FIGURE 9.

Mutational analyses of the SufC protein. A, comparison of the expression in wild-type and mutant SufC proteins by immunoblot analysis using an antibody against SufC. In the cell, the wild-type and SufC variants are expressed equally. B–E, comparison of the size exclusion chromatograms of the native SufBCD complex (B) and the SufC mutant complex of K40R (C), E171Q (D), and H203A (E). These SufC mutants form a stable SufB₁-SufC₂-SufD₁ complex similar to the wild-type complex. Elution curves from the gel filtration column (Sephacryl S-200) are monitored by the absorbance at 280 nm. The inset shows SDS-PAGE analysis of each peak fraction.