title: The plant Selaginella moellendorffii possesses enzymes for synthesis and hydrolysis of the compatible solutes mannosylglycerate and glucosylglycerate.
abstract: A mannosylglycerate synthase (MgS) gene detected in the genome of Selaginella moellendorffii was expressed in E. coli and the recombinant enzyme was purified and characterized. A remarkable and unprecedented feature of this enzyme was the ability to efficiently synthesize mannosylglycerate (MG) and glucosylglycerate (GG) alike, with maximal activity at 50 °C, pH 8.0 and with Mg(2+) as reaction enhancer. We have also identified a novel glycoside hydrolase gene in this plant's genome, which was functionally confirmed to be highly specific for the hydrolysis of MG and GG and named MG hydrolase (MgH), due to its homology with bacterial MgHs. The recombinant enzyme was maximally active at 40 °C and at pH 6.0-6.5. The activity was independent of cations, but Mn(2+) was a strong stimulator. Regardless of these efficient enzymatic resources we could not detect MG or GG in S. moellendorffii or in the extracts of five additional Selaginella species. Herein, we describe the properties of the first eukaryotic enzymes for the synthesis and hydrolysis of the compatible solutes, MG and GG.
authors.affiliation: CNC, Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517, Coimbra, Portugal.
authors.forename: Ana
authors.initials: A
authors.lastname: Nobre
authors.forename: Nuno
authors.initials: N
authors.lastname: Empadinhas
authors.forename: Maria Fernanda
authors.initials: MF
authors.lastname: Nobre
authors.forename: Eva Correia
authors.initials: EC
authors.lastname: Lourenço
authors.forename: Christopher
authors.initials: C
authors.lastname: Maycock
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Ventura
authors.forename: Ana
authors.initials: A
authors.lastname: Mingote
authors.forename: Milton S
authors.initials: MS
authors.lastname: da Costa
mesh_terms: D017343:Genes, Plant; D005988:Glyceric Acids / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008358:Mannose / Q000031:analogs & derivatives* / Q000096:biosynthesis; D008364:Mannosyltransferases / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D032503:Selaginellaceae / Q000201:enzymology* / Q000235:genetics; D020539:Sequence Analysis, Protein; D013045:Species Specificity; D013696:Temperature
chemical_list: D005988:Glyceric Acids; D011994:Recombinant Proteins; C402688:mannosylglycerate; D008364:Mannosyltransferases; C402687:mannosylglycerate synthase; D008358:Mannose