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Determination of the molecular states of the processive endocellulase Thermobifida fusca Cel9A during crystalline cellulose depolymerization

Authors

  • Maxim Kostylev,

    Corresponding author
    1. Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853; telephone: 607-255-6476; fax: 607-255-6249
    • Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853; telephone: 607-255-6476; fax: 607-255-6249.
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  • Jose M. Moran-Mirabal,

    1. Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York
    Current affiliation:
    1. Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S4L8, Canada.
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  • Larry P. Walker,

    1. Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York
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  • David B. Wilson

    1. Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
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Abstract

Detailed understanding of cell wall degrading enzymes is important for their modeling and industrial applications, including in the production of biofuels. Here we used Cel9A, a processive endocellulase from Thermobifida fusca, to demonstrate that cellulases that contain a catalytic domain (CD) attached to a cellulose binding module (CBM) by a flexible linker exist in three distinct molecular states. By measuring the ability of a soluble competitor to reduce Cel9A activity on an insoluble substrate, we show that the most common state of Cel9A is bound via its CBM, but with its CD unoccupied by the insoluble substrate. These findings are relevant for kinetic modeling and microscopy studies of modular glycoside hydrolases. Biotechnol. Bioeng. 2012;109: 295–299. © 2011 Wiley Periodicals, Inc.

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