Sequences of two tandem genes regulated by carbon sources, one being essential for n-alkane assimilation in Candida maltosa

Several n-alkane-inducible clones were isolated from the genomic library of an n-alkane-assimilation yeast, Candida maltosa, by the differential hybridization method. Among these, one of the most predominantly expressed clones was analyzed. The nucleotide sequence of the cloned DNA fragment showed that it contained two open reading frames, one encoding a protein of 127 amino acids (aa) and the other a protein of 276 aa. The former was named POX18Cm, because the sequence was highly homologous to that of the Candida tropicalis gene, POX18, which already had been identified as encoding a small oleate-inducible peroxisomal protein. The latter, named ALI1, had no homologous sequences in the EMBL database (1990 release). Northern-blot hybridization indicated that the expression of these two genes was regulated by carbon sources in the media. From gene-disruption experiments, it was concluded that ALI1 was essential for assimilation of n-alkane by C. maltosa.