2gez

Crystal structure of potassium-independent plant asparaginase

spinqualitylabelsall models 2gez, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2gez is a 8 chain structure with sequence from European yellow lupine. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CL, NA Related: 1k2x, 1jn9, 1t3m, 1seo, 1apy, 2gaw, 2a8j Activity: Asparaginase, with EC number 3.5.1.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [ASPG_LUPLU] Degrades proteins damaged by L-isoaspartyl residue formation (also known as beta-Asp residues). Also has L-asparaginase activity, which is used to liberate stored nitrogen during seed development. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed In plants, specialized enzymes are required to catalyze the release of ammonia from asparagine, which is the main nitrogen-relocation molecule in these organisms. In addition, K+-independent plant asparaginases are also active in splitting the aberrant isoaspartyl peptide bonds, which makes these proteins important for seed viability and germination. Here, we present the crystal structure of potassium-independent L-asparaginase from yellow lupine (LlA) and confirm the classification of this group of enzymes in the family of Ntn-hydrolases. The alpha- and beta-subunits that form the mature (alphabeta)2 enzyme arise from autoproteolytic cleavage of two copies of a precursor protein. In common with other Ntn-hydrolases, the (alphabeta) heterodimer has a sandwich-like fold with two beta-sheets flanked by two layers of alpha-helices (alphabetabetaalpha). The nucleophilic Thr193 residue, which is liberated in the autocatalytic event at the N terminus of subunit beta, is part of an active site that is similar to that observed in a homologous bacterial enzyme. An unusual sodium-binding loop of the bacterial protein, necessary for proper positioning of all components of the active site, shows strictly conserved conformation and metal coordination in the plant enzyme. A chloride anion complexed in the LlA structure marks the position of the alpha-carboxylate group of the L-aspartyl substrate/product moiety. Detailed analysis of the active site suggests why the plant enzyme hydrolyzes asparagine and its beta-peptides but is inactive towards substrates accepted by similar Ntn-hydrolases, such as taspase1, an enzyme implicated in some human leukemias. Structural comparisons of LlA and taspase1 provide interesting insights into the role of small inorganic ions in the latter enzyme. Crystal structure of plant asparaginase.,Michalska K, Bujacz G, Jaskolski M J Mol Biol. 2006 Jun 30;360(1):105-16. Epub 2006 May 15. PMID:16725155 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Aminopeptidase 3D structures Asparaginase 3D structures

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