Titel: Characterizing the role of CERT in Chlamydia psittaci infections of epithelial cells
Art: Abstractautor
Session: Workshop 01
Virulence Principles in Respiratory Tract Infections (FG MP)

Referent: Dagmar Heuer (Berlin)

Abstract - Text

  1. Introduction

Chlamydia psittaci is an obligate intracellular bacterium that causes infections in humans and animals. As all Chlamydiaceae, C. psittaci has a biphasic cycle of development that takes place inside the eukaryotic host cell within a membrane-bound vacuole, the inclusion. Chlamydia trachomatis is known to recruit the cellular ceramide transporter CERT to their inclusions and have been shown to take up sphingomyelin. How C. psittaci obtains this important lipid has not been addressed.


  1. Goals

The goal of our study is to decipher the role of the cellular ceramide transporter CERT in C. psittaci-infections of human cells.


  1. Material and Methods

Localization of CERT was studied in C. psittaci infected and control cells by immunofluorescence using specific antibodies against CERT and by ectopic expression of CERT fused to eGFP. CERT knockout cells were generated by CRISPR/Cas9. The function of CERT for C. psittaci development and lipid uptake was analyzed in these cells and compared to control cells.


  1. Results

We found that C. psittaci recruits the ceramide transport protein CERT to its inclusion. CRISPR/Cas9-mediated knockout of CERT showed CERT is a crucial factor for C. psittaci infections affecting inclusion growth and infectious progeny formation. Interestingly, in CERT-knockout cells, the uptake of fluorescently labeled sphingolipids into bacteria inside the inclusion was boosted.


  1. Conclusion

We identified the non-vesicular transport protein CERT as a crucial factor for infections with this C. psittaci. CERT affects different stages of the infection and unexpectedly restricts sphingolipid uptake into C. psittaci inclusions suggesting a function beyond sphingolipid uptake. Interestingly, the recruitment of CERT is conserved between different Chlamydia species but its functions seem to be species-specific.