This domain can be found in the C terminus of threonylcarbamoyl-AMP synthases, including Sua5 from Saccharomyces cerevisiae and YwlC from Bacillus subtilis. Threonylcarbamoyl-AMP synthase is required for the formation of a threonylcarbamoyl group on adenosine at position 37 (t6A37) in tRNAs that read codons beginning with adenine [1,2]. This domain adopts the Rossmann fold and may be involved in GTP and/or tRNA binding based on structural similarity with both GTP and tRNA binding proteins [3].

1: The universal YrdC/Sua5 family is required for the formation of threonylcarbamoyladenosine in tRNA. El Yacoubi B, Lyons B, Cruz Y, Reddy R, Nordin B, Agnelli F, Williamson JR, Schimmel P, Swairjo MA, de Crecy-Lagard V; Nucleic Acids Res. 2009;37:2894-2909. PMID:19287007

2: Mechanism of N6-threonylcarbamoyladenonsine (t(6)A) biosynthesis: isolation and characterization of the intermediate threonylcarbamoyl-AMP. Lauhon CT; Biochemistry. 2012;51:8950-8963. PMID:23072323

3: X-ray crystal structure of a hypothetical Sua5 protein from Sulfolobus tokodaii strain 7. Agari Y, Sato S, Wakamatsu T, Bessho Y, Ebihara A, Yokoyama S, Kuramitsu S, Shinkai A; Proteins. 2008;70:1108-1111. PMID:18004774