Functional Coupling Between DnaK and Bacterial RNA Polymerase Through a Dedicated J-domain Protein System.

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• J-domain proteins (JDPs) are Hsp70/DnaK co-chaperones.
• The Atc system in Shewanella oneidensis is essential for cold adaptation.
• AtcB interacts with RNA polymerase, causing toxicity upon overexpression.

Purpose of the Study:

• Elucidate the coordinated function of DnaK, Atc proteins, and RNA polymerase.
• Identify molecular determinants of RNA polymerase-AtcB interaction.
• Understand the mechanism of cold adaptation involving this system.

Main Methods:

• Protein interaction mapping using mutagenesis.
• Analysis of cold growth phenotypes with mutant proteins.
• Investigating toxicity suppression through protein complex formation.

Main Results:

• Identified specific mutations affecting RNA polymerase-AtcB binding, crucial for cold growth.
• Demonstrated that the AtcJ-AtcC complex recruits DnaK.
• Showed DnaK recruitment suppresses AtcB toxicity by limiting inactive RNA polymerase.

Conclusions:

• The Atc system couples DnaK and RNA polymerase activity.
• This network represents a novel DnaK-dependent bacterial transcriptional regulatory pathway for cold adaptation.