Cellobiose dehydrogenase is essential for wood invasion and nonessential for kraft pulp delignification by Trametes versicolor

Dumonceaux, Tim J.; Bartholomew, Kirk A.; Valeanu, Loredana; Charles, Trevor C.; Archibald, Frederick

doi:10.1016/s0141-0229(01)00407-0

Cited by 73 publications

(38 citation statements)

References 32 publications

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“…S3), suggesting that CDH is dispensable for scavenging nutrients from these carbon sources. This is different from the results of Dumonceaux et al (28), who observed an inability to grow on wood. Unfortunately, Southern blot analysis did not provide full confirmation that inactivation of the single CDH gene was responsible for the phenotype in the Dumonceaux et al paper, leaving the possibility that lack of growth on wood was due to an additional genetic defect.…”

Section: Resultscontrasting

confidence: 99%

“…In basidiomycetes, a CDH gene has only been inactivated in T. versicolor (28), and the single CDH of this species was found to be important for wood invasion but not for kraft pulp delignification. Recently, Phillips et al (14) and Zhang et al (15) analyzed the phenotypes of the deletions of cdh1 and cdh2 genes in N. crassa and found a reduction in CDH activity.…”

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Inactivation of Cellobiose Dehydrogenases Modifies the Cellulose Degradation Mechanism of Podospora anserina

Tangthirasunun

Navarro

Garajová

et al. 2017

Appl Environ Microbiol

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Conversion of biomass into high-value products, including biofuels, is of great interest to developing sustainable biorefineries. Fungi are an inexhaustible source of enzymes to degrade plant biomass. Cellobiose dehydrogenases (CDHs) play an important role in the breakdown through synergistic action with fungal lytic polysaccharide monooxygenases (LPMOs). The three CDH genes of the model fungus Podospora anserina were inactivated, resulting in single and multiple CDH mutants. We detected almost no difference in growth and fertility of the mutants on various lignocellulose sources, except on crystalline cellulose, on which a 2-fold decrease in fertility of the mutants lacking P. anserina CDH1 (PaCDH1) and PaCDH2 was observed. A striking difference between wild-type and mutant secretomes was observed. The secretome of the mutant lacking all CDHs contained five beta-glucosidases, whereas the wild type had only one. P. anserina seems to compensate for the lack of CDH with secretion of beta-glucosidases. The addition of P. anserina LPMO to either the wild-type or mutant secretome resulted in improvement of cellulose degradation in both cases, suggesting that other redox partners present in the mutant secretome provided electrons to LPMOs. Overall, the data showed that oxidative degradation of cellulosic biomass relies on different types of mechanisms in fungi.IMPORTANCE Plant biomass degradation by fungi is a complex process involving dozens of enzymes. The roles of each enzyme or enzyme class are not fully understood, and utilization of a model amenable to genetic analysis should increase the comprehension of how fungi cope with highly recalcitrant biomass. Here, we report that the cellobiose dehydrogenases of the model fungus Podospora anserina enable it to consume crystalline cellulose yet seem to play a minor role on actual substrates, such as wood shavings or miscanthus. Analysis of secreted proteins suggests that Podospora anserina compensates for the lack of cellobiose dehydrogenase by increasing beta-glucosidase expression and using an alternate electron donor for LPMO.

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Section: Resultscontrasting

confidence: 99%

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Inactivation of Cellobiose Dehydrogenases Modifies the Cellulose Degradation Mechanism of Podospora anserina

Tangthirasunun

Navarro

Garajová

et al. 2017

Appl Environ Microbiol

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“…21) Certain roles of CDH related to cellulose degradation have been reported. [21][22][23][24][25][26] The CDH of P. chrysosporium with cellobiose and ferrous iron reduced the degree of polymerization (DP) of the cellulose by the Fenton reaction. 22) The hydroxyl radical, which is generated in the Fenton reaction, is formed by the reaction of Fe(II) and hydrogen peroxide, which are reduced from Fe(III) and oxygen respectively by CDH.…”

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confidence: 99%

“…26) Hence CDH is considered to be the key enzyme in the degrading of cellulose. In the present study, we purified and characterized CDH from T. hirsuta.…”

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confidence: 99%

Purification and Characterization of Cellobiose Dehydrogenase from White-Rot BasidiomyceteTrametes hirsuta

