Characterization of a hydroxyl-radical-producing glycoprotein and its presumptive genes from the white-rot basidiomycete Phanerochaete chrysosporium.

Abstract During wood decay, the white-rot basidiomycete Phanerochaete chrysosporium secretes low-molecular-mass glycoproteins that catalyze a redox reaction between O 2 and electron donors to produce hydroxyl radical. This reaction accounts for most of the hydroxyl radical produced in wood-degrading cultures of P. chrysosporium . In combination with phenol oxidases, hydroxyl radical is believed to play a role in lignin degradation. The secreted glycoproteins also reduce Fe(III) to Fe(II) and strongly bind Fe(II). The partially purified glycoproteins contain 1-amino-1-deoxy-2-ketose (ketoamine) produced by the condensation of side-chain amino groups and carbohydrate. cDNAs and two putative genes encoding these glycoproteins, glp1 and glp2 , have been isolated and sequenced. The 875 bp glp1 and 864 bp glp2 are found on scaffold 2 of the P. chrysosporium genome. These presumptive genes each consist of seven introns and eight exons. The latter encode a predicted protein of 138 amino acids and a 22-amino-acid signal sequence for secretion. The predicted protein sequences are nearly identical to N-terminal and internal sequences obtained from the partially purified glycoprotein. The molecular masses of the deduced mature proteins, 13,981 ( glp1 ) and 13,970 ( glp2 ), coincide with the molecular mass of the glycoprotein as determined by tricine-SDS-PAGE.