赵天永等《The Plant Journal》2023年

论文题目：Maize PIMT2 repairs the damaged 3-METHYLCROTONYL COA CARBOXYLASE in mitochondria controlling seed vigor

论文作者：Yumin Zhang，Xianbo Song，Wenli Zhang，Feijun Liu，Chunmei Wang，Ying Liu，Lynnette M.A. Dirk，A. Bruce Downie，Tianyong Zhao

论文摘要：

PROTEIN L-ISOASPARTYL O-METHYLTRANSFERASE (PIMT) regulates seed vigor by repairing damaged proteins. While capable of isoaspartyl repair in all proteins, those proteins most susceptible to isoAsp formation have not been well characterized and the mechanisms of PIMT regulation of seed vigor remains largely unknown. Using Co-IP and LC-MS/MS, maize (Zea mays) PIMT2 (ZmPIMT2) interacted predominantly with both subunits of maize 3-METHYLCROTONYL COA CARBOXYLASE (ZmMCC).ZmPIMT2is specifically expressed in maize embryo. Both mRNA and protein accumulation of ZmPIMT2 increased during seed maturation and declined during imbibition. Maize seed vigor was decreased in thezmpimt2mutant line while overexpression ofZmPIMT2in maize andArabidopsis thalianaincreased seed vigor upon artificial aging. ZmPIMT2 was localized in the mitochondria, as determined by subcellular localization assays in maize protoplast. ZmPIMT2 binding to ZmMCCα was confirmed by luciferase complementation tests in both tobacco (Nicotiana benthamiana) leaves and maize protoplasts. Knock down ofZmMCCα decreased maize seed aging tolerance. Furthermore, overexpression ofZmPIMT2decreased the accumulation of isoAsp of ZmMCCα protein in seed embryos that were treated with accelerated aging. Taken together, our results demonstrated that ZmPIMT2 binds ZmMCCα in mitochondria, repairing isoAsp damage, and positively regulates maize seed vigor.

异天冬氨酸甲基转移酶(PIMT)通过修复受损蛋白来调控种子活力。目前对PIMT修复的互作靶标蛋白及作用机制仍知之甚少。利用Co-IP和LC-MS/MS分析，鉴定到了玉米PIMT2 (ZmPIMT2)能够在线粒体中与3-甲基crotonyl COA羧化酶(ZmMCC)的两个亚基相互作用并对其受损蛋白进行修复。ZmPIMT2在玉米胚中特异性表达，在种子成熟过程中逐渐积累，在种子吸胀过程中减少。玉米zmpimt2突变体种子活力下降，而在玉米和拟南芥中过表达ZmPIMT2则提高了种子活力。通过玉米原生质体亚细胞定位鉴定到ZmPIMT2定位在线粒体中，在烟草叶片和玉米原生质体中通过荧光素酶互补试验证实了ZmPIMT2与ZmMCCα能够互作。玉米zmmccα突变体种子耐老化能力降低。此外，过表达ZmPIMT2降低了老化玉米种胚中ZmMCCα蛋白isoAsp的积累。综上所述，我们的研究结果表明ZmPIMT2与ZmMCCα蛋白在线粒体中互作并修复损伤的ZmMCCα蛋白正调控玉米种子活力。

论文链接：https://onlinelibrary.wiley.com/doi/10.1111/tpj.16225