Nakagame¹,

Furujyo²,

Sugiura³

2006

Bioscience, Biotechnology, and Biochemistry

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In order to save energy during the pulp making process, we tried to use white-rot basidiomycete, Trametes hirsuta, which degrades lignin efficiently. But a decrease in paper strength caused by cellulolytic activity ruled this out for practical application. Since the cellulolytic activity of the fungus must be decreased, we purified and characterized a cellobiose dehydrogenase (CDH) that was reported to damage pulp fiber. The CDH in the culture filtrate of C. hirsutus was purified by freeze-thawing and chromatographic methods. The pI of the enzyme was 4.2 and its molecular weight was 92 kDa. The optimal temperature and pH of the enzyme were 60-70 C and 5.0 respectively. Since the purified CDH decreased the viscosity of pulp in the presence of Fe(III) and cellobiose, it was shown that the suppression of CDH should be an effective way to reduce cellulose damage.

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“…4) as well as other polymers (5). The exact biological function of CDH has been a subject of lively debate, but recent results suggest that the enzyme is important for invasion and colonization of wood (6).…”

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Mechanism of the Reductive Half-reaction in Cellobiose Dehydrogenase

Hällberg¹,

Henriksson²,

Pettersson³

et al. 2003

Journal of Biological Chemistry

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The extracellular flavocytochrome cellobiose dehydrogenase (CDH; EC 1.1.99.18) participates in lignocellulose degradation by white-rot fungi with a proposed role in the early events of wood degradation. The complete hemoflavoenzyme consists of a catalytically active dehydrogenase fragment (DH cdh ) connected to a b-type cytochrome domain via a linker peptide. In the reductive half-reaction, DH cdh catalyzes the oxidation of cellobiose to yield cellobiono-1,5-lactone. The active site of DH cdh is structurally similar to that of glucose oxidase and cholesterol oxidase, with a conserved histidine residue positioned at the re face of the flavin ring close to the N5 atom. The mechanisms of oxidation in glucose oxidase and cholesterol oxidase are still poorly understood, partly because of lack of experimental structure data or difficulties in interpreting existing data for enzyme-ligand complexes. Here we report the crystal structure of the Phanerochaete chrysosporium DH cdh with a bound inhibitor, cellobiono-1,5-lactam, at 1.8-Å resolution. The distance between the lactam C1 and the flavin N5 is only 2.9 Å, implying that in an approximately planar transition state, the maximum distance for the axial 1-hydrogen to travel for covalent addition to N5 is 0.8 -0.9 Å. The lactam O1 interacts intimately with the side chains of His-689 and Asn-732. Our data lend substantial structural support to a reaction mechanism where His-689 acts as a general base by abstracting the O1 hydroxyl proton in concert with transfer of the C1 hydrogen as hydride to the re face of the flavin N5.Cellobiose dehydrogenases (CDHs 1 ; EC 1.1.99.18) are extracellular fungal flavocytochromes that are believed to participate in lignocellulose degradation by fungi. They are oxidoreductases carrying protoheme and FAD cofactors bound to separate domains. In vitro, CDH from the white-rot Basidiomycete Phanerochaete chrysosporium depolymerizes cellulose, hemicelluloses, and lignin (Refs. 1-3; for review, see Ref. 4) as well as other polymers (5). The exact biological function of CDH has been a subject of lively debate, but recent results suggest that the enzyme is important for invasion and colonization of wood (6).The catalytic site is located in the flavoprotein domain, where the reductive half-reaction proceeds by oxidation of ␤-cellobiose (apparent k cat 15.7 s Ϫ1 and K m 0.11 mM, see Ref. 7) to yield cellobiono-1,5-lactone (Fig.

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Cellobiose dehydrogenase is essential for wood invasion and nonessential for kraft pulp delignification by Trametes versicolor

Cited by 73 publications

References 32 publications

Inactivation of Cellobiose Dehydrogenases Modifies the Cellulose Degradation Mechanism of Podospora anserina

Inactivation of Cellobiose Dehydrogenases Modifies the Cellulose Degradation Mechanism of Podospora anserina

Purification and Characterization of Cellobiose Dehydrogenase from White-Rot BasidiomyceteTrametes hirsuta

Mechanism of the Reductive Half-reaction in Cellobiose Dehydrogenase

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