Protein Family Models

This tRNA-guanine transglycosylase (tgt) differs from the tgt of E. coli and other Bacteria in the site of action and the modification that results. It exchanges 7-cyano-7-deazaguanine (preQ0) with guanine at position 15 of archaeal tRNA; this nucleotide is subsequently converted to archaeosine, found exclusively in the Archaea. This enzyme from Haloferax volcanii has been purified, characterized, and partially sequenced and is the basis for identifying this family. In contrast, bacterial tgt (TIGR00430) catalyzes the exchange of preQ0 or preQ1 for the guanine base at position 34; this nucleotide is subsequently modified to queuosine. Archeoglobus fulgidus has both enzymes, while some other Archaea have just this one.

Gene:

tgtA

Date:

2021-04-27

This uncharacterized domain is found a number of enzymes and uncharacterized proteins, often at the C-terminus. It is found in some but not all members of a family of related tRNA-guanine transglycosylases (tgt), which exchange a guanine base for some modified base without breaking the phosphodiester backbone of the tRNA. It is also found in rRNA pseudouridine synthase, another enzyme of RNA base modification not otherwise homologous to tgt. It is found, again at the C-terminus, in two putative glutamate 5-kinases. It is also found in a family of small, uncharacterized archaeal proteins consisting mostly of this domain.

Date:

2024-05-30

This tRNA-guanine transglycosylase includes enzymes that replace guanine at position 34 in bacteria with queuine (Tgt), and at position 15 in archaea with 7-cyano-7-carbaguanine.

Date:

2022-03-28