Related Experiment Video
Updated: Jun 7, 2026

Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking
Published on: December 17, 2013
Assembly of the type II secretion system: identification of ExeA residues critical for peptidoglycan binding and
Gang Li1, Alicia Miller, Harold Bull
1Department of Microbiology and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
Abstract:
Aeromonas hydrophila secretes a number of protein toxins across the outer membrane via the type II secretion system (T2SS). Assembly of the secretion channel ExeD secretin into the outer membrane is dependent on the peptidoglycan binding domain of ExeA. In this study, the peptidoglycan binding domain PF01471 family members were divided into a prokaryotic group and a eukaryotic group. By comparison of their sequence conservation profiles and their representative crystal structures, we found the prokaryotic members to have a highly conserved pocket(s) that is not present in the eukaryotic members. Substitution mutations of nine amino acids of the pocket were constructed in ExeA. Five of the substitution derivatives showed greatly decreased lipase secretion, accompanied by defects in secretin assembly. In addition, using in vivo cross-linking and in vitro cosedimentation assays, we showed that these mutations decreased ExeA-peptidoglycan interactions. These results suggest that the highly conserved pocket in ExeA is the binding site for its peptidoglycan ligand and identify residues critical for this binding.
More Related Videos
Related Concept Videos
Gram-negative Bacterial Protein Secretion Systems
Peptidoglycan Synthesis
Bacterial Translocation and Protein Secretion
Formation of Lipopolysaccharides
Overview of Secretory Vesicles
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
Insertion of Single-pass Transmembrane Proteins in the RER
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...

