Fig. 2.

Intracellular growth and levels of IcmQ protein after IPTG-induced gene deletion. (A) Deletion of icmQ in intracellular bacteria did not abolish the first cycle of replication. Mouse macrophages were infected with indicated strains at an MOI of 0.05 for 1 h. IPTG was then added for 5 h to a subset of samples infected with the icmQ knock-in strain. Bacterial counts at the indicated time points were determined. Data shown were from a representative of several independent experiments performed in triplicate. (B) IcmQ levels in broth-grown bacteria after gene deletion. IPTG was added to bacterial cultures at the indicated cell densities, and samples withdrawn at the indicated time points were probed for IcmQ. The cytosolic isocitrate dehydrogenase (ICDH) was probed as a loading control. (C) IcmQ levels in bacteria grown in macrophages. Lysates prepared from cells infected for 24 h were subjected to immunoprecipitation with an anti-IcmQ antibody, and SDS/PAGE-resolved samples were probed. Note that the ≈100-kDa band nonspecifically recognized by the antibody was used as a loading control.