Fig. 3: CryoEM structures of oxidized and reduced MoFeP.
A 2.39-Å resolution cryoEM structure of oxidized P2+ AvMoFeP obtained using the chameleon aerobically (without protective oil or NaDT). The C2 symmetry axis is indicated. B The EM density for the homocitrate-FeMoco ligand of the oxidized MoFeP does not exhibit significant change or damage. C The oxidized P-cluster (P2+ state) from the sample prepared aerobically (A) indicates clear density for linkages between the α1C88 amide backbone nitrogen with Fe5 (green arrow) and the β1S88 side-chain with Fe6 (red arrow) of the P-cluster. D 2.08-Å resolution cryoEM structure of reduced PN AvMoFeP obtained using the (an)aerobic chameleon protocol with protective oil and 60 mM NaDT. E The homocitrate and FeMoco do not show significant changes in the reduced MoFeP structure. F The linkages indicative of O2 damage are lacking in the (an)aerobically-prepared MoFeP, indicating a reduced PN P-cluster (red and green arrows). G 2.08-Å resolution cryoEM structure of reduced PN AvMoFeP obtained using the (an)aerobic chameleon protocol with protective oil and 20 mM NaDT. H The EM density for the homocitrate-FeMoco ligand of the reduced MoFeP does not exhibit significant change or damage. I The reduced PN P-cluster from the sample prepared anaerobically lacks clear density for linkages between the α1C88 amide backbone nitrogen with Fe5 (green arrow) and the β1S88 side-chain with Fe6 (red arrow) of the P-cluster. J 2.19-Å resolution cryoEM structure of reduced (PN) AvMoFeP obtained using the (an)aerobic chameleon protocol with protective oil and 5 mM NaDT. K Similar to (B), the homocitrate and FeMoco do not show significant changes in the reduced MoFeP structure. L The linkages indicative of O2 damage are lacking in the (an)aerobically-prepared MoFeP, indicating a reduced PN P-cluster (red and green arrows. B, C, E, F, H, I, K, L) Surrounding residues were rendered transparent for clarity.
