A Thylakoid-Located Two-Pore K + Channel Controls Photosynthetic Light Utilization in Plants

Abstract

pH Gradient in Light of Electroneutrality Photosynthesis in plant chloroplasts depends on a proton gradient to convert light energy into adenosine triphosphate. Studying Arabidopsis , Carraretto et al. (p. 114 , published online 5 September; see the Perspective by Rochaix ) identified the potassium channel TPK3 in the stacked membranes of the chloroplast's thylakoids as key to sustaining the proton gradient. As the thylakoid lumen acidifies on exposure to light, electroneutrality derives from TPK3 activity. TPK3 was able to optimize chloroplast responses to light across a wide range of intensities. Plants lacking functional TPK3 appeared normal when grown at modest light levels, but at higher light levels, the plants showed disruptions in overall growth and in thylakoid organization.