Crystal structure of tRNA-guanine transglycosylase: RNA modification by base exchange.Romier, C., Reuter, K., Suck, D., Ficner, R.
(1996) EMBO J. 15: 2850-2857
- PubMed: 8654383
- PubMed Abstract:
- Sequence Analysis and Overexpression of the Zymomonas Mobilis Tgt Gene Encoding tRNA-Guanine Transglycosylase: Purification and Biochemical Characterization of the Enzyme
Reuter, K.,Ficner, R.
(1995) J.Bacteriol. 177: 5284
- Purification, Crystallization, and Preliminary X-Ray Diffraction Studies of tRNA-Guanine Transglycosylase from Zymomonas Mobilis
Romier, C.,Ficner, R.,Reuter, K.,Suck, D.
(1996) Proteins 24: 516
tRNA-guanine transglycosylases (TGT) are enzymes involved in the modification of the anticodon of tRNAs specific for Asn, Asp, His and Tyr, leading to the replacement of guanine-34 at the wobble position by the hypermodified base queuine. In prokaryo ...
tRNA-guanine transglycosylases (TGT) are enzymes involved in the modification of the anticodon of tRNAs specific for Asn, Asp, His and Tyr, leading to the replacement of guanine-34 at the wobble position by the hypermodified base queuine. In prokaryotes TGT catalyzes the exchange of guanine-34 with the queuine (.)precursor 7-aminomethyl-7-deazaguanine (preQ1). The crystal structure of TGT from Zymomonas mobilis was solved by multiple isomorphous replacement and refined to a crystallographic R-factor of 19% at 1.85 angstrom resolution. The structure consists of an irregular (beta/alpha)8-barrel with a tightly attached C-terminal zinc-containing subdomain. The packing of the subdomain against the barrel is mediated by an alpha-helix, located close to the C-terminus, which displaces the eighth helix of the barrel. The structure of TGT in complex with preQ1 suggests a binding mode for tRNA where the phosphate backbone interacts with the zinc subdomain and the U33G34U35 sequence is recognized by the barrel. This model for tRNA binding is consistent with a base exchange mechanism involving a covalent tRNA-enzyme intermediate. This structure is the first example of a (beta/alpha)-barrel protein interacting specifically with a nucleic acid.
European Molecular Biology Laboratory, Structural Biology Programme, Heidelberg, Germany.