Related Experiment Video
Updated: Jul 18, 2026

A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
Published on: February 19, 2019
A positive feedback loop promotes transcription surge that jump-starts Salmonella virulence circuit
Dongwoo Shin1, Eun-Jin Lee, Henry Huang
1Department of Molecular Microbiology, Howard Hughes Medical Institute, Washington University School of Medicine, Campus Box 8230, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
Abstract:
The PhoP/PhoQ two-component system is a master regulator of Salmonella pathogenicity. Here we report that induction of the PhoP/PhoQ system results in an initial surge of PhoP phosphorylation; the occupancy of target promoters by the PhoP protein; and the transcription of PhoP-activated genes, which then subsides to reach new steady-state levels. This surge in PhoP activity is due to PhoP positively activating its own transcription, because a strain constitutively expressing the PhoP protein attained steady-state levels of activation asymptotically, without the surge. The strain constitutively expressing the PhoP protein was attenuated for virulence in mice, demonstrating that the surge conferred by PhoP's positive feedback loop is necessary to jump-start Salmonella's virulence program.
More Related Videos
10:57NF-κB-dependent Luciferase Activation and Quantification of Gene Expression in Salmonella Infected Tissue Culture Cells
Published on: January 12, 2020
11:10High-throughput Assay to Phenotype Salmonella enterica Typhimurium Association, Invasion, and Replication in Macrophages
Published on: August 11, 2014
Related Concept Videos
Regulation of Bacterial Virulence
Cell Signaling Feedback Loops
Negative feedback loops
Most signaling systems have negative feedback loops that can perform different functions such as output limiter, and adaptation.
Output limiter
Upon receiving an input signal, the cellular response rapidly increases until a threshold is reached. Beyond this threshold, a negative feedback loop...
Positive and Negative Feedback Loops
Prokaryotic Transcriptional Activators and Repressors
Transcription of prokaryotic...
Prokaryotic Transcriptional Activators and Repressors
Transcription of prokaryotic...
Gene Regulation in Microbial Communities: Quorum Sensing