Autophosphorylation of Specific Threonine and Tyrosine Residues in Arabidopsis CERK1 is Essential for the Activation of Chitin-Induced Immune Signaling

In this study, 41 Ser/Thr/Tyr and 15 Ser/Thr residues were identified as in vitro and in vivo autophosphorylation sites of Arabidopsis CERK1, which is essential for chitin signaling. Comprehensive analysis of transgenic plants expressing mutated CERK1 genes for each phosphorylation site in the cerk1-2 background indicated that the phosphorylation of T479 in the activation segment and Y428 located upstream of the catalytic loop is important for the activation of chitin-triggered defense responses. Contribution of the phosphorylation of T573 to the chitin responses was also suggested. In vitro evaluation of kinase activities of mutated kinase domains indicated that the phosphorylation of T479 and T573 is directly involved in the regulation of kinase activity of CERK1 but the phosphorylation of Y428 regulates chitin signaling independently of the regulation of kinase activity. These results indicated that the phosphorylation of specific residues in the kinase domain contributes to the regulation of downstream signaling either through the regulation of kinase activity or the different mechanisms, e.g. regulation of protein–protein interactions.

Source: Plant and Cell Physiology - November 3, 2016 Category: Cytology Authors: Suzuki, M., Shibuya, M., Shimada, H., Motoyama, N., Nakashima, M., Takahashi, S., Suto, K., Yoshida, I., Matsui, S., Tsujimoto, N., Ohnishi, M., Ishibashi, Y., Fujimoto, Z., Desaki, Y., Kaku, H., Kito, K., Shibuya, N. Tags: Regular Papers Source Type: research