Skip to main content
Log in

Identification of a unique 1,4-β-d-glucan glucohydrolase of glycoside hydrolase family 9 from Cytophaga hutchinsonii

  • Biotechnologically relevant enzymes and proteins
  • Published:
Applied Microbiology and Biotechnology Aims and scope Submit manuscript

Abstract

Cytophaga hutchinsonii is an aerobic cellulolytic soil bacterium that rapidly digests crystalline cellulose. The predicted mechanism by which C. hutchinsonii digests cellulose differs from that of other known cellulolytic bacteria and fungi. The genome of C. hutchinsonii contains 22 glycoside hydrolase (GH) genes, which may be involved in cellulose degradation. One predicted GH with uncertain specificity, CHU_0961, is a modular enzyme with several modules. In this study, phylogenetic tree of the catalytic modules of the GH9 enzymes showed that CHU_0961 and its homologues formed a new group (group C) of GH9 enzymes. The catalytic module of CHU_0961 (CHU_0961B) was identified as a 1,4-β-d-glucan glucohydrolase (EC 3.2.1.74) that has unique properties compared with known GH9 cellulases. CHU_0961B showed highest activity against barley glucan, but low activity against other polysaccharides. Interestingly, CHU_0961B showed similar activity against ρ-nitrophenyl β-d-cellobioside (ρ-NPC) and ρ-nitrophenyl β-d-glucopyranoside. CHU_0961B released glucose from the nonreducing end of cello-oligosaccharides, ρ-NPC, and barley glucan in a nonprocessive exo-type mode. CHU_0961B also showed same hydrolysis mode against deacetyl-chitooligosaccharides as against cello-oligosaccharides. The kcat/Km values for CHU_0961B against cello-oligosaccharides increased as the degree of polymerization increased, and its kcat/Km for cellohexose was 750 times higher than that for cellobiose. Site-directed mutagenesis showed that threonine 321 in CHU_0961 played a role in hydrolyzing cellobiose to glucose. CHU_0961 may act synergistically with other cellulases to convert cellulose to glucose on the bacterial cell surface. The end product, glucose, may initiate cellulose degradation to provide nutrients for bacterial proliferation in the early stage of C. hutchinsonii growth.

Key points

• CHU_0961 and its homologues formed a novel group (group C) of GH9 enzymes.

• CHU_0961 was identified as a 1,4-β- d -glucan glucohydrolase with unique properties.

• CHU_0961 may play an important role in the early stage of C. hutchinsonii growth.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6

Similar content being viewed by others

References

Download references

Funding

This work was financially supported by grant from the National Natural Science Foundation of China (grant no. 31560019) and the Guangxi Natural Science Foundation (grant no. 2018GXNSFAA138053).

Author information

Authors and Affiliations

Authors

Contributions

C-JD and J-XF conceived and designed research. NJ, X-DM, and L-HF conducted experiments. C-XL contributed bioinformational analysis. C-JD and NJ analyzed data. C-JD and NJ wrote the manuscript. All authors read and approved the manuscript.

Corresponding author

Correspondence to Cheng-Jie Duan.

Ethics declarations

Conflict of interest

The authors declare that they have no conflict of interests.

Ethical statement

This article does not contain any studies with human participants and/or animals performed by any of the authors

Additional information

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Electronic supplementary material

ESM 1

(PDF 1290 kb).

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Jiang, N., Ma, XD., Fu, LH. et al. Identification of a unique 1,4-β-d-glucan glucohydrolase of glycoside hydrolase family 9 from Cytophaga hutchinsonii. Appl Microbiol Biotechnol 104, 7051–7066 (2020). https://doi.org/10.1007/s00253-020-10731-8

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00253-020-10731-8

Keywords

Navigation