6FV5

QTRT2, the non-catalytic subunit of murine tRNA-Guanine Transglycosylase

Summary for 6FV5

• Entry DOI: 10.2210/pdb6fv5/pdb
• Descriptor: Queuine tRNA-ribosyltransferase accessory subunit 2, ZINC ION, DI(HYDROXYETHYL)ETHER, ... (5 entities in total)
• Functional Keywords: transferase, transglycosylase, tim barrel
• Biological source: Mus musculus (House Mouse)
• Total number of polymer chains: 2
• Total formula weight: 94777.40

Authors

Behrens, C.,Heine, A.,Reuter, K. (deposition date: 2018-03-01, release date: 2018-06-13, Last modification date: 2024-05-08)

Primary citation

Behrens, C.,Biela, I.,Petiot-Becard, S.,Botzanowski, T.,Cianferani, S.,Sager, C.P.,Klebe, G.,Heine, A.,Reuter, K.
Homodimer Architecture of QTRT2, the Noncatalytic Subunit of the Eukaryotic tRNA-Guanine Transglycosylase.
Biochemistry, 57:3953-3965, 2018

PubMed Abstract: The bacterial enzyme tRNA-guanine transglycosylase (TGT) is involved in the biosynthesis of queuosine, a modified nucleoside present in the anticodon wobble position of tRNA, tRNA, tRNA, and tRNA. Although it forms a stable homodimer endowed with two active sites, it is, for steric reasons, able to bind and convert only one tRNA molecule at a time. In contrast, its mammalian counterpart constitutes a heterodimer consisting of a catalytic and a noncatalytic subunit, termed QTRT1 and QTRT2, respectively. Both subunits are homologous to the bacterial enzyme, yet only QTRT1 possesses all the residues required for substrate binding and catalysis. In mice, genetic inactivation of the TGT results in the uncontrolled oxidation of tetrahydrobiopterin and, accordingly, phenylketonuria-like symptoms. For this reason and because of the recent finding that mammalian TGT may be utilized for the treatment of multiple sclerosis, this enzyme is of potential medical relevance, rendering detailed knowledge of its biochemistry and structural architecture highly desirable. In this study, we performed the kinetic characterization of the murine enzyme, investigated potential quaternary structures of QTRT1 and QTRT2 via noncovalent mass spectrometry, and, finally, determined the crystal structure of the murine noncatalytic TGT subunit, QTRT2. In the crystal, QTRT2 is clearly present as a homodimer that is strikingly similar to that formed by bacterial TGT. In particular, a cluster of four aromatic residues within the interface of the bacterial TGT, which constitutes a "hot spot" for dimer stability, is present in a similar constellation in QTRT2.

PubMed: 29862811
DOI: 10.1021/acs.biochem.8b00294

Experimental method

X-RAY DIFFRACTION (2.179 Å)