Abstract

Enterohemorrhagic Escherichia coli (EHEC) possess the ability to respond to its surroundings though two-component systems. We hypothesized that gastrointestinal cues such as bile, iron and pH promote EHEC resistance to cationic antimicrobial peptides (CAMPs) during infection. Killing assays reveal that exposure to low pH, high iron or bile salt mixture results in increased CAMP resistance that is dependent on pmrB but independent of pmrD. Low Mg+2 -induced CAMP resistance is dependent on pmrD. pmrD promoter analysis indicate that EHEC responds to PhoPQ-inducing conditions by increasing pmrD expression. However, pmrD expression is repressed upon exposure to low acid, bile salt mix and iron. This study suggests that a complex interplay of PhoPQ, PmrAB and PmrD is involved in EHEC’s response to various microenvironmental signals and in the promotion of EHEC’s resistance to CAMPS. The results also provide intriguing evidence of both cooperation and redundancy in the mediation of CAMP resistance by these molecular players.

Highlights

  • 1.1 Overview of enterohemorrhagic Escherichia coli (EHEC)Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a member of the large family of Enterobacteriaceae

  • cationic antimicrobial peptides (CAMPs), acidic pH, high ferric iron (Fe3+), high aluminum (Al3+) or low magnesium levels are the principal signals that stimulate the expression of lipid-modifying enzymes in gram-negative bacteria, resulting in increased CAMP resistance (Kim et al 2006, Chen and Groisman 2013). These findings suggest that various sections of human gastrointestinal tract can serve as an important environmental cue for EHEC by triggering protective modifications of the bacterial outer membrane, thereby increasing resistance to human CAMPs

  • Our purpose was to look at role of signal transduction pathways, the PmrD connector protein, and how the main host environmental conditions such as high acidity, high iron and bile salt mixtures are used as signals to mount the CAMP resistance ability

Read more

Summary

Introduction

1.1 Overview of enterohemorrhagic Escherichia coli (EHEC). Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a member of the large family of Enterobacteriaceae. It is a gram-negative, non-spore-forming, rod-shaped bacterium. The strains that are associated with human diarrheal diseases are usually classified into five pathotypes: enterohemorrhagic E. coli (EHEC), enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC) (Croxen et al 2013). Among these classes, EHEC is usually the most important pathogen from public health point of view (Lim et al 2010)

Methods
Results
Discussion
Conclusion
Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.