title: Analysis of sialyltransferase-like proteins from Oryza sativa.
abstract: Sialic acids are widely distributed among living creatures, from bacteria to mammals, but it has been commonly accepted that they do not exist in plants. However, with the progress of genome analyses, putative gene homologs of animal sialyltransferases have been detected in the genome of some plants. In this study, we cloned three genes from Oryza sativa (Japanese rice) that encode sialyltransferase-like proteins, designated OsSTLP1, 2, and 3, and analyzed the enzymatic activity of the proteins. OsSTLP1, 2, and 3 consist of 393, 396, and 384 amino acids, respectively, and each contains sequences similar to the sialyl motifs that are highly conserved among animal sialyltransferases. The recombinant soluble forms of OsSTLPs produced by COS-7 cells were analyzed for sialyltransferase-like activity. OsSTLP1 exhibited such activity toward the oligosaccharide Galbeta1,4GlcNAc and such glycoproteins as asialofetuin, alpha1-acid glycoprotein, and asialo-alpha1-acid glycoprotein; OsSTLP3 exhibited similar activity toward asialofetuin; and OsSTLP2 exhibited no sialyltransferase-like activity. The sialic acid transferred by OsSTLP1 or 3 was linked to galactose of Galbeta1,4GlcNAc through alpha2,6-linkage. This is the first report of plant proteins having sialyltransferase-like activity.
authors.affiliation: Cellular Biochemistry Laboratory and Plant Functions Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. staka@riken.jp
authors.forename: Shou
authors.initials: S
authors.lastname: Takashima
authors.forename: Tomoko
authors.initials: T
authors.lastname: Abe
authors.forename: Shigeo
authors.initials: S
authors.lastname: Yoshida
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kawahigashi
authors.forename: Tamio
authors.initials: T
authors.lastname: Saito
authors.forename: Shuichi
authors.initials: S
authors.lastname: Tsuji
authors.forename: Masafumi
authors.initials: M
authors.lastname: Tsujimoto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D004789:Enzyme Activation; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology*; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D012799:Sialyltransferases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; D012799:Sialyltransferases