MLKs kinases phosphorylate the ESCRT component FREE1 to suppress abscisic acid sensitivity of seedling establishment
MLKs kinases phosphorylate the ESCRT component FREE1 to suppress abscisic acid sensitivity of seedling establishment
复制标题
MLK 激酶磷酸化 ESCRT 成分 FREE1 以抑制幼苗形成的脱落酸敏感性
DOI：
10.1111/pce.14336
复制
发表时间：
2022-04-27
影响因子：
7.3
通讯作者：
Gao, Caiji
中科院分区：
文献类型：
--
作者：
Li, Hongbo;Wei, Juan;Gao, Caiji
内体分选所需的FYVE结构域蛋白1（FREE 1），其先前被鉴定为转运机制所需的内体分选复合物的植物特异性组分，在内体转运中起重要作用。此外，FREE 1还在脱落酸（阿坝）信号转导中起重要的负调节作用。FREE 1中存在多个磷酸化位点和泛素化位点，揭示FREE 1的翻译后调控因子对于全面了解FREE 1在植物生长过程中的调控网络具有重要意义。在这里，我们证明了植物特异性酪蛋白激酶I成员MUT 9样激酶1-4（MLKs 1-4）/拟南芥EL 1样1-4与丝氨酸残基S582处的FREE 1相互作用并使其磷酸化，从而调节FREE 1的核积累。因此，S582突变为非磷酸化残基导致FREE 1的核定位减少和阿坝反应增强。此外，mlk 123和mlk 134三重突变体在细胞核中积累较少的FREE 1，并显示对阿坝处理的过敏反应，而核定位的FREE 1的过表达可以恢复mlks三重突变体中幼苗建立的阿坝敏感性。总的来说，我们的研究表明了MLKs通过调节FREE 1的磷酸化和核积累来减弱细胞核中阿坝信号传导的先前未识别的功能。
The FYVE domain protein required for endosomal sorting 1 (FREE1), which was previously identified as a plant-specific component of the endosomal sorting complex required for transport machinery, plays an essential role in endosomal trafficking. Moreover, FREE1 also functions as an important negative regulator in abscisic acid (ABA) signalling. Multiple phosphorylations and ubiquitination sites have been identified in FREE1, hence unveiling the factors involved in posttranslational regulation of FREE1 is critical for comprehensively understanding FREE1-related regulatory networks during plant growth. Here, we demonstrate that plant-specific casein kinase I members MUT9-like kinases 1-4 (MLKs 1-4)/Arabidopsis EL1-like 1-4 interact with and phosphorylate FREE1 at serine residue S582, thereby modulating the nuclear accumulation of FREE1. Consequently, mutation of S582 to non-phosphorylable residue results in reduced nuclear localization of FREE1 and enhanced ABA response. In addition, mlk123 and mlk134 triple mutants accumulate less FREE1 in the nucleus and display hypersensitive responses to ABA treatment, whereas overexpression of the nuclear-localized FREE1 can restore the ABA sensitivity of seedling establishment in mlks triple mutants. Collectively, our study demonstrates a previously unidentified function of MLKs in attenuating ABA signalling in the nucleus by regulating the phosphorylation and nuclear accumulation of FREE1.