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Systems biology defines the biological significance of redox-active proteins during cellulose degradation in an aerobic bacterium

Lookup NU author(s): Dr Lucy Crouch, Dr Aurore Labourel, Emeritus Professor Harry Gilbert


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Microbial depolymerization of plant cell walls contributes to global carbon balance and is a critical component of renewable energy. The genomes of lignocellulose degrading microorganisms encode diverse classes of carbohydrate modifying enzymes, although currently there is a paucity of knowledge on the role of these proteins in vivo. We report the comprehensive analysis of the cellulose degradation system in the saprophytic bacterium Cellvibrio japonicus. Gene expression profiling of C. japonicus demonstrated that three of the 12 predicted -1,4 endoglucanases (cel5A, cel5B, and cel45A) and the sole predicted cellobiohydrolase (cel6A) showed elevated expression during growth on cellulose. Targeted gene disruptions of all 13 predicted cellulase genes showed that only cel5B and cel6A were required for optimal growth on cellulose. Our analysis also identified three additional genes required for cellulose degradation: lpmo10B encodes a lytic polysaccharide monooxygenase (LPMO), while cbp2D and cbp2E encode proteins containing carbohydrate binding modules and predicted cytochrome domains for electron transfer. CjLPMO10B oxidized cellulose and Cbp2D demonstrated spectral properties consistent with redox function. Collectively, this report provides insight into the biological role of LPMOs and redox proteins in cellulose utilization and suggests that C. japonicus utilizes a combination of hydrolytic and oxidative cleavage mechanisms to degrade cellulose.

Publication metadata

Author(s): Gardner JG, Crouch L, Labourel A, Forsberg Z, Bukhman YV, Vaaje-Kolstad G, Gilbert HJ, Keating DH

Publication type: Article

Publication status: Published

Journal: Molecular Microbiology

Year: 2014

Volume: 94

Issue: 5

Pages: 1121-1133

Print publication date: 01/12/2014

Online publication date: 03/11/2014

Acceptance date: 05/10/2014

ISSN (print): 0950-382X

ISSN (electronic): 1365-2958

Publisher: Wiley-Blackwell Publishing Ltd.


DOI: 10.1111/mmi.12821


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Funder referenceFunder name
College of Natural and Mathematical Sciences at the University of Maryland Baltimore County
6505Norwegian Academy of Science and Letters Vista Program
214138Norwegian Research Council
DE-FC02-07ER64494US Department of Energy (DOE BER Office of Science)