title: 5'-methylthioadenosine nucleosidase from yellow lupine (Lupinus luteus): molecular characterization and mutational analysis.
abstract: This is report of mutational analysis of higher plant 5'-methylthioadenosine nucleosidase (MTAN). We identified and characterized the gene encoding yellow lupine (Lupinus luteus) MTAN (LlMTAN). The role of active site amino acids residues Glu24, Phe134, Glu188 and Asp211 was analyzed by site-directed mutagenesis. The Glu24Gln and Asp211Asn substitutions completely abolished the enzyme activity. The Glu188Gln mutant showed only trace activity toward 5'-methylthioadenosine. These results indicate that these three amino acid residues are necessary for enzyme activity. Furthermore, as the result of replacement of Phe134 by less bulky leucine, LlMTAN acquired the ability to bind and hydrolyze S-adenosylhomocysteine. We also analyzed the sequence of the LlMTAN promoter region. It appeared that there may be a direct link between LlMTAN expression regulation and sulfate metabolism.
authors: Department of Biochemistry and Biotechnology, Poznań University of Life Sciences, Poznań, Poland. ewabretes@gmail.com
authors: Ewa
authors: E
authors: Bretes
authors: Andrzej
authors: A
authors: Guranowski
authors: Katarzyna
authors: K
authors: Nuc
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain / Q000235:genetics; D004252:DNA Mutational Analysis; D003839:Deoxyadenosines / Q000378:metabolism; D007700:Kinetics; D031297:Lupinus / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011683:Purine-Nucleoside Phosphorylase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D013379:Substrate Specificity; D013872:Thionucleosides / Q000378:metabolism
chemical_list: D003839:Deoxyadenosines; D013872:Thionucleosides; C008500:5'-methylthioadenosine; D011683:Purine-Nucleoside Phosphorylase; C021784:5'-methylthioadenosine phosphorylase