Role of the PAS1 gene of Pichia pastoris in peroxisome biogenesis

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Peroxisome biogenesis is essential for yeast growth on specific carbon sources.
• Mutations in peroxisome biogenesis genes result in non-functional peroxisomes.

Purpose of the Study:

• To clone and characterize the Pichia pastoris PAS1 gene, a homolog of Saccharomyces cerevisiae PAS1.
• To investigate the role of PAS1 in peroxisome formation and protein import.

Main Methods:

• Gene cloning and sequencing of Pichia pastoris PAS1.
• Creation and characterization of P. pastoris pas1 mutant strains.
• Electron microscopy, biochemical analysis, and sucrose gradient purification of peroxisomal structures.

Main Results:

• P. pastoris pas1 mutants lack normal peroxisomes but form "peroxisome ghosts."
• These ghosts proliferate and are inherited by daughter cells.
• Peroxisome ghosts import some peroxisomal proteins despite lacking others.

Conclusions:

• PAS1 plays a critical role in yeast peroxisome biogenesis.
• The presence and protein import capability of peroxisome ghosts in P. pastoris pas1 mutants provide new data on peroxisome formation.