2q6o | pdb_00002q6o
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SalL-Y70T with SAM and Cl
Overview
Halogen atom incorporation into a scaffold of bioactive compounds often amplifies biological activity, as is the case for the anticancer agent salinosporamide A (1), a chlorinated natural product from the marine bacterium Salinispora tropica. Significant effort in understanding enzymatic chlorination shows that oxidative routes predominate to form reactive electrophilic or radical chlorine species. Here we report the genetic, biochemical and structural characterization of the chlorinase SalL, which halogenates S-adenosyl-L-methionine (2) with chloride to generate 5'-chloro-5'-deoxyadenosine (3) and L-methionine (4) in a rarely observed nucleophilic substitution strategy analogous to that of Streptomyces cattleya fluorinase. Further metabolic tailoring produces a halogenated polyketide synthase substrate specific for salinosporamide A biosynthesis. SalL also accepts bromide and iodide as substrates, but not fluoride. High-resolution crystal structures of SalL and active site mutants complexed with substrates and products support the S(N)2 nucleophilic substitution mechanism and further illuminate halide specificity in this newly discovered halogenase family.
About this Structure
2Q6O is a Single protein structure of sequence from Bacteria with CL and SAM as ligands. Full crystallographic information is available from OCA.
Reference
Discovery and characterization of a marine bacterial SAM-dependent chlorinase., Eustaquio AS, Pojer F, Noel JP, Moore BS, Nat Chem Biol. 2008 Jan;4(1):69-74. Epub 2007 Dec 2. PMID:18059261
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