'''alpha-glucosyltransferase in complex with UDP-glucose and DNA containing an abasic site'''
===alpha-glucosyltransferase in complex with UDP-glucose and DNA containing an abasic site===
==Overview==
<!--
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.
The line below this paragraph, {{ABSTRACT_PUBMED_16081100}}, adds the Publication Abstract to the page
(as it appears on PubMed at http://www.pubmed.gov), where 16081100 is the PubMed ID number.
-->
{{ABSTRACT_PUBMED_16081100}}
==About this Structure==
==About this Structure==
Line 27:
Line 31:
[[Category: Sommer, N.]]
[[Category: Sommer, N.]]
[[Category: Transferase]]
[[Category: Transferase]]
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 15:55:39 2008''
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 23:08:13 2008''
Revision as of 23:08, 27 July 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
alpha-glucosyltransferase in complex with UDP-glucose and DNA containing an abasic sitealpha-glucosyltransferase in complex with UDP-glucose and DNA containing an abasic site
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
