Bacteriophage predation promotes serovar diversification in Listeria monocytogenes

• Published in: Molecular microbiology Vol. 97; no. 1; pp. 33 - 46
• Main Authors: Eugster, Marcel R., Morax, Laurent S., Hüls, Vanessa J., Huwiler, Simona G., Leclercq, Alexandre, Lecuit, Marc, Loessner, Martin J.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.07.2015
• Subjects: Acetylglucosamine - metabolism; Antigens; Bacteriophages - genetics; Bacteriophages - physiology; Biological variation; Cell Wall - chemistry; Cell Wall - genetics; Cell Wall - metabolism; Evolutionary biology; Genetic Complementation Test; Genetic Variation; Genotype & phenotype; Glycosylation; Gram-positive bacteria; Listeria monocytogenes - classification; Listeria monocytogenes - genetics; Listeria monocytogenes - virology; Molecular Sequence Data; Mutation; Nucleoside Diphosphate Sugars - genetics; Phenotype; Point Mutation; Rhamnose - metabolism; Serogroup; Serotyping; Teichoic Acids - genetics; Teichoic Acids - metabolism; Thymine Nucleotides - genetics
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/mmi.13009

Summary Listeria monocytogenes is a bacterial pathogen classified into distinct serovars (SVs) based on somatic and flagellar antigens. To correlate phenotype with genetic variation, we analyzed the wall teichoic acid (WTA) glycosylation genes of SV 1/2, 3 and 7 strains, which differ in decoration of the ribitol‐phosphate backbone with N‐acetylglucosamine (GlcNAc) and/or rhamnose. Inactivation of lmo1080 or the dTDP‐l‐rhamnose biosynthesis genes rmlACBD (lmo1081–1084) resulted in loss of rhamnose, whereas disruption of lmo1079 led to GlcNAc deficiency. We found that all SV 3 and 7 strains actually originate from a SV 1/2 background, as a result of small mutations in WTA rhamnosylation and/or GlcNAcylation genes. Genetic complementation of different SV 3 and 7 isolates using intact alleles fully restored a characteristic SV 1/2 WTA carbohydrate pattern, including antisera reactions and phage adsorption. Intriguingly, phage‐resistant L. monocytogenes EGDe (SV 1/2a) isolates featured the same glycosylation gene mutations and were serotyped as SV 3 or 7 respectively. Again, genetic complementation restored both carbohydrate antigens and phage susceptibility. Taken together, our data demonstrate that L. monocytogenes SV 3 and 7 originate from point mutations in glycosylation genes, and we show that phage predation represents a major driving force for serovar diversification and evolution of L. monocytogenes. We identified the genetic factors responsible for glycosylation of Listeria monocytogenes wall teichoic acids. Loss of rhamnose and/or GlcNAc by small mutations transforms serovar 1/2 strains into SV 3 or 7, which can be reverted by complementation. Our data demonstrate that these modifications are introduced by phage predation, which appears to be the major driving force for serovar diversification and evolution in Listeria.