1ixy

From Proteopedia

Ternary complex of T4 phage BGT with UDP and a 13 mer DNA duplex

Structural highlights

1ixy is a 6 chain structure with sequence from Escherichia virus T4. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.5Å
Ligands:	, , ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

GSTB_BPT4 Catalyzes the transfer of glucose (Glc) from uridine diphosphoglucose (UDP-Glc) to 5-hydroxymethylcytosine (5-HMC) in double-stranded DNA. Is involved in a DNA modification process to protect the phage genome against its own nucleases and the host restriction endonuclease system.

Publication Abstract from PubMed

T4 phage beta-glucosyltransferase (BGT) modifies T4 DNA. We crystallized BGT with UDP-glucose and a 13mer DNA fragment containing an abasic site. We obtained two crystal structures of a ternary complex BGT-UDP-DNA at 1.8A and 2.5A resolution, one with a Tris molecule and the other with a metal ion at the active site. Both structures reveal a large distortion in the bound DNA. BGT flips the deoxyribose moiety at the abasic site to an extra-helical position and induces a 40 degrees bend in the DNA with a marked widening of the major groove. The Tris molecule mimics the glucose moiety in its transition state. The base-flipping mechanism, which has so far been observed only for glycosylases, methyltransferases and endonucleases, is now reported for a glucosyltransferase. BGT is unique in binding and inserting a loop into the DNA duplex through the major groove only. Furthermore, BGT compresses the backbone DNA one base further than the target base on the 3'-side.

A base-flipping mechanism for the T4 phage beta-glucosyltransferase and identification of a transition-state analog.,Lariviere L, Morera S J Mol Biol. 2002 Nov 29;324(3):483-90. PMID:12445783^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Lariviere L, Morera S. A base-flipping mechanism for the T4 phage beta-glucosyltransferase and identification of a transition-state analog. J Mol Biol. 2002 Nov 29;324(3):483-90. PMID:12445783