Transcriptomic profiling of L-rhamnose utilization in Lmo0753 deletion mutant of Listeria monocytogenes EGDe from human foodborne outbreak associated lineage LII
Among the three major genetic lineages of L. monocytogenes (i.e. LI, LII, and LIII), LI and LII are predominantly associated with foodborne listeriosis outbreaks, whereas LIII is rarely implicated in human infections. In a previous study, we identified a Crp/Fnr family transcription factor lmo0753 that was highly specific to outbreak-associated LI and LII but absent from LIII. Lmo0753 shares two conserved functional domains including a DNA-binding domain with the well-characterized master virulence regulator PrfA in L. monocytogenes. In this study, we constructed a lmo0753 deletion and complementation mutants of the fully sequenced L. monocytogenes LII strain EGDe. We found that deletion of lmo0753 led to the loss of L-rhamnose utilization in EGDe. Transcriptomic comparison of the EGDe lmo0753 deletion mutant and the wild type incubated in phenol-red medium containing L-rhamnose as the sole carbon source revealed 126 (4.5%) and 546 (19.5%) out of 2,798 genes in the EGDe genome that were up- and down-regulated for more than 2-fold, respectively. Genes involved in biotin biosynthesis, general stress response and rhamnose metabolism were shown to be differentially regulated by Lmo0753.  Findings from this study may partially explain why LIII of L. monocytogenes is underrepresented in the environment and rarely associated with human listeriosis outbreaks due to the inability of rhamnose utilization. We report the transcriptomic profile of L. monocytogenes ?lmo0753 LII strain (EGDe) in broth media with L-rhamnose as the sole carbon source. Overall design: Examination of deletion of Lmo0753 on L-rhamnose utilization in L. monocytogenes. Two biological replicates per WT and ?lmo0753.