This enzyme belongs to the family of ligases, specifically those forming generic carbon-nitrogen bonds.
[1] In both forms the FTHFS domain consists of about 600 amino acid residues and is located in the C-terminal section of C1-THF synthase.
In prokaryotes FTHFS activity is expressed by a monofunctional homotetrameric enzyme of about 560 amino acid residues.
The crystal structure of N(10)-formyltetrahydrofolate synthetase from Moorella thermoacetica shows that the subunit is composed of three domains organised around three mixed beta-sheets.
The second domain contains a five-stranded beta-sheet with two alpha-helices packed on one side while the other two are a wall of the active site cavity.