title: A new divergent type of eukaryotic methionine adenosyltransferase is present in multiple distantly related secondary algal lineages.
abstract: S-adenosylmethionine is one of the most important metabolites in living cells and is synthesized in a single reaction catalyzed by methionine adenosyltransferase (MAT). At the sequence and structural level, this enzyme is one of the most conserved proteins known. Here we show that some representatives of three distantly related eukaryotic lineages--dinoflagellates, haptophytes, and euglenids--possess a highly divergent type of MAT, which we call MATX. Even though MATX contains all the sites known to be involved in catalysis and the association of monomers, it also has four insertions throughout the protein that are not observed in other MAT homologs. The phylogenetic distribution and affinities of MATX suggest that it originated in a single eukaryotic lineage and was spread via multiple events of eukaryote-to-eukaryote lateral gene transfer. We suggest a tentative model in which the origin of MATX is connected with the progression of secondary endosymbiosis.
authors.affiliation: Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada B3H 1X5. gabino.sanchez.perez@gmail.com
authors.forename: Gabino F
authors.initials: GF
authors.lastname: Sanchez-Perez
authors.forename: Vladimir
authors.initials: V
authors.lastname: Hampl
authors.forename: Alastair G B
authors.initials: AG
authors.lastname: Simpson
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Roger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain; D004141:Dinoflagellida / Q000201:enzymology* / Q000235:genetics; D016822:Euglenida / Q000201:enzymology* / Q000235:genetics; D056890:Eukaryota / Q000201:enzymology* / Q000235:genetics; D019143:Evolution, Molecular; D008716:Methionine Adenosyltransferase / Q000235:genetics*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D008716:Methionine Adenosyltransferase