The multicopy sRNA LhrC controls expression of the oligopeptide-binding protein OppA in Listeria monocytogenes

All three genes encode membrane-associated proteins: A putative substrate binding protein of an amino acid ABC transporter (Lmo2349); the CD4+ T cell-stimulating antigen TcsA, and the oligopeptide binding protein OppA, of which the latter two are required for full virulence of L. monocytogenes . For OppA, we show that LhrC acts by direct base paring to the ribosome binding site of the oppA mRNA, leading to an impediment of its translation and a decreased mRNA level.

The sRNA-mRNA interaction depends on two of three CU-rich regions in LhrC allowing binding of two oppA mRNAs to a single LhrC molecule. Finally, we found that LhrC contributes to infection in macrophage-like cells. These findings demonstrate a central role for LhrC in controlling the level of OppA and other virulence-associated cell envelope proteins in response to cell envelope stress.