Back to Search
Start Over
The laterally acquired GH5 ZgEngAGH5_4 from the marine bacterium Zobellia galactanivorans is dedicated to hemicellulose hydrolysis
- Source :
- Biochemical Journal, Biochemical Journal, Portland Press, 2018, 475 (22), pp.3609-3628. ⟨10.1042/BCJ20180486⟩
- Publication Year :
- 2018
- Publisher :
- Portland Press Ltd., 2018.
-
Abstract
- Cell walls of marine macroalgae are composed of diverse polysaccharides that provide abundant carbon sources for marine heterotrophic bacteria. Among them, Zobellia galactanivorans is considered as a model for studying algae–bacteria interactions. The degradation of typical algal polysaccharides, such as agars or alginate, has been intensively studied in this model bacterium, but the catabolism of plant-like polysaccharides is essentially uncharacterized. Here, we identify a polysaccharide utilization locus in the genome of Z. galactanivorans, induced by laminarin (β-1,3-glucans), and containing a putative GH5 subfamily 4 (GH5_4) enzyme, currently annotated as a endoglucanase (ZgEngAGH5_4). A phylogenetic analysis indicates that ZgEngAGH5_4 was laterally acquired from an ancestral Actinobacteria. We performed the biochemical and structural characterization of ZgEngAGH5_4 and demonstrated that this GH5 is, in fact, an endo-β-glucanase, most active on mixed-linked glucan (MLG). Although ZgEngAGH5_4 and GH16 lichenases both hydrolyze MLG, these two types of enzymes release different series of oligosaccharides. Structural analyses of ZgEngAGH5_4 reveal that all the amino acid residues involved in the catalytic triad and in the negative glucose-binding subsites are conserved, when compared with the closest relative, the cellulase EngD from Clostridium cellulovorans, and some other GH5s. In contrast, the positive glucose-binding subsites of ZgEngAGH5_4 are different and this could explain the preference for MLG, with respect to cellulose or laminarin. Molecular dynamics computer simulations using different hexaoses reveal that the specificity for MLG occurs through the +1 and +2 subsites of the binding pocket that display the most important differences when compared with the structures of other GH5_4 enzymes.
- Subjects :
- 0301 basic medicine
chemistry.chemical_classification
[SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Structural Biology [q-bio.BM]
biology
Chemistry
030106 microbiology
Cell Biology
Cellulase
biology.organism_classification
Polysaccharide
Biochemistry
Actinobacteria
Cell wall
03 medical and health sciences
Laminarin
chemistry.chemical_compound
030104 developmental biology
Catalytic triad
biology.protein
[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology
Molecular Biology
ComputingMilieux_MISCELLANEOUS
Clostridium cellulovorans
Glucan
Subjects
Details
- ISSN :
- 14708728 and 02646021
- Volume :
- 475
- Database :
- OpenAIRE
- Journal :
- Biochemical Journal
- Accession number :
- edsair.doi.dedup.....b944543244bf4cd21bce0068585921ef
- Full Text :
- https://doi.org/10.1042/bcj20180486