1,4-benzoquinone reductase from Phanerochaete chrysosporium: cDNA cloning and regulation of expression

A cDNA clone encoding a quinone reductase (QR) from the white rot basidiomy cete Phanerochaete chrysosporium was isolated and sequenced. The cDNA consi sted of 1,007 nucleotides and a poly(A) tail and encoded a deduced protein containing 271 amino acids. The experimentally determined eight-amino-acid N-terminal sequence of the purified QR protein from P. chrysosporium matche d amino acids 72 to 79 of the predicted translation product of the cDNA. Th e M-r of the predicted translation product, beginning with Pro-72, was esse ntially identical to the experimentally determined M-r, of one monomer of t he QR dimer, and this finding suggested that QR is synthesized as a proenzy me. The results of in vitro transcription-translation experiments suggested that QR is synthesized as a proenzyme with a 71-amino-acid leader sequence . This leader sequence contains two potential KEX2 cleavage sites and numer ous potential cleavage sites for dipeptidyl aminopeptidase. The QR activity in cultures of P. chrysosporium increased following the addition of 2-dime thoxybenzoquinone, vanillic acid, or several other aromatic compounds. An i mmunoblot analysis indicated that induction resulted in an increase in the amount of QR protein, and a Northern blot analysis indicated that this regu lation occurs at the level of the qr mRNA.