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Transformation of Chlamydia muridarum reveals a role for Pgp5 in suppression of plasmid-dependent gene expression

Yuanjun Liu1, Chaoqun Chen, Siqi Gong

  • 1Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.

Journal of Bacteriology
|December 24, 2013
PubMed

Insights

We developed a transformation system for Chlamydia muridarum, a bacterium that causes disease in mice. This system revealed a novel function of Pgp5 in regulating plasmid-dependent genes, advancing chlamydial research.

Area of Science:

  • Microbiology
  • Bacterial genetics
  • Pathogen research

Background:

  • Chlamydia trachomatis research is limited by its inability to cause relevant pathology in animal models.
  • Chlamydia muridarum naturally infects mice and can induce hydrosalpinx, a pathology also seen in human C. trachomatis infections.

Purpose of the Study:

  • To develop a transformation system for Chlamydia muridarum.
  • To identify the roles of plasmid genes (Pgps) in C. muridarum.
  • To investigate the function of Pgp5 in regulating plasmid-dependent gene expression.

Main Methods:

  • Development of a transformation system for Chlamydia muridarum.
  • Genetic manipulation of plasmid genes (Pgp1-8) including deletions and replacements.
  • Analysis of plasmid-dependent gene expression using techniques like mCherry gene replacement and premature translation termination.
  • Comparative analysis of Pgp5 function between C. muridarum and C. trachomatis.

Main Results:

  • Established a functional transformation system for Chlamydia muridarum.
  • Identified Pgp1, -2, -6, and -8 as essential for plasmid maintenance.
  • Confirmed Pgp3, -5, and -7 are dispensable for in vitro growth.
  • Pgp4 acts as a positive regulator, while Pgp5 acts as a negative regulator of plasmid-dependent genes.
  • Pgp5 protein, not its DNA sequence, mediates gene repression.
  • C. muridarum Pgp5 is a more potent suppressor of gene expression than C. trachomatis Pgp5.

Conclusions:

  • A novel negative regulatory function of Pgp5 on plasmid-dependent genes was discovered.
  • The developed C. muridarum transformation system is a valuable tool for studying chlamydial pathogenesis.
  • This system will facilitate the mapping of pathogenic and protective determinants in animal models.

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