Department of Life Science & Technology, Tokyo Institute of Technology, Yokohama, Japan.
Earth-Life Science Institute, Tokyo Institute of Technology, Japan.
FEBS Lett. 2023 Jul;597(13):1761-1769. doi: 10.1002/1873-3468.14687. Epub 2023 Jun 28.
The control of pH in chloroplasts is important to regulate photosynthesis, although details of the precise regulatory mechanisms of H homeostasis in chloroplasts are not fully understood. We recently found that the cyanobacterial PxcA homolog DLDG1 is involved in plastidial pH control. PxcA and DLDG1 have been thought to control light-dependent H extrusion across the cyanobacterial cytoplasmic and chloroplast envelope membranes, respectively. To investigate DLDG1-dependent pH control in chloroplasts, we crossed the dldg1 mutant with various mutants lacking known non-photochemical quenching (NPQ)-related proteins, such as fluctuating-light acclimation protein 1 (FLAP1), PsbS/NPQ4, and proton gradient regulation 5 (PGR5). Phenotypes of these double mutants revealed that PsbS works upstream of DLDG1, PGR5 affects NPQ independently from DLDG1, and the ΔpH regulation by FLAP1 and DLDG1 are independent of each other.
叶绿体中 pH 的控制对于调节光合作用很重要，尽管叶绿体中 H 动态平衡的精确调节机制的细节还不完全清楚。我们最近发现，蓝细菌的 PxcA 同源物 DLDG1 参与了质体 pH 的控制。人们一直认为 PxcA 和 DLDG1 分别控制着穿过蓝细菌细胞质和叶绿体膜的光依赖性 H 外排。为了研究 DLDG1 依赖的叶绿体 pH 控制，我们将 dldg1 突变体与各种缺乏已知非光化学猝灭（NPQ）相关蛋白的突变体杂交，例如波动光适应蛋白 1（FLAP1）、PsbS/NPQ4 和质子梯度调节 5（PGR5）。这些双突变体的表型表明，PsbS 在 DLDG1 的上游起作用，PGR5 独立于 DLDG1 影响 NPQ，而 FLAP1 和 DLDG1 的 ΔpH 调节彼此独立。
