Data from: The divergence and positive selection of the plant-specific BURP-containing protein family

BURP domain-containing proteins belong to a plant-specific protein family and have diverse roles in plant development and stress responses. However, our understanding about the genetic divergence patterns and evolutionary rates of these proteins remain inadequate. In this study, 15 plant genomes were explored to elucidate the genetic origins, divergence, and functions of these proteins. One hundred and twenty-five BURP protein-encoding genes were identified from four main plant lineages, including 13 higher plant species. The absence of BURP family genes in unicellular and multicellular algae suggests that this family (1) appeared when plants shifted from relatively stable aquatic environments to land, where conditions are more variable and stressful, and (2) is critical in the adaptation of plants to adverse environments. Promoter analysis revealed that several responsive elements to plant hormones and external environment stresses are concentrated in the promoter region of BURP protein-encoding genes. This finding confirms that these genes influence plant stress responses. Several segmentally and tandem-duplicated gene pairs were identified from eight plant species. Thus, in general, BURP domain-containing genes have been subject to strong positive selection, even though these genes have conformed to different expansion models in different species. Our study also detected certain critical amino acid sites that may have contributed to functional divergence among groups or subgroups. Unexpectedly, all of the critical amino acid residues of functional divergence and positive selection were exclusively located in the C-terminal region of the BURP domain. In conclusion, our results contribute novel insights into the genetic divergence patterns and evolutionary rates of BURP proteins.

含BURP结构域（BURP domain）的蛋白质属于植物特异性蛋白家族，在植物生长发育与胁迫应答中发挥多种功能。然而，目前学界对这类蛋白质的遗传分化模式与进化速率的认知仍存在不足。本研究选取15个植物基因组开展分析，以阐明这类蛋白质的遗传起源、分化模式及其功能。研究从四大主要植物谱系（涵盖13个高等植物物种）中鉴定得到125个BURP结构域蛋白编码基因。单细胞与多细胞藻类中均未发现BURP家族基因，这表明该家族（1）起源于植物从相对稳定的水生环境向条件更为多变且胁迫更强的陆地环境转型的时期，（2）在植物适应不良环境的过程中发挥关键作用。启动子分析结果显示，BURP结构域蛋白编码基因的启动子区域富集了多种植物激素响应元件与外界环境胁迫响应元件，该结果证实这类基因参与调控植物的胁迫应答过程。研究人员在8个植物物种中鉴定出多对片段复制与串联复制的基因对。综上，含BURP结构域的基因总体上受到了强烈的正选择作用，尽管不同物种中的该类基因遵循了不同的扩张模式。本研究还检测到若干关键氨基酸位点，这些位点可能是各分组及亚分组间产生功能分化的重要基础。令人意外的是，所有与功能分化及正选择相关的关键氨基酸残基均仅分布于BURP结构域的C端区域。综上，本研究结果为BURP结构域蛋白质的遗传分化模式与进化速率研究提供了全新的视角。