Arp2/3 complex and actin dynamics are required for actin-based mitochondrial motility in yeast

Area of Science:

• Cell Biology
• Molecular Biology
• Cytoskeletal Dynamics

Background:

• The Arp2/3 complex is known to regulate actin polymerization, crucial for processes like cell motility and intracellular pathogen movement.
• Mitochondrial dynamics and movement are essential for cellular energy homeostasis and function, but the precise mechanisms are still being elucidated.

Purpose of the Study:

• To investigate the role of the Arp2/3 complex in the movement of mitochondria within yeast cells.
• To determine if actin polymerization is the driving force behind mitochondrial transport in yeast.

Main Methods:

• Co-immunoprecipitation to assess the association between Arp2/3 subunits and mitochondria.
• Fluorescence microscopy to visualize the localization of Arp2p and actin structures around mitochondria.
• Analysis of mitochondrial movement velocity and morphology in wild-type and mutant yeast strains (ARP2, ARC15) and under conditions of reduced actin dynamics.

Main Results:

• The Arp2p and Arc15p subunits of the Arp2/3 complex associate with yeast mitochondria independently of actin.
• Arp2p colocalizes with mitochondria and forms actin clouds around them in intact yeast cells.
• Mutations in ARP2 or ARC15, or impaired actin dynamics, lead to reduced mitochondrial movement velocity, loss of directed movement, and morphological defects.

Conclusions:

• Mitochondrial movement in yeast is driven by actin polymerization.
• The Arp2/3 complex is essential for actin-driven mitochondrial motility and proper mitochondrial morphology in yeast.