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The catR gene encoding a catalase from Aspergillus niger primary structure and elevated expression through increased gene copy number and use of a strong promoter
Author(s) -
Fowler Timothy,
Rey Michael W.,
VähäVahe Peka,
Power Scott D.,
Berka Randy M.
Publication year - 1993
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1993.tb01228.x
Subject(s) - biology , complementary dna , gene , aspergillus niger , coding region , genomic dna , microbiology and biotechnology , genetics , intron , nucleic acid sequence , plasmid , southern blot , expression vector , biochemistry , recombinant dna
Summary Synthetic oligonucleotide probes based on amino acid sequence data were used to identify and clone cDNA sequences encoding a catalase (catalase‐R) of Aspergillus niger. One cDNA clone was subsequently used to isolate the corresponding genomic DNA sequences (designated catR). Nucleotide sequence analysis of both genomic and cDNA clones suggested that the catR coding region consists of five exons interrupted by four small introns. The deduced amino acid sequence of catalase‐R spans 730 residues which show significant homology to both prokaryotic and eukaryotic catalases, particularly in regions involved in catalytic activity and binding of the haem prosthetic group. Increased expression of the catR gene was obtained by transformation of an A. niger host strain with an integrative vector carrying the cloned genomic DNA segment. Several of these transformants produced three‐ to fivefold higher levels of catalase than the untransformed parent strain. Hybridization analyses indicated that these strains contained multiple copies of catR integrated into the genome. A second expression vector was constructed in which the catR coding region was functionally joined to the promoter and terminator elements of the A. niger glucoamylase (glaA) gene. A. niger transformants containing this vector produced from three‐ to 10‐fold higher levels of catalase‐R than the untransformed parent strain.