Comparison of the cis-acting control regions of two coordinately controlled genes involved in ethanol utilization in Aspergillus nidulans

Abstract

The alcA and aldA genes of Aspergillus nidulans are regulated in exactly the same manner, being subject to positive control by the product of the alcR gene. We report the complete nucleotide sequence of the alcA gene and its 5' non-coding region, preliminary localization of the region involved in the regulation of alcA expression, and a detailed comparison of this region to the 5' non-coding region of aldA (Pickett et al., 1987). The 5' flanking regions of the genes contain six similar sequence elements. Three of these elements are located upstream from the messenger RNA start points and one is related to a sequence element found in the region responsible for ethanol induction of the yeast ADH2 gene (Beier et al., 1985). The other homologous elements are located within the messenger RNA leader and may be associated with selection of messenger RNA start points. The amino acid sequence of alcohol dehydrogenase I (348 residues) shows a significant level of homology with analogous sequences in other organisms. Gene alcA contains introns which are similar in size and structure to other fungal introns. We discuss the positions of the introns in alcA of A. nidulans with particular reference to the conservation of intron position in and the evolutionary assembly of enzymes which possess NAD-binding domains.