tgt review notes
- Q88PL7 is a reviewed bacterial Tgt homodimer assigned to PTHR46499:SF1.
[file:PSEPK/tgt/tgt-uniprot.txt
"RecName: Full=Queuine tRNA-ribosyltransferase"]
[file:interpro/panther/PTHR46499/PTHR46499-entries.csv
"Q88PL7,Queuine tRNA-ribosyltransferase"]
- The bacterial reaction exchanges guanine 34 for preQ1. It is not the
eukaryotic reaction that inserts free queuine. [file:PSEPK/tgt/tgt-uniprot.txt
"queuine precursor 7-aminomethyl-7-deazaguanine (PreQ1) at position 34"]
PMID:40703034
- QuickGO GO:0008479 (retrieved 2026-07-27) defines
"guanosine34 in tRNA +
queuine = guanine + queuosine34 in tRNA" and cross-references RHEA:16633,
the free-queuine reaction.
- The repository's GOC-maintained rules apply GO:0008479 to bacterial Tgt:
file:rules/arba/_interpro2go.txt maps IPR004803 to GO:0008479, and
file:rules/unirule/UR000079182/UR000079182.json pairs GO:0008479 with
EC 2.4.2.29 and the preQ1 reaction RHEA:24104.
- The review therefore accepts the existing machine-sourced GO:0008479 mapping
with an explicit ontology-conflict caveat rather than demoting the core
activity to broad GO:0016763. A dedicated bacterial preQ1 transglycosylase
molecular-function term is proposed under GO:0016763.
- GO:0050147 remains unsuitable because it describes free-nucleoside
ribosyltransferase chemistry rather than a tRNA substrate.
- The reviewed record assigns one zinc ion per subunit, so GO:0008270 zinc ion
binding is added as a missing annotation. [file:PSEPK/tgt/tgt-uniprot.txt
"Note=Binds 1 zinc ion per subunit."]
- Upstream preQ0 production is outside scope; Tgt receives preQ1 from QueF and
supplies preQ1-tRNA to QueA.
OpenScientist reconciliation
Source: file:PSEPK/tgt/tgt-deep-research-openscientist.md.
- The report independently identifies Q88PL7 as bacterial Tgt and supports
preQ1 insertion at guanine 34 rather than the eukaryotic free-queuine
reaction.
- Its sequence, AlphaFold, operon, and pathway-completeness analyses are
computational corroboration, not organism-specific experimental evidence.
- The report explicitly found no biochemical, structural, kinetic, or genetic
study of Q88PL7 itself. The curated review therefore retains the existing
orthology-based confidence level and records this as a knowledge gap.