Yeast peroxisomes multiply by growth and division

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Peroxisomes are essential organelles with diverse metabolic functions.
• Peroxisome biogenesis can occur through de novo formation from the endoplasmic reticulum (ER) or by multiplication of existing peroxisomes via fission.
• The mechanisms regulating peroxisome multiplication and the roles of specific proteins, such as dynamin-related proteins (Drps), are not fully understood.

Purpose of the Study:

• To investigate the relative contributions of de novo formation and fission to peroxisome proliferation in Saccharomyces cerevisiae.
• To elucidate the role of Drps in peroxisome multiplication and de novo formation.
• To understand the dynamics of peroxisome biogenesis pathways.

Main Methods:

• Utilized pulse-chase and mating assays to track peroxisome populations.
• Employed microscopy techniques to visualize peroxisome structures and dynamics.
• Investigated gene deletion mutants lacking functional Drps.

Main Results:

• Wild-type cells primarily multiply peroxisomes through Drp-dependent fission, with no significant de novo formation observed.
• Cells lacking pre-existing peroxisomes initiate de novo formation from the ER.
• This de novo pathway is slower than fission and does not require Drps.
• Pex3-GFP, a marker for the maturation pathway, is trafficked from the ER to existing peroxisomes.

Conclusions:

• Peroxisome multiplication in wild-type yeast occurs mainly via growth and division (fission).
• The ER-to-peroxisome pathway serves to supply existing peroxisomes with membrane components.
• De novo peroxisome formation is an alternative pathway activated under specific conditions (e.g., absence of existing peroxisomes) and is independent of Drps, while fission is Drp-dependent.