Small RNA Regulation of Virulence in Pathogenic Escherichia coli

Abstract

Enteric and extraintestinal pathotypes of Escherichia coli utilize a wide range of virulence factors to colonize niches within the human body. During infection, virulence factors such as adhesins, secretions systems, or toxins require precise regulation and coordination to ensure appropriate expression. Additionally, the bacteria navigate rapidly changing environments with fluctuations in pH, temperature, and nutrient levels. Enteric pathogens utilize sophisticated, interleaved systems of transcriptional and post-transcriptional regulation to sense and respond to these changes and modulate virulence gene expression. Regulatory small RNAs and RNA-binding proteins play critical roles in the post-transcriptional regulation of virulence. In this review we discuss how the mosaic genomes of Escherichia coli pathotypes utilize small RNA regulation to adapt to their niche and become successful human pathogens.

Keywords: Escherichia coli; RNA-binding proteins; Shiga toxins; locus of enterocyte effacement; post-transcriptional regulation; sRNAs.

Figure 1

Post-transcriptional regulation to and from the Shiga toxin 2 phage. RNA sequencing data for the positive (top) and negative (bottom) strands are shown. Transcription start sites identified using differential RNA-seq (dRNA-seq) are indicated in green (GEO accession GSE143631). RNA 3’ends identified using Term-seq are indicated in purple. Hfq and RNase E-binding data from UV-crosslinking and sequencing experiments are shown in orange and blue, respectively (GEO accession GSE46118 and GSE77463). Regulatory RNAs encoded by the phage are indicated using outward arrows. Direct targets are indicated using solid line arrows, while dashed lines show indirect or unknown mechanisms of action.

Figure 2

Post-transcriptional regulation of the locus of enterocyte effacement. RNA sequencing data for the positive (top) and negative (bottom) strands are shown. Transcription start sites identified using differential RNA-seq (dRNA-seq) are indicated in green (GEO accession GSE143631). RNA 3’ends identified using Term-seq are indicated in purple (GEO accession GSE14363). Hfq and RNase E-binding data from UV-crosslinking and sequencing experiments are shown in orange and blue, respectively (GEO accession GSE46118 and GSE77463). Direct targets for post-transcriptional regulators are pointed to by solid black arrows, while indirect targets are indicated with dashed lines.