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.

Abstract

To identify components of the peroxisomal import pathway in yeast, we have isolated pas mutants affected in peroxisome biogenesis. Two mutants 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‐utilizing phenotype of the pas7‐1 strain. The DNA sequence predicts a 42.3 kDa polypeptide of 375 amino acids encoding a novel member of the beta‐transducin related (WD‐40) protein family. A Myc epitope‐tagged Pas7p, expressed under the control of the CUP1 promotor, was functionally active. Subcellular localization studies revealed that in the presence of thiolase this epitope‐tagged Pas7p in part associates with peroxisomes. However, in a thiolase‐deficient mutant, Pas7p was entirely found in the cytoplasm. We suggest that Pas7p mediates the binding of thiolase to these organelles.