1PUD

TRNA-GUANINE TRANSGLYCOSYLASE

Summary for 1PUD

• Entry DOI: 10.2210/pdb1pud/pdb
• Descriptor: TRNA-GUANINE TRANSGLYCOSYLASE, ZINC ION (3 entities in total)
• Functional Keywords: trna-modifying enzyme, transferase, glycosyltransferase
• Biological source: Zymomonas mobilis
• Total number of polymer chains: 1
• Total formula weight: 42991.11

Authors

Romier, C.,Reuter, K.,Suck, D.,Ficner, R. (deposition date: 1996-06-28, release date: 1997-07-07, Last modification date: 2024-02-21)

Primary citation

Romier, C.,Reuter, K.,Suck, D.,Ficner, R.
Crystal structure of tRNA-guanine transglycosylase: RNA modification by base exchange.
EMBO J., 15:2850-2857, 1996

PubMed Abstract: 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.

PubMed: 8654383

Experimental method

X-RAY DIFFRACTION (1.85 Å)