Monday, August 11, 2008 - 10:00 AM
S29
The duf-62 enzyme, SAM hydroxide adenosyltransferase,
David O'Hagan and Hai Deng. School of Chemistry, University of St Andrews, North Haugh, St Andrews, KY16 9ST, United Kingdom
We report a bacterial SAM enzyme that generates adenosine and L-methionine in a reaction with water. SAM is more commonly converted to adenosine, after demethylation to S-adenosylhomocysteine (SAH), by the action of SAH-lyase. This novel enzyme, a SAM hydroxide adenosyltransferase, catalyses a direct nucleophilic displacement of L-methionine by hydroxide generated from water. X-Ray crystallography reveals a highly conserved amino acid array that suggests a novel mechanism for water activation by an enzyme. The enzyme has some structural similarities to the fluorinase enzyme previously isolated from Streptomyces cattleya, however they differs substantially in their mechanisms of nucleophile activation. The enzyme is coded for by the duf-62 family of genes. This gene is replicated in upto 200 microorganism genomes, most of which are extremeophiles. The role of the new enzyme is not clear.
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See more of The Annual Meeting and Exhibition 2008 (August 10 - 14, 2008)