This family represents the N-terminal HUP domain in tRNA(5-methylaminomethyl-2-thiouridine)-methyltransferase which is involved in the biosynthesis of the modified nucleoside 5-methylaminomethyl-2-thiouridine present in the wobble position of some tRNAs [1].

1: Transfer RNA(5-methylaminomethyl-2-thiouridine)-methyltransferase from Escherichia coli K-12 has two enzymatic activities. Hagervall TG, Edmonds CG, McCloskey JA, Bjork GR; J Biol Chem 1987;262:8488-8495. PMID:3298234

2: The crystal structure of GMP synthetase reveals a novel catalytic triad and is a structural paradigm for two enzyme families. Tesmer JJ, Klem TJ, Deras ML, Davisson VJ, Smith JL; Nat Struct Biol 1996;3:74-86. PMID:8548458

3: Snapshots of tRNA sulphuration via an adenylated intermediate. Numata T, Ikeuchi Y, Fukai S, Suzuki T, Nureki O; Nature. 2006;442:419-424. PMID:16871210

4: Substrate specificity and oligomerization of human GMP synthetase. Welin M, Lehtio L, Johansson A, Flodin S, Nyman T, Tresaugues L, Hammarstrom M, Graslund S, Nordlund P; J Mol Biol. 2013;425:4323-4333. PMID:23816837

5: Crystallographic and mutational studies on the tRNA thiouridine synthetase TtuA. Nakagawa H, Kuratani M, Goto-Ito S, Ito T, Katsura K, Terada T, Shirouzu M, Sekine S, Shigi N, Yokoyama S; Proteins. 2013;81:1232-1244. PMID:23444054

6: Nonredox thiolation in tRNA occurring via sulfur activation by a [4Fe-4S] cluster. Arragain S, Bimai O, Legrand P, Caillat S, Ravanat JL, Touati N, Binet L, Atta M, Fontecave M, Golinelli-Pimpaneau B; Proc Natl Acad Sci U S A. 2017;114:7355-7360. PMID:28655838