FIG. 2.
Detection of inlA transcript and InlA protein. (A) Total RNA was isolated from wild-type L. monocytogenes as well as from ΔsigB and ΔP2prfA strains, and inlA transcript levels were assayed by RT-PCR. rpoB, encoding the β subunit of the DNA-dependent RNA polymerase, was used as an internal control. No PCR products were obtained in the absence of RNA (data not shown). Lane 1, DNA markers in base pairs (bp); lane 2, wild type; lane 3, ΔsigB; lane 4, ΔP2prfA. (B) Cell wall proteins were isolated from wild-type L. monocytogenes as well as from ΔsigB, ΔP2prfA, and ΔinlA strains, and InlA was detected by Western immunoblotting. Samples were normalized for equal CFU (7.5 × 108) from each original culture. Lane 1, prestained protein markers; lane 2, wild type; lane 3, ΔsigB; lane 4, ΔP2prfA; lane 5, ΔinlA. kD, kilodaltons.