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| Main Authors: | , , , , , , , , |
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| Format: | Artículo científico |
| Language: | en |
| Published: |
Applied and environmental microbiology
2026
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| Subjects: | |
| Online Access: | https://pubmed.ncbi.nlm.nih.gov/41940666/ |
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Table of Contents:
- Characterization of a GH17 laminarinase, GH17A, from a laminarin polysaccharide utilization locus in the marine bacterium . Allahgholi, Leila Derks, Maik G N Moenaert, Antoine Dong, Zehui Dobruchowska, Justyna M Linares-Pastén, Javier A Friðjónsson, Ólafur H Hreggviðsson, Guðmundur Óli Nordberg Karlsson, Eva Glucans Bacterial Proteins Glycoside Hydrolases Polysaccharides Aquatic Organisms Phylogeny Heterotrophic marine microorganisms have the capability to degrade and metabolize laminarin, which is the most abundant source of energy and nutrients in the marine environment, via enzymes encoded by genes clustered in polysaccharide utilization loci (PULs). In this study, a PUL potentially responsible for laminarin utilization was identified in the genome of the marine bacterium strain ISCAR-4703, with conserved synteny in the genus . A GH17 laminarinase (GH17A) encoded in the newly identified PUL was cloned, produced, and characterized as an endo-acting laminarinase, exhibiting the ability to degrade laminarin and laminari-oligosaccharides with a degree of polymerization (DP) greater than four into laminaribiose, laminaritriose, and laminaritetraose, with laminaritriose as the main product, making up >50% of the produced oligosaccharide products. The three-dimensional model of the enzyme revealed the presence of seven putative subsites, including four glycone subsites (-4 to -1) and three aglycone subsites (+1 to +3), with a wide cleft to accommodate branches at the -2 subsite, enabling it to act on β-1,3-linked backbones in polysaccharides with β-1,6-linked branches. This enzyme is, along with the recently characterized β-1,3 glucanosyltransglycosylase (GH17B), conserved in several species and is suggested to play a crucial role in the utilization of laminarin by these bacteria. Laminarin, a β-1,3-glucan with occasional β-1,6 branching, is the most abundant source of energy and nutrients in the marine environment. In this study, polysaccharide utilization loci (PULs) for laminarin degradation were identified in various marine species, encoding a range of glycoside hydrolases and transglycosylases. In ISCAR-4703, the PUL included two GH17 enzymes, separated by a GH30 enzyme and a major facilitator superfamily (MFS) transporter, a feature observed in all corresponding PULs. A novel endoacting laminarinase from the PUL, GH17A, was characterized and shown to hydrolyze laminarin into laminaribiose, laminaritriose, and laminaritetraose, with laminaritriose as the main product. Bioinformatic analysis showed that the enzyme lacked the typical subdomain found in GH17 plant β-glucanases, leading to a lower number of aglycone subsites (+1 to +3). Instead, GH17A possessed more glycone subsites (-1 to -4), attributed to the β3-α3 loop, which was longer than in GH17 plant β-glucanases.