Dual glycosylation of wall teichoic acid modulates the O-antigen pattern and virulence in serovar 4b Listeria monocytogenes.

Abstract

Among the 14 serovars of Listeria monocytogenes (Lm), serovar 4b strains are the most predominant isolates linked to human listeriosis outbreaks-a phenotype associated with their unique wall teichoic acid (WTA) decorated with galactose (Gal) and glucose (Glu). A wealth of knowledge is available for galactosylated-WTA (Gal-WTA) manipulating bacterial homeostasis and virulence, whereas the relationship between glucosylated-WTA (Glu-WTA) and Gal-WTA in listerial physiology and pathogenesis remains unclear. Here, we find that Glu-WTA and Gal-WTA jointly constitute the O-antigen pattern of serovar 4b Lm; however, Glu-WTA specifically serves as the indispensable ligand for listeriophage LP4 adsorption. Moreover, the co-operation between Glu- and Gal-WTA increases biofilm formation and bacterial resistance to cationic antimicrobial peptide (CRAMP). We further demonstrate that Gal-WTA modulates the anchoring of surface proteins, including IspC, Ami, and InlB. Additionally, dual glycosylated WTA interaction with ActA facilitates bacterial intracellular motility and dissemination. Consistently, Glu-WTA significantly enhances bacterial colonization ability in the mesenteric lymph nodes (MLNs), ileum, liver, and brain of mouse, cooperating with Gal-WTA to facilitate Lm dissemination to distant organs and tissues. In conclusion, we reveal the crucial roles of Glu-WTA in synergizing with Gal-WTA to modulate the integrity of the cell wall structure and exacerbate bacterial infection, providing a global understanding of the hypervirulence and pathogenicity of invasive serovar 4b Lm.