6uql | pdb_00006uql

Crystal structure of R471A variant of cytosolic fumarate hydratase from Leishmania major in a complex with S-malate

spinqualitylabelsall models 6uql, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6uql is a 2 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: GOL, LMR, SF4 Related: 6unz, 6uo0, 6uoi, 6uoj, 6up9, 6upm, 6upo, 6uq8, 6uq9, 6uqb, 6uqm, 6uqn Activity: Fumarate hydratase, with EC number 4.2.1.2 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Class I fumarate hydratases (FHs) are central metabolic enzymes that use a [4Fe-4S] cluster to catalyze the reversible conversion of fumarate to S-malate. The parasite Leishmania major, which is responsible for leishmaniasis, expresses two class I FH isoforms: mitochondrial LmFH-1 and cytosolic LmFH-2. In this study, we present kinetic characterizations of both LmFH isoforms, present 13 crystal structures of LmFH-2 variants, and employ site-directed mutagenesis to investigate the enzyme's mechanism. Our kinetic data confirm that both LmFH-1 and LmFH-2 are susceptible to oxygen-dependent inhibition, with data from crystallography and electron paramagnetic resonance spectroscopy showing that oxygen exposure converts an active [4Fe-4S] cluster to an inactive [3Fe-4S] cluster. Our anaerobically conducted kinetic studies reveal a preference for fumarate over S-malate. Our data further reveal that single alanine substitutions of T467, R421, R471, D135, and H334 decrease kcat values 9-16000-fold without substantially affecting Km values, suggesting that these residues function in catalytic roles. Crystal structures of LmFH-2 variants are consistent with this idea, showing similar bidentate binding to the unique iron of the [4Fe-4S] cluster for substrate S-malate as observed in wild type FH. We further present LmFH-2 structures with substrate fumarate and weak inhibitors succinate and malonate bound in the active site and the first structure of an LmFH that is substrate-free and inhibitor-free, the latter showing increased mobility in the C-terminal domain. Collectively, these data provide insight into the molecular basis for the reaction catalyzed by LmFHs, enzymes that are potential drug targets against leishmaniasis. Structural and Biochemical Investigations of the [4Fe-4S] Cluster-Containing Fumarate Hydratase from Leishmania major.,Feliciano PR, Drennan CL Biochemistry. 2019 Nov 27. doi: 10.1021/acs.biochem.9b00923. PMID:31743022 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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