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Annotation rule MF_00168
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General rule information [?]

Accession MF_00168
Dates 1-JUN-2001 (Created)
18-NOV-2019 (Last updated, Version 36)
Name Q_tRNA_Tgt
Templates P28720 (TGT_ZYMMO); P0A847 (TGT_ECOLI): [Recover all]
case <OC:Bacteria>
end case

Propagated annotation [?]

Identifier, protein and gene names [?]

case <OC:Bacteria>
Protein name
RecName: Full=Queuine tRNA-ribosyltransferase;
AltName: Full=Guanine insertion enzyme;
AltName: Full=tRNA-guanine transglycosylase;
else case <OC:Archaea>
Protein name
RecName: Full=Putative queuine tRNA-ribosyltransferase;
AltName: Full=Guanine insertion enzyme;
AltName: Full=tRNA-guanine transglycosylase;
end case
Gene name

Comments [?]

Function Catalyzes the base-exchange of a guanine (G) residue with the queuine precursor 7-aminomethyl-7-deazaguanine (PreQ1) at position 34 (anticodon wobble position) in tRNAs with GU(N) anticodons (tRNA-Asp, -Asn, -His and -Tyr). Catalysis occurs through a double-displacement mechanism. The nucleophile active site attacks the C1' of nucleotide 34 to detach the guanine base from the RNA, forming a covalent enzyme-RNA intermediate. The proton acceptor active site deprotonates the incoming PreQ1, allowing a nucleophilic attack on the C1' of the ribose to form the product. After dissociation, two additional enzymatic reactions on the tRNA convert PreQ1 to queuine (Q), resulting in the hypermodified nucleoside queuosine (7-(((4,5-cis-dihydroxy-2-cyclopenten-1-yl)amino)methyl)-7-deazaguanosine).
Catalytic activity RHEA:24104: 7-aminomethyl-7-carbaguanine + guanosine(34) in tRNA = 7-aminomethyl-7-carbaguanosine(34) in tRNA + guanine
case <FTGroup:1>
Cofactor Zn(2+)
Note: Binds 1 zinc ion per subunit.
end case
case <OC:Bacteria>
Pathway tRNA modification; tRNA-queuosine biosynthesis.
end case
Subunit Homodimer. Within each dimer, one monomer is responsible for RNA recognition and catalysis, while the other monomer binds to the replacement base PreQ1.
Similarity Belongs to the queuine tRNA-ribosyltransferase family.

Keywords [?]

case <OC:Bacteria>
end case
case <FTGroup:1>
end case

Gene Ontology [?]

GO:0008479; Molecular function: queuine tRNA-ribosyltransferase activity.
case <OC:Bacteria>
GO:0008616; Biological process: queuosine biosynthetic process.
end case
GO:0008033; Biological process: tRNA processing.

Cross-references [?]

Pfam PF01702; TGT; 1;
TIGRFAMs TIGR00430; Q_tRNA_tgt; 1;
TIGR00449; Tgt_general; 1;

Features [?]

From: TGT_ZYMMO (P28720)
Key     From     To       Description   Tag   Condition   FTGroup
REGION     102     106       Substrate binding     D-S-G-G-[FY]  
REGION     261     267       RNA binding     G-[VIG]-G-x(4)  
REGION     285     289       RNA binding; important for wobble base 34 recognition     [TA]-[RK]-x(2)-R  
ACT_SITE     102     102       Proton acceptor     D  
ACT_SITE     280     280       Nucleophile     D  
METAL     318     318       Zinc     C   1
METAL     320     320       Zinc     C   1
METAL     323     323       Zinc     C   1
METAL     349     349       Zinc; via pros nitrogen     H   1
BINDING     156     156       Substrate     D  
BINDING     203     203       Substrate     Q  
BINDING     230     230       Substrate; via amide nitrogen     G  

Additional information [?]

Size range 361-403 amino acids
Related rules None
Fusion None