Cellobiose dehydrogenase from the ligninolytic basidiomycete Ceriporiopsis subvermispora.
Cellobiose dehydrogenase (CDH), an extracellular flavocytochrome produced by several wood-degrading fungi, was detected in cultures of the selective delignifier Ceriporiopsis subvermispora when grown on a cellulose- and yeast extract-based liquid medium. CDH amounted to up to 2.5% of total extracellular protein during latter phases of the cultivation and thus suggested an important function for the fungus under the given conditions. The enzyme was purified 44-fold to apparent homogeneity. It was found to be present in two glycoforms of 98 kDa and 87 kDa with carbohydrate contents of 16 and 4%, respectively. The isoelectric point of both glycoforms is around 3.0, differing by 0.1 units, which is the most acidic value so far reported for a CDH. By using degenerated primers of known CDH sequences, one cdh gene was found in the genomic DNA, cloned, and sequenced. Alignment of the 774-amino-acid protein sequence revealed a high similarity to CDH from other white rot fungi. One notable difference was found in the longer interdomain peptide linker, which might affect the interdomain electron transfer at higher temperatures. The preferred substrate of C. subvermispora CDH is cellobiose, while glucose conversion is strongly discriminated by a 155,000-fold-lower catalytic efficiency. This is a typical feature of a basidiomycete CDH, as are the acidic pH optima for all tested electron acceptors in the range from 2.5 to 4.5.
Harreither
Wolfgang
W
Department of Food Sciences and Technology, Division of Food Biotechnology, BOKU University of Natural Resources and Applied Life Sciences, A-1190 Vienna, Austria.
Sygmund
Christoph
C
Dünhofen
Evelyn
E
Vicuña
Rafael
R
Haltrich
Dietmar
D
Ludwig
Roland
R
D002237:Carbohydrate Dehydrogenases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D002475:Cellobiose / Q000378:metabolism; D055453:Coriolaceae / Q000201:enzymology* / Q000235:genetics; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007527:Isoenzymes / Q000737:chemistry; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013696:Temperature
D004271:DNA, Fungal; D005656:Fungal Proteins; D007527:Isoenzymes; D002475:Cellobiose; D002237:Carbohydrate Dehydrogenases; C019859:cellobiose-quinone oxidoreductase; D005947:Glucose