"Preparation of oxygen-sensitive nitrogenase for high-resolution cryoEM structure determination using blot-free vitrification device"
Sarah Narehood
PhD Student and current Interfaces Trainee
Chemistry & Biochemistry Department
Co-mentors: Mark Herzik, PhD and Akif Tezcan, PhD - Chemistry & Biochemistry
Seminar Information
Nitrogenase is the only known enzyme that can catalyze the reduction of dinitrogen (N₂) to ammonia (NH₃), a vital precursor to nucleic and amino acids as well as countless commodity chemicals. Despite decades of research, the mechanism by which nitrogenase fixes nitrogen into ammonia within ambient conditions is still not entirely known. Understanding how nitrogenase can sustainably fix nitrogen under such benign conditions would revolutionize how we can produce some of the basic building blocks of life. Through single-particle cryogenic electron microscopy (cryoEM) we can start to answer these outstanding questions with atomic-resolution snapshots of nitrogenase, from reaction intermediates during catalysis to the formation of large scale dynamic nitrogenase complexes with interacting partners. However, traditional cryoEM grid preparation workflows are not tailored towards oxygen-sensitive proteins, like nitrogenase. Current practices call for anaerobic grid vitrification devices to be placed in anoxic chambers, which presents numerous hurdles, including temperature and humidity control, optimization of freezing conditions, costs for purchase and operation as well as accessibility. I will present a streamlined approach that allows for the vitrification of oxygen-sensitive proteins using an automated aerobic blot-free grid vitrification device. This establishes a workflow that not only leads to high-resolution structure determination of nitrogenase but has the potential to unlock a subset class of proteins that continue to evade structural study.