[FeFe]-Hydrogenase Maturation: HydG-Catalyzed Synthesis of Carbon Monoxide

• Published in: Journal of the American Chemical Society Vol. 132; no. 27; pp. 9247 - 9249
• Main Authors: Shepard, Eric M, Duffus, Benjamin R, George, Simon J, McGlynn, Shawn E, Challand, Martin R, Swanson, Kevin D, Roach, Peter L, Cramer, Stephen P, Peters, John W, Broderick, Joan B
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14.07.2010
• Subjects: Carbon Monoxide - metabolism; Catalysis; Clostridium; Escherichia coli Proteins; Hydrogenase - metabolism; S-Adenosylmethionine; Trans-Activators; Tyrosine - metabolism
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja1012273

Biosynthesis of the unusual organometallic H-cluster at the active site of the [FeFe]-hydrogenase requires three accessory proteins, two of which are radical AdoMet enzymes (HydE, HydG) and one of which is a GTPase (HydF). We demonstrate here that HydG catalyzes the synthesis of CO using tyrosine as a substrate. CO production was detected by using deoxyhemoglobin as a reporter and monitoring the appearance of the characteristic visible spectroscopic features of carboxyhemoglobin. Assays utilizing 13C-tyrosine were analyzed by FTIR to confirm the production of HbCO and to demonstrate that the CO product was synthesized from tyrosine. CO ligation is a common feature at the active sites of the [FeFe], [NiFe], and [Fe]-only hydrogenases; however, this is the first report of the enzymatic synthesis of CO in hydrogenase maturation.