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Literature summary for 2.4.2.48 extracted from

  • Bai, Y.; Fox, D.; Lacy, J.; Van Lanen, S.; Iwata-Reuyl, D.
    Hypermodification of tRNA in thermophilic archaea. Cloning, overexpression, and characterization of tRNA-guanine transglycosylase from Methanococcus jannaschii (2000), J. Biol. Chem., 275, 28731-28738.
    View publication on PubMed
Search for more literature for 2.4.2.48

Cloned(Commentary)

Cloned (Comment) Organism
gene tgt, overexpression in Escherichia coli strain BL21(DE3)/pYB-I-120, subcloning in Escherichia coli strain DH5alpha Methanocaldococcus jannaschii

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
guanine15 in tRNA + 7-cyano-7-carbaguanine Methanocaldococcus jannaschii i.e. 7-(cyano)-7-deazaguanine = preQ0 7-cyano-7-carbaguanine15 in tRNA + guanine
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 ?

Organism

Organism UniProt Comment Textmining
Methanocaldococcus jannaschii Q57878 gene tgtA, orf MJ0436; gene tgt
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Purification (Commentary)

Purification (Comment) Organism
recombinant TGT 16.8fold from Escherichia coli strain BL21(DE3)/pYB-I-120 by ammonium sulfate fractionation, anion and cation exchange chromatography, and heat treatment Methanocaldococcus jannaschii

Specific Activity [micromol/min/mg]

Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
134
-
 purified recombinant TGT, pH 5.5, 80°C Methanocaldococcus jannaschii

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
guanine15 in tRNA + 7-cyano-7-carbaguanine i.e. 7-(cyano)-7-deazaguanine = preQ0 Methanocaldococcus jannaschii 7-cyano-7-carbaguanine15 in tRNA + guanine
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 ?
guanine15 in tRNA + 7-cyano-7-carbaguanine i.e. 7-(cyano)-7-deazaguanine = preQ0. Haloferax volcanii tRNASer is used as substrate Methanocaldococcus jannaschii 7-cyano-7-carbaguanine15 in tRNA + guanine
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 ?
additional information the enzyme catalyzes a transglycosylation reaction in which guanine is eliminated from position 15 of the tRNA and an archaeosine precursor (preQ0) is inserted. The enzyme is able to utilize both guanine and the 7-deazaguanine base preQ0 as substrates, but not other 7-deazaguanine bases, and is able to modify tRNA from all three phylogenetic domains. The enzyme shows good activity with the tRNASer transcript as well as tRNA from Escherichia coli and yeast Methanocaldococcus jannaschii ?
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 ?

Synonyms

Synonyms Comment Organism
TGT
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 Methanocaldococcus jannaschii
tRNA-guanine transglycosylase
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 Methanocaldococcus jannaschii

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
additional information
-
 optimal activity at high temperatures Methanocaldococcus jannaschii
80
-
 assay at Methanocaldococcus jannaschii

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
additional information
-
 optimal activity at acidic pH Methanocaldococcus jannaschii
5.5
-
 assay at Methanocaldococcus jannaschii

General Information

General Information Comment Organism
evolution biogenetic relationship of queuosine and archaeosine, overview. The elements necessary for tRNA recognition by the enzyme are not unique to archaeal tRNA Methanocaldococcus jannaschii
metabolism GTP is apparently the primary precursor in the biosynthesis of queuosine, which in a series of steps is converted to 7-(cyano)-7-deazaguanine, i.e. preQ0. PreQ0 is then reduced to PreQ1, and preQ1 is subsequently inserted into the tRNA by the enzyme TGT in a transglycosylation reaction in which the genetically encoded base guanine is eliminated Methanocaldococcus jannaschii
additional information the nature of the temperature dependence is consistent with a requirement for some degree of tRNA tertiary structure in order for recognition by the enzyme to occur Methanocaldococcus jannaschii