Specificity of a β-porphyranase produced by the carrageenophyte red alga Chondrus crispus and implications of this unexpected activity on red algal biology.

Autor: Manat G; CNRS, Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France., Fanuel M; INRAE, UR BIA, Nantes, France; INRAE, BIBS Facility, Nantes, France., Jouanneau D; CNRS, FR 2424, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France., Jam M; CNRS, Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France., Mac-Bear J; INRAE, UR BIA, Nantes, France., Rogniaux H; INRAE, UR BIA, Nantes, France; INRAE, BIBS Facility, Nantes, France., Mora T; CNRS, Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France., Larocque R; CNRS, FR 2424, Station Biologique de Roscoff, Sorbonne Université, Roscoff, France., Lipinska A; CNRS, Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France., Czjzek M; CNRS, Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France., Ropartz D; INRAE, UR BIA, Nantes, France; INRAE, BIBS Facility, Nantes, France., Ficko-Blean E; CNRS, Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, Roscoff, France. Electronic address: efickoblean@sb-roscoff.fr.
Jazyk: angličtina
Zdroj: The Journal of biological chemistry [J Biol Chem] 2022 Dec; Vol. 298 (12), pp. 102707. Date of Electronic Publication: 2022 Nov 17.
DOI: 10.1016/j.jbc.2022.102707
Abstrakt: The carrageenophyte red alga Chondrus crispus produces three family 16 glycoside hydrolases (CcGH16-1, CcGH16-2, and CcGH16-3). Phylogenetically, the red algal GH16 members are closely related to bacterial GH16 homologs from subfamilies 13 and 14, which have characterized marine bacterial β-carrageenase and β-porphyranase activities, respectively, yet the functions of these CcGH16 hydrolases have not been determined. Here, we first confirmed the gene locus of the ccgh16-3 gene in the alga to facilitate further investigation. Next, our biochemical characterization of CcGH16-3 revealed an unexpected β-porphyranase activity, since porphyran is not a known component of the C. crispus extracellular matrix. Kinetic characterization was undertaken on natural porphyran substrate with an experimentally determined molecular weight. We found CcGH16-3 has a pH optimum between 7.5 and 8.0; however, it exhibits reasonably stable activity over a large pH range (pH 7.0-9.0). CcGH16-3 has a K M of 4.0 ± 0.8 μM, a k cat of 79.9 ± 6.9 s -1 , and a k cat /K M of 20.1 ± 1.7 μM -1  s -1 . We structurally examined fine enzymatic specificity by performing a subsite dissection. CcGH16-3 has a strict requirement for D-galactose and L-galactose-6-sulfate in its -1 and +1 subsites, respectively, whereas the outer subsites are less restrictive. CcGH16-3 is one of a handful of algal enzymes characterized with a specificity for a polysaccharide unknown to be found in their own extracellular matrix. This β-porphyranase activity in a carrageenophyte red alga may provide defense against red algal pathogens or provide a competitive advantage in niche colonization.
Competing Interests: Conflicts of interest The authors declare that they have no conflicts of interest with the contents of this article.
(Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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