Related Experiment Video
Updated: Nov 3, 2025
13:11
Super-Resolution Imaging of Bacterial Secreted Proteins Using Genetic Code Expansion
Published on: February 10, 2023
1.7K
α-Helices in the Type III Secretion Effectors: A Prevalent Feature with Versatile Roles
Anastasia D Gazi1, Michael Kokkinidis2,3, Vasiliki E Fadouloglou4
1Unit of Technology & Service Ultrastructural Bio-Imaging (UTechS UBI), Institut Pasteur, 75015 Paris, France.
International Journal of Molecular Sciences
|June 2, 2021
Summary
Type III Secretion Systems (T3SSs) deliver bacterial proteins into host cells. This review details how Type III Secretion Effectors (T3SEs) utilize unique protein folds, particularly alpha-helices, to manipulate host functions.
Area of Science:
- Microbiology
- Molecular Biology
- Structural Biology
Background:
- Type III Secretion Systems (T3SSs) are complex molecular machines in Gram-negative bacteria.
- T3SSs translocate bacterial proteins, known as effectors (T3SEs), into eukaryotic host cells.
Purpose of the Study:
- To review the diverse protein folds of T3SEs.
- To highlight the structural and functional significance of alpha-helices and helical domains in T3SEs.
Main Methods:
- Literature review of T3SS and T3SE structure-function relationships.
- Analysis of T3SE protein folding and unfolding mechanisms for translocation.
Main Results:
- T3SEs possess unique folds enabling unfolding for passage through the T3SS channel and refolding for activity.
- Alpha-helices and helical domains are crucial for T3SE function and host cell manipulation.
- T3SEs mimic eukaryotic proteins to hijack cellular processes, impacting host metabolism and defense.
Conclusions:
- The structural adaptability of T3SEs, particularly their helical elements, is key to their function.
- Understanding T3SE folds provides insights into bacterial pathogenesis and host-pathogen interactions.
Related Concept Videos
01:28Fimbriae, Pili, and Axial Filaments
841
Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
841
01:17Gram-negative Bacterial Protein Secretion Systems
297
Gram-negative bacteria utilize sophisticated protein secretion systems to transport proteins across their double-membrane envelope into the extracellular environment or host cells. Based on their mechanism of action, these systems are classified into one-step and two-step pathways.One-Step Secretion Systems (Types I, III, IV, and VI)One-step secretion systems bypass the periplasm entirely, forming a continuous channel that spans both the inner and outer membranes:Type I Secretion System (T1SS):...
297
00:55DNA Helicases
22.9K
DNA unwinding helicase enzymes are a type of motor protein. Motor proteins can translocate along filaments or polymers using energy generated from ATP hydrolysis. Helicases are involved in all the important cellular processes where DNA unwinding is required, such as DNA replication, repair, recombination, and transcription. They are present in all living organisms, but vary in their structure, function, and mechanism of action. For example, in prokaryotes, DnaB helicase binds and translocates...
22.9K
01:29Cytoskeletal Proteins in Bacteria
3.8K
Bacterial cells were initially considered simple, randomly organized structures lacking a cytoskeleton. However, the discovery of cytoskeleton homologs in bacteria led to the change of this opinion. Bacterial cytoskeletal filaments regulate the cell shape, cell polarity, cell division, and partitioning of plasmids during cell division. It was later discovered that bacterial cytoskeletal proteins, mainly actin and tubulin homologs, are diverse compared to their eukaryotic counterparts. On the...
3.8K
01:23Surface Appendages of Archaea
334
Archaeal surface appendages are highly specialized structures essential for environmental adaptation, encompassing roles in adhesion, biofilm formation, and motility. Among these appendages, pili and archaella stand out for their distinct morphologies and functionalities, enabling archaea to thrive in diverse and often extreme environments.Pili: Adhesion and Biofilm FormationPili are filamentous structures assembled from pilin protein subunits, primarily contributing to adhesion and biofilm...
334
01:26Tension Response at Adherens Junctions
3.1K
The adherens junctions that anchor cells together are multi-protein complexes that dynamically adapt to mechanical stimuli such as tensile forces and shear stress. Mechanosensory proteins in these junctions can sense such mechanical stimuli and undergo a shift in their conformation, resulting in an altered function — a process called mechanotransduction.
α-Catenin as a Mechanosensory Protein
The α-catenin of adherens junctions is an allosteric protein with three VH (vinculin...
α-Catenin as a Mechanosensory Protein
The α-catenin of adherens junctions is an allosteric protein with three VH (vinculin...
3.1K