IPSiM, Univ Montpellier, CNRS, INRAE, Institut Agro, Montpellier, 34060, France.
Plant Science Research Laboratory (LRSV), UMR5546 CNRS/University of Toulouse 3, Auzeville Tolosane, France.
FEBS Lett. 2023 Aug;597(16):2048-2058. doi: 10.1002/1873-3468.14706. Epub 2023 Aug 2.
Manganese (Mn) is essential for plants but is toxic when taken up in excess. To maintain Mn homeostasis, the root Mn transporter natural resistance associated macrophage protein 1 (NRAMP1) cycles from the plasma membrane to endosomes upon phosphorylation. To identify the kinase involved, a split-luciferase screening was carried out between NRAMP1 and kinases of the CIPK family and identified CIPK23 as a partner of NRAMP1. The interaction was confirmed by split-mCitrine bimolecular fluorescence complementation and co-immunoprecipitation assays. In vitro phosphorylation assays pinpointed two CIPK23 target residues in NRAMP1, among which serine 20, important for endocytosis. Interestingly, Mn-induced internalization of NRAMP1 was unaffected by cipk23 mutation suggesting a potential redundancy between CIPK23 and other kinase(s). How CIPK23 could regulate NRAMP1 in response to Mn availability is discussed.
锰（Mn）是植物必需的微量元素，但过量摄入会产生毒性。为了维持锰的体内平衡，根锰转运蛋白天然抗性相关巨噬细胞蛋白 1（NRAMP1）在磷酸化后从质膜循环到内体。为了鉴定涉及的激酶，在 NRAMP1 和 CIPK 家族的激酶之间进行了分裂萤光素酶筛选，并鉴定出 CIPK23 是 NRAMP1 的伴侣。通过分裂-mCitrine 双分子荧光互补和共免疫沉淀实验证实了相互作用。体外磷酸化实验确定了 NRAMP1 中两个 CIPK23 的靶位残基，其中丝氨酸 20 对内吞作用很重要。有趣的是，cipk23 突变对 Mn 诱导的 NRAMP1 内化没有影响，这表明 CIPK23 和其他激酶之间可能存在冗余。CIPK23 如何根据 Mn 的可用性来调节 NRAMP1 将在讨论中进行探讨。
