Structural and functional analysis of NDH-1 supercomplexes

膜蛋白复合物在生物能量学中起着至关重要的作用，特别是在光合生物中。它们负责光合作用初级反应中的光能到化学能的转换，从而推动促进和维持地球上几乎所有生命的能量梯度。在这个基本过程中，它们将光驱动的电子传输与质子跨膜的矢量传输相结合。我们特别感兴趣的是这些分子机器中的一种，复合物I（又名NDH-1），它是光合和呼吸电子传递链的一部分。它以一种尚不清楚的方式将从铁氧还蛋白（Fd）到质体醌的电子转移与质子穿过类囊体膜的转移结合起来，由于缺乏基于结构-功能的突变研究，有关其精确分子功能的许多问题仍未得到解答体外和体内。原则上，作为高效的质子泵，它们可以通过在循环电子传递中经由Fd从光系统I（PSI）接受电子来促进光驱动的质子动力（PMF）的形成，但它们在体内的作用相当不清楚。从陆地植物中已知PSI和NDH-1形成超复合物，然而目前的结构模型是不完整的并且缺少Fd相互作用亚基。此外，在蓝藻超复合物形成NDH-1与PSI和CpcG 2-藻胆体或与H2酶/黄递酶作为替代途径仍然是难以捉摸的。该项目将提供新的分子见解NDH-1功能和其整合到动态电子传递网络的细胞的基础上，我们最近的进展，在蓝藻复合体的结构分析。具体来说，我们将重点关注与PSI和H2酶/心肌黄酶的超复合物形成，以了解其在PMF形成中的作用。蓝细菌超复合体将在模式生物集胞藻属PCC 6803和丝状重氮蓝细菌鱼腥藻属PCC 7120中被靶向，其将与陆地植物超复合体形式的brabente P. patens进行比较，brabente P. patens是一种遗传可及系统，其允许相对容易地扩大生物质生产。

Membrane protein complexes play a crucial role in bioenergetics, particularly in photosynthetic organisms. They are responsible for the light-to-chemical energy conversion in the primary reactions of photosynthesis, thereby driving the energy gradient that promotes and sustains almost all life on our planet. In this fundamental process, they combine the light-driven transport of electrons with the vectorial transport of protons across a membrane. We are particularly interested in one type of these molecular machines, complex I (aka NDH-1), which is part of photosynthetic as well as respiratory electron transport chains. It combines electron transfer from ferredoxin (Fd) to plastoquinone with the transfer of protons across the thylakoid membrane in a yet unknown fashion and many questions concerning their precise molecular function remain unanswered due to the lack of structure-function based mutagenesis studies in vitro and in vivo. In principle, as highly efficient proton pumps, they could contribute to light-driven proton motive force (PMF) formation substantially by accepting electrons from photosystem I (PSI) via Fd in cyclic electron transport, but their role in vivo is rather unclear. It is known from land plants that PSI and NDH-1 form a supercomplex, however current structural models are incomplete and miss the Fd interacting subunits. Moreover, in cyanobacteria supercomplex formation of NDH-1 with PSI and CpcG2-phycobilisomes or with H2ase/Diaphorase as an alternative pathway is still elusive. The project will provide novel molecular insights into NDH-1 function and its integration into the dynamic electron transport network of the cell based on our recent advances in structural analysis of the cyanobacterial complex. Specifically, we will focus on supercomplex formation with PSI and with H2ase/Diaphorase to understand its role in PMF formation. Cyanobacterial supercomplexes will be targeted in the model organisms Synechocystis sp. PCC 6803 and the filamentous, diazotrophic cyanobacterium Anabaena sp. PCC 7120, which will be compared to the land plant supercomplex form the bryophyte P. patens, a genetically accessible system that allows comparatively easy upscaling of biomass production.