Structural basis for the selection mechanism of specific kinase signaling pathways via stimuli-dependent modulations of the functional equilibrium

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K15083
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Structural biochemistry
• Research Institution: National Institute of Advanced Industrial Science and Technology
• Principal Investigator: Tokunaga Yuji 国立研究開発法人産業技術総合研究所, 生命工学領域, 研究員 (80713354)
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: タンパク質キナーゼ / シグナル伝達 / ストレス応答 / pH依存性 / MAPキナーゼp38 / 基質特異性 / ダイナミクス / 溶液NMR法

Outline of Final Research Achievements

It remained to be elucidated how MAPK p38α, involved in various cellular responses, phosphorylates a substrate, which is optimal to each type of response, out of a number of its specific substrates. Here, I investigated a mechanism of substrate selection under the stress condition that lead to weak acidification of cytosol. It was shown that the phosphorylation of ATF2, a substrate of p38α under stress stimuli, is enhanced under weakly acidic conditions, irrespective of coexistence of a high-affinity substrate, MK2. This was achieved by the multi-site protonation of the allositeric interaction site of ATF2 that contains four unique histidine residues. In addition, protonation of a histidine residue in the substrate-binding site of p38α weakened the affinity for phosphoacceptor sites, thereby exclude non-specific pseudo-substrates. These findings demonstrate the regulatory role of pH in achieving a high fidelity stress response, by directing p38α toward the optimal substrate.

Free Research Field

構造生物学

Academic Significance and Societal Importance of the Research Achievements

本研究では、細胞応答に不可欠である、刺激に適合したシグナル経路の活性化機構を、申請者が独自に発見した分子機構に基づき、刺激に付随した細胞内環境の変化を新たに考慮して解析し、仮説を裏付ける結果を得た。環境依存的なシグナル選別は、p38αのみならず、膜受容体や転写因子など、シグナル伝達ネットワークのハブタンパク質に共通すると考えられ、このような新たな研究分野の開拓を促す重要な成果と言える。また、シグナル選別機構の理解は、標的のシグナル経路のみを遮断する副作用の少ない薬剤等の開発にもつながる基礎的知見を提供することから、研究成果の社会的な意義も大きい。