Vanhanen, Sipo, West, Mark, Kroon, Johan T.M., Lindner, Nigel, Casey, John, Cheng, Qi, Elborough, Kieran M., and Slabas, Antoni R.
The yeast Candida cloacaeis capable of growing on alkanes and fatty acids as sole carbon sources. Transfer of cultures from a glucose medium to one containing oleic acid induced seven proteins of Mr102,000, 73,000, 61,000, 54,000, and 46,000 and two in the region ofMr45,000 and repressed a protein ofMr64,000. The induction of theMr73,000 protein reached a 7-fold maximum 24 h after induction. The protein was confirmed by its enzyme activity to be a long-chain fatty-acid alcohol oxidase (LC-FAO) and purified to homogeneity from microsomes by a rapid procedure involving hydrophobic chromatography. An internal peptide of 30 amino acids was sequenced. A 1100-base pair cDNA fragment containing the LC-FAO peptide coding sequence was used to isolate a single exon genomic clone containing the full-length coding sequence of an LC-FAO (fao1). The fao1gene product was expressed inEscherichia coliand was translated as a functional long-chain alcohol oxidase, which was present in the membrane fraction. In addition, full-length coding sequences for a Candida tropicalisLC-FAO (faoT) and a second C. cloacaeLC-FAO (fao2) were isolated. The DNA sequences obtained had open reading frames of 2094 (fao1), 2091 (fao2), and 2112 (faoT) base pairs. The derived amino acid sequences of fao2and faoTshowed 89.4 and 76.2% similarities to fao1. Thefao1gene is much more highly induced on alkane than isfao2. Although this study describes the first known DNA sequences encoding LC-FAOs from any source, there are unassignedArabidopsissequences and an unassignedMycobacteriumsequence in the GenBankTMData Bank that show strong homology to the described LC-FAO sequences. The conservation of sequence between yeast, plants, and bacteria suggests that an as yet undescribed family of long-chain fatty-acid oxidases exists in both eukaryotes and prokaryotes.