PMID:28118504

Citation	Nelson, CE, Rogowski, A, Morland, C, Wilhide, JA, Gilbert, HJ and Gardner, JG (2017) Systems analysis in Cellvibrio japonicus resolves predicted redundancy of β-glucosidases and determines essential physiological functions. Mol. Microbiol. 104:294-305
Abstract	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.
Links	PubMed PMC5398764 Online version:10.1111/mmi.13625
Keywords	Carbohydrate Metabolism/physiology; Cellulases/metabolism; Cellulases/physiology; Cellulose/analogs & derivatives; Cellulose/metabolism; Cellvibrio/physiology; Dextrins/metabolism; Disaccharides/metabolism; Enzymes; Escherichia coli/genetics; Kinetics; Polysaccharides/metabolism; Systems Analysis
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
CELJU:B3PDN7		GO:2000892: cellobiose catabolic process	ECO:0001225: knockout evidence used in manual assertion		P		Mutant strains with individual and combinatorial mutations were generated and growth assays were conducted to determine which genes were essential for allowing Cellvibrio japonicus to metabolize cellobiose, a disaccharide that composes cellulose. According to Figure 1A, cel3B deletion most significantly hinders growth of C. japonicus on cellobiose. Figure 2D also showed that the cel3B single mutants (triangles) had decreased cellobiose consumption and a longer lag phase compared to the wild type (circles). This shows that the gene product of cel3B, an enzyme, helps the cell use cellobiose as a carbon source.	complete CACAO 13660
CELJU:B3PDN7		GO:2000891: cellobiose metabolic process	ECO:0001147: anion-exchange chromatography evidence used in manual assertion		P		In Figure 2, wild type C. japonicus and cel3b, cel3Acel3B, and 4BG mutants were grown on cellobiose and glucose (control). The four strains showed no significant changes in glucose consumption during growth (Fig. 2A & 2B). However, the cel3b mutant showed a decreased rate of cellobiose consumption (Fig. 2C & 2D). This shows that cel3b has a role in efficient cellobiose utilization in C. japonicus.	complete CACAO 13722

References

See Help:References for how to manage references in GONUTS.