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Marine bacteroidetes use a conserved enzymatic cascade to digest diatom β-mannan
- The polysaccharide β-mannan, which is common in terrestrial plants but unknown in microalgae, was recently detected during diatom blooms. We identified a β-mannan polysaccharide utilization locus (PUL) in the genome of the marine flavobacterium Muricauda sp. MAR_2010_75. Proteomics showed β-mannan induced translation of 22 proteins encoded within the PUL. Biochemical and structural analyses deduced the enzymatic cascade for β-mannan utilization. A conserved GH26 β-mannanase with endo-activity depolymerized the β-mannan. Consistent with the biochemistry, X-ray crystallography showed the typical TIM-barrel fold of related enzymes found in terrestrial β-mannan degraders. Structural and biochemical analyses of a second GH26 allowed the prediction of an exo-activity on shorter manno-gluco oligosaccharides. Further analysis demonstrated exo-α-1,6-galactosidase- and endo-β-1,4-glucanase activity of the PUL-encoded GH27 and GH5_26, respectively, indicating the target substrate is a galactoglucomannan. Epitope deletion assays with mannanases as analytic tools indicate the presence of β-mannan in the diatoms Coscinodiscus wailesii and Chaetoceros affinis. Mannanases from the PUL were active on diatom β-mannan and polysaccharide extracts sampled during a microalgal bloom at the North Sea. Together these results demonstrate that marine microorganisms use a conserved enzymatic cascade to degrade β-mannans of marine and terrestrial origin and that this metabolic pathway plays a role in marine carbon cycling.
Author: | Irena Beidler, Craig S. Robb, Silvia Vidal-Melgosa, Marie-Katherin Zühlke, Daniel Bartosik, Vipul Solanki, Stephanie Markert, Dörte BecherORCiD, Thomas Schweder, Jan-Hendrik Hehemann |
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URN: | urn:nbn:de:gbv:9-opus-107377 |
DOI: | https://doi.org/10.1038/s41396-022-01342-4 |
ISSN: | 1751-7370 |
Parent Title (English): | ISME Journal |
Publisher: | Springer Nature |
Place of publication: | Berlin |
Document Type: | Article |
Language: | English |
Date of Publication (online): | 2022/11/21 |
Date of first Publication: | 2023/02/01 |
Release Date: | 2024/02/26 |
Volume: | 17 |
Issue: | 2 |
First Page: | 276 |
Last Page: | 285 |
Faculties: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Pharmazie |
Collections: | weitere DFG-förderfähige Artikel |
Licence (German): | Creative Commons - Namensnennung 4.0 International |