The Tat Pathway Is Prevalent in Listeria monocytogenes Lineage II and Is Not Required for Infection and Spread in Host Cells

作者：Machado Henrique; Lourenco Antonio; Carvalho Filipe; Cabanes Didier; Kallipolitis Birgitte H; Brito Luisa^*

来源：Journal of Molecular Microbiology and Biotechnology, 2013, 23(3): 209-218.

DOI：10.1159/000348245

• Listeria monocytogenes
• Tat pathway
• Foodborne pathogen
• Virulence

Listeria monocytogenes, a foodborne pathogenic bacterium, remains a serious public health concern due to its frequent occurrence in food products coupled with a high mortality rate. Bacterial pathogenicity depends greatly on the ability to secrete virulence factors to or beyond the bacterial cell surface. The Tat pathway, one of the secretion systems present in L. monocytogenes, was until now only investigated in silico. In L. monocytogenes strain EGDe two genes constitute this pathway, tatC (lmo0361) and tatA (lmo0362). Here we show that tatC and tatA are cotranscribed in a bicistronic- and growth-phase-dependent manner, being down-regulated in the stationary phase. An EGDe tatAC mutant strain (EGDe Delta tatAC) was constructed, confirming that the Tat pathway is not essential for L. monocytogenes survival or biofilm-forming ability. When compared to the wild-type EGDe, deletion of tatAC did not decrease the virulence potential of EGDe Delta tatAC in HT-29 human epithelial cell line and even increased (p %26lt; 0.05) the virulence potential for mice. Moreover, we show that tat genes are prevalent in L. monocytogenes strains belonging to genetic lineage II and are generally absent from lineage I, which is more associated with human cases, thus excluding the possibility of using the Tat system as a target for novel antimicrobial compounds targeting L. monocytogenes.

• 出版日期2013