Tuning Electron Flux through Nitrogenase with Methanogen Iron Protein Homologues

5 years ago

Tuning Electron Flux through Nitrogenase with Methanogen Iron Protein Homologues

Martin T. Stiebritz, Caleb J. Hiller, Yilin Hu, Jasper Liedtke, Chi Chung Lee

Nitrogenase uses a reductase component called Fe protein to deliver electrons to its catalytic partner for substrate reduction. The essential role of Fe protein in catalysis makes it an ideal target for regulating the electron flux and enzymatic activity of nitrogenase without perturbing the cofactor site. This work reports that hybrids between the Fe protein homologs of Methanosarcina acetivorans and the catalytic components of Azotobacter vinelandii can trap substrate CO through reduced electron fluxes. In addition, homology modeling/in silico docking is used to define markers for binding energy and specificity between the component proteins that correlate with the experimentally determined activities. This homologue-based approach could be further developed to allow identification or design of hybrids between homologous nitrogenase components for mechanistic investigations of nitrogenase through capture of substrates/ intermediates or for transgenic expression of nitrogenase through synthetic biology. A homologue-based approach facilitates capture of multiple CO molecules at the nitrogenase cofactor site through reduction of the electron flow through a nitrogenase hybrid between homologous component proteins, suggesting the utility of this approach in tuning electron fluxes to enable trapping of substrates and relevant intermediates for mechanistic investigations of this enzyme.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201704378