[FeFe]-Hydrogenase Oxygen Inactivation Is Initiated at the H Cluster 2Fe Subcluster

Kevin D. Swanson, Michael W. Ratzloff, David W. Mulder, Jacob H. Artz, Shourjo Ghose, Andrew Hoffman, Spencer White, Oleg A. Zadvornyy, Joan B. Broderick, Brian Bothner, Paul W. King, John W. Peters

Research output: Contribution to journalArticlepeer-review

111 Scopus Citations

Abstract

The [FeFe]-hydrogenase catalytic site H cluster is a complex iron sulfur cofactor that is sensitive to oxygen (O2). The O2 sensitivity is a significant barrier for production of hydrogen as an energy source in water-splitting, oxygenic systems. Oxygen reacts directly with the H cluster, which results in rapid enzyme inactivation and eventual degradation. To investigate the progression of O2-dependent [FeFe]-hydrogenase inactivation and the process of H cluster degradation, the highly O2-sensitive [FeFe]-hydrogenase HydA1 from the green algae Chlamydomonas reinhardtii was exposed to defined concentrations of O2 while monitoring the loss of activity and accompanying changes in H cluster spectroscopic properties. The results indicate that H cluster degradation proceeds through a series of reactions, the extent of which depend on the initial enzyme reduction/oxidation state. The degradation process begins with O2 interacting and reacting with the 2Fe subcluster, leading to degradation of the 2Fe subcluster and leaving an inactive [4Fe-4S] subcluster state. This final inactive degradation product could be reactivated in vitro by incubation with 2Fe subcluster maturation machinery, specifically HydFEG, which was observed by recovery of enzyme activity.

Original languageAmerican English
Pages (from-to)1809-1816
Number of pages8
JournalJournal of the American Chemical Society
Volume137
Issue number5
DOIs
StatePublished - 2015

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.

NREL Publication Number

  • NREL/JA-2700-62523

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