title: L-Rhamnosylation of Listeria monocytogenes Wall Teichoic Acids Promotes Resistance to Antimicrobial Peptides by Delaying Interaction with the Membrane.
abstract: Listeria monocytogenes is an opportunistic Gram-positive bacterial pathogen responsible for listeriosis, a human foodborne disease. Its cell wall is densely decorated with wall teichoic acids (WTAs), a class of anionic glycopolymers that play key roles in bacterial physiology, including protection against the activity of antimicrobial peptides (AMPs). In other Gram-positive pathogens, WTA modification by amine-containing groups such as D-alanine was largely correlated with resistance to AMPs. However, in L. monocytogenes, where WTA modification is achieved solely via glycosylation, WTA-associated mechanisms of AMP resistance were unknown. Here, we show that the L-rhamnosylation of L. monocytogenes WTAs relies not only on the rmlACBD locus, which encodes the biosynthetic pathway for L-rhamnose, but also on rmlT encoding a putative rhamnosyltransferase. We demonstrate that this WTA tailoring mechanism promotes resistance to AMPs, unveiling a novel link between WTA glycosylation and bacterial resistance to host defense peptides. Using in vitro binding assays, fluorescence-based techniques and electron microscopy, we show that the presence of L-rhamnosylated WTAs at the surface of L. monocytogenes delays the crossing of the cell wall by AMPs and postpones their contact with the listerial membrane. We propose that WTA L-rhamnosylation promotes L. monocytogenes survival by decreasing the cell wall permeability to AMPs, thus hindering their access and detrimental interaction with the plasma membrane. Strikingly, we reveal a key contribution of WTA L-rhamnosylation for L. monocytogenes virulence in a mouse model of infection.
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal.
authors.forename: Filipe
authors.initials: F
authors.lastname: Carvalho
authors.affiliation: Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: Magda L
authors.initials: ML
authors.lastname: Atilano
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal.
authors.forename: Rita
authors.initials: R
authors.lastname: Pombinho
authors.affiliation: Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: Gonçalo
authors.initials: G
authors.lastname: Covas
authors.affiliation: Division of Dermatology, Department of Medicine, University of California San Diego, San Diego, California, United States of America.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Gallo
authors.affiliation: Laboratory of Bacterial Cell Surfaces and Pathogenesis, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: Sérgio R
authors.initials: SR
authors.lastname: Filipe
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Porto, Portugal.
authors.forename: Sandra
authors.initials: S
authors.lastname: Sousa
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Porto, Portugal.
authors.forename: Didier
authors.initials: D
authors.lastname: Cabanes
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D002478:Cells, Cultured; D024881:Drug Resistance, Bacterial / Q000187:drug effects*; D006031:Glycosylation; D006801:Humans; D008089:Listeria monocytogenes / Q000502:physiology*; D008088:Listeriosis / Q000188:drug therapy / Q000382:microbiology*; D008264:Macrophages / Q000187:drug effects / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D012210:Rhamnose / Q000737:chemistry*; D013682:Teichoic Acids / Q000494:pharmacology*; D014774:Virulence
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D013682:Teichoic Acids; D012210:Rhamnose