Dabravolski Siarhei A, Isayenkov Stanislav V
Department of Clinical Diagnostics, Vitebsk State Academy of Veterinary Medicine [UO VGAVM], 21002 Vitebsk, Belarus.
International Research Center for Environmental Membrane Biology, Foshan University, Foshan 528000, China.
Plants (Basel). 2021 Oct 28;10(11):2328. doi: 10.3390/plants10112328.
Potassium (K) is a crucial element of plant nutrition, involved in many physiological and molecular processes. K membrane transporters are playing a pivotal role in K transport and tissue distribution as well as in various plant stress responses and developmental processes. Two-pore K-channels (TPKs) are essential to maintain plant K homeostasis and are mainly involved in potassium transport from the vacuoles to the cytosol. Besides vacuolar specialization, some TPK members display different membrane localization including plasma membrane, protein storage vacuole membrane, and probably the organelles. In this manuscript, we elucidate the evolution of the voltage-independent TPK (two-pore K-channels) family, which could be represented in some species by one pore, K-inward rectifier (Kir)-like channels. A comprehensive investigation of existing databases and application of modern bioinformatic tools allowed us to make a detailed phylogenetic inventory of TPK/KCO3 (KCO: potassium channel, outward rectifying) channels through many taxa and gain insight into the evolutionary origin of TPK family proteins. Our results reveal the fundamental evolutional difference between the first and second pores, traced throughout multiple taxa variations in the ion selection filter motif, presence of thansposon, and methylation site in the proximity of some KCO members and suggest virus-mediated horizontal transfer of a KCO3-like ancestor by viruses. Additionally, we suggest several interconnected hypotheses to explain the obtained results and provide a theoretical background for future experimental validation.
钾（K）是植物营养的关键元素，参与许多生理和分子过程。钾膜转运蛋白在钾的运输和组织分布以及各种植物应激反应和发育过程中起着关键作用。双孔钾通道（TPK）对于维持植物钾稳态至关重要，主要参与钾从液泡到细胞质的运输。除了液泡特化外，一些TPK成员还表现出不同的膜定位，包括质膜、蛋白质储存液泡膜，可能还有细胞器膜。在本论文中，我们阐明了电压非依赖性TPK（双孔钾通道）家族的进化，在某些物种中，该家族可能由单孔内向整流钾通道（Kir）样通道代表。通过对现有数据库的全面调查和现代生物信息学工具的应用，我们得以详细梳理TPK/KCO3（KCO：钾通道，外向整流）通道在多个分类群中的系统发育情况，并深入了解TPK家族蛋白的进化起源。我们的结果揭示了第一孔和第二孔之间的根本进化差异，这种差异在多个分类群中表现为离子选择过滤器基序的变化、转座子的存在以及一些KCO成员附近的甲基化位点，并表明病毒介导了类似KCO3祖先的水平转移。此外，我们提出了几个相互关联的假设来解释所得结果，并为未来的实验验证提供理论背景。
