Summary information and primary citation
- PDB-id
-
1q2s;
DSSR-derived features in text and
JSON formats; DNAproDB
- Class
- transferase-RNA
- Method
- X-ray (3.2 Å)
- Summary
- Chemical trapping and crystal structure of a catalytic
trna guanine transglycosylase covalent intermediate
- Reference
-
Xie W, Liu X, Huang RH (2003): "Chemical
trapping and crystal structure of a catalytic tRNA
guanine transglycosylase covalent intermediate."
Nat.Struct.Biol., 10, 781-788.
doi: 10.1038/nsb976.
- Abstract
- Prokaryotic tRNA guanine transglycosylase (TGT)
catalyzes replacement of guanine (G) by
7-aminomethyl-7-deazaguanine (PreQ1) at the wobble position
of four specific tRNAs. Addition of 9-deazaguanine (9dzG)
to a reaction mixture of Zymomonas mobilis TGT and an RNA
substrate allowed us to trap, purify and crystallize a
chemically competent covalent intermediate of the
TGT-catalyzed reaction. The crystal structure of the
TGT-RNA-9dzG ternary complex at a resolution of 2.9 A
reveals, unexpectedly, that RNA is tethered to TGT through
the side chain of Asp280. Thus, Asp280, instead of the
previously proposed Asp102, acts as the nucleophile for the
reaction. The RNA substrate adopts an unusual conformation,
with four out of seven nucleotides in the loop region
flipped out. Interactions between TGT and RNA revealed by
the structure provide the molecular basis of the RNA
substrate requirements by TGT. Furthermore, reaction of
PreQ1 with the crystallized covalent intermediate provides
insight into the necessary structural changes required for
the TGT-catalyzed reaction to occur.
