title: Genetic analyses unravel the crucial role of a horizontally acquired alginate lyase for brown algal biomass degradation by Zobellia galactanivorans.
abstract: Comprehension of the degradation of macroalgal polysaccharides suffers from the lack of genetic tools for model marine bacteria, despite their importance for coastal ecosystem functions. We developed such tools for Zobellia galactanivorans, an algae-associated flavobacterium that digests many polysaccharides, including alginate. These tools were used to investigate the biological role of AlyA1, the only Z. galactanivorans alginate lyase known to be secreted in soluble form and to have a recognizable carbohydrate-binding domain. A deletion mutant, ΔalyA1, grew as well as the wild type on soluble alginate but was deficient in soluble secreted alginate lyase activity and in digestion of and growth on alginate gels and algal tissues. Thus, AlyA1 appears to be essential for optimal attack of alginate in intact cell walls. alyA1 appears to have been recently acquired via horizontal transfer from marine Actinobacteria, conferring an adaptive advantage that might benefit other algae-associated bacteria by exposing new substrate niches. The genetic tools described here function in diverse members of the phylum Bacteroidetes and should facilitate analyses of polysaccharide degradation systems and many other processes in these common but understudied bacteria.
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, P. O. Box 413, Milwaukee, WI, 53201, USA.
authors.forename: Yongtao
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Integrative Biology of Marine Models, Sorbonne Université, UPMC, Centre National de la Recherche Scientifique, UMR 8227, Station Biologique de Roscoff, Roscoff, France.
authors.forename: François
authors.initials: F
authors.lastname: Thomas
authors.affiliation: Integrative Biology of Marine Models, Sorbonne Université, UPMC, Centre National de la Recherche Scientifique, UMR 8227, Station Biologique de Roscoff, Roscoff, France.
authors.forename: Robert
authors.initials: R
authors.lastname: Larocque
authors.affiliation: State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province, 430072, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Li
authors.affiliation: Integrative Biology of Marine Models, Sorbonne Université, UPMC, Centre National de la Recherche Scientifique, UMR 8227, Station Biologique de Roscoff, Roscoff, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Duffieux
authors.affiliation: Integrative Biology of Marine Models, Sorbonne Université, UPMC, Centre National de la Recherche Scientifique, UMR 8227, Station Biologique de Roscoff, Roscoff, France.
authors.forename: Lionel
authors.initials: L
authors.lastname: Cladière
authors.affiliation: Integrative Biology of Marine Models, Sorbonne Université, UPMC, Centre National de la Recherche Scientifique, UMR 8227, Station Biologique de Roscoff, Roscoff, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Souchaud
authors.affiliation: Integrative Biology of Marine Models, Sorbonne Université, UPMC, Centre National de la Recherche Scientifique, UMR 8227, Station Biologique de Roscoff, Roscoff, France.
authors.forename: Gurvan
authors.initials: G
authors.lastname: Michel
authors.affiliation: Department of Biological Sciences, University of Wisconsin-Milwaukee, P. O. Box 413, Milwaukee, WI, 53201, USA.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: McBride
mesh_terms: D000464:Alginates / Q000378:metabolism*; D018533:Biomass; D002473:Cell Wall / Q000378:metabolism; D041965:Flavobacteriaceae / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D020723:Glucuronic Acid / Q000378:metabolism; D006603:Hexuronic Acids / Q000378:metabolism; D000459:Phaeophyceae / Q000382:microbiology*; D011133:Polysaccharide-Lyases / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion / Q000235:genetics
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020723:Glucuronic Acid; D011133:Polysaccharide-Lyases; C016158:poly(beta-D-mannuronate) lyase