Listeria monocytogenes Wall Teichoic Acid Glycosylation Promotes Surface Anchoring of Virulence Factors, Resistance to Antimicrobial Peptides, and Decreased Susceptibility to Antibiotics

Abstract

The cell wall of Listeria monocytogenes (Lm), a major intracellular foodborne bacterial pathogen, comprises a thick peptidoglycan layer that serves as a scaffold for glycopolymers such as wall teichoic acids (WTAs). WTAs contain non-essential sugar substituents whose absence prevents bacteriophage binding and impacts antigenicity, sensitivity to antimicrobials, and virulence. Here, we demonstrated, for the first time, the triple function of Lm WTA glycosylations in the following: (1) supporting the correct anchoring of major Lm virulence factors at the bacterial surface, namely Ami and InlB; (2) promoting Lm resistance to antimicrobial peptides (AMPs); and (3) decreasing Lm sensitivity to some antibiotics. We showed that while the decoration of WTAs by rhamnose in Lm serovar 1/2a and by galactose in serovar 4b are important for the surface anchoring of Ami and InlB, N-acetylglucosamine in serovar 1/2a and glucose in serovar 4b are dispensable for the surface association of InlB or InlB/Ami. We found that the absence of a single glycosylation only had a slight impact on the sensibility of Lm to AMPs and antibiotics, however the concomitant deficiency of both glycosylations (rhamnose and N-acetylglucosamine in serovar 1/2a, and galactose and glucose in serovar 4b) significantly impaired the Lm capacity to overcome the action of antimicrobials. We propose WTA glycosylation as a broad mechanism used by Lm, not only to properly anchor surface virulence factors, but also to resist AMPs and antibiotics. WTA glycosyltransferases thus emerge as promising drug targets to attenuate the virulence of bacterial pathogens, while increasing their susceptibility to host immune defenses and potentiating the action of antibiotics.

Whole Genome Sequence Analysis of Phage-Resistant Listeria monocytogenes Serotype 1/2a Strains from Turkey Processing Plants

“…The resulting resistance to phage may contribute to the apparent FPE persistence of the ST321 and ST391 strains investigated here, which were closely related and recovered from the same FPE over more than two years. However, in addition to serving as phage receptors, WTA glycosylation is increasingly recognized for its importance in other functions including surface adhesion, biofilm formation, anchoring of virulence determinants to the cell surface and resistance to antimicrobial peptides [ 14 , 19 , 47 , 48 , 49 ]. It will be of interest to investigate such potential trade-offs with the strains investigated here and other FPE-derived phage-resistant strains of serotype 1/2a.…”

Listeria innocua isolated from diseased ruminants harbour minor virulence genes of L. monocytogenes

“…Taking into account our results, we wonder if the genes identified in VFDB (Figure 1 ) could provide the molecular basis to explain the pathogenic behaviour of the isolates of this work. Some of these genes have been reported in L. monocytogenes and other Gram‐positive bacteria, individually associated with roles in virulence and/or pathogenicity (Burkholder & Bhunia, 2010 ; Forster et al., 2011 ; Keeney et al., 2007 ; Meireles et al., 2020 ; Osanai et al., 2013 ; Rae et al., 2011 ; Réglier‐Poupet et al., 2003a,b ; Vázquez‐Boland et al., 2001 ). At least 5 of the 13 virulence genes found encode proteins related to bacterial adhesion to, and/or invasion into mammalian cells.…”

“…The gtcA gene encodes an enzyme that catalyses teichoic acid glycosylation on L. monocytogenes wall. Proper glycosylation mediates key pathogenicity features: the correct anchoring of major surface virulence factors (Ami e InlB); resistance to antimicrobial peptides and decreased susceptibility to antibiotics (Meireles et al., 2020 ). The second gene present is prsA2 , which encodes a peptidyl prolyl cis‐trans isomerase that assists in correct protein folding.…”

Nanotechnology-Based Delivery Systems for Antimicrobial Peptides

“…Studies have reported specific microbial resistance and their mechanisms against AMPs [117][118][119][120][121][122][123]. Pathogens can rapidly evolve and confer resistance to AMPs in vitro [124].…”