FIG 5.

Time-dependent profile of Nif protein accumulation upon nitrogen step-down in wild-type A. vinelandii (closed symbols) and the ΔfdxN mutant (open symbols). Proteins are organized by their role in nitrogenase biogenesis: proteins involved in early steps of FeMo-co synthesis (A), proteins involved in late steps of FeMo-co synthesis (B), proteins involved in FeMo-co insertion into apo-NifDK (C), and nitrogenase structural proteins (D). The total cell volume was used to calculate protein concentrations (μM). Data are the averages of three biological replicates ± SEs.