Domain Annotation: SCOP/SCOPe Classification SCOP-e Database Homepage

ChainsDomain InfoClassFoldSuperfamilyFamilyDomainSpeciesProvenance Source (Version)
Ad1puda_ Alpha and beta proteins (a/b) TIM beta/alpha-barrel tRNA-guanine transglycosylase tRNA-guanine transglycosylase Queosine tRNA-guanine transglycosylase (Zymomonas mobilis ) [TaxId: 542 ], SCOPe (2.08)

Domain Annotation: SCOP2 Classification SCOP2 Database Homepage

ChainsTypeFamily Name Domain Identifier Family IdentifierProvenance Source (Version)
ASCOP2B SuperfamilytRNA-guanine transglycosylase 8040041 3000635 SCOP2B (2022-06-29)

Domain Annotation: ECOD Classification ECOD Database Homepage

ChainsFamily NameDomain Identifier ArchitecturePossible HomologyHomologyTopologyFamilyProvenance Source (Version)
ATGTe1pudA1 A: a/b barrelsX: TIM beta/alpha-barrelH: TIM barrels (From Topology)T: TIM barrelsF: TGTECOD (1.6)

Domain Annotation: CATH CATH Database Homepage

ChainDomainClassArchitectureTopologyHomologyProvenance Source (Version)
A3.20.20.105 Alpha Beta Alpha-Beta Barrel TIM Barrel Queuine tRNA-ribosyltransferase-likeCATH (4.3.0)

Protein Family Annotation Pfam Database Homepage

ChainsAccessionNameDescriptionCommentsSource
PF01702Queuine tRNA-ribosyltransferase (TGT)Queuine tRNA-ribosyltransferase- Family

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

ChainsPolymerMolecular FunctionBiological ProcessCellular Component
TRNA-GUANINE TRANSGLYCOSYLASE

Structure Motif Annotation: Mechanism and Catalytic Site Atlas M-CSA Database Homepage

ChainsEnzyme NameDescriptionCatalytic Residues
tRNA-guanine transglycosylase  M-CSA #881

A variety of modified bases are found in RNAs and around 1 % of the Escherichia coli genome codes for proteins involved in tRNA modification. The hypermodified base quenine, a 7-deazaguanine derivative, replaces guanine-34 at the wobble position of tRNAs specific for Asn, Asp, His and Tyr. In vitro and in vivo studies showed that quenine in tRNAs affects codon selection and prevents stop codon readthrough of tobacco mosaic virus RNA in a codon context-dependent manner. However, its general function remains not very well understood [PMID:8654383]. Quenine is synthesised de novo in prokaryotes, whereas it is a nutrient for eukaryotes. In prokaryotes, the quenine biosynthesis requires several steps, not all of them yet known [PMID:8654383]. The biosynthesis begins outside of the tRNA with the conversion of GTP to the quenine precursor 7-aminomethyl-7-deazaguanine (preQ1). tRNA-guanine transglycosylase (TGT) replaces the guanine-34 at the wobble position of the cognate tRNAs with preQ1. tRNA-preQ1 is modified further by the S-adenosylmethionine-requiring enzyme QueA and an unknown vitamin B12-dependent enzyme leading to quenine [PMID:8654383].

Defined by 6 residues: ASP:A-102ASP:A-280CYS:A-318CYS:A-320CYS:A-323HIS:A-349
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