Molecular analysis of arylalcohol dehydrogenase of Coriolus versicolor expressed against exogenous addition of dibenzothiophene derivatives

Using the differential display reverse-transcriptional polymerase chain reaction (DDRT-PCR) technique, several cDNA fragments were isolated as chemical stress responsive genes from the white-rot basidiomycete, Coriolus versicolor, exposed to either 4-methyldibenzothiophene-5-oxide (4MDBTO) or dibenzothiophene-5-oxide (DBTO). A database search on deduced amino acid sequences of cDNAs revealed that they showed a high similarity with various proteins from other organisms. These results strongly suggested that cell responding systems might be involved in the fungal metabolism of exogenous chemicals by C. versicolor. One of the significantly up-regulated cDNA fragments by MDBTO, DD16gc, showed a high similarity to arylalcohol dehydrogenases (AADs) from several microorganisms. The full-length cDNA sequence of the DD16gc determined by 5' rapid amplification of cDNA ends method revealed that the gene consisted 1,295 nucleotide and poly(A) tail, encoding 394 amino acids in an open reading frame. The deduced protein showed a remarkable homology to AAD from Phanerochaete chrysosporium (66% identity) and to that from Saccharomyces cerevisiae (54% identity). The AAD gene was specifically transcripted under chemically-stressed conditions by 4MDBTO, suggesting that the enzyme encoded by the stress responsive gene may play an important role in the fungal conversion of 4MDBTO or its metabolic product(s).