上海大学在Plant Cell报道玉米籽粒突变基因研究进展

上海大学生命科学学院科研人员对玉米经典突变proline responding1(pro1)基因进行了克隆和功能解析，揭示了pro1基因在调控玉米普通蛋白合成和细胞周期中所起的关键作用。相关研究成果日前在线发表于《植物细胞》。

据了解，pro1作为玉米中第一个被发现的营养缺陷型突变而被广泛研究。pro1基因作为玉米中合成脯氨酸过程的关键酶，对玉米生理生化的影响是多方面且重要的。脯氨酸的信号分子作用会涉及细胞内部多种多样的生理平衡和生化过程。

上海大学生科院、上海市能源作物育种及应用重点实验室副教授王刚、教授宋任涛分别是本文的第一作者和通讯作者。科研人员证实，玉米pro1基因的突变造成了突变体细胞中脯氨酸合成受阻，从而导致脯氨酸积累的减少。突变体中脯氨酸的缺乏引起了相应的转运RNA空载形式的增多，从而激活了细胞中的GCN2激酶，该激酶通过磷酸化真核生物翻译起始因子eIF2α从而抑制了细胞中蛋白合成的普遍抑制。同时，突变体中脯氨酸的缺乏也引起了细胞周期相关基因、DNA复制相关基因以及细胞增殖相关基因表达的下调，从而抑制了细胞周期从G1到S期的转换。

专家认为，pro1基因功能的解析，有助于了解脯氨酸在植物生长与发育中的调控作用机理，进而更全面地理解它在细胞生命活动过程中的重要作用，使人们对脯氨酸的功能有了新的认识。

原文摘要：

Proline responding1 Plays a Critical Role in Regulating General Protein Synthesis and the Cell Cycle in Maize

Gang Wang, Jushan Zhang, Guifeng Wang, Xiangyu Fan, Xin Sun, Hongli Qin, Nan Xu, Mingyu Zhong, Zhenyi Qiao, Yuanping Tang and Rentao Song

Proline, an important amino acid, accumulates in many plant species. Besides its role in Plant Cell responses to environmental stresses, the potential biological functions of proline in growth and development are unclear. Here, we report cloning and functional characterization of the maize (Zea mays) classic mutantproline responding1 (pro1) gene. This gene encodes a Δ1-pyrroline-5- carboxylate synthetase that catalyzes the biosynthesis of proline from glutamic acid. Loss of function of Pro1 significantly inhibits proline biosynthesis and decreases its accumulation in the pro1 mutant. Proline deficiency results in an increased level of uncharged tRNApro AGG accumulation and triggers the phosphorylation of eukaryotic initiation factor 2α (eIF2α) in the pro1 mutant, leading to a general reduction in protein synthesis in this mutant. Proline deficiency also downregulates major cyclin genes at the transcriptional level, causing cell cycle arrest and suppression of cell proliferation. These processes are reversible when external proline is supplied to the mutant, suggesting that proline plays a regulatory role in the cell cycle transition. Together, the results demonstrate that proline plays an important role in the regulation of general protein synthesis and the cell cycle transition in plants.

作者：黄辛