Pyrenoid loss in Chlamydomonas reinhardtii causes limitations in CO2 supply, but not thylakoid operating efficiency.
Pyrenoid loss in Chlamydomonas reinhardtii causes limitations in CO2 supply, but not thylakoid operating efficiency.
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DOI：
10.1093/jxb/erx197
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发表时间：
2017-06-01
影响因子：
6.9
通讯作者：
Griffiths H
中科院分区：
文献类型：
--
作者：
Caspari OD;Meyer MT;Tolleter D;Wittkopp TM;Cunniffe NJ;Lawson T;Grossman AR;Griffiths H
莱茵衣藻蛋白核是一个含有Rubisco的微区室，主要负责促进碳的积累，并不影响类囊体膜光合能量。单细胞绿色莱茵衣藻的蛋白核是位于杯状叶绿体中心的一个微区室，含有高达90%的细胞Rubisco。蛋白核被致密、打结的类囊体小管网络穿过，被认为影响类囊体的生物发生和超微结构。由于表达Rubisco小亚基的维管植物版本，不能组装蛋白核基质的突变体表现出严重的生长和光合缺陷，并且具有无效的碳浓缩机制（CCM）。本研究着手确定这些蛋白核较少的线光合限制的原因。我们测试了电子传递和光的利用是否受到损害，作为蛋白核损失的直接结构后果，或作为较低CCM活性下游的代谢效应，并导致CO2限制。类囊体组织在突变体中没有变化，包括保留蛋白核内型类囊体小管，通过将细胞暴露于升高的CO2水平来拯救与蛋白核缺失相关的光合限制。这些结果表明，Rubisco聚集在蛋白核的功能作为一个必不可少的元素CO2输送的CCM的一部分，并没有发挥其他作用，在维持光合膜能量。
The Chlamydomonas reinhardtii pyrenoid is a Rubisco-containing microcompartment primarily responsible for facilitating carbon accumulation and does not affect thylakoid membrane photosynthetic energetics. The pyrenoid of the unicellular green alga Chlamydomonas reinhardtii is a microcompartment situated in the centre of the cup-shaped chloroplast, containing up to 90% of cellular Rubisco. Traversed by a network of dense, knotted thylakoid tubules, the pyrenoid has been proposed to influence thylakoid biogenesis and ultrastructure. Mutants that are unable to assemble a pyrenoid matrix, due to expressing a vascular plant version of the Rubisco small subunit, exhibit severe growth and photosynthetic defects and have an ineffective carbon-concentrating mechanism (CCM). The present study set out to determine the cause of photosynthetic limitation in these pyrenoid-less lines. We tested whether electron transport and light use were compromised as a direct structural consequence of pyrenoid loss or as a metabolic effect downstream of lower CCM activity and resulting CO2 limitation. Thylakoid organization was unchanged in the mutants, including the retention of intrapyrenoid-type thylakoid tubules, and photosynthetic limitations associated with the absence of the pyrenoid were rescued by exposing cells to elevated CO2 levels. These results demonstrate that Rubisco aggregation in the pyrenoid functions as an essential element for CO2 delivery as part of the CCM, and does not play other roles in maintenance of photosynthetic membrane energetics.
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影响因子：
4.2
作者：
Blackman, F. F.
通讯作者：
Blackman, F. F.
DOI：
10.1073/pnas.081593498
发表时间：
2001-04-24
影响因子：
11.1
作者：
Fukuzawa, H;Miura, K;Ohyama, K
通讯作者：
Ohyama, K
影响因子：
4.8
作者：
Johnson, Xenie;Alric, Jean
通讯作者：
Alric, Jean
DOI：
10.1016/0005-2728(72)90147-8
发表时间：
1972-01-01
期刊：
BIOCHIMICA ET BIOPHYSICA ACTA
影响因子：
--
作者：
HIYAMA, T;KE, B
通讯作者：
KE, B
DOI：
10.1073/pnas.93.24.13689
发表时间：
1996-11-26
影响因子：
11.1
作者：
Khrebtukova, I;Spreitzer, RJ
通讯作者：
Spreitzer, RJ