In plants, heteromeric acetyl-CoA carboxylase (hetACCase) initiates de novo fatty acid synthesis (FAS) by generating malonyl-CoA in the first committed step of this process. hetACCase activity is precisely regulated to meet the cellular demand for acyl chains during the plant life cycle. In this study, we performed a systematic co-expression analysis of hetACCase and its regulators in Arabidopsis (Arabidopsis thaliana) to better understand the regulatory mechanism of hetACCase. Our analysis uncovered REGULATOR OF FATTY ACID SYNTHESIS 1 (RFS1), whose expression is positively correlated with that of other regulators of hetACCase. The RFS gene family encodes two plastid inner envelope membrane proteins with undiscovered roles. Further analysis revealed that RFS1 co-localizes and directly interacts with CARBOXYLTRANSFERASE INTERACTOR 1 (CTI1). CRISPR/Cas9-mediated knockouts of RFSs exhibit enhanced hetACCase activity, higher FAS rates, and increased fatty acid contents, with particularly marked accumulation of absolute triacylglycerol levels in leaves, similar to cti mutants. The mutations of rfs and cti alter the plastid membrane distribution pattern of α-carboxyltransferase, leading to reduced hetACCase activity on the membrane, which could potentially be the original mechanism through which RFSs restrain hetACCase activity. Thus, we reveal a unique regulatory module that regulates de novo FAS and a genetic locus that may contribute to breeding of improved oil crops.

中文翻译：

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脂肪酸合成调节因子蛋白通过调节 hetACCase 分布来调节从头脂肪酸合成


在植物中，异聚乙酰辅酶 A 羧化酶 （hetACCase） 通过在该过程的第一个承诺步骤中生成丙二酰辅酶 A 来启动从头脂肪酸合成 （FAS）。hetACCase 活性受到精确调节，以满足植物生命周期中细胞对酰基链的需求。在本研究中，我们对拟南芥 （Arabidopsis thaliana） 中的 hetACCase 及其调节因子进行了系统的共表达分析，以更好地了解 hetACCase 的调控机制。我们的分析发现了脂肪酸合成调节因子 1 （RFS1），其表达与 hetACCase 的其他调节因子呈正相关。RFS 基因家族编码两种具有未被发现作用的质体内包膜蛋白。进一步分析显示，RFS1 与羧基转移酶相互作用者 1 （CTI1） 共定位并直接相互作用。CRISPR/Cas9 介导的 RFS 敲除表现出增强的 hetACCase 活性、更高的 FAS 速率和增加的脂肪酸含量，特别是叶片中绝对三酰基甘油水平的显着积累，类似于 cti 突变体。rfs 和 cti 的突变改变了 α-羧基转移酶的质体膜分布模式，导致膜上的 hetACCase 活性降低，这可能是 RFS 抑制 hetACCase 活性的原始机制。因此，我们揭示了一个调节从头 FAS 的独特调节模块和一个可能有助于培育改良油料作物的遗传位点。