水稻S5-ORF3蛋白质的进化分析

生殖隔离在形成新物种和物种同一性的保持中有重要作用,因而在水稻优化育种中有重要的意义。S5位点是一个已克隆的控制水稻生殖隔离的基因,它产生的S5-ORF3,ORF4和ORF5蛋白质共同调控着indica-japonica杂交后代的育性,特别是S5-ORF3蛋白质在打破水稻亚种indica-japonica之间的生殖隔离与促进物种间的基因交流中发挥重要作用。针对S5-ORF3的进化分析对于研究它的功能和起源很重要,但目前尚无报道。本文基于序列和进化分析,提出S5-ORF3为一种定位在内质网中的新的HSP70家族蛋白,但缺乏HSP70的C端的多肽结合结构域,推测S5-ORF3可能通过影响alpha-淀粉酶的合成来作用于内质网压力;找到了ORF3的19条同源蛋白,并用极大似然算法构建了可靠的进化树,发现水稻的S5-ORF3与节节麦的luminal-binding蛋白进化关系最为密切;作了置信度100%的S5-ORF3蛋白质的三维结构预测,预测了居中的配体绑定位点;发现了水稻的S5-ORF3与其他HSP70蛋白相比独特的基序,为进一步研究S5-ORF3的作用机理和演化历史提供了线索和数据支持。

Evolution analysis of rice protein S5-ORF3

Reproductive isolation is important in speciation and maintaining species identity, so it is very significant in optimization of breeding rice. S5 locus is a cloned gene controlling the reproductive isolation, which produces proteins S5-ORF3, ORF4 and ORF5 that work together to regulate fertility in indica-japonica hybrids, and especially the S5-ORF3 protein plays a very important role in distorting reproductive isolation among indica-japonica and enhancing gene flow among populations. The evolutionary analysis of S5-ORF3 is significant for studying its function and origin, which is still no reported. In this paper, based on sequence and evolution analysis, it is proposed that the S5-ORF3 is a new HSP70 family protein which is located in endoplasmic reticulum (ER) and lacks of multi-peptide binding domain. Evolution analysis suggests that S5-ORF3 might act on ER stress via affecting alpha-amylase synthesis; moreover, 19 homologous proteins of S5-ORF3 are found, ML phylogenetic tree is constructed, and it is found that there is close evolution relationship between rice S5-ORF3 and a luminal-binding protein of Aegilops tauschii; the 3D structure of S5-ORF3 with confidence of 100% is predicted, as well as a ligand-binding site located in the middle of S5-ORF3. The specific motif of rice S5-ORF3 among HSP70 family is also found. This work may provide some clues and data for studying function and evolution history of rice S5-ORF3.