Physiological importance of autophosphorylation of NtCDPK1 involved in gibberellin signal transduction

2016 Fiscal Year Final Research Report

• Project/Area Number: 15K18555
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Plant molecular biology/Plant physiology
• Research Institution: Hiroshima University
• Principal Investigator: Takeshi Ito 広島大学, 理学研究科, 助教 (30636139)
• Project Period (FY): 2015-04-01 – 2017-03-31
• Keywords: 自己リン酸化 / キナーゼ / カルシウム / ジベレリン / 基質認識 / 基質特異性 / タンパク質リン酸化酵素 / 植物ホルモン

Outline of Final Research Achievements

The tobacco calcium-dependent protein kinase, NtCDPK1, was previously shown to be autophosphorylated in a calcium-dependent manner. Here, we investigated the functional importance of autophosphorylation in NtCDPK1. Autophosphorylation sites of NtCDPK1 were shown to be located in the variable N-terminal domain. The autophosphorylation reduced the binding affinity of NtCDPK1 for RSG. Furthermore, the autophosphorylation decreased the phosphorylation efficiency of RSG, yet increased that of myelin basic protein. Autophosphorylation sites of NtCDPK1 were phosphorylated in response to GAs in plants. The substitution of these autophosphorylation sites with Ala enhanced the NtCDPK1 overexpression-induced sensitization of seeds to a GA biosynthetic inhibitor during germination. These results suggest new functions of autophosphorylation in CDPKs, namely, the autophosphorylation can prevent the excessive phosphorylation of substrates and alter the substrate preference of CDPKs.

Free Research Field

植物生理学・分子生物学