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Functional roles in S ‐adenosyl‐ l ‐methionine binding and catalysis for active site residues of the thiostrepton resistance methyltransferase
Author(s) -
Myers Cullen L.,
Kuiper Emily G.,
Grant Pei C.,
Hernandez Jennifer,
Conn Graeme L.,
Honek John F.
Publication year - 2015
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2015.09.028
Subject(s) - thiostrepton , active site , binding site , asparagine , biochemistry , amino acid , chemistry , methionine , mutant , arginine , methyltransferase , enzyme , streptomyces , stereochemistry , ribosome , biology , methylation , bacteria , genetics , rna , gene
Resistance to the antibiotic thiostrepton, in producing Streptomycetes , is conferred by the S ‐adenosyl‐ l ‐methionine (SAM)‐dependent SPOUT methyltransferase Tsr. For this and related enzymes, the roles of active site amino acids have been inadequately described. Herein, we have probed SAM interactions in the Tsr active site by investigating the catalytic activity and the thermodynamics of SAM binding by site‐directed Tsr mutants. Two arginine residues were demonstrated to be critical for binding, one of which appears to participate in the catalytic reaction. Additionally, evidence consistent with the involvement of an asparagine in the structural organization of the SAM binding site is presented.