2022 Fiscal Year Final Research Report

Elucidation of intramolecular heat transfer mechanism for construction of highly effective photothermal protein heaters

Planned Research

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Project Area	Next-generation non-invasive biological deep-tissue manipulation by biomolecular engineering and low physical energy logistics
Project/Area Number	20H05756
Research Category	Grant-in-Aid for Transformative Research Areas (B)
Allocation Type	Single-year Grants
Review Section	Transformative Research Areas, Section (III)
Research Institution	Osaka University
Principal Investigator	Mizuno Misao 大阪大学, 大学院理学研究科, 助教 (10464257)
Project Period (FY)	2020-10-02 – 2023-03-31
Keywords	タンパク質ヒーター / 光熱エネルギー変換 / 振動エネルギー移動 / アンチストークスラマン散乱
Outline of Final Research Achievements	Diffusion processes of excess vibrational energy generated by photoexcitation of heme in heme proteins were spatiotemporally mapped at the level of a single amino acid residue using the anti-Stokes Raman scattering of a tryptophan residue in the protein as a spectroscopic probe. Taking advantage of characteristic structures of proteins, we observed the dependence of the vibrational energy flow on the distance from the heme group and revealed that the protein is highly thermally conductive due to its dense packing. We also demonstrated that the anti-Stokes Raman intensity of tryptophan is an excellent spectroscopic thermometer to determine the local internal temperature in the protein in a nonequilibrium state. In addition, we demonstrated that heme proteins have sufficient heat releasability following photothermal energy conversion on heme as protein-based molecular heaters.
Free Research Field	生物物理化学
Academic Significance and Societal Importance of the Research Achievements	タンパク質を細胞中で分子ヒーターとして利用した熱シグナルによる細胞操作はこれまでに例がない。本研究では、ヘムタンパク質が高効率な光熱エネルギー変換分子ヒーターとして機能することを、分子内熱伝導機構の解明および水溶媒加熱能計測により明らかにした。タンパク質ヒーターは、生合成されるため生体への負荷が非常に小さく、遺伝子工学により細胞内の特定のオルガネラに局在できる。光熱変換タンパク質ヒーターを用いた細胞内熱シグナルの制御は、高い加熱効率かつ高い空間選択性という点で従来法に比べて優位性があり、オプトジェネティクスに比肩する革新的な細胞操作技術の創成に本研究成果は重要な知見を与えた。