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Systems analysis in Cellvibrio japonicus resolves predicted redundancy of β-glucosidases and determines essential physiological functions

Lookup NU author(s): Dr Artur Rogowski, Carl Morland, Emeritus Professor Harry Gilbert

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Abstract

© 2017 John Wiley & Sons Ltd. Degradation of polysaccharides forms an essential arc in the carbon cycle, provides a percentage of our daily caloric intake, and is a major driver in the renewable chemical industry. Microorganisms proficient at degrading insoluble polysaccharides possess large numbers of carbohydrate active enzymes (CAZymes), many of which have been categorized as functionally redundant. Here we present data that suggests that CAZymes that have overlapping enzymatic activities can have unique, non-overlapping biological functions in the cell. Our comprehensive study to understand cellodextrin utilization in the soil saprophyte Cellvibrio japonicus found that only one of four predicted β-glucosidases is required in a physiological context. Gene deletion analysis indicated that only the cel3B gene product is essential for efficient cellodextrin utilization in C. japonicus and is constitutively expressed at high levels. Interestingly, expression of individual β-glucosidases in Escherichia coli K-12 enabled this non-cellulolytic bacterium to be fully capable of using cellobiose as a sole carbon source. Furthermore, enzyme kinetic studies indicated that the Cel3A enzyme is significantly more active than the Cel3B enzyme on the oligosaccharides but not disaccharides. Our approach for parsing related CAZymes to determine actual physiological roles in the cell can be applied to other polysaccharide-degradation systems.

Publication metadata

Author(s): Nelson CE, Rogowski A, Morland C, Wilhide JA, Gilbert HJ, Gardner JG

Publication type: Article

Publication status: Published

Journal: Molecular Microbiology

Year: 2017

Volume: 104

Issue: 2

Pages: 294-305

Print publication date: 04/04/2017

Online publication date: 24/01/2017

Acceptance date: 17/01/2017

ISSN (print): 0950-382X

ISSN (electronic): 1365-2958

Publisher: Blackwell Publishing Ltd

URL: https://doi.org/10.1111/mmi.13625

DOI: 10.1111/mmi.13625

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