The HydG Enzyme Generates an Fe(CO)2(CN) Synthon in Assembly of the FeFe Hydrogenase H-Cluster

• Published in: Science (American Association for the Advancement of Science) Vol. 343; no. 6169; pp. 424 - 427
• Main Authors: Kuchenreuther, Jon M., Myers, William K., Suess, Daniel L. M., Stich, Troy A., Pelmenschikov, Vladimir, Shiigi, Stacey A., Cramer, Stephen P., Swartz, James R., Britt, R. David, George, Simon J.
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 24.01.2014; The American Association for the Advancement of Science
• Subjects: Bacterial Proteins - chemistry; Biocatalysts; Catalysis; Catalytic Domain; Data lines; Electron spectroscopy; Electron transfer; Enzymes; Hydrogenase - chemistry; Hydrogenases; Infrared spectroscopy; Iron Carbonyl Compounds - metabolism; Iron-Sulfur Proteins - chemistry; Kinetics; Ligands; Line spectra; Protein synthesis; Proteins; Shewanella putrefaciens - enzymology; Spectral index; Spectroscopy; Spectroscopy, Fourier Transform Infrared; Time dependence
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1246572

Three iron-sulfur proteins–HydE, HydF, and HydG–play a key role in the synthesis of the [2Fe]H component of the catalytic H-cluster of FeFe hydrogenase. The radical S-adenosyl-L-methionine enzyme HydG lyses free tyrosine to produce p-cresol and the CO and CN– ligands of the [2Fe]H cluster. Here, we applied stopped-flow Fourier transform infrared and electron-nuclear double resonance spectroscopies to probe the formation of HydG-bound Fe-containing species bearing CO and CN– ligands with spectroscopic signatures that evolve on the 1- to 1000-second time scale. Through study of the 13C, 15N, and 57Fe isotopologs of these intermediates and products, we identify the final HydG-bound species as an organometallic Fe(CO)2(CN) synthon that is ultimately transferred to apohydrogenase to form the [2Fe]H component of the H-cluster.