Reevaluation of the role of Pex1 and dynamin-related proteins in peroxisome membrane biogenesis

摘要

A recent model for peroxisome biogenesis postulates that peroxisomes form de novo continuously in wild-type cells byudheterotypic fusion of endoplasmic reticulum–derived vesicles containing distinct sets of peroxisomal membrane proteins.udThis model proposes a role in vesicle fusion for the Pex1/Pex6 complex, which has an established role in matrix proteinudimport. The growth and division model proposes that peroxisomes derive from existing peroxisomes. We tested theseudmodels by reexamining the role of Pex1/Pex6 and dynamin-related proteins in peroxisome biogenesis. We found thatudinduced depletion of Pex1 blocks the import of matrix proteins but does not affect membrane protein delivery to peroxisomes;udmarkers for the previously reported distinct vesicles colocalize in pex1 and pex6 cells; peroxisomes undergoudcontinued growth if ission is blocked. Our data are compatible with the established primary role of the Pex1/Pex6udcomplex in matrix protein import and show that peroxisomes in Saccharomyces cerevisiae multiply mainly byudgrowth and division.