Function of thylakoid low molecular weight proteins and assembly factors in the biogenesis, activity and stability of photosynthetic complexes

类囊体膜光合复合物的一个有趣的特征是它们大量的低分子量（LMW）蛋白质，这些蛋白质由核和质体编码。在这里，我们调查的不同功能的组装因子和个别低分子量蛋白质的生物发生，光吸收，电子传递过程中，磷酸化，稳定和修复主要是光系统（PS）II使用相应的核和质体基因在拟南芥和烟草，分别敲除。此外，突变体库将用于确定组装过程中出现的亚复合物的组成，以及它们在类囊体系统内的定位，使用天然凝胶，共免疫沉淀（Co-IP），色谱，交联，标记蛋白，分级分离技术和质谱。我们提供了明确的证据表明，低分子量膜蛋白PsbN，迄今为止被注释为PSII亚基，是不是这个复杂的一部分，但基本上需要组装其异二聚体反应中心。将确定PsbN和与PsbN一起在几个precomplex中相关的蛋白质的直接相互作用伙伴，已经获得的相互作用因子将使用分裂泛素测定法，蛋白质覆盖测定法，SPR光谱法，Co-IP与PsbN的标记版本和质谱法进行验证和分析。所解决的问题有助于我们理解的逐步组装，光捕获，电子转移内和外出的PSII，水裂解和O2的演变，膜动力学和恢复敏感的PSII从光抑制和热失活。

An intriguing feature of the photosynthetic complexes of the thylakoid membrane is their high number of low molecular weight (LMW) proteins, which are nuclear and plastid encoded. Here we investigate the distinct function of assembly factors and of individual LMW proteins in the biogenesis, light absorbance, electron transport processes, phosphorylation, stabilisation and repair mainly of photosystem (PS)II using available knockouts of corresponding nuclear and plastid genes in Arabidopsis and tobacco, respectively. Furthermore, the mutant repertoire will be used to identify the composition of subcomplexes appearing during assembly and their localisation within the thylakoid system using native gels, co-immunoprecipitation (Co-IP), chromatography, cross-linking, tagged proteins, fractionation techniques and mass spectrometry. We provide clear evidence that the LMW membrane protein PsbN, which hitherto was annotated as PSII subunit, is not part of this complex but essentially required for assembly of its heterodimeric reaction centre. Direct interaction partners of PsbN and proteins associated in several precomplexes together with PsbN will be identified, already obtained interacting factors will be verified and analysed using split-ubiquitin assays, protein overlay assays, SPR spectrometry, Co-IP with tagged versions of PsbN and mass spectrometry. The addressed issues assist in our understanding of the stepwise assembly, light capture, transfer of electrons within and outgoing of PSII, water splitting and O2 evolution, membrane dynamics and recovery of the susceptible PSII from photoinhibition and heat inactivation.