Aspergillus oryzae has two nearly identical Taka-amylase genes, each containing eight introns.
cDNA and genomic DNA for two nearly identical genes, AmyI and AmyII, coding for the enzyme Taka-amylase A (TA-A) of the fungus Aspergillus oryzae have been cloned and characterized. These genes are apparently unlinked, differing by only 3 nucleotides (nt) out of the 2720 nt that span the coding regions. The 617-nt 5'-flanking regions differ only at nt -372 (T or A) from the putative ATG start codon and contain four sets of short, inverted repeats (IR) upstream from the putative TATAAA box at nt -100 and the transcription start point at nt -69. The coding regions consist of 499 codons disrupted by eight intervening sequences. The putative proenzymes differ by only two amino acids (aa) and consist of the 478-aa extracellular enzyme plus a 21-aa hydrophobic leader sequence. Except for the replacement site changes in codons 35 (Arg----Gln) and 151 (Phe----Leu), the identity of the two genes continues downstream for 58 nt past the TGA stop codon before diverging. Exon 9 codes for 94 of the 98 aa of the domain B of mature TA-A. Little conservation of TA-A exons was found when these exons were aligned with those of human amylase. The genes are flanked by at least 6 to 10 kb of unrelated chromosomal nucleotide sequence. The Amy genes are co-expressed, since mRNA (cDNA) specific to the 3'-UTR of both genes was recovered from mycelia grown on starch, a known inducer of TA-A biosynthesis. The 3'-UTRs of cDNAs related to AmyI are shorter (128 nt and 145 nt) than those of AmyII (179 nt and 297 nt). The AmyI specific 3'-UTR is characterized by the absence of IR sequences and the presence of a putative 'AATAAA' polyadenylation signal.
Gines
M J
MJ
Division of Biological Sciences, National Research Council of Canada, Ottawa.
Dove
M J
MJ
Seligy
V L
VL
D000595:Amino Acid Sequence; D001230:Aspergillus / Q000235:genetics*; D001236:Aspergillus oryzae / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D003062:Codon; D004271:DNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D001330:Electronic Data Processing; D004792:Enzyme Precursors / Q000235:genetics*; D005091:Exons; D005796:Genes; D005800:Genes, Fungal; D005822:Genetic Vectors; D007438:Introns; D008969:Molecular Sequence Data; D014158:Transcription, Genetic; D000516:alpha-Amylases / Q000235:genetics*
D003062:Codon; D004271:DNA, Fungal; D004792:Enzyme Precursors; D000516:alpha-Amylases