4hdk

Crystal Structure of ArsAB in Complex with Phloroglucinol

spinqualitylabelsall models 4hdk, resolution 1.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4hdk is a 2 chain structure with sequence from Sporomusa ovata. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: 13X, CL, EDO Related: 4hdm, 4hdr, 4hds, 4hdn Gene: arsA (Sporomusa ovata), arsB (Sporomusa ovata) Activity: Nicotinate-nucleotide--dimethylbenzimidazole phosphoribosyltransferase, with EC number 2.4.2.21 Resources: FirstGlance, OCA, RCSB, PDBsum Function [F6MZ55_9FIRM] Catalyzes the synthesis of alpha-ribazole-5'-phosphate from nicotinate mononucleotide (NAMN) and 5,6-dimethylbenzimidazole (DMB).[SAAS:SAAS00013329] Publication Abstract from PubMed Cobamides (Cbas) are cobalt (Co) containing tetrapyrrole-derivatives involved in enzyme-catalyzed carbon skeleton rearrangements, methyl-group transfers, and reductive dehalogenation. The biosynthesis of cobamides is complex and is only performed by some bacteria and achaea. Cobamides have an upper (Cobeta) ligand (5'-deoxyadenosyl or methyl) and a lower (Coalpha) ligand base that contribute to the axial Co coordinations. The identity of the lower Coalpha ligand varies depending on the organism synthesizing the Cbas. The homoacetogenic bacterium Sporomusa ovata synthesizes two unique phenolic cobamides (i.e., Coalpha-(phenolyl/p-cresolyl)cobamide), which are used in the catabolism of methanol and 3,4-dimethoxybenzoate by this bacterium. The S. ovata ArsAB enzyme activates a phenolic lower ligand prior to its incorporation into the cobamide. ArsAB consists of two subunits, both of which are homologous ( approximately 35% identity) to the well-characterized Salmonella enterica CobT enzyme, which transfers nitrogenous bases such as 5,6-dimethylbenzimidazole (DMB) and adenine, but cannot utilize phenolics. Here we report the three-dimensional structure of ArsAB, which shows that the enzyme forms a pseudosymmetric heterodimer, provide evidence that only the ArsA subunit has base:phosphoribosyl-transferase activity, and propose a mechanism by which phenolic transfer is facilitated by an activated water molecule. Structural Insights into the Function of the Nicotinate Mononucleotide:phenol/p-cresol Phosphoribosyltransferase (ArsAB) Enzyme from Sporomusa ovata.,Newmister SA, Chan CH, Escalante-Semerena JC, Rayment I Biochemistry. 2012 Oct 15. PMID:23039029 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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