Overexpression of Outer Membrane Protein X (OmpX) Compensates for the Effect of TolC Inactivation on Biofilm Formation and Curli Production in Extraintestinal Pathogenic Escherichia coli (ExPEC).

Binyou Li,Mei Liu,Xianrong Meng,Qi Huang,Liyuan Zhang,Shaowen Li,Xueling Liu,Bo Hou,Ailian Cui

doi:10.3389/fcimb.2018.00208

Abstract

Our previous study showed that the inactivation of the efflux pump TolC could abolish biofilm formation and curli production of extraintestinal pathogenic Escherichia coli (ExPEC) strain PPECC42 under hyper-osmotic conditions. In this study we investigated the role of OmpX in biofilm formation and curli production of ExPEC PPECC42. Our data showed that OmpX disruption or overexpression didn't significantly affect the biofilm formation and curli production of the wild-type strain. However, in the tolC-deleted mutant, overexpressing OmpX suppressed the effect of TolC inactivation on ExPEC biofilm formation and curli production under hyper-osmotic growth conditions. Real-time qRT-PCR confirmed that OmpX overexpression affected curli production by regulating the transcription of the curli biosynthesis-related genes in the ΔtolC strain. Our findings suggest that OmpX is involved in biofilm formation and curli production.

Highlights

Extraintestinal pathogenic Escherichia coli (ExPEC) are a sub group of pathogenic E. coli strains causing a variety of infections and diseases at extraintestinal sites in humans and animals, which are typically characterized by multi-organ infections including urinary tract infections, meningitis, polyserositis, and septicemia (Johnson and Russo, 2005; Smith et al, 2007; Köhler and Dobrindt, 2011; Manges and Johnson, 2012; Mitchell et al, 2015)
The growth curves of each strain were determined in Lysogeny broth (LB) medium, M9 minimal medium, and 1/2 M9 minimal medium, and the results showed that all the strains presented a similar growth pattern to the WT strain (Figures 1B–D), indicating that outer membrane protein X (OmpX) inactivation and overexpression do not significantly affect the growth of extraintestinal pathogenic Escherichia coli (ExPEC)
We investigated the effect of OmpX deletion and overexpression on biofilm formation of ExPEC

Summary

Introduction

Extraintestinal pathogenic Escherichia coli (ExPEC) are a sub group of pathogenic E. coli strains causing a variety of infections and diseases at extraintestinal sites in humans and animals, which are typically characterized by multi-organ infections including urinary tract infections, meningitis, polyserositis, and septicemia (Johnson and Russo, 2005; Smith et al, 2007; Köhler and Dobrindt, 2011; Manges and Johnson, 2012; Mitchell et al, 2015). ExPEC strains were frequently isolated from clinical samples of pigs (Ding et al, 2012). They were widely found in pork, retail chicken, beef, and ready-to-eat foods, which pose a potential threat to public health (Lyhs et al, 2012; Aslam et al, 2014; Mitchell et al, 2015). Biofilms can serve as a physical barrier to protect bacteria from eradication by the host immune defense system (Donlan and Costerton, 2002), and are considered to be an important virulence factor in ExPEC (Magistro et al, 2015). Exploration of the role of biofilm formation in pathogenesis and virulence is important in investigating factors that influence biofilm formation and for addressing means to prevent or inhibit/eradicate biofilms in the production and human settings

Methods

Results

Conclusion