758 / 2019-05-27 15:31:16

Regulatory network of proton motive force in chloroplasts

chloroplast,photosynthesis,proton motive force

全体主题 > Photosynthesis

Photosynthetic electron transport in chloroplasts is coupled with proton translocation across the thylakoid membrane. Both proton concentration gradient (∆pH) and membrane potential (∆Ψ) contribute to ATP synthesis as proton motive force (pmf). The ∆pH component pmf also downregulates electron transport via inducing NPQ and photosynthetic control (∆pH-dependent downergulation of the Cyt b6f complex). Cyclic electron transport around PSI generates pmf without accumulating NADPH, regulating the size of pmf. In contrast, the putative H+/K+ antipoter KEA3 is localized to the thylakoid membrane and regulates the partitioning of pmf components. Both mechanisms are needed for optimizing photosynthesis under fluctuating light intensity. We overexpressed the KEA3 genes in Arabidopsis. We also overexpressed the mutant version of KEA3 (DPGR-type), in which activity of KEA3 was enhanced. In both transgenic plants ∆pH-dependent regulation of electron transport was severely impaired especially in the DPGR-type lines. Consequently, PSI was sensitive to fluctuating light intensity in the lines.