Author:
Buchert Felix,Bailleul Benjamin,Joliot Pierre
Abstract
AbstractThe chloroplast ATP synthase (CF1Fo) contains a specific feature to the green lineage: a γ-subunit redox domain which contains a cysteine couple and interacts with the torque-generating βDELSEED-loop. Based on the recently solved structure of this domain, it was proposed to function as a chock.In vitro,γ-disulfide formation slows down the activity of the CF1Foat low transmembrane electrochemical proton gradient. Here, we utilizein vivoabsorption spectroscopy measurements for functional CF1Foactivity characterization in Arabidopsis leaves. The spectroscopic method allows us to measure thepresent in dark-adapted leaves, and to identify its mitochondrial sources. Furthermore, we follow the fate of the extragenerated by an illumination, including its osmotic and electric components, and from there we estimate the lifetime of the light-generated ATP. In contrast with a previous report [Joliot and Joliot, Biochim. Biophys. Acta, 1777 (2008) 676-683], the CF1Foγ-subunit exists mostly in an oxidized form in the dark-adapted state. To study the redox regulation of the CF1Fo, we used thiol agent infiltration in WT and a mutant that does not form the γ-disulfide. The obtained-dependent CF1Foactivity profile in the two γ-redox statesin vivoreconciles with previous biochemicalin vitrofindings [Junesch and Gräber, Biochim. Biophys. Acta, 893 (1987) 275-288]. The highest rates of ATP synthesis we measured in the two γ-redox state were similar at high. In the presence of the γ-dithiol, similar rates were obtained at a ~45 mV lowervalue compared to the oxidized state, which closely resembled the energetic gap of 0.7 ΔpH units reportedin vitro.
Publisher
Cold Spring Harbor Laboratory
Cited by
1 articles.
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