PEX11 mediates intralumenal vesicle formation in peroxisomes

Area of Science:

• Plant cell biology
• Organelle biogenesis
• Molecular genetics

Background:

• Peroxisomes are vital eukaryotic organelles involved in diverse metabolic processes.
• The peroxisomal membrane protein PEX11 family regulates peroxisome size, shape, and number.
• Arabidopsis thaliana possesses five PEX11 isoforms with largely uncharacterized functional differences.

Purpose of the Study:

• To elucidate the distinct functions of Arabidopsis PEX11 isoforms.
• To investigate the roles of PEX11 in peroxisome morphology and physiology.

Main Methods:

• Generation and analysis of null pex11 mutants in Arabidopsis.
• Utilized reporter systems to visualize peroxisome membranes and lumen.
• Assessed peroxisome size, intralumenal vesicle formation, and fatty acid beta-oxidation.

Main Results:

• PEX11C/D/E isoforms promote intralumenal vesicle formation, limit peroxisome size, and are essential for fatty acid beta-oxidation during germination.
• PEX11A/B isoforms also promote intralumenal vesicle formation and limit peroxisome enlargement during seedling lipid mobilization.
• Complete loss of PEX11 function leads to seedling lethality despite abundant peroxisomes.

Conclusions:

• Arabidopsis PEX11 isoforms have specialized roles in shaping internal peroxisome membranes.
• These distinct functions are critical for cellular physiology and essential for plant development.
• PEX11's role extends beyond peroxisome division to include membrane dynamics and metabolic regulation.