Recombinant Protochlamydia amoebophila Queuine tRNA-ribosyltransferase (tgt)
Description
Introduction to Recombinant Protochlamydia amoebophila Queuine tRNA-ribosyltransferase (TGT)
Recombinant Protochlamydia amoebophila Queuine tRNA-ribosyltransferase (TGT), also known as tRNA-guanine transglycosylase, is an enzyme that facilitates a crucial post-transcriptional modification of transfer RNAs (tRNAs) . This modification involves replacing a guanine base with queuine at position 34 in the anticodon loop of specific tRNA isoacceptors . TGT is present in almost all eukaryotic organisms and some bacteria .
Queuine and its Role
Queuine is a modified pyrrolopyrimidine nucleobase derived from bacteria . It is inserted into tRNA by the TGT enzyme through a base-for-base exchange reaction, where guanine is replaced by queuine . This modification is essential for the proper function of tRNA in protein synthesis .
Importance of tRNA Modification
tRNA modification with queuine is an irreversible event and is a characteristic of differentiated cells . Rapidly proliferating cells, such as those found in tumors, often exhibit tRNA hypomodification, making them susceptible to base modification . The enzyme QTRT1, a key enzyme involved in the post-transcriptional modification of tRNAs, is located on chromosome 19p13.2 and contains 10 exons spanning approximately 12 kb .
TGT in Therapeutics
TGT is essential for therapeutic effects, and animals deficient in TGT activity were refractory to therapy . Targeting tRNA modification has potential medicinal relevance in treating chronic diseases such as multiple sclerosis .
Activity Assays
The activity of TGT can be assessed through tRNA-$$^{14}C$$ guanine incorporation assays . These assays measure the ability of TGT to insert labeled guanine into the anticodon loop of tRNA that has been modified with guanine, queuine, or other nucleobases .
TGT in Bacteria
Escherichia coli TGT catalyzes the base-exchange of a guanine residue with the queuine precursor 7-aminomethyl-7-deazaguanine (PreQ1) at position 34 . Protochlamydia amoebophila, an intracellular bacterium, also possesses a TGT enzyme, highlighting the widespread importance of this enzyme in various organisms .
Relevance in Pathogen-Host Interactions
In Escherichia coli O157:H7 (EHEC), the Pho regulon, which responds to phosphate-limitation stress, plays a role in the virulence of EHEC during its transmission cycle . EHEC encounters amoebae during their transmission cycle .
Impact of tRNA Modifications in Streptomyces
Post-transcriptional tRNA modifications (PTTMs) play an important role in the maturation and functionality of tRNAs . In the antibiotic-producing actinobacterial genus Streptomyces, certain PTTMs depend on enzymes that show no sequence similarity to known PTTM enzymes from model species .
TrpR Regulation in Chlamydia trachomatis
In Chlamydia trachomatis, the tryptophan repressor (TrpR) regulates the expression of tryptophan synthase (trpBA) . Recombinant chlamydial TrpR binds to the operator sequence upstream of trpR, and 5-fluorotryptophan activates this binding .
Table 1: QTRT1 Expression and Methylation in LUAD
| Feature | Normal Group | LUAD Group | Dataset | P-value |
|---|---|---|---|---|
| QTRT1 Expression Level | Low | High | GSE10072 | 0.0024 |
| QTRT1 Methylation Level | High | Low | GSE49996 | Decreasing Trend |
| QTRT1 Methylation Level | High | Low | GSE63384 | Decreasing Trend |
Product Specs
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Target Background
KEGG: pcu:pc0794
STRING: 264201.pc0794
