An Chuanjing, Gao Yuefang
State Key Laboratory of Natural and Biomimetic Drugs, Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University, Beijing, China.
College of Horticulture, Northwest A&F University, Yangling, China.
Front Plant Sci. 2021 Apr 15;12:657300. doi: 10.3389/fpls.2021.657300. eCollection 2021.
Ethylene Overproduction 1 (ETO1) is a negative regulator of ethylene biosynthesis. However, the regulation mechanism of ETO1 remains largely unclear. Here, a novel allele () was isolated with typical triple phenotypes due to an amino acid substitution of G480C in the uncharacterized linker sequence between the TPR1 and TPR2 motifs. Further genetic and biochemical experiments confirmed the mutation site. Sequence analysis revealed that G480 is conserved not only in two paralogs, EOL1 and EOL2, in , but also in the homologous protein in other species. The glycine mutations (, , and ) do not influence the mRNA abundance of , which is reflected by the mRNA secondary structure similar to that of WT. According to the protein-protein interaction analysis, the abnormal root phenotype of might be caused by the disruption of the interaction with type 2 1-aminocyclopropane-1-carboxylic acid (ACC) synthases (ACSs) proteins. Overall, these data suggest that the linker sequence between tetratricopeptide repeat (TPR) motifs and the glycine in TPR motifs or the linker region are essential for ETO1 to bind with downstream mediators, which strengthens our knowledge of ETO1 regulation in balancing ACSs.
乙烯过量产生1（ETO1）是乙烯生物合成的负调控因子。然而，ETO1的调控机制在很大程度上仍不清楚。在此，通过在TPR1和TPR2基序之间未表征的连接序列中G480C的氨基酸取代，分离出一种具有典型三重表型的新等位基因（）。进一步的遗传和生化实验证实了该突变位点。序列分析表明，G480不仅在拟南芥中的两个旁系同源物EOL1和EOL2中保守，而且在其他物种的同源蛋白中也保守。甘氨酸突变（、和）不影响ETO1的mRNA丰度，这由与野生型相似的mRNA二级结构反映出来。根据蛋白质-蛋白质相互作用分析，ETO1异常的根表型可能是由于与2型1-氨基环丙烷-1-羧酸（ACC）合成酶（ACSs）蛋白相互作用的破坏所致。总体而言，这些数据表明，四肽重复（TPR）基序之间的连接序列以及TPR基序中的甘氨酸或连接区域对于ETO1与下游介质结合至关重要，这增强了我们对ETO1在平衡ACSs中的调控的认识。
