title: Biochemical and structural characterization of 5'-methylthioadenosine nucleosidases from Arabidopsis thaliana.
abstract: 5'-Methylthioadenosine (MTA) and S-adenosylhomocysteine (SAH) are important metabolites in all living organisms. Two similar nucleosidases for hydrolyzing MTA in Arabidopsis thaliana (AtMTAN1 and AtMTAN2) exist, but only AtMTAN2 shows markedly broad substrate specificity for hydrolysis of SAH. To examine the biochemical characteristics of AtMTAN2, it was over-expressed in Escherichia coli and purified to homogeneity. Spectroscopic assays confirm AtMTAN2 catalyzes MTA as well as SAH hydrolysis, compared to AtMTAN1 which only hydrolyzes MTA. In addition, crystal structure of the AtMTAN2 enzyme in complex with, adenine was determined at 2.9A resolution. Finally, a structural comparison of AtMTAN2 performed with previously determined structures of AtMTAN1 and an E. coli homolog provides clues for the substrate specificity of MTA nucleosidases in A. thaliana.
authors.affiliation: Korea University, Anam-Dong, Seongbuk-Gu, Seoul, Republic of Korea.
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Park
authors.forename: Woo Suk
authors.initials: WS
authors.lastname: Choi
authors.forename: Seung-Ick
authors.initials: SI
authors.lastname: Oh
authors.forename: Kyung-Nam
authors.initials: KN
authors.lastname: Kim
authors.forename: Jeong Sheop
authors.initials: JS
authors.lastname: Shin
authors.forename: Hyun Kyu
authors.initials: HK
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002384:Catalysis; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011683:Purine-Nucleoside Phosphorylase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D011683:Purine-Nucleoside Phosphorylase; C021784:5'-methylthioadenosine phosphorylase; C540168:MTAN1 protein, Arabidopsis; C540169:MTAN2 protein, Arabidopsis