In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 115, No. 10 ( 2018-03-06)
Abstract:
[NiFe] hydrogenases catalyze the reversible splitting of H 2 into protons and electrons at a deeply buried active site. The catalytic center can be accessed by gas molecules through a hydrophobic tunnel network. While most [NiFe] hydrogenases are inactivated by O 2 , a small subgroup, including the membrane-bound [NiFe] hydrogenase (MBH) of Ralstonia eutropha , is able to overcome aerobic inactivation by catalytic reduction of O 2 to water. This O 2 tolerance relies on a special [4Fe3S] cluster that is capable of releasing two electrons upon O 2 attack. Here, the O 2 accessibility of the MBH gas tunnel network has been probed experimentally using a “soak-and-freeze” derivatization method, accompanied by protein X-ray crystallography and computational studies. This combined approach revealed several sites of O 2 molecules within a hydrophobic tunnel network leading, via two tunnel entrances, to the catalytic center of MBH. The corresponding site occupancies were related to the O 2 concentrations used for MBH crystal derivatization. The examination of the O 2 -derivatized data furthermore uncovered two unexpected structural alterations at the [4Fe3S] cluster, which might be related to the O 2 tolerance of the enzyme.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.1712267115
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2018
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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