SAXS scattering shows that FusC(E⁸³A) undergoes major conformational change upon ferredoxin binding but remains elongated in solution.

<p>Static-SAXS titration of ferredoxin into FusC (30 μM) mapping conformational changes that occur in FusC upon ferredoxin binding. (A) Scattering angle versus intensity plot for FusC(E⁸³A) with increasing concentration of ferredoxin. (B) Kratky plot of FusC(E⁸³A) scattering showing a shift from a multidomain structure to a single domain upon ferredoxin binding. (C) P_r distribution of FusC(E⁸³A) in the absence of ferredoxin (0 μM), partially saturated (50 μM), and saturated (100 and 150 μM), showing a conformational tightening of FusC upon ferredoxin binding. (D) A plot of the Guinier region of FusC(E⁸³A) at increasing ferredoxin concentration. (E) A plot of volume of FusC(E⁸³A) with increasing ferredoxin concentration. The observed increase and plateau of Porod volume is indicative of ferredoxin binding and saturation of FusC(E⁸³A). (F) A plot of the maximum dimension of FusC(E⁸³A) in solution, showing that the protease remains elongated in solution when in complex with ferredoxin. All SAXS data used to generate plots in this figure have been deposited at SASBDB, accession: SASDDU6. SASDDV6, SASDDW6, SASDDX6, SASDDY6, SASDDZ6, SASDD27, SASDD37, SASDD47, SASDD57, SASDD67, SASDD77. SASBDB, Small Angle Scattering Biological Databank; SAXS, small-angle X-ray scattering.