3qit | pdb_00003qit

Thioesterase Domain From Curacin Biosynthetic Pathway

spinqualitylabelsall models 3qit, resolution 1.68Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3qit is a 4 chain structure with sequence from Lyngbya majuscula 19l. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Gene: curM (Lyngbya majuscula 19L) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Curacin A is a polyketide synthase (PKS)-non-ribosomal peptide synthetase (NRPS) derived natural product with potent anticancer properties generated by the marine cyanobacterium Lyngbya majuscula. Type I modular PKS assembly lines typically employ a thioesterase (TE) domain to offload carboxylic acid or macrolactone products from an adjacent acyl carrier protein (ACP) domain. In a striking departure from this scheme the curacin A PKS employs tandem sulfotransferase (ST) and TE domains to form a terminal alkene moiety. ST sulfonation of beta-hydroxy-acyl-ACP is followed by TE hydrolysis, decarboxylation and sulfate elimination (Gu, 2009, J. Amer. Chem. Soc. 131, 16033). With low sequence identity to other PKS TEs (<15%), the curacin TE represents a new thioesterase sub-family. The 1.7-A curacin TE crystal structure reveals how the familiar alpha/beta hydrolase architecture is adapted to specificity for beta-sulfated substrates. A Ser-His-Glu catalytic triad is centered in an open active-site cleft between the core domain and a lid sub-domain. Unlike TEs from other PKSs, the lid is fixed in an open conformation on one side by dimer contacts of a protruding helix and on the other side by an arginine anchor from the lid into the core. Adjacent to the catalytic triad, another arginine residue is positioned to recognize the substrate beta-sulfate group. The essential features of the curacin TE are conserved in sequences of five other putative bacterial ACP-ST-TE tridomains. Formation of a sulfate leaving group as a biosynthetic strategy to facilitate acyl chain decarboxylation is of potential value as a route to hydrocarbon biofuels. Terminal alkene formation by the thioesterase of curacin a biosynthesis: Structure of a decarboxylating thioesterase.,Gehret JJ, Gu L, Gerwick WH, Wipf P, Sherman DH, Smith JL J Biol Chem. 2011 Feb 27. PMID:21357626 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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