4ifk | pdb_00004ifk

Arginines 51 and 239* from a Neighboring Subunit are Essential for Catalysis in a Zinc-dependent Decarboxylase

spinqualitylabelsall models 4ifk, resolution 2.01Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4ifk is a 2 chain structure with sequence from "bacillus_fluorescens_liquefaciens"_flugge_1886 "bacillus fluorescens liquefaciens" flugge 1886. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: MG, ZN Related: 4ifo, 4ifr, 4ig2, 4ih3 Gene: nbaD ("Bacillus fluorescens liquefaciens" Flugge 1886) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Although the crystal structure of alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase from Pseudomonas fluorescens was solved as a dimer, this enzyme is a mixture of monomer, dimer, and higher order structures in solution. In this work, we found that the dimeric state, not the monomeric state, is the functionally active form. Two conserved arginine residues are present in the active site: Arg-51 and an intruding Arg-239* from the neighboring subunit. In this study, they were each mutated to alanine and lysine, and all four mutants were catalytically inactive. The mutants were also incapable of accommodating pyridine-2,6-dicarboxylic acid, a competitive inhibitor of the native enzyme, suggesting that the two Arg residues are involved in substrate binding. It was also observed that the decarboxylase activity was partially recovered in a heterodimer hybridization experiment when inactive R51(A/K) and R239(A/K) mutants were mixed together. Of the 20 crystal structures obtained from mixing inactive R51A and R239A homodimers that diffracted to a resolution lower than 3.00 A, two structures are clearly R51A/R239A heterodimers and belong to the C2 space group. They were refined to 1.80 and 2.00 A resolutions, respectively. Four of the remaining crystals are apparently single mutants and belong to the P42212 space group. In the heterodimer structures, one active site is shown to contain dual mutation of Ala-51 and Ala-239*, whereas the other contains the native Arg-51 and Arg-239* residues, identical to the wild-type structure. Thus, these observations provide the foundation for a molecular mechanism by which the oligomerization state of alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase could regulate the enzyme activity. The power of two: arginine 51 and arginine 239* from a neighboring subunit are essential for catalysis in alpha-amino-beta-carboxymuconate-epsilon-semialdehyde decarboxylase.,Huo L, Davis I, Chen L, Liu A J Biol Chem. 2013 Oct 25;288(43):30862-71. doi: 10.1074/jbc.M113.496869. Epub, 2013 Sep 9. PMID:24019523 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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