Cyanobacterial carboxysomes contain an unique rubisco-activase-like protein
Cyanobacterial carboxysomes contain an unique rubisco-activase-like protein
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DOI：
10.1111/nph.16195
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发表时间：
2019-10-25
期刊：
影响因子：
9.4
通讯作者：
Kerfeld, Cheryl A.
中科院分区：
文献类型：
--
作者：
Lechno-Yossef, Sigal;Rohnke, Brandon A.;Kerfeld, Cheryl A.
在植物中，Rubisco活化酶（Rca）通过去除抑制性分子（例如1，5-二磷酸核酮糖（RuBP））来调节Rubisco。在蓝藻中，一种同源蛋白（激活酶样蓝藻蛋白，ALC），含有一个独特的C-末端融合类似于Rubisco的小亚基。虽然蓝藻rubisco被认为是不太敏感的RuBP抑制，ALC广泛分布在不同的蓝藻。本研究采用显微镜、生物化学和分子生物学等方法，对双倍管弗氏菌ALC的细胞定位、对细胞/羧基体超微结构的影响及其体外功能进行了研究。生物信息学分析揭示了ALC和rubisco之间的进化关系。ALC定位于羧基体并表现出ATP酶活性。此外，ALC以类似于另一种羧基体蛋白M35的方式诱导rubisco聚集，并且这种活性受ATP影响。一个alc缺失突变体表现出修改细胞形态时，生长在丰富的CO2和受损的调控下的羧基体生物合成，而不影响生长速度。RuBP对弗氏菌rubisco的氨甲酰化有抑制作用，但ALC不能解除这种抑制作用。ALC似乎不像一个典型的Rca的功能，相反，它发挥作用的反应，CO2的可用性在代谢模块的水平上，羧基，通过rubisco网络的形成，和羧基组织。
In plants, rubisco activase (Rca) regulates rubisco by removing inhibitory molecules such as ribulose-1,5-bisphosphate (RuBP). In cyanobacteria, a homologous protein (activase-like cyanobacterial protein, ALC), contains a distinctive C-terminal fusion resembling the small-subunit of rubisco. Although cyanobacterial rubisco is believed to be less sensitive to RuBP inhibition, the ALC is widely distributed among diverse cyanobacteria. Using microscopy, biochemistry and molecular biology, the cellular localization of the ALC, its effect on carboxysome/cell ultrastructure in Fremyella diplosiphon, and its function in vitro were studied. Bioinformatic analysis uncovered evolutionary relationships between the ALC and rubisco. ALC localizes to carboxysomes and exhibits ATPase activity. Furthermore, the ALC induces rubisco aggregation in a manner similar to that of another carboxysomal protein, M35, and this activity is affected by ATP. An alc deletion mutant showed modified cell morphology when grown under enriched CO2 and impaired regulation of carboxysome biogenesis, without affecting growth rate. Carbamylation of Fremyella recombinant rubisco was inhibited by RuBP, but this inhibition was not relieved by the ALC. The ALC does not appear to function like a canonical Rca; instead, it exerts an effect on the response to CO2 availability at the level of a metabolic module, the carboxysome, through rubisco network formation, and carboxysome organization.