Details

Autor(en) / Beteiligte

• Lariviere, L
• Morera, S

Titel

A base-flipping mechanism for the T4 phage beta-glucosyltransferase and identification of a transition-state analog

Ist Teil von

• Journal of molecular biology, 2002-11, Vol.324 (3), p.483-490

Ort / Verlag

England

Erscheinungsjahr

2002

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• 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.