title: Autophosphorylation of Specific Threonine and Tyrosine Residues in Arabidopsis CERK1 is Essential for the Activation of Chitin-Induced Immune Signaling.
abstract: Pattern recognition receptors on the plant cell surface mediate the recognition of microbe/damage-associated molecular patterns (MAMPs/DAMPs) and activate downstream immune signaling. Autophosphorylation of signaling receptor-like kinases is a critical event for the activation of downstream responses but the function of each phosphorylation site in the regulation of immune signaling is not well understood. 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.
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.|These authors contributed equally to this work.
authors: Maruya
authors: M
authors: Suzuki
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.|These authors contributed equally to this work.
authors: Masatoshi
authors: M
authors: Shibuya
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.|These authors contributed equally to this work.
authors: Hikaru
authors: H
authors: Shimada
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.|These authors contributed equally to this work.
authors: Noriko
authors: N
authors: Motoyama
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Masato
authors: M
authors: Nakashima
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Shohei
authors: S
authors: Takahashi
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Kenkichi
authors: K
authors: Suto
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Issei
authors: I
authors: Yoshida
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Saki
authors: S
authors: Matsui
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Natsumi
authors: N
authors: Tsujimoto
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Mihoko
authors: M
authors: Ohnishi
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Yuko
authors: Y
authors: Ishibashi
authors: National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki, 305-8602, Japan.
authors: Zui
authors: Z
authors: Fujimoto
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Yoshitake
authors: Y
authors: Desaki
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan.
authors: Hanae
authors: H
authors: Kaku
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan shibuya@meiji.ac.jp kito@meiji.ac.jp.
authors: Keiji
authors: K
authors: Kito
authors: Department of Life Sciences, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, 214-8571, Japan shibuya@meiji.ac.jp kito@meiji.ac.jp.
authors: Naoto
authors: N
authors: Shibuya
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000276:immunology*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D002686:Chitin / Q000494:pharmacology*; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D057865:Plant Immunity / Q000187:drug effects; D030821:Plants, Genetically Modified; D000072417:Protein Domains; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013912:Threonine / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D002686:Chitin; D013912:Threonine; D014443:Tyrosine; C525882:CERK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases
keywords: 
  Arabidopsis thaliana
  ; CERK1; Chitin; PRR; Phosphorylation site; Plant immunity; Signal transduction