Abstract

Glycoside hydrolase family 7 (GH7) cellobiohydrolases (CBHs) play a key role in biomass recycling in nature. They are typically the most abundant enzymes expressed by potent cellulolytic fungi, and are also responsible for the majority of hydrolytic potential in enzyme cocktails for industrial processing of plant biomass. The thermostability of the enzyme is an important parameter for industrial utilization. In this study, Cel7 enzymes from different fungi were expressed in a fungal host and assayed for thermostability, including Hypocrea jecorina Cel7A as a reference. The most stable of the homologues, Humicola grisea var. thermoidea Cel7A, exhibits a 10 degrees C higher melting temperature (T-m of 72.5 degrees C) and showed a 4-5 times higher initial hydrolysis rate than H. jecorina Cel7A on phosphoric acid-swollen cellulose and showed the best performance of the tested enzymes on pretreated corn stover at elevated temperature (65 degrees C, 24 h). The enzyme shares 57% sequence identity with H. jecorina Cel7A and consists of a GH7 catalytic module connected by a linker to a C-terminal CBM1 carbohydrate-binding module. The crystal structure of the H. grisea var. thermoidea Cel7A catalytic module (1.8 angstrom resolution; R-work and R-free of 0.16 and 0.21, respectively) is similar to those of other GH7 CBHs. The deviations of several loops along the cellulose-binding path between the two molecules in the asymmetric unit indicate higher flexibility than in the less thermostable H. jecorina Cel7A.

Published in

Acta Crystallographica Section D: Biological Crystallography
2014, Volume: 70, pages: 2356-2366
Publisher: WILEY-BLACKWELL

SLU Authors

• Haddad Momeni, Majid

  • The Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences
    

• Hansson, Henrik

  • The Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences
    

• Karkehabadi, Saeid

  • The Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences
    

• Askarieh, Glareh

  • The Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences
    

• Ståhlberg, Jerry

  • The Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences
    

• Sandgren, Mats

  • The Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Biochemistry and Molecular Biology
Structural Biology


Publication identifier

DOI: https://doi.org/10.1107/S1399004714013844

Permanent link to this page (URI)

https://res.slu.se/id/publ/65928