Journal
PROTEIN AND PEPTIDE LETTERS
Volume 18, Issue 8, Pages 817-824Publisher
BENTHAM SCIENCE PUBL LTD
DOI: 10.2174/092986611795714023
Keywords
5 '-Methylthioadenosine; 5 '-Methylthioadenosine nucleosidase; Site-directed mutagenesis
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Funding
- Ministry of Science and Higher Education (MNiSW) [N N 302 0386636]
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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.
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