Independent regulation of full-length and 5′-truncated PAS5 mRNAs in Saccharomyces cerevisiae

Peroxisome assembly in Saccharomyces cerevisiae requires the products of several genes. In this report, the PAS5 gene has been characterized. The gene is on the left arm of chromosome X and encodes a polypeptide with similarity to the mammalian peroxisome assembly factor-1 (PAF-1). Two different length transcripts are produced from the yeast PAS5 gene. The longer mRNAs encompass an open reading frame, while the shorter transcripts initiate 46-110 base pairs downstream of the first in-frame AUG. The longer transcripts are induced four-fold on medium containing fatty acids as the sole carbon source, while the shorter transcripts are induced up to ten-fold on medium containing glycerol as a carbon source. The full-length coding sequence encodes a protein with a calculated molecular weight of 30-7 kDa. A protein of 25 kDa could be translated from the shorter transcripts and would lack a very acidic domain found in the ammo-terminal extension of the longer protein. The common portion of the proteins is very basic; the calculated pi of the longer polypeptide is 9-02 and that of the shorter protein is 10-06. The PAS5 GenBank accession number is M86538.