RNA helicases play crucial roles in RNA biology. In plants, RNA helicases are encoded by large gene families, performing roles in abiotic stress responses, development, the post-transcriptional regulation of gene expression, as well as housekeeping functions. Several of these RNA helicases are targeted to the organelles, the mitochondria and chloroplasts. Cyanobacteria are the direct evolutionary ancestors of plant chloroplasts. The cyanobacterium Synechocystis 6803 encodes a single DEAD-box RNA helicase, CrhR, that is induced by a range of abiotic stresses, including low temperature. Though the ΔcrhR mutant exhibits a severe cold-sensitive phenotype, the physiological function(s) performed by CrhR have not been described. To identify transcripts interacting with CrhR, we performed RNA co-immunoprecipitation with extracts from a Synechocystis crhR deletion mutant expressing the FLAG-tagged native CrhR or a K57A mutated version with an anticipated enhanced RNA binding. The composition of the interactome was strikingly biased towards photosynthesis-associated and redox-controlled transcripts. A transcript highly enriched in all experiments was the crhR mRNA, suggesting an autoregulatory molecular mechanism. The identified interactome explains the described physiological role of CrhR in response to the redox poise of the photosynthetic electron transport chain and characterizes CrhR as an enzyme with a diverse range of transcripts as molecular targets.

中文翻译：

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温度调节的死盒 RNA 解旋酶 CrhR 相互作用组：自动调节和光合作用相关转录本

RNA 解旋酶在 RNA 生物学中起着至关重要的作用。在植物中，RNA 解旋酶由大型基因家族编码，在非生物胁迫反应、发育、基因表达的转录后调控以及管家功能中发挥作用。其中一些 RNA 解旋酶靶向细胞器、线粒体和叶绿体。蓝藻是植物叶绿体的直接进化祖先。蓝藻 Synechocystis 6803 编码单个 DEAD-box RNA 解旋酶 CrhR，该酶由包括低温在内的一系列非生物胁迫诱导。尽管 ΔcrhR 突变体表现出严重的冷敏感表型，但尚未描述 CrhR 执行的生理功能。为了识别与 CrhR 相互作用的转录本，我们用来自集胞藻属 crhR 缺失突变体的提取物进行 RNA 共免疫沉淀，该突变体表达 FLAG 标记的天然 CrhR 或具有预期增强的 RNA 结合的 K57A 突变版本。相互作用组的组成明显偏向于光合作用相关和氧化还原控制的转录本。在所有实验中高度富集的转录本是 crhR mRNA，表明其具有自动调节分子机制。鉴定出的相互作用组解释了 CrhR 对光合电子传递链的氧化还原平衡所描述的生理作用，并将 CrhR 描述为一种具有多种转录物作为分子靶标的酶。相互作用组的组成明显偏向于光合作用相关和氧化还原控制的转录本。在所有实验中高度富集的转录本是 crhR mRNA，表明其具有自动调节分子机制。鉴定出的相互作用组解释了 CrhR 对光合电子传递链的氧化还原平衡所描述的生理作用，并将 CrhR 描述为一种具有多种转录物作为分子靶标的酶。相互作用组的组成明显偏向于光合作用相关和氧化还原控制的转录本。在所有实验中高度富集的转录本是 crhR mRNA，表明其具有自动调节分子机制。鉴定出的相互作用组解释了 CrhR 对光合电子传递链的氧化还原平衡所描述的生理作用，并将 CrhR 描述为一种具有多种转录物作为分子靶标的酶。