3hf5

Crystal structure of 4-methylmuconolactone methylisomerase in complex with 3-methylmuconolactone

spinqualitylabelsall models 3hf5, resolution 1.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3hf5 is a 4 chain structure with sequence from Pseudomonas reinekei. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.4Å Ligands: 3ML Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function C5MR76_9PSED Publication Abstract from PubMed When methyl-substituted aromatic compounds are degraded via ortho (intradiol)-cleavage of 4-methylcatechol, the dead-end metabolite 4-methylmuconolactone (4-ML) is formed. Degradation of 4-ML has only been described in few bacterial species, including Pseudomonas reinekei MT1. The isomerization of 4-ML to 3-methylmuconolactone (3-ML) is the first step required for the mineralization of 4-ML and is catalyzed by an enzyme termed 4-methylmuconolactone methylisomerase (MLMI). We identified the gene encoding MLMI in P. reinekei MT1 and solved the crystal structures of MLMI in complex with 3-ML at 1.4-A resolution, with 4-ML at 1.9-A resolution and with a MES buffer molecule at 1.45-A resolution. MLMI exhibits a ferredoxin-like fold and assembles as a tight functional homodimeric complex. We were able to assign the active site clefts of MLMI from P. reinekei MT1 and of the homologous MLMI from Cupriavidus necator JMP134, which has previously been crystallized in a structural genomics project. Kinetic and structural analysis of wild-type MLMI and variants created by site-directed mutagenesis indicate Tyr-39 and His-26 to be the most probable catalytic residues. The previously proposed involvement of Cys-67 in covalent catalysis can now be excluded. Residue His-52 was found to be important for substrate affinity, with only marginal effect on catalytic activity. Based on these results, a novel catalytic mechanism for the isomerization of 4-ML to 3-ML by MLMI, involving a bislactonic intermediate, is proposed. This broadens the knowledge about the diverse group of proteins exhibiting a ferredoxin-like fold. Crystal structure and catalytic mechanism of 4-methylmuconolactone methylisomerase.,Marin M, Heinz DW, Pieper DH, Klink BU J Biol Chem. 2009 Nov 20;284(47):32709-16. Epub 2009 Sep 29. PMID:19801657 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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