Synthesis of protein in host-free reticulate bodies of Chlamydia psittaci and Chlamydia trachomatis

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Molecular Biology

Background:

• Chlamydia are obligate intracellular bacteria, making in vitro study of their metabolic processes challenging.
• Understanding Chlamydia's protein synthesis is crucial for developing targeted therapies.

Purpose of the Study:

• To demonstrate and characterize protein synthesis by host-free Chlamydia psittaci and Chlamydia trachomatis reticulate bodies.
• To identify the conditions and requirements for extracellular protein synthesis in Chlamydia.

Main Methods:

• Isolated reticulate bodies from host cells (host-free chlamydiae).
• Measured [35S]methionine and [35S]cysteine incorporation into proteins.
• Assessed the effects of various supplements (ATP, ions, amino acids) and inhibitors (antibiotics, ionophore) on synthesis.
• Analyzed synthesized proteins using molecular weight.

Main Results:

• Host-free Chlamydia reticulate bodies synthesized proteins for up to 2 hours.
• Protein synthesis was dependent on exogenous ATP, an ATP-regenerating system, and Na+/K+ ions.
• Magnesium ions and amino acids stimulated synthesis, while inhibitors blocked it.
• Synthesized proteins matched those produced intracellularly, including outer membrane proteins.
• Elementary bodies could not synthesize proteins, even with reducing agents.

Conclusions:

• Protein synthesis can occur in host-free Chlamydia reticulate bodies under specific conditions.
• This extracellular synthesis mimics intracellular processes and produces essential proteins.
• Elementary bodies are transcriptionally and translationally inactive.