The effect of two ribonucleases on the production of Shiga toxin and stx-bearing bacteriophages in Enterohaemorrhagic Escherichia coli

Patricia B Lodato

doi:10.1038/s41598-021-97736-z

Abstract

Enterohaemorrhagic Escherichia coli (EHEC) comprise a group of intestinal pathogens responsible for a range of illnesses, including kidney failure and neurological compromise. EHEC produce critical virulence factors, Shiga toxin (Stx) 1 or 2, and the synthesis of Stx2 is associated with worse disease manifestations. Infected patients only receive supportive treatment because some conventional antibiotics enable toxin production. Shiga toxin 2 genes (stx2) are carried in λ-like bacteriophages (stx2-phages) inserted into the EHEC genome as prophages. Factors that cause DNA damage induce the lytic cycle of stx2-phages, leading to Stx2 production. The phage Q protein is critical for transcription antitermination of stx2 and phage lytic genes. This study reports that deficiency of two endoribonucleases (RNases), E and G, significantly delayed cell lysis and impaired production of both Stx2 and stx2-phages, unlike deficiency of either enzyme alone. Moreover, scarcity of both enzymes reduced the concentrations of Q and stx2 transcripts and slowed cell growth.

Highlights

Enterohaemorrhagic Escherichia coli (EHEC) comprise a group of intestinal pathogens responsible for a range of illnesses, including kidney failure and neurological compromise
We previously reported the construction of an EHEC strain in which reports that deficiency of two endoribonucleases (RNases) E synthesis is controlled by addition of a chemical to the culture medium[49]
To induce the stx2-phage lytic cycle, cultures of the TEA028 parental strain and its RNase E and G derivatives were treated with subinhibitory concentrations of mitomycin C (MMC) (1 μg/mL)

Summary

Introduction

Enterohaemorrhagic Escherichia coli (EHEC) comprise a group of intestinal pathogens responsible for a range of illnesses, including kidney failure and neurological compromise. EHEC produce critical virulence factors, Shiga toxin (Stx) 1 or 2, and the synthesis of Stx[2] is associated with worse disease manifestations. Factors that cause DNA damage induce the lytic cycle of stx2-phages, leading to Stx[2] production. This study reports that deficiency of two endoribonucleases (RNases), E and G, significantly delayed cell lysis and impaired production of both Stx[2] and stx2-phages, unlike deficiency of either enzyme alone. Scarcity of both enzymes reduced the concentrations of Q and stx[2] transcripts and slowed cell growth. In vivo studies indicate that other antibiotics (e.g., rifaximin, azithromycin) do not trigger the synthesis of toxin in certain Stx-producing E. coli[33,34,35,36]

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