State Key Laboratory of Cotton Biology, Institute of Cotton Research of CAAS, Anyang, 455000, China.
College of Agronomy, Northwest A&F University, Yangling, 712100, China.
BMC Genomics. 2020 Jun 29;21(1):445. doi: 10.1186/s12864-020-06842-1.
Multiple C2 domains and transmembrane region proteins (MCTPs) may act as transport mediators of other regulators. Although increased number of MCTPs in higher plants implies their diverse and specific functions in plant growth and development, only a few plant MCTPs have been studied and no study on the MCTPs in cotton has been reported.
In this study, we identified 31 MCTPs in G. hirsutum, which were classified into five subfamilies according to the phylogenetic analysis. GhMCTPs from subfamily V exhibited isoelectric points (pIs) less than 7, whereas GhMCTPs from subfamily I, II, III and IV exhibited pIs more than 7.5, implying their distinct biological functions. In addition, GhMCTPs within subfamily III, IV and V exhibited more diverse physicochemical properties, domain architectures and expression patterns than GhMCTPs within subfamily I and II, suggesting that GhMCTPs within subfamily III, IV and V diverged to perform more diverse and specific functions. Analyses of conserved motifs and pIs indicated that the N-terminus was more divergent than the C-terminus and GhMCTPs' functional divergence might be mainly contributed by the N-terminus. Furthermore, yeast two-hybrid assay indicated that the N-terminus was responsible to interact with target proteins. Phylogenetic analysis classified multiple N-terminal C2 domains into four subclades, suggesting that these C2 domains performed different molecular functions in mediating the transport of target proteins.
Our systematic characterization of MCTPs in G. hirsutum will provide helpful information to further research GhMCTPs' molecular roles in mediating other regulators' transport to coordinate growth and development of various cotton tissues.
多个 C2 结构域和跨膜区蛋白（MCTPs）可能作为其他调节剂的转运介质。虽然高等植物中 MCTPs 的数量增加表明它们在植物生长发育中具有多样化和特异性的功能，但仅有少数植物 MCTPs 得到了研究，而棉花中的 MCTPs 则尚未有报道。
本研究在棉属中鉴定到 31 个 MCTPs，根据系统发育分析将其分为五个亚家族。亚家族 V 的 GhMCTPs 等电点（pI）小于 7，而亚家族 I、II、III 和 IV 的 GhMCTPs pI 大于 7.5，暗示它们具有不同的生物学功能。此外，亚家族 III、IV 和 V 中的 GhMCTPs 表现出比亚家族 I 和 II 中 GhMCTPs 更多样的理化性质、结构域结构和表达模式，表明亚家族 III、IV 和 V 中的 GhMCTPs 发生了分化，以执行更多样化和特异性的功能。保守基序和 pI 的分析表明，N 端比 C 端更具多样性，GhMCTPs 的功能分化可能主要归因于 N 端。此外，酵母双杂交分析表明，N 端负责与靶蛋白相互作用。系统发育分析将多个 N 端 C2 结构域分为四个亚簇，表明这些 C2 结构域在介导靶蛋白的运输中发挥不同的分子功能。
我们对棉属 MCTPs 的系统表征将为进一步研究 GhMCTPs 在介导其他调节剂的运输以协调各种棉花组织的生长和发育中的分子作用提供有价值的信息。
