Fe protein docking transduces conformational changes to MoFe nitrogenase active site in a nucleotide-dependent manner

The reduction of dinitrogen to ammonia catalyzed by nitrogenase involves a complex series of events, including ATP hydrolysis, electron transfer, and activation of metal clusters for N2 reduction. Early evidence shows that an essential part of the mechanism involves transducing information between the nitrogenase component proteins through conformational dynamics. Here, millisecond time-resolved hydrogen-deuterium exchange mass spectrometry was used to unravel peptide-level protein motion on the time scale of catalysis of Mo-dependent nitrogenase from Azotobacter vinelandii. Normal mode analysis calculations complemented this data, providing insights into the specific signal transduction pathways that relay information across protein interfaces at distances spanning 100 angstrom. Together, these results show that conformational changes induced by protein docking are rapidly transduced to the active site, suggesting a specific mechanism for activating the metal cofactor in the enzyme active site. The reduction of dinitrogen to ammonia catalyzed by nitrogenase involves long-range conformational changes within the enzyme complex, however, direct biophysical evidence of communication between the Fe protein and the MoFe protein is lacking. Here, the authors combine millisecond time-resolved hydrogen-deuterium exchange mass spectrometry and normal mode analysis, revealing molecular-level insights into how the Fe protein alters the stability and dynamics of the MoFe protein near the active site in a nucleotide-dependent manner.

Automated summary

This study investigates protein motion during the catalysis of nitrogenase using time-resolved mass spectrometry and normal mode analysis. The results reveal the conformational changes induced by protein docking and their impact on the activity of metal cofactor, providing insights into the signal transduction pathways involved in this reaction.