Advances in Understanding Carboxysome Assembly in Prochlorococcus and Synechococcus Implicate CsoS2 as a Critical Component.
Advances in Understanding Carboxysome Assembly in Prochlorococcus and Synechococcus Implicate CsoS2 as a Critical Component.
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DOI：
10.3390/life5021141
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发表时间：
2015-03-27
期刊：
影响因子：
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通讯作者：
Kerfeld CA
中科院分区：
文献类型：
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作者：
Cai F;Dou Z;Bernstein SL;Leverenz R;Williams EB;Heinhorst S;Shively J;Cannon GC;Kerfeld CA
海洋聚球藻和原绿球藻是海洋中数量上占优势的蓝藻，在全球碳固定中具有重要作用。它们已经进化出一种CO2浓缩机制，其中心成分是羧基体，一种自组装的蛋白质细胞器。两种类型的羧基体，α和β，分别包裹IA型和IB型d-核酮糖-1，5-二磷酸羧化酶/加氧酶，在基因组织和相关蛋白质方面不同。与β-羧基体相反，α-羧基体的组装过程是神秘的。此外，一个绝对保守的α-羧基体蛋白CsoS2，是未知的功能，并已被证明是不稳定的结晶。在这里，我们目前的研究CsoS2蛋白在三个模式生物，并表明CsoS2是至关重要的α-羧基体生物合成。CsoS2的一级结构由N-末端、中间（M）-和C-末端区域组成。在N-和M-区域中可以鉴定重复基序。多条证据表明CsoS2是高度灵活的，可能是一种内在无序的蛋白质。基于我们从生物信息学，生物物理学，遗传学和生物化学方法，包括蛋白质-蛋白质相互作用的肽阵列扫描的结果，我们提出了一个CsoS2功能及其在α-羧基体中的空间定位的模型。讨论了β-羧基体生物发生途径与我们的α-羧基体组装模型之间的相似性。
The marine Synechococcus and Prochlorococcus are the numerically dominant cyanobacteria in the ocean and important in global carbon fixation. They have evolved a CO2-concentrating-mechanism, of which the central component is the carboxysome, a self-assembling proteinaceous organelle. Two types of carboxysome, α and β, encapsulating form IA and form IB d-ribulose-1,5-bisphosphate carboxylase/oxygenase, respectively, differ in gene organization and associated proteins. In contrast to the β-carboxysome, the assembly process of the α-carboxysome is enigmatic. Moreover, an absolutely conserved α-carboxysome protein, CsoS2, is of unknown function and has proven recalcitrant to crystallization. Here, we present studies on the CsoS2 protein in three model organisms and show that CsoS2 is vital for α-carboxysome biogenesis. The primary structure of CsoS2 appears tripartite, composed of an N-terminal, middle (M)-, and C-terminal region. Repetitive motifs can be identified in the N- and M-regions. Multiple lines of evidence suggest CsoS2 is highly flexible, possibly an intrinsically disordered protein. Based on our results from bioinformatic, biophysical, genetic and biochemical approaches, including peptide array scanning for protein-protein interactions, we propose a model for CsoS2 function and its spatial location in the α-carboxysome. Analogies between the pathway for β-carboxysome biogenesis and our model for α-carboxysome assembly are discussed.