The role of TarA in regulating gene expression and physiological processes in Vibrio cholerae

Abstract

Vibrio cholerae causes the diarrheal disease cholera. The pathogen is a particular problem in countries where water quality measures are lacking. Two virulence factors are required for disease: cholera toxin, and toxin-co-regulated pilus, regulated by the transcriptional activator ToxT. In addition, ToxT activates transcription of a small RNA (tarA). TarA controls glucose uptake by negatively regulating expression of ptsG, a major glucose transporter. Objective: We hypothesize that TarA regulates other transcripts. Methods: To test this, we used a deep-sequencing based transcriptomic approach (RNAseq), comparing expression of RNAs in wild-type V. cholerae, and a deletion strain lacking tarA. RNA was isolated from cells grown under toxin inducing conditions. cDNA libraries were prepared and sequenced on an Illumina platform. To complement our RNAseq study, we assessed physiological growth differences between wild-type and DtarA using BioLog phenotype arrays. Results: Deep sequencing of mRNA transcripts revealed differentially expressed transcripts in DtarA compared to wild-type V. cholerae, including those for amino acid biosynthesis (ilvY, argF), sugar transport (mshD, manA), and metal transport (znuACB). Additionally, we observed growth differences corresponding to sugars (glucose, glycerol, and fructose) and amino acids (glutamic acid, proline, and aspartic acid). This suggests that TarA may be involved in regulating many metabolic processes. Further study of the mechanism by which TarA controls gene expression is needed to fully understand its role in V. cholerae growth and pathogenesis. Research Supported by NIH NIAID AI045125; UMICH SROP