Functional conversion to novel photoreactions using light-dependent enzymes as a platform

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K06542
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 43030:Functional biochemistry-related
• Research Institution: Nagoya University
• Principal Investigator: YAMAMOTO Haruki 名古屋大学, 生命農学研究科, 助教 (80615451)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 光合成色素 / クロロフィル / 酵素

Outline of Final Research Achievements

In this study, an in vivo complementation system was established for COR, an enzyme involved in photosynthetic pigment, bacteriochlorophyll biosynthesis, using gene-deficient strains of photosynthetic bacteria, and the experimental system was used to screen mutant LPORs that retain COR activity from a mutant library in which random mutations were introduced into the light-dependent enzyme LPOR. So far, more than 70,000 mutant LPORs have been screened, but no mutant LPOR with significant COR activity was obtained. Therefore, this COR activity evaluation system was used to identify the amino acid residues that determine the difference in activity for the two different kind CORs with different activities. We found that the amino acid mutation P189S in BchY had a significant effect on the activity.

Free Research Field

生化学

Academic Significance and Societal Importance of the Research Achievements

本研究では光合成細菌のCOR欠損株を用いた相補系を確立し高感度でCOR活性の検出を可能とした。その相補系を用いて異なる二つの活性を保持するCORについて、その活性の違いを決定づけるアミノ酸残基について網羅的な探索を行った。その結果活性の変化に影響を与えるBchYのP189Sを含む複数のアミノ酸置換を見出した。このように共通の酵素からアミノ酸置換を経て異なる活性を持つ酵素への分岐していくメカニズムに関する知見は酵素進化において非常に重要な根拠与える。また本研究課題で開発したCOR検出系はCOR活性を持つ可能性がある機能未知の酵素の活性確認に有用なツールとなると考えられる。