title: The mannitol utilization system of the marine bacterium Zobellia galactanivorans.
abstract: Mannitol is a polyol that occurs in a wide range of living organisms, where it fulfills different physiological roles. In particular, mannitol can account for as much as 20 to 30% of the dry weight of brown algae and is likely to be an important source of carbon for marine heterotrophic bacteria. Zobellia galactanivorans (Flavobacteriia) is a model for the study of pathways involved in the degradation of seaweed carbohydrates. Annotation of its genome revealed the presence of genes potentially involved in mannitol catabolism, and we describe here the biochemical characterization of a recombinant mannitol-2-dehydrogenase (M2DH) and a fructokinase (FK). Among the observations, the M2DH of Z. galactanivorans was active as a monomer, did not require metal ions for catalysis, and featured a narrow substrate specificity. The FK characterized was active on fructose and mannose in the presence of a monocation, preferentially K(+). Furthermore, the genes coding for these two proteins were adjacent in the genome and were located directly downstream of three loci likely to encode an ATP binding cassette (ABC) transporter complex, suggesting organization into an operon. Gene expression analysis supported this hypothesis and showed the induction of these five genes after culture of Z. galactanivorans in the presence of mannitol as the sole source of carbon. This operon for mannitol catabolism was identified in only 6 genomes of Flavobacteriaceae among the 76 publicly available at the time of the analysis. It is not conserved in all Bacteroidetes; some species contain a predicted mannitol permease instead of a putative ABC transporter complex upstream of M2DH and FK ortholog genes.
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France; CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Groisillier
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France; CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France.
authors.forename: Aurore
authors.initials: A
authors.lastname: Labourel
authors.affiliation: Sorbonne Universités, UPMC Université Paris 06, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France; CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, 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, Roscoff, France; CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, Roscoff, France tonon@sb-roscoff.fr.
authors.forename: Thierry
authors.identifier: http://orcid.org/0000-0002-1454-6018
authors.initials: T
authors.lastname: Tonon
mesh_terms: D002244:Carbon / Q000378:metabolism; D020536:Enzyme Activators / Q000378:metabolism; D041965:Flavobacteriaceae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D005631:Fructokinases / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D023061:Gene Order; D007477:Ions / Q000378:metabolism; D008353:Mannitol / Q000378:metabolism*; D008354:Mannitol Dehydrogenases / Q000235:genetics / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D008670:Metals / Q000378:metabolism; D009876:Operon; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D020536:Enzyme Activators; D007477:Ions; D008670:Metals; D011994:Recombinant Proteins; D008353:Mannitol; D002244:Carbon; D008354:Mannitol Dehydrogenases; D005631:Fructokinases; C046173:fructokinase