2iwa

Unbound glutaminyl cyclotransferase from Carica papaya.

spinqualitylabelsall models 2iwa, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2iwa is a 1 chain structure with sequence from Carica papaya. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, GOL, NAG Activity: Glutaminyl-peptide cyclotransferase, with EC number 2.3.2.5 Resources: FirstGlance, OCA, RCSB, PDBsum 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 Cyclisation of N-terminal glutamine and/or glutamate to yield pyroglutamate is an essential posttranslational event affecting a plethora of bioactive peptides and proteins. It is directly linked with pathologies ranging from neurodegenerative diseases to inflammation and several types of cancers. The reaction is catalysed by ubiquitous glutaminyl cyclotransferases (QCs), which present two distinct prototypes. Mammalian QCs are zinc-dependent enzymes with an alpha/beta-hydrolase fold. Here we present the 1.6-A-resolution structure of the other prototype, the plant analogue from Carica papaya (PQC). The hatbox-shaped molecule consists of an unusual five-fold beta-propeller traversed by a central channel, a topology that has hitherto been described only for some sugar-binding proteins and an extracellular nucleotidase. The high resistance of the enzyme to denaturation and proteolytic degradation is explained by its architecture, which is uniquely stabilised by a series of tethering elements that confer rigidity. Strikingly, the N-terminus of PQC specifically interacts with residues around the entrance to the central channel of a symmetry-related molecule, suggesting that this location is the putative active site. Cyclisation would follow a novel general-acid/base working mechanism, pivoting around a strictly conserved glutamate. This study provides a lead structure not only for plant QC orthologues, but also for bacteria, including potential human pathogens causing diphtheria, plague and malaria. Papaya glutamine cyclotransferase shows a singular five-fold beta-propeller architecture that suggests a novel reaction mechanism.,Guevara T, Mallorqui-Fernandez N, Garcia-Castellanos R, Garcia-Pique S, Ebert Petersen G, Lauritzen C, Pedersen J, Arnau J, Gomis-Ruth FX, Sola M Biol Chem. 2006 Oct-Nov;387(10-11):1479-86. PMID:17081122 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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