The molecular basis of high light photoacclimation in diatoms

硅藻的光合效率和生产力可能取决于光环境，这在水生生态系统中可能是高度可变的。为了在不断变化的环境中保持最佳的光合作用，硅藻已经进化出许多调节机制。光保护性NPQ（非光化学荧光淬灭）过程允许质体安全地耗散在光胁迫期间吸收的过量能量。硅藻的NPQ程度可能相当高。叶黄素色素和特定的捕光复合物（LHC）多肽是NPQ机制所必需的。我们想解决的问题是，大型强子对撞机天线的组织和组成（多肽和色素）如何使硅藻能够科普光强度的压力增加。特别是，我们希望获得有关参与细胞对强光的反应的LHC多肽的知识，并鉴定可能参与NPQ过程控制的特殊LHC天线多肽。在这种情况下，我们将集中在这些多肽的一个特定的组：高光诱导蛋白（HLIP）。在硅藻中，关于它们在LHC天线中的位置，它们在基因和蛋白质水平上作为光的函数的调节，以及它们在硅藻对强光胁迫的生理反应中的作用，都是未知的。我们将研究这些方面的适应高光硅藻耦合蛋白质组学的方法对LHC系统，基因表达分析与光，在体内遗传调制的HLIPs和生理特性。

The photosynthetic efficiency and productivity of diatoms may depend on the light environment which can be highly variable in aquatic ecosystems. To maintain optimal photosynthesis in a permanently changing environment, diatoms have evolved a number of regulatory mechanisms. The photoprotective NPQ (non-photochemical fluorescence quenching) process allows the plastid to safely dissipate the excess energy absorbed during a light stress. The extent of NPQ can be rather high in diatoms. Xanthophyll pigments and specific light-harvesting complex (LHC) polypeptides are necessary for the NPQ mechanism. We want to address the question how the organization and composition (polypeptide and pigment) of the LHC antenna enable the diatoms to cope with the stressful increase of light intensity. Especially, we want to gain knowledge on the LHC polypeptide(s) involved in the response of the cells to high light, and to identify the special LHC antenna polypeptide(s) possibly involved in the control of the NPQ process. In this context, we will focus on a particular group of these polypeptides: the High Light Induced Proteins (HLlPs). In diatoms, nothing is known concerning their location in the LHC antenna, their regulation as a function of light at the gene and protein levels, and their role in the physiological response of the diatoms to high light stress. We will study these aspects of the acclimation to high light in diatoms by coupling a proteomic approach on the LHC system, gene expression analysis versus light, in vivo genetic modulation of HLIPs and physiological characterization.