Project description:LF82, an adherent invasive Escherichia coli (AIEC) pathobiont, is associated with Crohn’s disease, an inflammatory bowel disease of unknown etiology. No genetic features have been identified that distinguish AIEC strains, such as LF82, from “commensal” or pathogenic E. coli. We investigated an extremely rare single nucleotide polymorphism (SNP) within the highly conserved rpoD gene, encoding sigma70 [primary sigma factor, RNA polymerase (RNAP)]. We demonstrate that sigma70 D445V results in transcriptome and phenotypic changes consistent with LF82 phenotypes, including increased biofilm formation and antibiotic resistance. The position of D445V within RNAP is predicted to affect spacer interaction; in vitro transcriptions reveal that the variant increases transcription from several promoters with a 16 bp spacer and a -14G:C. Our work demonstrates that a single SNP within the bacterial primary sigma can lead to myriad gene expression changes/ new phenotypes and suggests an underrecognized mechanism by which pathobionts and other strain variants can emerge.
Project description:Our aim was to identify candidate transcripts that distinguish AIEC from non-invasive E. coli (NIEC) strains and might be useful for rapid and accurate identification of AIEC by culture-independent technology. We performed comparative RNA-Sequence (RNASeq) analysis using AIEC strain LF82 and NIEC strain HS during exponential and stationary growth.
