(a) Iodine-induced disulfide crosslinking of positions 158 and 214 in the contest of the new (i.e., linker-containing) FliF–FliG fusion protein, expressed from the chromosome. (b) Product yield versus size (number of crosslinked subunits), and effect of pretreatment with NEM (6 mM for 3 min). (c) Crosslinking of native-sized, plasmid-expressed FliG to the FliF–FliG fusion proteins. Results with both the old and new fusion constructs are shown. The FliF–FliG fusions contained the 158C/214C replacements. The plasmid-expressed FliG either carried the same Cys replacements or was wild type (with no Cys residues), as indicated; plasmids were derivatives of pKP619, induced with 40 μM IPTG.