Partitioning of the proton motive force into delta phi and delta pH and its role in light regulation of photosynthesis

光合作用是由光能转化为化学能驱动的。总的质子动力（pmf =跨膜电势（Δ phi）和pH梯度（Δ pH）的总和）代表ATP合成的驱动力，其沿着光合电子传递而跨越类囊体膜建立。然而，Δ phi对于由管腔pH（并且因此也由pH梯度）调节的其他过程（例如能量耗散和玉米黄质合成）的重要性在很大程度上未被充分研究。PMF分成其两个组分，Δ φ和Δ pH，可以很容易地在植物体内条件下通过测量电致变色吸收的变化，这是跨膜电场的直接测量来研究。我们的初步数据表明，在体内条件下，PMF的分区的动态不符合pH调节的能量耗散的动态，支持的假设，也跨膜电场可能有助于这种光保护机制。计划中的项目的目标是阐明跨膜电场（delta phi）在光激活，光适应和光合作用调节中的作用。为此，我们希望遵循光谱方法（i）进行详细的表征的动力学pmf分区响应于不同的光照条件和pH值调节的光合作用过程和（ii）研究的影响，人工修改的相对贡献的Δ phi和Δ pH值的整体pmf pH值调节的过程。

Photosynthesis is driven by the conversion of light energy into chemical energy. The overall proton motive force (pmf = the sum of the transmembrane electric potential (delta phi) and pH gradient (delta pH)) which is built up across the thylakoid membrane along with photosynthetic electron transport represents the driving force for ATP synthesis. However, the importance of delta phi for other processes, that are regulated by the lumen pH (and hence also by the pH gradient), such as energy dissipation and zeaxanthin synthesis, is largely understudied. The partitioning of the pmf into its two components, delta phi and delta pH, can easily be studied in plants under in vivo conditions by measuring electrochromic absorption changes which are a direct measure for the transmembrane electric field. Our preliminary data indicated that the dynamics of the partitioning of the pmf do not correspond well with the dynamics of pH-regulated energy dissipation under in vivo conditions, supporting the hypothesis that also the transmembrane electric field may contribute to this photoprotective mechanism. The goal of the planned project is to elucidate the role of the transmembrane electric field (delta phi) in light activation, light acclimation, and regulation of photosynthesis. To this end we want to follow a spectroscopic approach (i) to perform a detailed characterization of the dynamics of pmf partitioning in response to different light conditions and in relation to pH-regulated photosynthetic processes and (ii) to study the impact of the artificial modification of the relative contributions of delta phi and delta pH to the overall pmf on pH-regulated processes.