Elucidating VIPP function in thylakoid biogenesis with VIPPaccumulating mutants as entry point

以 VIPP 累积突变体为切入点阐明 VIPP 在类囊体生物发生中的功能

• 批准号: 254835863
• 负责人: Professor Dr. Michael Schroda
• 金额: --
• 依托单位: Fachgebiet Molekulare Biotechnologie und Systembiologie
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/254835863?language=en
• 关键词: Elucidating; VIPP; function; thylakoid; biogenesis

VIPP1 (originally termed vesicle inducing protein in plastids 1) is important for the biogenesis of thylakoid membranes (TMs), as Arabidopsis knock-out mutants lack thylakoid membranes and knockdown mutants contain fewer TMs and TM protein complexes. VIPPs overaccumulate in Chlamydomonas cells exposed to high-light intensities and in mutants with reduced levels of proteins involved in the translocation/ integration of TM proteins (alb3.1, secA). This suggests that the role of VIPP1 during TM biogenesis might not be at the level of membrane biogenesis via vesicle formation, but rather at the level of the biogenesis/repair of TM protein complexes. Based on these findings we performed a forward genetics screen with Chlamydomonas reinhardtii to identify mutants that constitutively overexpress VIPPs. As all mutants analyzed so far (7 out of 13) have defects in the accumulation of subunits of the four major TM protein complexes and/or in the repair of photosystem II from photodamage, this indeed indicates a role for VIPPs in TM protein complex biogenesis/repair. In this project we wish to characterize these mutants in detail to (i) learn about the roles of the affected genes in TM protein complex biogenesis/repair and (ii) understand why and how their functions are supported by VIPPs. Moreover, having identified a lipid component to which recombinant VIPPs strongly bind, we wish to investigate the role of this lipid component for VIPP membrane binding and oligomerization in vitro and in vivo.

VIPP 1（最初称为质体中的囊泡诱导蛋白1）对于类囊体膜（TM）的生物发生是重要的，因为拟南芥敲除突变体缺乏类囊体膜并且敲除突变体含有较少的TM和TM蛋白复合物。VIPP在暴露于强光强度的衣原体细胞中以及在涉及TM蛋白（alb3.1，secA）易位/整合的蛋白质水平降低的突变体中过度积累。这表明VIPP 1在TM生物合成过程中的作用可能不是通过囊泡形成在膜生物合成水平上，而是在TM蛋白复合物的生物合成/修复水平上。基于这些发现，我们用莱茵衣藻进行了正向遗传学筛选，以鉴定组成型过表达VIPP的突变体。由于到目前为止分析的所有突变体（13个中的7个）在四种主要TM蛋白复合物的亚基积累和/或光系统II的光损伤修复中存在缺陷，这确实表明VIPP在TM蛋白复合物生物发生/修复中的作用。在这个项目中，我们希望详细描述这些突变体，以（i）了解受影响的基因在TM蛋白复合物生物发生/修复中的作用，（ii）了解VIPP为什么以及如何支持它们的功能。此外，已经确定了重组VIPP强烈结合的脂质成分，我们希望研究这种脂质成分在体外和体内VIPP膜结合和寡聚化的作用。