PAS7 ENCODES A NOVEL YEAST MEMBER OF THE WD-40 PROTEIN FAMILY ESSENTIAL FOR IMPORT OF 3-OXOACYL-COA THIOLASE, A PTS2-CONTAINING PROTEIN, INTO PEROXISOMES

To identify components of the peroxisomal import pathway in yeast, we have isolated pas mutants affected in peroxisome biogenesis. Two mutan ts assigned to complementation group 7 define a new gene, PAS7, whose product is necessary for import of thiolase, a PTS2-containing protein , but not for that of SKL (PTS1)-containing proteins, into peroxisomes . We have cloned PAS7 by complementation of the oleic acid non-utilizi ng phenotype of the pas7-1 strain. The DNA sequence predicts a 42.3 kD a polypeptide of 375 amino acids encoding a novel member of the beta-t ransducin related (WD-40) protein family. A Myc epitope-tagged Pas7p, expressed under the control of the CUP1 promotor, was functionally act ive. Subcellular localization studies revealed that in the presence of thiolase this epitope-tagged Pas7p in part associates with peroxisome s. However, in a thiolase-deficient mutant, Pas7p was entirely found i n the cytoplasm. We suggest that Pas7p mediates the binding of thiolas e to these organelles.