부산대학교 도서관

Listeria monocytogenes is a foodborne pathogen able to infect humans and many other mammalian species, leading to serious, often fatal disease. We have previously identified a five-gene locus in the genome of L. monocytogenes EGD-e which comprised three contiguous genes encoding paralogous type I signal peptidases. In the present study, we focused on the two distal genes of the locus (Imo1272 and Imo1273), encoding proteins sharing significant similarities with the YIqF and RnhB proteins, respectively, of Bacillus subtilis. Imo1273 could complement an Escherichia coli rnhA-rnhB thermosensitive growth phenotype, suggesting that it encodes a functional RNase H. Strikingly, inactivation of Imo1273 provoked a strong attenuation of virulence in the mouse model, and kinetic studies in infected mice revealed that multiplication of the Imo 1273 mutant in target organs was significantly impaired. However, the mutation did not impair L. monocytogenes intracellular multiplication or cell-to-cell spread in cell culture models. Transcriptional profiles obtained with an Imo1273-overexpressing strain were compared to those of the wild-type strain, using microarray analyses. The data obtained suggest a pleiotropic regulatory role of Lmo1273 and possible links with amino acid uptake.