Structural Dynamics of Nitric Oxide Reductases Srudied by Time-Resolved Techniques

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H00926
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 37:Biomolecular chemistry and related fields
• Research Institution: University of Hyogo
• Principal Investigator: Shiro Yoshitsugu 兵庫県立大学, 理学研究科, 特任教授 (70183051)
• Co-Investigator(Kenkyū-buntansha): 村本 和優 兵庫県立大学, 理学研究科, 准教授 (50305679)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 一酸化窒素還元酵素 / 一酸化窒素 / 脱窒 / 亜酸化窒素 / 抗菌ガス / 呼吸酵素の分子進化 / 抗菌剤開発

Outline of Final Research Achievements

Membrane-bound nitric oxide reductases (NORs), which have a binuclear complex of heme and non-heme irons at the active center, are key enzymes in anaerobic respiration, denitrification, since they catalyze reduction of toxic nitric oxide NO for its detoxification. They are also involved in life cycle of pathogenic bacteria in their host.
I determined both monomeric and dimeric structures of Neisseria meningitidis qNOR, and also analyzed its reaction with NO in the absence and presence of inhibitors. These data provided bases for design and construct of anti-bacterial drugs.
Using Pseudomonas aeruginosa cNOR as a target enzyme, I followed the enzymatic reaction with NO with time-resolved visible and IR spectroscopic, and cryo-reduction annealing ESR spectroscopic techniques. In these measurements, I proposed the molecular mechanism of NOR enzymatic reaction. The results are highly related to the molecular evolution of the respiratory enzyme.

Free Research Field

構造生命科学

Academic Significance and Societal Importance of the Research Achievements

髄膜炎菌のqNORは、菌が宿主内でバイオフィルム内で嫌気呼吸をおこない、なおかつ宿主が産生する抗菌ガスNOを無毒化する上で、鍵となる酵素である。本研究で分子構造と反応プロトンの移動との関係、阻害剤との相互作用の詳細が明らかになったことにより、抗菌薬設計の基礎データとなる。また、緑膿菌cNORを用いた反応解析から、酵素反応の分子機構が提案でき、好気呼吸酵素との比較が可能となり、呼吸酵素の分子進化を議論できるようになった。さらに、NOR反応の生成物が、地球環境破壊に関係していることから、環境科学の観点からも今後注目される成果となった。