title: Chemical and enzymatic fractionation of cell walls from Fucales: insights into the structure of the extracellular matrix of brown algae.
abstract: OBJECTIVE
  Brown algae are photosynthetic multicellular marine organisms evolutionarily distant from land plants, with a distinctive cell wall. They feature carbohydrates shared with plants (cellulose), animals (fucose-containing sulfated polysaccharides, FCSPs) or bacteria (alginates). How these components are organized into a three-dimensional extracellular matrix (ECM) still remains unclear. Recent molecular analysis of the corresponding biosynthetic routes points toward a complex evolutionary history that shaped the ECM structure in brown algae.
  
  
  METHODS
  Exhaustive sequential extractions and composition analyses of cell wall material from various brown algae of the order Fucales were performed. Dedicated enzymatic degradations were used to release and identify cell wall partners. This approach was complemented by systematic chromatographic analysis to study polymer interlinks further. An additional structural assessment of the sulfated fucan extracted from Himanthalia elongata was made.
  
  
  RESULTS
  The data indicate that FCSPs are tightly associated with proteins and cellulose within the walls. Alginates are associated with most phenolic compounds. The sulfated fucans from H. elongata were shown to have a regular α-(1→3) backbone structure, while an alternating α-(1→3), (1→4) structure has been described in some brown algae from the order Fucales.
  
  
  CONCLUSIONS
  The data provide a global snapshot of the cell wall architecture in brown algae, and contribute to the understanding of the structure-function relationships of the main cell wall components. Enzymatic cross-linking of alginates by phenols may regulate the strengthening of the wall, and sulfated polysaccharides may play a key role in the adaptation to osmotic stress. The emergence and evolution of ECM components is further discussed in relation to the evolution of multicellularity in brown algae.
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France CNRS, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France.
authors.forename: Estelle
authors.initials: E
authors.lastname: Deniaud-Bouët
authors.affiliation: Service RMN-RPE, UFR Sciences et Techniques, Université de Bretagne Occidentale (UBO), Avenue Le Gorgeu, 29200 Brest, France.
authors.forename: Nelly
authors.initials: N
authors.lastname: Kervarec
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France CNRS, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France.
authors.forename: Gurvan
authors.initials: G
authors.lastname: Michel
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France CNRS, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Tonon
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France CNRS, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Kloareg
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France CNRS, UMR 8227 Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, France cecile.herve@sb-roscoff.fr.
authors.forename: Cécile
authors.initials: C
authors.lastname: Hervé
mesh_terms: D005075:Biological Evolution; D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism*; D005643:Fucose / Q000378:metabolism; D008961:Models, Structural; D000459:Phaeophyceae / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D011134:Polysaccharides / Q000378:metabolism*
chemical_list: D011134:Polysaccharides; D005643:Fucose; D002482:Cellulose; C007789:fucoidan
keywords: Brown algae; ECM; FCSP; Fucales; Himanthalia elongata; cell wall architecture; extracellular matrix; fucose-containing sulfated polysacharides; plant cell wall evolution; sequential extractions; sulfated fucan