Redox tuning of the H-cluster by second coordination sphere amino acids in the sensory [FeFe] hydrogenase from Thermotoga maritima

Chongdar, N; Rodríguez-Maciá, P; Reijerse, EJ; Lubitz, W; Ogata, H; Birrell, JA

Journal article

Redox tuning of the H-cluster by second coordination sphere amino acids in the sensory [FeFe] hydrogenase from Thermotoga maritima

Abstract:: [FeFe] hydrogenases are exceptionally active catalysts for the interconversion of molecular hydrogen with protons and electrons. Their active site, the H-cluster, is composed of a [4Fe-4S] cluster covalently linked to a unique [2Fe] subcluster. These enzymes have been extensively studied to understand how the protein environment tunes the properties of the Fe ions for efficient catalysis. The sensory [FeFe] hydrogenase (HydS) from Thermotoga maritima has low activity and displays a very positive redox potential for the [2Fe] subcluster compared to that of the highly active prototypical enzymes. Using site directed mutagenesis, we investigate how second coordination sphere interactions of the protein environment with the H-cluster in HydS influence the catalytic, spectroscopic and redox properties of the H-cluster. In particular, mutation of the non-conserved serine 267, situated between the [4Fe-4S] and [2Fe] subclusters, to methionine (conserved in prototypical catalytic enzymes) gave a dramatic decrease in activity. Infra-red (IR) spectroelectrochemistry revealed a 50 mV lower redox potential for the [4Fe-4S] subcluster in the S267M variant. We speculate that this serine forms a hydrogen bond to the [4Fe-4S] subcluster, increasing its redox potential. These results demonstrate the importance of the secondary coordination sphere in tuning the catalytic properties of the H-cluster in [FeFe] hydrogenases and reveal a particularly important role for amino acids interacting with the [4Fe-4S] subcluster

Publication status:: Published

Peer review status:: Peer reviewed

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APA Style

Chongdar, N., Rodríguez-Maciá, P., Reijerse, E. J., Lubitz, W., Ogata, H., & Birrell, J. A. (2023). Redox tuning of the H-cluster by second coordination sphere amino acids in the sensory [FeFe] hydrogenase from Thermotoga maritima. Chemical Science, 14(13), 3682–3692.

MLA Style

Chongdar, N, et al. “Redox Tuning of the H-Cluster by Second Coordination Sphere Amino Acids in the Sensory [FeFe] Hydrogenase from Thermotoga Maritima.” Chemical Science, vol. 14, no. 13, 2023, pp. 3682–92.

Chicago Style

Chongdar, N, P Rodríguez-Maciá, EJ Reijerse, W Lubitz, H Ogata, and JA Birrell. 2023. “Redox Tuning of the H-Cluster by Second Coordination Sphere Amino Acids in the Sensory [FeFe] Hydrogenase from Thermotoga Maritima.” Chemical Science 14 (13): 3682–92.
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