Related Experiment Video
Updated: Jul 2, 2026
07:18
Application of Biolayer Interferometry (BLI) for Studying Protein-Protein Interactions in Transcription
Published on: July 26, 2019
Chlamydial effector proteins localized to the host cell cytoplasmic compartment
Betsy Kleba1, Richard S Stephens
1Program in Infectious Diseases and Immunity, University of California, Berkeley, CA 94720, USA.
Infection and Immunity
|August 20, 2008
Summary
Researchers identified bacterial proteins secreted into host cells by Chlamydia trachomatis and C. pneumoniae. These translocated proteins, crucial for pathogenesis, vary between species and change during the infection cycle.
Area of Science:
- Microbiology
- Pathogenesis
- Cell Biology
Background:
- Bacterial pathogens employ secretion systems to deliver effector proteins into host cells, modulating cellular functions.
- Gram-negative bacteria, including Chlamydiae, utilize type III secretion systems (T3SS) for pathogenesis.
- Understanding translocated effectors is key to deciphering bacterial virulence mechanisms.
Purpose of the Study:
- To identify Chlamydial effector proteins translocated into the host cell cytosol.
- To compare effector protein profiles between Chlamydia trachomatis and Chlamydia pneumoniae.
- To investigate the relationship between effector translocation and the Chlamydial developmental cycle.
Main Methods:
- Selective permeabilization of host cell membranes to isolate cytosolic contents.
- Metabolic labeling of bacterial proteins to distinguish them from host proteins.
- Proteomic analysis to identify Chlamydial proteins within the host cell cytosol.
Main Results:
- Over 20 Chlamydia trachomatis and C. pneumoniae proteins were identified in the host cell cytoplasm.
- Some translocated proteins were common to both species, while others were unique.
- The repertoire of translocated proteins varied with the progression of the Chlamydial developmental cycle.
Conclusions:
- Chlamydiae translocate a significant number of effector proteins into the host cell cytosol via their T3SS.
- Species-specific effector proteins contribute to differential pathogenesis between Chlamydia species.
- Effector protein translocation is a dynamic, developmentally regulated process in Chlamydia infections.
More Related Videos
Related Concept Videos
01:29Bacterial Phylum Chlamydiae
The phylum Chlamydiae or Chlamydiota is composed of a single order, Chlamydiales. This phylum consists entirely of obligate intracellular parasites that infect eukaryotic hosts. While human pathogens within this group have been studied extensively, the phylum encompasses many species capable of interacting with various eukaryotic organisms. Members of Chlamydiae are typically small cocci, approximately 0.5 μm in diameter, and exhibit a distinctive developmental cycle. As is characteristic of...
01:29Cytoskeletal Proteins in Bacteria
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...
01:17Gram-negative Bacterial Protein Secretion Systems
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):...
01:10Intracellular Movement of Viruses and Bacteria
Intracellular bacteria and viruses often comprise a group of highly infectious pathogens that can cause several diseases. Bacterial pathogens include those belonging to the genus Rickettsia responsible for conditions such as rocky mountain spotted fever and the Mediterranean spotted fever; Chlamydia, a genus responsible for a sexually transmitted disease; Coxiella burnetii, an agent responsible for Q fever. Viral pathogens include vaccinia—a poxvirus, and herpes simplex virus—a virus that...
01:26Bacterial Translocation and Protein Secretion
Bacterial protein secretion involves translocation systems to ensure proteins reach their designated locations, including the plasma membrane, periplasm, outer membrane, or the external environment. These translocation systems are vital for bacterial physiology, supporting processes like membrane assembly, enzymatic activity in the periplasm, and interactions with the external environment. The division of labor between Sec and Tat pathways ensures efficiency in handling proteins with diverse...
01:09GPCRs Regulate Adenylyl Cylase Activity
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of cells.
Two...
Two...