OppA of Listeria monocytogenes, an oligopeptide-binding protein required for bacterial growth at low temperature and involved in intracellular survival

We identified a new oligopeptide permease operon in the pathogen Listeria m onocytogenes. This opp operon consists of five genes (oppA, oppB, oppC, opp D, and oppF) and displays the same genetic organization as those of several bacterial species. The first gene of this operon, oppA, encodes a 62-kDa p rotein sharing 33% identity with OppA of Bacillus subtilis and is expressed predominantly during exponential growth. The function of oppA was studied by constructing an oppA deletion mutant. The phenotype analysis of this mut ant revealed that OppA mediates the transport of oligopeptides and is requi red for bacterial growth at low temperature. The wild-type phenotype was re stored by complementing the mutant with oppA, We also found that OppA is in volved in intracellular survival in macrophages and in bacterial growth in organs of mice infected with L. monocytogenes, although the level of virule nce was not altered in the mutant. These results show the major role of Opp A in the uptake of oligopeptides and the pleiotropic effects of this oligop eptide-binding protein on the behavior of this pathogen in the environment and in its host.