Biological Sciences, University of Southampton, Life Sciences Building 85, Highfield Campus, Southampton, SO17 1BJ, Hampshire, United Kingdom.
Departamento de Botânica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, 91501-970, Brazil.
Sci Rep. 2017 Nov 10;7(1):15258. doi: 10.1038/s41598-017-15324-6.
Membrane transporters play a key role in obtaining sufficient quantities of manganese (Mn) but also in protecting against Mn toxicity. We have characterized OsMTP11, a member of the Cation Diffusion Facilitator/Metal Tolerance Protein (CDF/MTP) family of metal cation transporters in Oryza sativa. We demonstrate that OsMTP11 functions in alleviating Mn toxicity as its expression can rescue the Mn-sensitive phenotype of the Arabidopsis mtp11-3 knockout mutant. When expressed stably in Arabidopsis and transiently in rice and tobacco, it localises to the Golgi. OsMTP11 partially rescues the Mn-hypersensitivity of the pmr1 yeast mutant but only slightly alleviates the Zn sensitivity of the zrc1 cot1 yeast mutant. Overall, these results suggest that OsMTP11 predominantly functions as a Mn-transporting CDF with lower affinity for Zn. Site-directed mutagenesis studies revealed four substitutions in OsMTP11 that appear to alter its transport activity. OsMTP11 harbouring a substitution of leucine 150 to a serine fully rescued pmr1 Mn-sensitivity at all concentrations tested. The other substitutions, including those at conserved DxxxD domains, reduced complementation of pmr1 to different levels. This indicates their importance for OsMTP11 function and is a starting point for refining transporter activity/specificity.
膜转运蛋白在获取足够数量的锰（Mn）方面起着关键作用，但也在保护免受 Mn 毒性方面起着关键作用。我们已经对水稻中的阳离子扩散促进剂/金属耐受蛋白（CDF/MTP）家族的金属阳离子转运蛋白 OsMTP11 进行了表征。我们证明 OsMTP11 在缓解 Mn 毒性方面起作用，因为其表达可以挽救拟南芥 mtp11-3 敲除突变体的 Mn 敏感表型。当在拟南芥中稳定表达并在水稻和烟草中瞬时表达时，它定位于高尔基体。OsMTP11 部分挽救了 pmr1 酵母突变体的 Mn 超敏性，但仅略微减轻了 zrc1 cot1 酵母突变体的 Zn 敏感性。总的来说，这些结果表明 OsMTP11 主要作为 Mn 转运 CDF 发挥作用，对 Zn 的亲和力较低。定点突变研究表明，OsMTP11 中有四个取代似乎改变了其转运活性。携带亮氨酸 150 取代为丝氨酸的 OsMTP11 完全挽救了所有测试浓度下 pmr1 的 Mn 敏感性。其他取代，包括保守的 DxxxD 结构域中的取代，将 pmr1 的互补作用降低到不同的水平。这表明它们对 OsMTP11 功能很重要，并且是细化转运蛋白活性/特异性的起点。
