FIG 4.

The defect of the rrp1 mutant in rpoS expression can be overcome by overexpression of plzA or by low pH. (A) Wild-type B. burgdorferi B31-5A4NP1 (WT), the rrp1 mutant (rrp1), the plzA mutant (plzA), and the rrp1 mutant carrying a constitutive copy of plzA (rrp1/flgBp-plzA) were harvested at late logarithmic (L) or stationary (S) phase, and the whole-cell lysates were subjected to immunoblot analyses by chemiluminescence using a mix of monoclonal antibodies against RpoS and FlaB or antibody against OspC. FlaB serves as a loading control. (B) Cells were grown in BSK-II at pH 7.5 or 7.0 and harvested at stationary phase. Whole-cell lysates were subjected to SDS-PAGE (top) or immunoblotting (bottom) by chemiluminescence using monoclonal antibodies against RpoS, OspC, or FlaB. (C) qRT-PCR analysis of rpoS and RpoS-regulated genes in B. burgdorferi strains grown in standard BSK-II medium and harvested at late logarithmic phase.