[ODP-002] Sequence mutations in Vibrio cholerae hapR affect gene function and biofilm formation
Vibrio cholerae, the causative agent of cholera, is a waterborne pathogen capable of causing human infections. The HapR, a transcriptional regulator involved in quorum sensing, is directly involved in the regulation of the secreted hemagglutinin (HA)/protease that acts as a “detachase” during colonization. It represses AphA which actively regulates biofilm formation. It was previously reported that sequence polymorphisms in this regulator affects the biofilm formation/dispersion of V. cholerae biofilms. Thus, the current study aimed to provide further elucidation on the hapR phylogeny and the influence of hapR mutations on the biofilm formation of V. cholerae. Phylogenetic analysis confirmed two major hapR haplogroups. Moreover, a hypothetical hapR ancestral sequence was observed from a constructed haplotype network. Neutrality test between the haplogroups revealed that the evolution of hapR2 was attributed to a recent selective sweep and population expansion. Higher nucleotide and haplotype diversity indices were observed in hapR1, while insertion/deletion occurred dominantly in hapR2. Terminal deletion or frameshift mutants showed significantly higher biofilms and lower hapA gene expression. In the current study, sequence mutations that lead to the disruption on the transcription factor-binding sites or HapR dimerization could result in a robust biofilm of V. cholerae.