InterPro domain: IPR000905

This domain was identified in proteins including Kae1 and Gcp (YgjD), which were originally thought to be endopeptidases belonging to the peptidase M22 family [ 1 ]. However, there is a lack of experimental evidence to support peptidase activity as a general property, and this has not been confirmed in other orthologues [ 2 , 3 ]. Recent research indicates that the Kae1 and Gcp proteins are involved in the biosynthesis of N6-threonylcarbamoyl adenosine, a universal modification found at position 37 of tRNAs that read codons beginning with adenine [ 4 ]. This domain is also present in Bacillus subtilis YdiC and Escherichia coli YeaZ. These proteins have been recently renamed as TsaB, and have also been shown to be involved in N6-Threonylcarbamoylad enonsine (t(6)A) biosynthesis [ 5 , 6 ].

1. Cloning, nucleotide sequence, and expression of the Pasteurella haemolytica A1 glycoprotease gene. J. Bacteriol. 173, 5597-603
2. An archaeal orthologue of the universal protein Kae1 is an iron metalloprotein which exhibits atypical DNA-binding properties and apurinic-endonuclease activity in vitro. Nucleic Acids Res. 35, 6042-51
3. The highly conserved KEOPS/EKC complex is essential for a universal tRNA modification, t6A. EMBO J. 30, 873-81
4. A role for the universal Kae1/Qri7/YgjD (COG0533) family in tRNA modification. EMBO J. 30, 882-93
5. Mechanism of N6-Threonylcarbamoyladenonsine (t(6)A) Biosynthesis: Isolation and Characterization of the Intermediate Threonylcarbamoyl-AMP. Biochemistry 51, 8950-63
6. Biosynthesis of threonylcarbamoyl adenosine (t6A), a universal tRNA nucleoside. J. Biol. Chem. 287, 13666-73