1xv5

alpha-glucosyltransferase (AGT) in complex with UDPalpha-glucosyltransferase (AGT) in complex with UDP

Structural highlights 1xv5 is a 1 chain structure with sequence from Enterobacteria phage t4. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: , , , NonStd Res: Related: 1y6f, 1y6g, 1y8z, 1ya6 Activity: DNA alpha-glucosyltransferase, with EC number 2.4.1.26 Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed The Escherichia coli T4 bacteriophage uses two glycosyltransferases to glucosylate and thus protect its DNA: the retaining alpha-glucosyltransferase (AGT) and the inverting beta-glucosyltransferase (BGT). They glucosylate 5-hydroxymethyl cytosine (5-HMC) bases of duplex DNA using UDP-glucose as the sugar donor to form an alpha-glucosidic linkage and a beta-glucosidic linkage, respectively. Five structures of AGT have been determined: a binary complex with the UDP product and four ternary complexes with UDP or UDP-glucose and oligonucleotides containing an A:G, HMU:G (hydroxymethyl uracyl) or AP:G (apurinic/apyrimidinic) mismatch at the target base-pair. AGT adopts the GT-B fold, one of the two folds known for GTs. However, while the sugar donor binding mode is classical for a GT-B enzyme, the sugar acceptor binding mode is unexpected and breaks the established consensus: AGT is the first GT-B enzyme that predominantly binds both the sugar donor and acceptor to the C-terminal domain. Its active site pocket is highly similar to four retaining GT-B glycosyltransferases (trehalose-6-phosphate synthase, glycogen synthase, glycogen and maltodextrin phosphorylases) strongly suggesting a common evolutionary origin and catalytic mechanism for these enzymes. Structure-guided mutagenesis and kinetic analysis do not permit identification of a nucleophile residue responsible for a glycosyl-enzyme intermediate for the classical double displacement mechanism. Interestingly, the DNA structures reveal partially flipped-out bases. They provide evidence for a passive role of AGT in the base-flipping mechanism and for its specific recognition of the acceptor base. Structural evidence of a passive base-flipping mechanism for AGT, an unusual GT-B glycosyltransferase.,Lariviere L, Sommer N, Morera S J Mol Biol. 2005 Sep 9;352(1):139-50. PMID:16081100 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

spinqualitylabelsall models 1xv5, resolution 1.73Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image