Functional cooperativity between the trigger factor chaperone and the ClpXP proteolytic complex.

Area of Science:

• Cellular biology
• Molecular mechanisms of protein homeostasis

Background:

• Ribosome-associated trigger factor (TF) is a chaperone involved in protein folding.
• The ClpXP complex is a major cellular protease responsible for protein degradation.

Purpose of the Study:

• To investigate the functional relationship between trigger factor (TF) and the ClpXP degradation complex.
• To understand how TF influences ClpXP-mediated protein degradation.

Main Methods:

• Bioinformatic analyses of gene proximity (tig and ClpXP genes).
• Experimental assessment of TF's effect on the degradation rates of various protein substrates by ClpXP.
• Investigation of TF-ClpX interaction dynamics.

Main Results:

• TF and ClpXP genes are conserved in close proximity, suggesting a functional link.
• TF's effect on ClpXP degradation is substrate-dependent, sometimes increasing degradation rates.
• TF enhances the degradation of specific substrates, including RpoS and SsrA-tagged proteins, affecting ~2% of newly synthesized proteins.
• TF dynamically interacts with ClpX via multiple sites to promote degradation.

Conclusions:

• A functional association exists between the TF chaperone and the ClpXP protease.
• TF acts as an adaptor for ClpXP, facilitating the degradation of a subset of cellular proteins.
• This chaperone-protease cooperation represents an ancient mechanism for maintaining protein homeostasis.