4fsd | pdb_00004fsd

ArsM arsenic(III) S-adenosylmethionine methyltransferase with As(III)

spinqualitylabelsall models 4fsd, resolution 1.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4fsd is a 1 chain structure with sequence from Cyanidioschyzon sp. 5508. This structure supersedes the now removed PDB entry 3qnh. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ARS, CA, CL Related: 4fs8, 4fr0 Gene: arsM (Cyanidioschyzon sp. 5508) Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed Enzymatic methylation of arsenic is a detoxification process in microorganisms but in humans may activate the metalloid to more carcinogenic species. We describe the first structure of an As(III) S-adenosylmethionine methyltransferase by X-ray crystallography that reveals a novel As(III) binding domain. The structure of the methyltransferase from the thermophilic eukaryotic alga Cyanidioschyzon merolae reveals the relationship between the arsenic and S-adenosylmethionine binding sites to a final resolution of approximately 1.6 A. As(III) binding causes little change in conformation, but binding of SAM reorients helix alpha4 and a loop (residues 49-80) toward the As(III) binding domain, positioning the methyl group for transfer to the metalloid. There is no evidence of a reductase domain. These results are consistent with previous suggestions that arsenic remains trivalent during the catalytic cycle. A homology model of human As(III) S-adenosylmethionine methyltransferase with the location of known polymorphisms was constructed. The structure provides insights into the mechanism of substrate binding and catalysis. Structure of an As(III) S-Adenosylmethionine Methyltransferase: Insights into the Mechanism of Arsenic Biotransformation.,Ajees AA, Marapakala K, Packianathan C, Sankaran B, Rosen BP Biochemistry. 2012 Jun 29. PMID:22712827 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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