How Escherichia coli is equipped to oxidize hydrogen under different redox conditions.
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.
Lukey
Michael J
MJ
From the Department of Inorganic Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom and.
Parkin
Alison
A
From the Department of Inorganic Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom and.
Roessler
Maxie M
MM
From the Department of Inorganic Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom and.
Murphy
Bonnie J
BJ
From the Department of Inorganic Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom and.
Harmer
Jeffrey
J
From the Department of Inorganic Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom and.
Palmer
Tracy
T
the College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, United Kingdom.
Sargent
Frank
F
the College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, Scotland, United Kingdom. Electronic address: F.Sargent@dundee.ac.uk.
Armstrong
Fraser A
FA
From the Department of Inorganic Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom and. Electronic address: fraser.armstrong@chem.ox.ac.uk.
D000332:Aerobiosis; D004305:Dose-Response Relationship, Drug; D055664:Electrochemical Techniques / Q000379:methods; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010088:Oxidoreductases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D021122:Protein Subunits / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013053:Spectrophotometry / Q000379:methods
D029968:Escherichia coli Proteins; D021122:Protein Subunits; D006859:Hydrogen; D010088:Oxidoreductases; C029746:uptake hydrogenase; D010100:Oxygen