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Characterization of the two Neurospora crassa cellobiose dehydrogenases and their connection to oxidative cellulose degradation.

ABSTRACT: The genome of Neurospora crassa encodes two different cellobiose dehydrogenases (CDHs) with a sequence identity of only 53%. So far, only CDH IIA, which is induced during growth on cellulose and features a C-terminal carbohydrate binding module (CBM), was detected in the secretome of N. crassa and preliminarily characterized. CDH IIB is not significantly upregulated during growth on cellulosic material and lacks a CBM. Since CDH IIB could not be identified in the secretome, both CDHs were recombinantly produced in Pichia pastoris. With the cytochrome domain-dependent one-electron acceptor cytochrome c, CDH IIA has a narrower and more acidic pH optimum than CDH IIB. Interestingly, the catalytic efficiencies of both CDHs for carbohydrates are rather similar, but CDH IIA exhibits 4- to 5-times-higher apparent catalytic constants (k(cat) and K(m) values) than CDH IIB for most tested carbohydrates. A third major difference is the 65-mV-lower redox potential of the heme b cofactor in the cytochrome domain of CDH IIA than CDH IIB. To study the interaction with a member of the glycoside hydrolase 61 family, the copper-dependent polysaccharide monooxygenase GH61-3 (NCU02916) from N. crassa was expressed in P. pastoris. A pH-dependent electron transfer from both CDHs via their cytochrome domains to GH61-3 was observed. The different properties of CDH IIA and CDH IIB and their effect on interactions with GH61-3 are discussed in regard to the proposed in vivo function of the CDH/GH61 enzyme system in oxidative cellulose hydrolysis.

SUBMITTER: Sygmund C

PROVIDER: S-EPMC3416632 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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Characterization of the two Neurospora crassa cellobiose dehydrogenases and their connection to oxidative cellulose degradation.

Sygmund Christoph C Kracher Daniel D Scheiblbrandner Stefan S Zahma Kawah K Felice Alfons K G AK Harreither Wolfgang W Kittl Roman R Ludwig Roland R

Applied and environmental microbiology 20120622 17

The genome of Neurospora crassa encodes two different cellobiose dehydrogenases (CDHs) with a sequence identity of only 53%. So far, only CDH IIA, which is induced during growth on cellulose and features a C-terminal carbohydrate binding module (CBM), was detected in the secretome of N. crassa and preliminarily characterized. CDH IIB is not significantly upregulated during growth on cellulosic material and lacks a CBM. Since CDH IIB could not be identified in the secretome, both CDHs were recomb ...[more]

PMID: 22729546

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Dataset Information

Characterization of the two Neurospora crassa cellobiose dehydrogenases and their connection to oxidative cellulose degradation.

Publications

Characterization of the two Neurospora crassa cellobiose dehydrogenases and their connection to oxidative cellulose degradation.

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