of the oxidized ? subunit introduces a torsional constraint to stabilize the two ? hairpin structures. Once reduced, free cysteines alleviate this constraint, resulting in a concerted motion of the enzyme complex and a smooth transition between rotary states to facilitate the ATP synthesis. We added an uncompetitive inhibitor, tentoxin, in the reduced sample to limit the flexibility of the enzyme and obtained high-resolution details. Our cryo-EM structures provide mechanistic insight into the redox modulation of the energy regulation activity of chloroplast ATP synthase.

SUBMITTER: Yang JH 

PROVIDER: S-EPMC7468127 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature