Please use this identifier to cite or link to this item: http://dx.doi.org/10.14279/depositonce-6287
Main Title: Cofactor composition and function of a H2-sensing regulatory hydrogenase as revealed by Mossbauer and EPR spectroscopy
Author(s): Roncaroli, Federico
Bill, Eckhard
Friedrich, Bärbel
Lenz, Oliver
Lubitz, Wolfgang
Pandelia, Maria-Eirini
Type: Article
Language Code: en
Abstract: The regulatory hydrogenase (RH) from Ralstonia eutropha H16 acts as a sensor for the detection of environmental H-2 and regulates gene expression related to hydrogenase-mediated cellular metabolism. In marked contrast to prototypical energy-converting [NiFe] hydrogenases, the RH is apparently insensitive to inhibition by O-2 and CO. While the physiological function of regulatory hydrogenases is well established, little is known about the redox cycling of the [NiFe] center and the nature of the iron-sulfur (FeS) clusters acting as electron relay. The absence of any FeS cluster signals in EPR had been attributed to their particular nature, whereas the observation of essentially only two active site redox states, namely Ni-SI and Ni-C, invoked a different operant mechanism. In the present work, we employ a combination of Mossbauer, FTIR and EPR spectroscopic techniques to study the RH, and the results are consistent with the presence of three [4Fe-4S] centers in the small subunit. In the as-isolated, oxidized RH all FeS clusters reside in the EPR-silent 2+ state. Incubation with H2 leads to reduction of two of the [4Fe-4S] clusters, whereas only strongly reducing agents lead to reduction of the third cluster, which is ascribed to be the [4Fe-4S] center in 'proximal' position to the [NiFe] center. In the two different active site redox states, the low-spin FeII exhibits distinct Mossbauer features attributed to changes in the electronic and geometric structure of the catalytic center. The results are discussed with regard to the spectral characteristics and physiological function of H-2-sensing regulatory hydrogenases.
URI: https://depositonce.tu-berlin.de//handle/11303/6948
http://dx.doi.org/10.14279/depositonce-6287
Issue Date: 2015
Date Available: 25-Oct-2017
DDC Class: 540 Chemie und zugeordnete Wissenschaften
Sponsor/Funder: DFG, EXC 314, Unifying Concepts in Catalysis
Creative Commons License: https://creativecommons.org/licenses/by/3.0/
Journal Title: Chemical Science
Publisher: Royal Society of Chemistry
Publisher Place: Cambridge
Volume: 6
Issue: 8
Publisher DOI: 10.1039/c5sc01560j
Page Start: 4495
Page End: 4507
EISSN: 2041-6539
ISSN: 2041-6520
Appears in Collections:Fachgebiet Physikalische Chemie / Biophysikalische Chemie » Publications

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