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Conversion of Thermobifida fusca free exoglucanases into cellulosomal components: Comparative impact on cellulose-degrading activity

Paper ID Volume ID Publish Year Pages File Format Full-Text
24914 43545 2008 7 PDF Available
Title
Conversion of Thermobifida fusca free exoglucanases into cellulosomal components: Comparative impact on cellulose-degrading activity
Abstract

Cellulosomes are multi-enzyme complexes produced by certain anaerobic bacteria that exhibit efficient degradation of plant cell wall polysaccharides. To understand their enhanced levels of hydrolysis, we are investigating the effects of converting a free-cellulase system into a cellulosomal one. To achieve this end, we are replacing the cellulose-binding module of the native cellulases, produced by the aerobic bacterium Thermobifida fusca, with a cellulosome-derived dockerin module of established specificity, to allow their incorporation into defined “designer cellulosomes”. In this communication, we have attached divergent dockerins to the two exoglucanases produced by T. fusca exoglucanase, Cel6B and Cel48A. The resultant fusion proteins were shown to bind efficiently and specifically to their matching cohesins, and their activities on several different cellulose substrates were compared. The lack of a cellulose-binding module in Cel6B had a deleterious effect on its activity on crystalline substrates. In contrast, the dockerin-bearing family-48 exoglucanase showed increased levels of hydrolytic activity on carboxymethyl cellulose and on both crystalline substrates tested, compared to the wild-type enzyme. The marked difference in the response of the two exoglucanases to incorporation into a cellulosome, suggests that the family-48 cellulase is more appropriate than the family-6 enzyme as a designer cellulosome component.

Keywords
CBM, cellulose-binding module; CBM2, T. fusca family-2 CBM; CBM3, family-3a CBM derived from the C. thermocellum cellulosomal scaffoldin; Cel6A, wild-type T. fusca cellulase containing a CBM2 module downstream of a GH6 catalytic module; Cel6B, wild-type T
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Conversion of Thermobifida fusca free exoglucanases into cellulosomal components: Comparative impact on cellulose-degrading activity
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 135, Issue 4, 31 July 2008, Pages 351–357
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us