4nqy

The reduced form of MJ0499

spinqualitylabelsall models 4nqy, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4nqy is a 2 chain structure with sequence from Methanocaldococcus jannaschii DSM 2661. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function LEUC_METJA Enzyme with broad specificity that catalyzes reversible hydroxyacid isomerizations via dehydration/hydration reactions. Catalyzes the isomerization between 2-isopropylmalate and 3-isopropylmalate, via the formation of 2-isopropylmaleate, a step involved in leucine biosynthesis. Catalyzes the isomerization between 2-methylmalate and 3-methylmalate, via the formation of 2-methylmaleate (citraconate), a step involved in isoleucine biosynthesis. Also displays malease activity, i.e. catalyzes the hydration of maleate to form (R)-malate. Publication Abstract from PubMed The aconitase family of proteins includes three classes of hydro-lyase enzymes: aconitases, homoaconitases and isopropylmalate (IPM) isomerases. They have a common Fe-S cluster-binding site and catalyze the isomerization of specific substrates by sequential dehydration and hydration. The archaeon Methanococcus jannaschii contains two aconitase family proteins, IPM isomerase and homoaconitase, which have 50% sequence identity. These two enzymes are heterodimeric proteins composed of large and small subunits encoded by separate genes. Although structures have been reported for the small subunits of the two enzymes, the first structures of oxidized and reduced forms of the large subunit of IPM isomerase (ox-MJ0499 and red-MJ0499, respectively) from M. jannaschii are reported here at 1.8 and 2.7 A resolution, respectively, together with the structure of the large subunit of homoaconitase (MJ1003) at 2.5 A resolution. The structures of both proteins have unbound Fe-S clusters and contain a fourth cysteine in the active site. The active site of MJ1003 is homologous to that of aconitase, whereas MJ0499 has significant structural distortion at the active site compared with aconitase. In addition, significant large conformational changes were observed in the active site of red-MJ0499 when compared with ox-MJ0499. The active sites of the two proteins adopt two different states before changing to the Fe-S cluster-bound `activated' state observed in aconitase. MJ1003 has an `open' active site, which forms an active pocket for the cluster, while ox-MJ0499 has a `closed' active site, with four cysteines in disulfide bonds. These data will be helpful in understanding the biochemical mechanism of clustering of the Fe-S protein family. Structural characterization and comparison of the large subunits of IPM isomerase and homoaconitase from Methanococcus jannaschii.,Lee EH, Lee K, Hwang KY Acta Crystallogr D Biol Crystallogr. 2014 Apr 1;70(Pt 4):922-31. doi:, 10.1107/S1399004713033762. Epub 2014 Mar 19. PMID:24699638 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Isopropylmalate isomerase

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