Royal Botanic Garden Edinburgh, Edinburgh, Scotland, United Kingdom.
Kanagawa University, Yokohama-shi, Kanagawa, Japan.
PLoS One. 2021 Apr 15;16(4):e0249735. doi: 10.1371/journal.pone.0249735. eCollection 2021.
Multidomain proteins can have a complex evolutionary history that may involve de novo domain evolution, recruitment and / or recombination of existing domains and domain losses. Here, the domain evolution of the plant-specific Ca2+-permeable mechanosensitive channel protein, MID1-COMPLEMENTING ACTIVITY (MCA), was investigated. MCA, a multidomain protein, possesses a Ca2+-influx-MCAfunc domain and a PLAC8 domain. Profile Hidden Markov Models (HMMs) of domains were assessed in 25 viridiplantae proteomes. While PLAC8 was detected in plants, animals, and fungi, MCAfunc was found in streptophytes but not in chlorophytes. Full MCA proteins were only found in embryophytes. We identified the MCAfunc domain in all streptophytes including charophytes where it appeared in E3 ubiquitin ligase-like proteins. Our Maximum Likelihood (ML) analyses suggested that the MCAfunc domain evolved early in the history of streptophytes. The PLAC8 domain showed similarity to Plant Cadmium Resistance (PCR) genes, and the coupling of MCAfunc and PLAC8 seemed to represent a single evolutionary event. This combination is unique in MCA, and does not exist in other plant mechanosensitive channels. Within angiosperms, gene duplications increased the number of MCAs. Considering their role in mechanosensing in roots, MCA might be instrumental for the rise of land plants. This study provides a textbook example of de novo domain emergence, recombination, duplication, and losses, leading to the convergence of function of proteins in plants.
多结构域蛋白可能具有复杂的进化历史，其中可能涉及新结构域的进化、现有结构域的招募和/或重组以及结构域的丢失。在这里，我们研究了植物特异性 Ca2+渗透性机械敏感通道蛋白 MID1-互补活性（MCA）的结构域进化。MCA 是一种多结构域蛋白，具有 Ca2+内流-MCAfunc 结构域和 PLAC8 结构域。在 25 个绿藻蛋白质组中评估了结构域的 Profile Hidden Markov Models（HMMs）。虽然在植物、动物和真菌中检测到了 PLAC8，但在绿藻中没有检测到 MCAfunc。只有在胚胎植物中才发现完整的 MCA 蛋白。我们在所有的石松植物中都鉴定出了 MCAfunc 结构域，包括在 E3 泛素连接酶样蛋白中发现的轮藻中。我们的最大似然（ML）分析表明，MCAfunc 结构域在石松植物的早期历史中进化而来。PLAC8 结构域与植物镉抗性（PCR）基因具有相似性，MCAfunc 和 PLAC8 的结合似乎代表了一个单一的进化事件。这种组合在 MCA 中是独特的，在其他植物机械敏感通道中不存在。在被子植物中，基因重复增加了 MCAs 的数量。考虑到它们在根部机械感觉中的作用，MCA 可能对陆地植物的兴起至关重要。本研究提供了一个新结构域出现、重组、重复和丢失的典型例子，导致了植物中蛋白质功能的趋同。
