Fig. 6.
ExbD(D25N) and TonB(H20A) fractionate identically to the wild-type forms of each protein. Strains expressing chromosomally-encoded ExbD and TonB (W3110), ExbD(D25N) (RA1021/pKP1064), and TonB(H20A) (KP1344/pKP381) were fractionated using sucrose density gradient fractionation, as described in Materials and Methods. No inducer was needed for ExbD(D25N). TonB(H20A) was induced with .00025% (w/v) arabinose. Samples were resolved on 13% SDS-polyacrylamide gels and immunoblotted. ExbD and TonB were visualized with ExbD-specific polyclonal or TonB-specific monoclonal antibodies, respectively.