Host-derived O-glycans inhibit toxigenic conversion by a virulence-encoding phage in Vibrio cholerae

Pandemic and endemic strains of Vibrio cholerae arise from toxigenic conversion by the CTXf bacteriophage, a process by which CTXf infects non-toxigenic strains of V. cholerae. CTXf encodes the cholera toxin, an enterotoxin responsible for the watery diarrhea associated with cholera infections. Despite the critical role of CTXf during infections, signals that affect CTXf-driven toxigenic conversion or expression of the CTXf-encoded cholera toxin remain poorly characterized, particularly in the context of the gut mucosa. Here, we identify mucin polymers as potent regulators of CTXf-driven pathogenicity in V. cholerae. Our results indicate that mucin-associated O-glycans block toxigenic conversion by CTXf and suppress the expression of CTXf-related virulence factors, including the toxin co-regulated pilus and cholera toxin, by interfering with the TcpP/ToxR/ToxT virulence pathway. By synthesizing individual mucin glycan structures de novo, we identify the Core 2 motif as the critical structure governing this virulence attenuation. Overall, our results highlight a novel mechanism by which mucins and their associated O-glycan structures affect CTXf-mediated evolution and pathogenicity of V. cholerae, underscoring the potential regulatory power housed within mucus. Overall design: We performed RNA-seq to identify changes in gene expression in V. cholerae in response to a purified pool of mucin glycans. Comparative RNA-seq comparing +/- mucin glycans