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Science. 2017 Sep 1;357(6354):928-932. doi: 10.1126/science.aan4497.

Structural basis of the redox switches in the NAD+-reducing soluble [NiFe]-hydrogenase.

Author information

1
Institute of Quantum Beam Science, Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan. hig@sci.u-hyogo.ac.jp yasuhito.shomura.s@vc.ibaraki.ac.jp.
2
Department of Picobiology, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan.
3
Core Research for Evolutional Science and Technology (CREST), Japan and Science Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan.
4
Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan.
5
Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
6
Department of Bioresource Science, College of Agriculture, Ibaraki University, 3-21-1, Chu-ou, Ami, Ibaraki 300-0393, Japan.
7
World Premier International Research Center Initiative-International Institute for Carbon Neutral Energy Research (WPI-ICNER), Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan.
8
SPring-8 Center, RIKEN, 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan.
9
Department of Picobiology, Graduate School of Life Science, University of Hyogo, 3-2-1 Koto, Kamigori-cho, Ako-gun, Hyogo 678-1297, Japan. hig@sci.u-hyogo.ac.jp yasuhito.shomura.s@vc.ibaraki.ac.jp.

Abstract

NAD+ (oxidized form of NAD:nicotinamide adenine dinucleotide)-reducing soluble [NiFe]-hydrogenase (SH) is phylogenetically related to NADH (reduced form of NAD+):quinone oxidoreductase (complex I), but the geometrical arrangements of the subunits and Fe-S clusters are unclear. Here, we describe the crystal structures of SH in the oxidized and reduced states. The cluster arrangement is similar to that of complex I, but the subunits orientation is not, which supports the hypothesis that subunits evolved as prebuilt modules. The oxidized active site includes a six-coordinate Ni, which is unprecedented for hydrogenases, whose coordination geometry would prevent O2 from approaching. In the reduced state showing the normal active site structure without a physiological electron acceptor, the flavin mononucleotide cofactor is dissociated, which may be caused by the oxidation state change of nearby Fe-S clusters and may suppress production of reactive oxygen species.

PMID:
28860386
DOI:
10.1126/science.aan4497
[Indexed for MEDLINE]

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