Structure of the glucanase inhibitor protein (GIP) family from Phytophthora species suggests coevolution with plant endo-β-1,3-glucanases
Structure of the glucanase inhibitor protein (GIP) family from Phytophthora species suggests coevolution with plant endo-β-1,3-glucanases
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DOI：
10.1094/mpmi-21-6-0820
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发表时间：
2008-06-01
影响因子：
3.5
通讯作者：
Rose, Jocelyn K. C.
中科院分区：
文献类型：
--
作者：
Damasceno, Cynthia M. B.;Bishop, John G.;Rose, Jocelyn K. C.
卵菌属疫霉属的物种在入侵植物宿主的过程中分泌葡聚糖酶抑制蛋白（GIP）到植物质外体中，其结合并抑制植物胞外内切β-1，3-葡聚糖酶（EGases）的活性。GIP显示出与胰凝乳蛋白酶类丝氨酸蛋白酶（SP）的结构同源性，但由于缺乏完整的催化三联体而缺乏蛋白水解活性，因此属于称为丝氨酸蛋白酶同系物（SPH）的更广泛的蛋白质类。为了研究GIP和功能性SP之间的进化关系，使用数据库搜索来鉴定大豆疫霉、分枝疫霉和致病疫霉基因组中的48个GIP同源物，其组成GIP、SPH和潜在功能性SP。致病疫霉接种的番茄叶片的分析表明，致病疫霉GIP和番茄EGases存在于质外体中，并在植物中形成稳定的复合物。对来自致病疫霉的四元GIP家族（PiGIP 1至PiGIP 4）的时间表达的研究进一步揭示，这些基因在感染时程期间显示出明显不同的模式。GIP同源物的密码子进化分析确定了几个积极选择的肽位点和结构建模揭示了它们是在快速发展的EGase残基的附近，这表明GIP和EGases之间的相互作用具有共同进化的分子军备竞赛的标志。
During invasion of their plant hosts, species of the oomycete genus Phytophthora secrete glucanase inhibitor proteins (GIPs) into the plant apoplast, which bind and inhibit the activity of plant extracellular endo-beta-1,3-glucanases (EGases). GIPs show structural homology to the chymotrypsin class of serine proteases (SP) but lack proteolytic activity due to the absence of an intact catalytic triad and, thus, belong to a broader class of proteins called serine protease homologs (SPH). To study the evolutionary relationship between GIPs and functional SP, database searches were used to identify 48 GIP homologs in the P sojae, P. ramorum, and P. infestans genomes, composing GIPs, SPH, and potentially functional SP. Analyses of P. infestans-inoculated tomato leaves showed that P. infestans GIPs and tomato EGases are present in the apoplast and form stable complexes in planta. Studies of the temporal expression of a four-membered GIP family from P. infestans (PiGIP1 to PiGIP4) further revealed that the genes show distinctly different patterns during an infection timecourse. Codon evolution analyses of GIP homologs identified several positively selected peptide sites and structural modeling revealed them to be in close proximity to rapidly evolving EGase residues, suggesting that the interaction between GIPs and EGases has the hallmarks of a coevolving molecular arms race.