蛋白类
莱茵衣藻
衣原体
鲁比斯科
类囊体
生物
叶绿体
拟南芥
细胞生物学
生物物理学
拟南芥
光合作用
植物
生物化学
突变体
基因
作者
Liat Adler,Chun Sing Lau,Kashif M. Shaikh,Kim A. van Maldegem,Alex L. Payne-Dwyer,Cécile Lefoulon,Philipp Girr,Nicky Atkinson,James Barrett,Tom Z. Emrich-Mills,Emilija Dukic,Michael R. Blatt,Mark C. Leake,Gilles Peltier,Cornelia Spetea,Adrien Burlacot,Alistair J. McCormick,Luke C. M. Mackinder,Charlotte E. Walker
标识
DOI:10.1093/plphys/kiae450
摘要
Abstract In many eukaryotic algae, CO2 fixation by Rubisco is enhanced by a CO2-concentrating mechanism, which utilizes a Rubisco-rich organelle called the pyrenoid. The pyrenoid is traversed by a network of thylakoid membranes called pyrenoid tubules, which are proposed to deliver CO2. In the model alga Chlamydomonas (Chlamydomonas reinhardtii), the pyrenoid tubules have been proposed to be tethered to the Rubisco matrix by a bestrophin-like transmembrane protein, BST4. Here, we show that BST4 forms a complex that localizes to the pyrenoid tubules. A Chlamydomonas mutant impaired in the accumulation of BST4 (bst4) formed normal pyrenoid tubules, and heterologous expression of BST4 in Arabidopsis (Arabidopsis thaliana) did not lead to the incorporation of thylakoids into a reconstituted Rubisco condensate. Chlamydomonas bst4 mutants did not show impaired growth under continuous light at air level CO2 but were impaired in their growth under fluctuating light. By quantifying the non-photochemical quenching (NPQ) of chlorophyll fluorescence, we propose that bst4 has a transiently lower thylakoid lumenal pH during dark-to-light transition compared to control strains. We conclude that BST4 is not a tethering protein but is most likely a pyrenoid tubule ion channel involved in the ion homeostasis of the lumen with particular importance during light fluctuations.
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