Agitation down-regulates immunoglobulin binding protein EibG expression in Shiga toxin-producing Escherichia coli (STEC).

Thorsten Kuczius,Wenlan Zhang,Alexander Mellmann,Helge Karch,Phillip I Tarr,Viktor Merkel

doi:10.1371/journal.pone.0119583

Thorsten Kuczius, Wenlan Zhang + Show 4 more

Open Access

https://doi.org/10.1371/journal.pone.0119583

Copy DOI

Abstract

Shiga toxin (Stx)-producing Escherichia coli (STEC) carrying eibG synthesize Escherichia coli immunoglobulin binding protein (EibG). EibG nonspecifically binds to immunoglobulins and tends to aggregate in multimers but is poorly expressed in wild-type strains. To study synthesis of the proteins and their regulation in the pathogens, we identified natural growth conditions that increased EibG synthesis. EibG proteins as well as corresponding mRNA were highly expressed under static growth conditions while shearing stress created by agitation during growth repressed protein synthesis. Further regulation effects were driven by reduced oxygen tension, and pH up-regulated EibG expression, but to a lesser extent than growth conditions while decreased temperature down-regulated EibG. Bacteria with increased EibG expression during static growth conditions showed a distinct phenotype with chain formation and biofilm generation, which disappeared with motion. High and low EibG expression was reversible indicating a process with up- and down-regulation of the protein expression. Our findings indicate that shear stress represses EibG expression and might reduce bacterial attachments to cells and surfaces.

Highlights

Bacterial surface proteins that interact with immunoglobulins from different mammalian species in a non-immune manner have been described for many species [1]
Increased Escherichia coli immunoglobulin binding protein (EibG) expression was observed under microaerophilic growth conditions, less intense signals were detected with aerobic growth, and only very faint bands were visible with anaerobic growth
We demonstrated that EibG protein expression in E. coli is mainly influenced by static and agitated growth conditions

Summary

Introduction

Bacterial surface proteins that interact with immunoglobulins from different mammalian species in a non-immune manner have been described for many species [1]. Proteins A and G synthesized by staphylococci and streptococci have well characterized immunoaffinity phenotypes [2, 3], and immunoglobulin binding proteins are found in pathogens such as Aeromonas [4, 5], Pseudomonas [6] and Yersinia species [7]. EibG high and low expression by strains is reversible, whereby up- and down-regulation is mainly affected by static growth or cell motion, respectively. This regulatory process might influence bacterial community phenotype as chain formation and interactions with eukaryotic cells

Materials and Methods

Results

Discussion