Peroxisomal acyl-coenzyme A oxidase multigene family of the yeast Candida tropicalis; nucleotide sequence of a third gene and its protein product

Abstract

We have determined the complete nucleotide sequence of gene POX2, which encodes one of the major peroxisomal polypeptides (PXPs) of Candida tropicalis. POX2 is linked to gene POX4, which codes for a subunit (PXP-4) of long-chain acyl-CoA oxidase. Southern blot analysis revealed that POX2 had a significant homology to POX4, and also to gene POX5 which encodes a subunit (PXP-5) of the isozyme of acyl-CoA oxidase. PXP-2, the protein product of POX2, was co-purified with PXP-4 from the isolated peroxisomes. PXP-2 itself was a flavoprotein and likely to form an equimolar complex with PXP-4, although its enzymatic activity was uncertain. POX2 corresponds to a single open reading frame of 724 amino acids and has no introns. The N-terminal sequence and the calculated Mr of the deduced polypeptide were consistent with those of isolated PXP-2. The primary structure was highly homologous to those of PXP-4 and PXP-5 in respect of the amino acid sequence and the hydropathy profile. We conclude that POX2 is a third gene of the peroxisomal acyl-COA oxidase multigene family.