lmo1273, a novel gene involved in Listeria monocytogenes virulence

Abstract

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 (lmo1272 and lmo1273), encoding proteins sharing significant similarities with the YlqF and RnhB proteins, respectively, of Bacillus subtilis. lmo1273 could complement an Escherichia coli rnhA-rnhB thermosensitive growth phenotype, suggesting that it encodes a functional RNase H. Strikingly, inactivation of lmo1273 provoked a strong attenuation of virulence in the mouse model, and kinetic studies in infected mice revealed that multiplication of the lmo1273 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 lmo1273-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.

Replication-Transcription Conflicts Generate R-Loops that Orchestrate Bacterial Stress Survival and Pathogenesis

“…RNase HIII is categorized as a type 2 RNase H due to homology to RNase HII, but its activity is more similar to RNase HI (Ohtani et al, 1999b). In the Grampositive model bacterium Bacillus subtilis ( B. subtilis ) and most of its close relatives including important pathogens such as Listeria monocytogenes ( L. monocytogenes ) there are functional (or putative) RNase HII and HIII enzymes, encoded by the genes rnhB and rnhC , respectively (Bigot et al, 2009; Itaya et al, 1999; Ohtani et al, 1999b). B. subtilis encodes two genes, ypeP and ypdQ , that are annotated to be in the RNase HI family of enzymes, though it is unclear whether these genes encode functional RNase HI enzymes (Fukushima et al, 2007; Itaya et al, 1999; Itaya et al, 1999; Ohtani et al, 1999b).…”

Deep impact of the inactivation of the SecA2-only protein export pathway on the proteosurfaceome of Listeria monocytogenes

“…As already mentioned for AppA involved in vacuolar escape [36], OppA is the LP component of an oligopeptide ABC transport system and is also required for the virulence of L. monocytogenes as it is involved in intracellular survival, intracytoplasmic multiplication in macrophages and phagosomal escape [65]. Upon gene deletion, which resulted in attenuated virulence in mouse model, GlnP was also demonstrated to play a role in virulence by inducing immune response during intracellular growth in macrophages [77,78]. While Sod [39] and FbpA [79] 20 could not be presently identified in the proteosurfaceome, Lap [40,41] and TcsA [66], together with OppA, were previously described as SecA2-dependent virulence factors in L. monocytogenes.…”

The Role of Ribonucleases and sRNAs in the Virulence of Foodborne Pathogens

“…Interestingly, overexpression of this protein also attenuates virulence, which means that Imo1273 is expressed in an appropriate level to promote an efficient infection (Bigot et al, 2009). As such, Imo1273 seems a good target to be further studied to control L. monocytogenes virulence.…”