The algal PETC-Pro171-Leu suppresses electron transfer in the cytochrome b6f under acidic lumenal condition
The algal PETC-Pro171-Leu suppresses electron transfer in the cytochrome b6f under acidic lumenal condition
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酸性腔内条件下藻类 PETC-Pro171-Leu 抑制细胞色素 b6f 中的电子转移
DOI：
10.1101/2021.12.15.472847
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Takahashi Yuichiro
中科院分区：
文献类型：
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作者：
Ozawa Shin-Ichiro;Buchert Felix;Reuys Ruby;Hippler Michael;Takahashi Yuichiro
线性光合电子流（LEF）产生NADPH，并在用于合成ATP的类囊体膜上产生质子电化学电位梯度，这两者都是二氧化碳固定所必需的。由于细胞对ATP和NADPH的需求是可变的，PSI和细胞色素6f复合物（b6f）之间的循环电子流（CEF）产生额外的ATP。b6f通过光合作用调控LEF和CEF，这是一种ph依赖性的管腔部位的塑料喹啉氧化减慢。维管植物拟南芥（abidopsis thaliana）的pgr1突变体在更碱性的管腔pH值下触发这种保护机制，该突变体在b6frieske铁硫蛋白中携带Pro194Leu。在这项工作中，我们引入了绿藻莱茵藻（chlamydomonas reinhardtii, PETC-P171L）的pgr1突变。与pgr1表型一致，petc - p171l在强光条件下表现出NPQ诱导受损以及光自养生长减慢。我们的数据提供了证据，证明在petc - p171ΔpH组分依赖于氧的可用性。只有在低氧条件下，ΔpH成分才足以触发algalpetc - p171l的表型，其中突变体更局限于氧化PQ池，并显示通过b6f复合物的电子流减少。通过位点定向诱变将PETC转化为P171L改变了光合作用控制机制的pH依赖性
Linear photosynthetic electron flow (LEF) produces NADPH and generates a proton electrochemical potential gradient across the thylakoid membrane used to synthesize ATP, both of which are required for CO2fixation. As cellular demand for ATP and NADPH are variable, cyclic electron flow (CEF) between PSI and cytochromeb6fcomplex (b6f) produces extra ATP. Theb6fregulates LEF and CEF via photosynthetic control, which is a pH-dependentb6fslowdown of plastoquinol oxidation at the lumenal site. This protection mechanism is triggered at more alkaline lumen pH in thepgr1mutant of the vascular plantArabidopsis thaliana, carrying Pro194Leu in theb6fRieske Iron-sulfur protein. In this work, we introducedpgr1mutation in the green algaChlamydomonas reinhardtii(PETC-P171L). Consistent withpgr1phenotype,PETC-P171Ldisplayed an impaired NPQ induction along with slower photoautotrophic growth under high light conditions. Our data provides evidence that the ΔpH component inPETC-P171Lis dependent on oxygen availability. Only under low oxygen conditions the ΔpH component was sufficient to trigger a phenotype in algalPETC-P171Lwhere the mutantb6fwas more restricted to oxidize the PQ pool and showed a diminished electron flow through theb6fcomplex.One sentence summaryChange of PETC to P171L via site directed mutagenesis alters the pH dependency of the photosynthetic control mechanism