Genome-wide analysis identifies gain and loss/change of function within the small multigenic insecticidal Albumin 1 family of Medicago truncatula.
Genome-wide analysis identifies gain and loss/change of function within the small multigenic insecticidal Albumin 1 family of Medicago truncatula.
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DOI：
10.1186/s12870-016-0745-0
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发表时间：
2016-03-10
影响因子：
5.3
通讯作者：
Royer C
中科院分区：
文献类型：
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作者：
Karaki L;Da Silva P;Rizk F;Chouabe C;Chantret N;Eyraud V;Gressent F;Sivignon C;Rahioui I;Kahn D;Brochier-Armanet C;Rahbé Y;Royer C
白蛋白 1b 肽 (A1b) 是豆科（也称为豆科）产生的小二硫键杀虫肽。迄今为止，该植物家族的多样性基本上已通过生化和基于 PCR 的方法进行了研究。几种豆科物种（其中模式物种蒺藜苜蓿（Mtr））的高质量基因组资源的可用性，允许对该蛋白质家族进行基因组分析，目的是i）破译A1b蛋白质的进化历史及其与A1b结节蛋白的联系，A1b结节蛋白是参与根瘤信号传导的短非杀虫二硫键肽，ii）探索A1b作为新型生物活性分子的功能多样性。对 Mtr 基因组的研究揭示了白蛋白 1 (A1) 基因的显着扩展，主要是通过串联复制，在基因和蛋白质水平上保留了几乎所有相同的规范结构。系统发育分析表明，祖先分子很可能具有杀虫作用，并产生了 A1b 结节蛋白等。表达荟萃分析表明，许多 A1b 编码基因是沉默的，并且 A1 转录物/肽在植物器官内广泛分布。进化速率分析强调了具有正选择特征的分支和位点，其中包括两个对杀虫活性至关重要的位点。七种肽在体外化学合成和折叠，然后测定其生物活性。其中，AG41（又名 MtrA1013 同工型，由孤儿 TA24778 重叠群编码）显示出出乎意料的高杀虫活性。该研究强调了与其他可获得全基因组的分类单元相比，紫花苜蓿属内 A1 肽多样性的独特爆发：迄今为止，莲花或红三叶草中还没有 A1 成员，而鹰嘴豆、大豆或木豆基因组中只有少数存在。 A1 家族在苜蓿属中的扩展让人想起在同一物种中发现的另一个富含二硫键的肽家族，即“富含根瘤特异性半胱氨酸”(NCR) 的情况。最古老的杀虫 A1b 毒素是从槐树中发现的，这种种子防御功能的诞生可以追溯到 5800 万年前，并使这种植物/昆虫毒素/受体（A1b/昆虫 v-ATP 酶）模型成为已知最古老的模型之一。本文的在线版本 (doi:10.1186/s12870-016-0745-0) 包含补充材料，可供授权用户使用。
Albumin 1b peptides (A1b) are small disulfide-knotted insecticidal peptides produced by Fabaceae (also called Leguminosae). To date, their diversity among this plant family has been essentially investigated through biochemical and PCR-based approaches. The availability of high-quality genomic resources for several fabaceae species, among which the model species Medicago truncatula (Mtr), allowed for a genomic analysis of this protein family aimed at i) deciphering the evolutionary history of A1b proteins and their links with A1b-nodulins that are short non-insecticidal disulfide-bonded peptides involved in root nodule signaling and ii) exploring the functional diversity of A1b for novel bioactive molecules. Investigating the Mtr genome revealed a remarkable expansion, mainly through tandem duplications, of albumin1 (A1) genes, retaining nearly all of the same canonical structure at both gene and protein levels. Phylogenetic analysis revealed that the ancestral molecule was most probably insecticidal giving rise to, among others, A1b-nodulins. Expression meta-analysis revealed that many A1b coding genes are silent and a wide tissue distribution of the A1 transcripts/peptides within plant organs. Evolutionary rate analyses highlighted branches and sites with positive selection signatures, including two sites shown to be critical for insecticidal activity. Seven peptides were chemically synthesized and folded in vitro, then assayed for their biological activity. Among these, AG41 (aka MtrA1013 isoform, encoded by the orphan TA24778 contig.), showed an unexpectedly high insecticidal activity. The study highlights the unique burst of diversity of A1 peptides within the Medicago genus compared to the other taxa for which full-genomes are available: no A1 member in Lotus, or in red clover to date, while only a few are present in chick pea, soybean or pigeon pea genomes. The expansion of the A1 family in the Medicago genus is reminiscent of the situation described for another disulfide-rich peptide family, the “Nodule-specific Cysteine-Rich” (NCR), discovered within the same species. The oldest insecticidal A1b toxin was described from the Sophorae, dating the birth of this seed-defense function to more than 58 million years, and making this model of plant/insect toxin/receptor (A1b/insect v-ATPase) one of the oldest known. The online version of this article (doi:10.1186/s12870-016-0745-0) contains supplementary material, which is available to authorized users.