How Escherichia coli is equipped to oxidize hydrogen under different redox conditions

Michael J Lukey, Alison Parkin, Maxie M Roessler, Bonnie J Murphy, Jeffrey Harmer, Tracy Palmer, Frank Sargent, Fraser A Armstrong

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The enterobacterium Escherichia coli synthesizes two H(2) uptake enzymes, Hyd-1 and Hyd-2. We show using precise electrochemical kinetic measurements that the properties of Hyd-1 and Hyd-2 contrast strikingly, and may be individually optimized to function under distinct environmental conditions. Hyd-2 is well suited for fast and efficient catalysis in more reducing environments, to the extent that in vitro it behaves as a bidirectional hydrogenase. In contrast, Hyd-1 is active for H(2) oxidation under more oxidizing conditions and cannot function in reverse. Importantly, Hyd-1 is O(2) tolerant and can oxidize H(2) in the presence of air, whereas Hyd-2 is ineffective for H(2) oxidation under aerobic conditions. The results have direct relevance for physiological roles of Hyd-1 and Hyd-2, which are expressed in different phases of growth. The properties that we report suggest distinct technological applications of these contrasting enzymes.
Original languageEnglish
Pages (from-to)3928-3938
Number of pages11
JournalJournal of Biological Chemistry
Issue number6
Publication statusPublished - 5 Feb 2010

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