核心调控因子NODULE INCEPTION（NIN）控制着根瘤启动的许多方面，研究人员证明它也通过信号肽酶复合物的蛋白水解处理来调节向固氮的过渡。NIN的加工结果是一个羧基末端的NIN片段，含有DNA结合基团，它激活了一系列与共生体发育和固氮有关的基因。在蒺藜苜蓿（Medicago truncatula）和百脉根（Lotus japonicus）中也观察到类似的NIN加工，这意味着一个保守的细胞状态转换机制。
这些发现解释了豆科植物的根瘤是如何过渡到固氮状态的，以及一个单一的转录因子可以调节在激活和调节固氮过程中许多不同的发育过程。
据悉，豆科植物的根瘤为细胞内细菌共生体固定大气中的氮创造了一个环境。
附：英文原文
Title: Processing of NODULE INCEPTION controls the transition to nitrogen fixation in root nodules
Author: Jian Feng, Tak Lee, Katharina Schiessl, Giles E. D. Oldroyd
Issue&Volume: 2021-10-29
Abstract: Legume nodules create an environment for intracellular bacterial symbionts to fix atmospheric nitrogen. The master regulator NODULE INCEPTION (NIN) controls many aspects of nodule initiation, and we demonstrate that it also regulates the transition to nitrogen fixation via proteolytic processing by a signal peptidase complex. Processing of NIN results in a carboxyl-terminal NIN fragment containing the DNA binding motifs, which activates a suite of genes associated with symbiosome development and nitrogen fixation. Similar NIN processing is observed in Medicago truncatula and Lotus japonicus, implying a conserved mechanism of cell state transition. These findings explain how legume nodules transition to a nitrogen-fixing state and a mechanism by which a single transcription factor can regulate many different developmental processes necessary in the activation and regulation of nitrogen fixation.
DOI: abg2804
Source: https://www.science.org/doi/10.1126/science.abg2804