In:
Applied and Environmental Microbiology, American Society for Microbiology, Vol. 85, No. 18 ( 2019-09-15)
Abstract:
As classified by the Carbohydrate-Active Enzymes (CAZy) database, enzymes in glycoside hydrolase (GH) family 10 (GH10) are all monospecific or bifunctional xylanases (except a tomatinase), and no endo-β-1,4-glucanase has been reported in the family. Here, we identified Arcticibacterium luteifluviistationis carboxymethyl cellulase ( Al CMCase) as a GH10 endo-β-1,4-glucanase. Al CMCase originated from an Arctic marine bacterium, Arcticibacterium luteifluviistationis SM1504 T . It shows low identity ( 〈 35%) with other GH10 xylanases. The gene encoding Al CMCase was overexpressed in Escherichia coli . Biochemical characterization showed that recombinant Al CMCase is a cold-adapted and salt-tolerant enzyme. Al CMCase hydrolyzes cello- and xylo-configured substrates via an endoaction mode. However, in comparison to its significant cellulase activity, the xylanase activity of Al CMCase is negligible. Correspondingly, Al CMCase has remarkable binding capacity for cello-oligosaccharides but no obvious binding capacity for xylo-oligosaccharides. Al CMCase and its homologs are grouped into a branch separate from other GH10 xylanases in a phylogenetic tree, and two homologs also displayed the same substrate specificity as Al CMCase. These results suggest that Al CMCase and its homologs form a novel subfamily of GH10 enzymes that have robust endo-β-1,4-glucanase activity. In addition, given the cold-adapted and salt-tolerant characters of Al CMCase, it may be a candidate biocatalyst under certain industrial conditions, such as low temperature or high salinity. IMPORTANCE Cellulase and xylanase have been widely used in the textile, pulp and paper, animal feed, and food-processing industries. Exploring novel cellulases and xylanases for biocatalysts continues to be a hot issue. Enzymes derived from the polar seas might have novel hydrolysis patterns, substrate specificities, or extremophilic properties that have great potential for both fundamental research and industrial applications. Here, we identified a novel cold-adapted and salt-tolerant endo-β-1,4-glucanase, Al CMCase, from an Arctic marine bacterium. It may be useful in certain industrial processes, such as under low temperature or high salinity. Moreover, Al CMCase is a bifunctional representative of glycoside hydrolase (GH) family 10 that preferentially hydrolyzes β-1,4-glucans. With its homologs, it represents a new subfamily in this family. Thus, this study sheds new light on the substrate specificity of GH10.
Type of Medium:
Online Resource
ISSN:
0099-2240
,
1098-5336
DOI:
10.1128/AEM.01029-19
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2019
detail.hit.zdb_id:
223011-2
detail.hit.zdb_id:
1478346-0
SSG:
12
Bookmarklink