Cryptococcal Hsf3 controls intramitochondrial ROS homeostasis by regulating the respiratory process

Area of Science:

• Cell Biology
• Molecular Biology
• Mycology

Background:

• Mitochondrial quality control is crucial for preventing cellular damage from reactive oxygen species (ROS).
• Mechanisms regulating mitochondrial ROS (mtROS) are not fully understood, especially in fungal pathogens like Cryptococcus neoformans.
• Heat shock factors (HSFs) are known regulators of cellular stress responses.

Purpose of the Study:

• To investigate the role of Cryptococcus neoformans heat shock factor 3 (CnHsf3) in regulating mtROS.
• To elucidate the mechanisms by which CnHsf3 controls mtROS homeostasis.
• To determine if CnHsf3's function is linked to the unfolded protein response.

Main Methods:

• Gene expression analysis in Cryptococcus neoformans.
• Subcellular localization studies of CnHsf3.
• Analysis of CnHsf3's DNA-binding activity under stress conditions.
• Mutagenesis studies to identify functional domains of CnHsf3.

Main Results:

• CnHsf3 regulates mtROS independently of the unfolded protein response.
• CnHsf3 functions in both the nucleus and mitochondria, requiring specific targeting signals.
• CnHsf3 modulates gene expression of the tricarboxylic acid cycle and electron transport chain.
• Oxidation of a cysteine residue in CnHsf3's DNA-binding domain enhances its activity in response to intramitochondrial stress.

Conclusions:

• Cryptococcus neoformans HSF3 plays a novel role in mtROS homeostasis.
• HSF proteins can regulate mtROS through mechanisms distinct from the unfolded protein response.
• CnHsf3's dual organelle function and stress-responsive DNA binding offer new insights into mitochondrial quality control.