Structural and physiological analyses of the pressure adaptation in the deep-sea enzyme.

2016 Fiscal Year Final Research Report

• Project/Area Number: 25450121
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Applied microbiology
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: KATO Chiaki 国立研究開発法人海洋研究開発機構, 海洋生物多様性研究分野, シニアスタッフ (90360750)
• Co-Investigator(Renkei-kenkyūsha): WATANABE Nobuhisa 名古屋大学, シンクロトロン光研究センター, 教授 (70212321) ; YAMADA Yasuyuki 立教大学, 理学部, 教授 (80386507)
• Project Period (FY): 2013-04-01 – 2017-03-31
• Keywords: 高圧力 / 深海 / 微生物 / 酵素 / 構造解析

Outline of Final Research Achievements

3-Isopropylmalate dehydrogenase (IPMDH) from the extreme piezophile Shewanella benthica (SbIPMDH) is more pressure-tolerant than that from the atmospheric pressure-adapted Shewanella oneidensis (SoIPMDH). To understand the molecular mechanisms of this pressure tolerance, we analyzed mutated enzymes. The results indicate that only a single mutation at position 266, corresponding to Ala (SbIPMDH) and Ser (SoIPMDH), essentially affects activity under higher-pressure (HP) conditions. 3D-structural analyses of SoIPMDH suggests that penetration of three water molecules into the cleft around Ser266 under HP conditions could reduce the activity of the wild-type enzyme; however, no water molecule is observed in the Ala266 mutant. Water penetration into the cleft under HP conditions would appear to be less frequent than for the atmospheric-adapted SoIPMDH due to the reduced probability of forming a hydrogen bond, and as a consequence, SbIPMDH could adapt to the HP conditions of the deep sea.

Free Research Field

微生物学、分子生物学