Compensatory Evolution of pbp Mutations Restores the Fitness Cost Imposed by β-Lactam Resistance in Streptococcus pneumoniae
Figure 5
Stability in vivo of wild-type and mutant PBPs.
Strains Cp1015 (Panel A), Cp1015 pbp2b28 (Panel B) and Cp1015 pbp2b28pbp2x28 pbp1a28 (Panel C) expressing HA-tagged PBPs were grown in Todd Hewitt broth with 0.5% Yeast Extract to an OD600 nm of 0.2 prior to the addition of kanamycin (500 µg/ml) to inhibit protein synthesis. At the time intervals indicated, aliquots were withdrawn and analyzed by SDS-PAGE followed by immunoblotting with an anti-HA monoclonal antibody (see Material and Methods).