Carbon dioxide fixation under extreme conditions by Archaea

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 10460036
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 応用微生物学・応用生物化学
• Research Institution: The University of Tokyo
• Principal Investigator: IGARASHI Yasuo The University of Tokyo, Graduate school of agricultural and Life Sciences, Professor, 大学院・農学生命科学研究科, 教授 (90114363)
• Co-Investigator(Kenkyū-buntansha): ISHII Masaharu The University of Tokyo, Graduate school of agricultural and Life Sciences, Assoc. Professor, 大学院・農学生命科学研究科, 助教授 (30193262)
• Project Period (FY): 1998 – 1999
• Keywords: carbon dioxide fixation / acidianus

Research Abstract

In order to clarify carbon dioxide fixation in Archaea, RubisCo from Halofelux, an extremely hahophilic microorganism, and a novel carbon dioxide pathway from Acidianus, an extremely acidophilic microorganism, were investigated in detail.
(A) Through the following experiments, 3-Hydroxypropionate cycle was proposed to be operative in Acidianus ; incorporation of radio active substance, measurement of enzymatic activities, and effect of various inhibitors on the growth. Also, key enzymes for carbon dioxide fixation in the cycle, acetyl-CoA carboxylase and propionyl-CoA carboxylase, were analyzed in terms of molecular weight through detection of biotin protein after electrophoresis. Moreover both carboxylases were purified in terms of chromatography.
(B) In order to obtain good activity of RubisCO from Halofelux, culture condition was investigated on nutrition and aeration. Then, cell-free extract was obtained and was used for the purification of RubisCO by applying the extract onto anion-exchange chromatography and on gel-feltration chromatography. By using the purified enzyme (in terms of chromatography), optimum pH, optimum temperature, thermal stability, and pH stability were measured.