Changes in particulate-bound protease activity during cold acclimation in Tetrahymena pyriformis

Area of Science:

• Cell Biology
• Biochemistry
• Protozoology

Background:

• Tetrahymena pyriformis is a ciliate protozoan model organism.
• Protease activity is crucial for cellular functions and can be influenced by environmental factors.
• Temperature is a key environmental parameter affecting cellular processes.

Purpose of the Study:

• To investigate the effects of temperature changes on protease activity in Tetrahymena pyriformis.
• To determine if protease secretion or intracellular activity is altered by thermal shifts.
• To elucidate the molecular mechanisms underlying temperature-induced protease modulation.

Main Methods:

• Culturing Tetrahymena pyriformis NT-1 at constant and shifted temperatures (39°C and 15°C).
• Assaying intracellular and extracellular protease activity using azocasein as a substrate at pH 8.0.
• Utilizing cycloheximide and actinomycin D to assess the role of protein synthesis.

Main Results:

• Constant growth at 39°C or 15°C led to decreased intracellular protease activity with secretion.
• Shifting from 39°C to 15°C caused a 28-fold increase in intracellular protease activity within 8 hours.
• This cold-induced protease enhancement was blocked by cycloheximide and actinomycin D, indicating de novo protein synthesis.
• Warming back to 39°C rapidly restored protease activity to control levels and resumed cell division.
• No significant protease secretion was observed during cold acclimation.

Conclusions:

• Temperature shifts, particularly cold shock, profoundly regulate protease activity in Tetrahymena pyriformis.
• The observed increase in protease activity upon cold exposure is an active, protein synthesis-dependent process.
• This response is reversible and linked to cell division recovery upon rewarming.