Related Experiment Video
Updated: Jun 17, 2025

Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking
Published on: December 17, 2013
The HtrA chaperone monitors sortase-assembled pilus biogenesis in Enterococcus faecalis
Cristina Colomer-Winter1, Adeline M H Yong2,3, Kelvin K L Chong2
1Department of Microbiology and Molecular Medicine, University of Geneva, Geneva, Switzerland.
Enterococcus faecalis uses high temperature requirement A (HtrA) to clear aberrant pili. Without HtrA and sortase A (SrtA), pili accumulate, causing cell stress and altering antibiotic resistance.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Sortase-assembled pili are virulence factors in Gram-positive bacteria.
- In Enterococcus faecalis, pili polymerization (SrtC) and cell wall anchoring (SrtA) are critical.
- Aberrant pili, not anchored by SrtA, remain membrane-bound.
Purpose of the Study:
- Investigate the role of high temperature requirement A (HtrA) in E. faecalis pilus biogenesis.
- Determine the function of HtrA as a quality control system for membrane-bound pili.
- Elucidate the connection between pilus homeostasis and the CroRS two-component system.
Main Methods:
- Genetic manipulation of E. faecalis strains (ΔsrtA, ΔhtrA, ΔsrtAΔhtrA, ΔcroR).
- Analysis of pilus localization and cell envelope stress markers.
- Assessment of antibiotic resistance profiles (cephalosporins, daptomycin).
Main Results:
- HtrA functions as a chaperone/protease to clear aberrant, membrane-bound pili.
- Absence of HtrA and SrtA leads to pili accumulation, cell envelope stress, and CroRS system induction.
- CroRS inactivation partially rescues defects in the ΔsrtAΔhtrA mutant.
- Loss of SrtA and HtrA reduces resistance to cephalosporins and daptomycin.
Conclusions:
- HtrA acts as a crucial quality control mechanism for sortase-assembled pili in E. faecalis.
- Pilus mislocalization triggers cell envelope stress and activates the CroRS response system.
- This pathway impacts bacterial morphology, piliation, and antibiotic resistance.
More Related Videos
09:05High Resolution Electron Microscopy of the Helicobacter pylori Cag Type IV Secretion System Pili Produced in Varying Conditions of Iron Availability
Published on: November 21, 2014
07:14Author Spotlight: Exploring Heat Shock Proteins in Malaria and Tuberculosis Infections
Published on: March 8, 2024
Related Concept Videos
Molecular Chaperones and Protein Folding
The...
Tail-anchoring of Proteins in the ER Membrane
Export of Misfolded Proteins out of the ER
Cotranslational Protein Translocation
Sec61 channel partners for cotranslational translocation
During cotranslational translocation, the Sec61 channel partners with the signal recognition particle (SRP), the signal recognition particle receptor (SR), and the ribosomes to transport the nascent polypeptide chain...
Coat Assembly and GTPases
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Protein Translocation Machinery on the ER Membrane
Sec61 protein conducting channel
In eukaryotes, the translocon complex comprises a core heterotrimeric translocator channel called the Sec61 complex. This channel includes three transmembrane proteins, Sec61α, Sec61β, and Sec61γ, and is the largest subunit of the...