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Gene expression profiles of Chlamydophila pneumoniae during the developmental cycle and iron depletion-mediated

André P Mäurer1, Adrian Mehlitz, Hans J Mollenkopf

  • 1Department of Molecular Biology, Max Planck Institute for Infection Biology, Berlin, Germany.

Plos Pathogens
|June 26, 2007
PubMed

Insights

This study reveals Chlamydophila pneumoniae (Cpn) gene expression changes during infection. Late genes correlate with elementary body (EB) proteins, while tardy genes lead to EB mRNA, suggesting a mid-cycle arrest during persistence.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genomics

Background:

  • Chlamydophila pneumoniae (Cpn) is an obligate intracellular bacterium and a significant human pathogen.
  • Understanding Cpn's biphasic developmental cycle, including acute infection and chronic persistence, is crucial for disease management.
  • The transcriptomic changes during these stages are largely unknown, hindering insights into Cpn pathogenesis.

Purpose of the Study:

  • To comprehensively analyze the Chlamydophila pneumoniae CWL029 transcriptome during its acute infection cycle.
  • To differentiate gene expression patterns associated with distinct developmental stages, including "late" and "tardy" gene clusters.
  • To investigate the transcriptomic basis of Cpn persistence, particularly in response to iron depletion.

Main Methods:

  • Designed a pathogen-specific oligonucleotide microarray for Cpn gene expression analysis.
  • Optimized RNA extraction methods for Chlamydophila pneumoniae.
  • Utilized self-organizing map clustering to categorize gene expression profiles into "early", "mid", "late", and "tardy" clusters during acute infection.

Main Results:

  • Identified distinct gene expression clusters during acute Cpn infection, with "late" genes correlating to elementary body (EB) proteins and "tardy" genes to EB mRNA.
  • Compared gene expression during iron depletion-mediated persistence with acute infection profiles.
  • Found that iron depletion-induced persistence resembles a mid-cycle developmental arrest rather than a completely novel expression pattern.

Conclusions:

  • The study elucidates the Chlamydophila pneumoniae transcriptome during acute infection, distinguishing key gene sets related to developmental stages.
  • The findings suggest that "late" and "tardy" gene expression profiles are linked to EB protein and mRNA production, respectively.
  • Hypothesize that the transcriptomic "clock" of Cpn arrests during the mid-cycle phase when establishing iron-mediated persistence.

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