FIG. 1.

Addition of a Cys residue at the C terminus of CorA allows dimer formation. Salmonella serovar Typhimurium strains MM1318 (Cys191Ser), MM1322 (Cys317), and MM1324 (Cys191Ser Cys317) and a wild-type strain (MM1442) were grown in LB broth to an OD₆₀₀ of 0.5 to 1.0, and membrane fractions were incubated with or without 10 mM tetrathionate. The samples were then run on nondenaturing PAGE before Western blotting with anti-CorA antibody and scanning into Canvas. No editing was performed except adjustment of brightness and contrast. Panel A shows the wild-type, the Cys⁻ mutant, and the double mutant strains treated with tetrathionate. Some preparations showed a small amount of the 91-kDa band before tetrathionate oxidation (see panel B); the amount of the 91-kDa species was markedly increased by oxidation with tetrathionate. Panel B shows the formation of a third band at 110 kDa in the Cys 317 mutant containing both a cytoplasmic (Cys317) and a periplasmic (Cys191) cysteine. The band was enhanced by tetrathionate oxidation, in addition to the 91- and 44-kDa bands.