Basic Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Infect Dis. May 15, 2020; 10(1): 14-23
Published online May 15, 2020. doi: 10.5495/wjcid.v10.i1.14
GadE regulates fliC gene transcription and motility in Escherichia coli
William R Schwan, Nicole L Flohr, Abigail R Multerer, Jordan C Starkey
William R Schwan, Nicole L Flohr, Abigail R Multerer, Jordan C Starkey, Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI 54601, United States
Author contributions: Schwan WR, Flohr NL, Multerer AR, and Starkey JC designed the research, performed the research; Schwan WR, Flohr NL, and Multerer AR analyzed the data; Schwan WR wrote the paper.
Supported by the National Institutes of Health, No. 1R15AI-065432.
Institutional review board statement: No humans or samples from human were used in this study.
Institutional animal care and use committee statement: No animals were used in this study.
Conflict-of-interest statement: The authors report no conflict of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: William R Schwan, PhD, Professor, Department of Microbiology, University of Wisconsin-La Crosse, 1725 State St, La Crosse, WI 54601, United States.
Received: February 7, 2020
Peer-review started: February 7, 2020
First decision: March 5, 2020
Revised: March 25, 2020
Accepted: May 5, 2020
Article in press: May 5, 2020
Published online: May 15, 2020
Research background

Uropathogenic Escherichia coli (UPEC) is the number one cause of urinary tract infection in women. Motility driven by the action of flagella is critical for UPEC pathogenesis. How Escherichia coli (E. coli) adapts to a low pH/high osmolarity environment is essential for the species survival. Acid tolerance systems, such as the System two system, are important for UPEC survival in a low pH environment.

Research motivation

Our key problem to be solved was whether GadE, a part of the acid response two system, regulates transcription of the fliC gene, and in turn, UPEC motility.

Research objectives

Determine whether GadE regulated fliC transcription and subsequent motility of the E. coli.

Research methods

We created a fliC-lacZ reporter system on a single-copy number plasmid and measured b-galactosidase levels in both a K-12 and UPEC clinical isolate. Furthermore, motility was assessed in both E. coli strains by inoculating wild-type, gadE mutant, and complemented gadE mutant strains onto motility agar.

Research results

Transcription of fliC was significantly lower in E. coli grown in pH 5.5 Luria Bertani compared to pH 7.0 Luria Bertani. A mutation in the gadE gene led to higher fliC expression in that strain vs wild-type bacteria. Motility was significantly higher in the gadE mutant strain compared to the wild-type strain.

Research conclusions

We confirmed that fliC transcription was down-regulated in E. coli grown in a low pH/high osmolarity environment compared to a neutral pH/low osmolarity environment. GadE appears to either directly or indirectly regulate fliC transcription in E. coli.

Research perspectives

Future work could be done to affirm the GadE regulation of flagella expression in E. coli.