Data from: The NBS-LRR architectures of plant R-proteins and metazoan NLRs evolved in independent events

There are intriguing parallels between plants and animals, with respect to the structures of their innate immune receptors, that suggest universal principles of innate immunity. The cytosolic nucleotide binding site–leucine rich repeat (NBS-LRR) resistance proteins of plants (R-proteins) and the so-called NOD-like receptors of animals (NLRs) share a domain architecture that includes a STAND (signal transduction ATPases with numerous domains) family NTPase followed by a series of LRRs, suggesting inheritance from a common ancestor with that architecture. Focusing on the STAND NTPases of plant R-proteins, animal NLRs, and their homologs that represent the NB-ARC (nucleotide-binding adaptor shared by APAF-1, certain R gene products and CED-4) and NACHT (named for NAIP, CIIA, HET-E, and TEP1) subfamilies of the STAND NTPases, we analyzed the phylogenetic distribution of the NBS-LRR domain architecture, used maximum-likelihood methods to infer a phylogeny of the NTPase domains of R-proteins, and reconstructed the domain structure of the protein containing the common ancestor of the STAND NTPase domain of R-proteins and NLRs. Our analyses reject monophyly of plant R-proteins and NLRs and suggest that the protein containing the last common ancestor of the STAND NTPases of plant R-proteins and animal NLRs (and, by extension, all NB-ARC and NACHT domains) possessed a domain structure that included a STAND NTPase paired with a series of tetratricopeptide repeats. These analyses reject the hypothesis that the domain architecture of R-proteins and NLRs was inherited from a common ancestor and instead suggest the domain architecture evolved at least twice. It remains unclear whether the NBS-LRR architectures were innovations of plants and animals themselves or were acquired by one or both lineages through horizontal gene transfer.植物与动物在先天免疫受体的结构层面存在引人入胜的平行特征，这暗示了先天免疫的通用运作原则。植物胞质中的核苷酸结合位点-亮氨酸富集重复（nucleotide binding site–leucine rich repeat, NBS-LRR）抗病蛋白（下称R蛋白），与动物的NOD样受体（NOD-like receptors, NLRs）共享一套结构域排布：包含一个STAND（多结构域信号转导ATP酶，signal transduction ATPases with numerous domains, STAND）家族的NTP酶，随后连接一系列LRR结构域，这提示二者起源于具有该结构的共同祖先。本研究聚焦于植物R蛋白、动物NLRs及其同源物所对应的STAND NTP酶，这类酶属于STAND NTP酶的NB-ARC（APAF-1、部分R基因产物与CED-4共享的核苷酸结合适配结构域，nucleotide-binding adaptor shared by APAF-1, certain R gene products and CED-4, NB-ARC）与NACHT（由NAIP、CIIA、HET-E及TEP1命名，NAIP, CIIA, HET-E, and TEP1, NACHT）亚家族。我们分析了NBS-LRR结构域排布的系统发育分布特征，采用最大似然法推断了R蛋白NTP酶结构域的系统发育树，并重构了携带植物R蛋白与NLRs的STAND NTP酶结构域共同祖先的蛋白质的结构域组成。我们的分析结果否定了植物R蛋白与NLRs单系起源的假说，并提出：植物R蛋白与动物NLRs（进而涵盖所有NB-ARC与NACHT结构域）的STAND NTP酶的最后共同祖先所对应的蛋白质，其结构域排布包含一个STAND NTP酶与一系列四肽重复结构域（tetratricopeptide repeats, TPRs）配对的形式。这些分析推翻了"R蛋白与NLRs的结构域排布源自共同祖先"的原有假说，反而提示该结构域排布至少独立演化了两次。目前仍无法明确NBS-LRR结构究竟是动植物自身演化出的创新特征，还是二者之一或二者通过水平基因转移获得的外来结构。