Lin Guangzhong, Zhang Liang, Han Zhifu, Yang Xinru, Liu Weijia, Li Ertong, Chang Junbiao, Qi Yijun, Shpak Elena D, Chai Jijie
Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
College of Life Sciences, Peking University, Beijing 100871, China.
Genes Dev. 2017 May 1;31(9):927-938. doi: 10.1101/gad.297580.117. Epub 2017 May 23.
Stomata are microscopic openings that allow for the exchange of gases between plants and the environment. In , stomatal patterning is specified by the ERECTA family (ERf) receptor kinases (RKs), the receptor-like protein (RLP) TOO MANY MOUTHS (TMM), and EPIDERMAL PATTERNING FACTOR (EPF) peptides. Here we show that TMM and ER or ER-LIKE1 (ERL1) form constitutive complexes, which recognize EPF1 and EPF2, but the single ERfs do not. TMM interaction with ERL1 creates a binding pocket for recognition of EPF1 and EPF2, indicating that the constitutive TMM-ERf complexes function as the receptors of EPF1 and EPF2. EPFL9 competes with EPF1 and EPF2 for binding to the ERf-TMM complex. EPFL4 and EPFL6, however, are recognized by the single ERfs without the requirement of TMM. In contrast to EPF1,2, the interaction of EPFL4,6 with an ERf is greatly reduced in the presence of TMM. Taken together, our data demonstrate that TMM dictates the specificity of ERfs for the perception of different EPFs, thus functioning as a specificity switch for the regulation of the activities of ERfs.
气孔是植物与环境之间进行气体交换的微小开口。在拟南芥中，气孔模式由ERECTA家族（ERf）受体激酶（RKs）、类受体蛋白（RLP）过多的口器（TMM）和表皮模式因子（EPF）肽决定。在这里，我们表明TMM与ER或类ER1（ERL1）形成组成型复合物，它们识别EPF1和EPF2，但单个ERf则不能。TMM与ERL1的相互作用形成了一个用于识别EPF1和EPF2的结合口袋，表明组成型TMM-ERf复合物作为EPF1和EPF2的受体发挥作用。EPFL9与EPF1和EPF2竞争结合ERf-TMM复合物。然而，EPFL4和EPFL6可被单个ERf识别，而无需TMM参与。与EPF1、2相反，在有TMM存在的情况下，EPFL4、6与ERf的相互作用会大大降低。综上所述，我们的数据表明，TMM决定了ERf对不同EPF感知的特异性，从而作为调节ERf活性的特异性开关发挥作用。
