Eukaryotic Clathrin Adapter Protein and Mediator of Cholesterol Homeostasis, PICALM, Affects Trafficking to the Chlamydial Inclusion.

The obligate intracellular pathogen has unique metabolic requirements as it proceeds through its biphasic developmental cycle from within the inclusion within the host cell. In our previous study, we identified a host protein, PICALM, which localizes to the chlamydial inclusion. PICALM functions in many host pathways including the recycling of receptors, specific SNARE proteins, and molecules like transferrin, and maintaining cholesterol homeostasis.

Inclusion Membrane Growth and Composition Are Altered by Overexpression of Specific Inclusion Membrane Proteins in Chlamydia trachomatis L2.

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections. This obligate intracellular bacterium develops within a membrane-bound vacuole called an inclusion, which sequesters the chlamydiae from the host cytoplasm. Host-pathogen interactions at this interface are mediated by chlamydial inclusion membrane proteins (Incs).

Eukaryotic SNARE VAMP3 Dynamically Interacts with Multiple Chlamydial Inclusion Membrane Proteins.

, an obligate intracellular pathogen, undergoes a biphasic developmental cycle within a membrane-bound vacuole called the chlamydial inclusion. To facilitate interactions with the host cell, modifies the inclusion membrane with type III secreted proteins, called Incs. As with all chlamydial proteins, Incs are temporally expressed, modifying the chlamydial inclusion during the early and mid-developmental cycle.

Proximity Labeling To Map Host-Pathogen Interactions at the Membrane of a Bacterium-Containing Vacuole in Chlamydia trachomatis-Infected Human Cells.

Many intracellular bacteria, including the obligate intracellular pathogen , grow within a membrane-bound bacterium-containing vacuole (BCV). Secreted cytosolic effectors modulate host activity, but an understanding of the host-pathogen interactions that occur at the BCV membrane is limited by the difficulty in purifying membrane fractions from infected host cells. We used the ascorbate peroxidase (APEX2) proximity labeling system, which labels proximal proteins with biotin , to study the protein-protein interactions that occur at the chlamydial vacuolar, or inclusion, membrane.

Proximity Labeling of the Chlamydia trachomatis Inclusion Membrane.

In the study of intracellular bacteria that reside within a membrane-bound vacuole, there are many questions related to how prokaryotic or eukaryotic transmembrane or membrane-associated proteins are organized and function within the membranes of these pathogen-containing vacuoles. Yet this host-pathogen interaction interface has proven difficult to experimentally resolve. For example, one method to begin to understand protein function is to determine the protein-binding partners; however, examining protein-protein interactions of hydrophobic transmembrane proteins is not widely successful using standard immunoprecipitation or coimmunoprecipitation techniques.

Development of a Proximity Labeling System to Map the Inclusion Membrane.

grows within a membrane-bound vacuole termed an inclusion. The cellular processes that support the biogenesis and integrity of this pathogen-specified parasitic organelle are not understood. secretes integral membrane proteins called Incs that insert into the chlamydial inclusion membrane (IM).