Evidence for an iron center in the ammonia monooxygenase from Nitrosomonas europaea

FEBS Letters

Hooper, Alan B.¹  Arciero, David M.¹  DiSpirito, Alan A.²  Zahn, James A.² 

[1]Department of Genetics and Cell Biology, University of Minnesota, St. Paul, MN 55108, USA

[2]Department of Microbiology, Immunology and Preventive Medicine, Iowa State University, Ames, IA 50011, USA

关键词: Ammonia monooxygenase;    Ammonia oxidation;    Nitrification;    Nitrapyrin;    Nitrosomonas europaea;    AMO;    ammonia monooxygenase;    DMSO;    dimethyl sulfoxide;    3-[N-morpholino]propane-sulfornic acid;    MOPS;    pMMO;    membrane-associated methane monooxygenase;    sMMO;    soluble methane monooxygenase;   

DOI  :  10.1016/S0014-5793(96)01116-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Binding of the ligand, nitric oxide, in the presence of reductant was used to identify a ferrous S=3/2 signal, characteristic of a ferrous nitrosyl complex, and a g=2.03 copper of iron signal in membranes of the ammonia-oxidizing bacterium, Nitrosomonas europaea. The same ferrous S=3/2 signal is thought to be a component of the membrane-associated methane monooxygenase (pMMO) of Methylococcus capsulatus Bath, since it is seen in the membrane fraction of cells expressing pMMO and in the purified enzyme, but not in the membrane fraction of cells expressing the soluble MMO [Zahn, J.A. and DiSpirito, A.A. (1996) J. Bacteriol. 178, 1018–1029]. Treatment of resting membranes or cells of N. europaea with nitrapyrin, 2-chloro,6-trichloromethylpyridine, resulted in the increase in magnitude of a g = 6, high-spin ferric iron signal. In the presence of NO and reductant, nitrapyrin prevented the formation of the S=3/2 nitrosyl-iron complex while increasing the intensity of the g=6 signal. Nitrapyrin is a specific inhibitor of, and is reduced by, the ammonia monoxygenase (AMO) [Bédard, C. and Knowles, R. (1989) Microbiol. Rev. 53, 38–83]. Taken together the data suggest that iron capable of forming the S=3/2 complex is a catalytic component of AMO of N. europaea, possibly a part of the oxygen-activating center. Inactivation of the membrane-associated AMO with acetylene did not diminish the S=3/2 nitrosyl-iron signal, the g=6 signal, or the g=6 signal.

【 授权许可】

Unknown