1xv5: Difference between revisions
No edit summary |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:1xv5.gif|left|200px]] | [[Image:1xv5.gif|left|200px]] | ||
<!-- | |||
The line below this paragraph, containing "STRUCTURE_1xv5", creates the "Structure Box" on the page. | |||
You may change the PDB parameter (which sets the PDB file loaded into the applet) | |||
or the SCENE parameter (which sets the initial scene displayed when the page is loaded), | |||
or leave the SCENE parameter empty for the default display. | |||
| | --> | ||
| | {{STRUCTURE_1xv5| PDB=1xv5 | SCENE= }} | ||
}} | |||
'''alpha-glucosyltransferase (AGT) in complex with UDP''' | '''alpha-glucosyltransferase (AGT) in complex with UDP''' | ||
| Line 29: | Line 26: | ||
[[Category: Morera, S.]] | [[Category: Morera, S.]] | ||
[[Category: Sommer, N.]] | [[Category: Sommer, N.]] | ||
[[Category: | [[Category: Transferase]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 15:32:46 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 15:32, 3 May 2008
alpha-glucosyltransferase (AGT) in complex with UDP
OverviewOverview
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.
About this StructureAbout this Structure
1XV5 is a Single protein structure of sequence from Enterobacteria phage t4. Full crystallographic information is available from OCA.
ReferenceReference
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 Page seeded by OCA on Sat May 3 15:32:46 2008