InterPro domain: IPR039429

Proteins containing this domain include serine hydroxymethyltransferase and fluorothreonine transaldolase.

Serine hydroxymethyltransferase (SHMT) is a pyridoxal phosphate-dependent enzyme that catalyzes the reversible conversion of serine and tetrahydrofolate to glycine and methylenetetrahydrofolate [ 1 ]. This reaction generates single carbon units for purine, thymidine, and methionine biosynthesis. It belongs to the aspartate aminotransferase superfamily (fold type I) [ 2 ]. The pyridoxal-P group is attached to a lysine residue around which the sequence is highly conserved in all forms of the enzyme [ 3 ]. SHMT catalyses the transfer of a hydroxymethyl group from N5, N10- methylene tetrahydrofolate to glycine, resulting in the formation of serine and tetrahydrofolate. Both eukaryotic and prokaryotic SHMT enzymes form tight obligate homodimers and the mammalian enzyme forms a homotetramer [ 4 , 4 ].

Fluorothreonine transaldolase catalyzes the final step in 4-fluorothreonine biosynthesis. It mediates a L-threonine/fluoroaceldehyde to 4-fluoro-L-threonine/acetaldehyde crossover reaction. It shares protein sequence similarity with SHMT [ 5 ].

1. Structure of a murine cytoplasmic serine hydroxymethyltransferase quinonoid ternary complex: evidence for asymmetric obligate dimers. Biochemistry 39, 13313-23
2. The genetic organization and protein crystallographic structure of human serine hydroxymethyltransferase. Adv. Enzyme Regul. 40, 353-403
3. The primary structure of sheep liver cytosolic serine hydroxymethyltransferase and an analysis of the evolutionary relationships among serine hydroxymethyltransferases. Biochim. Biophys. Acta 1204, 75-83
4. Crystal structure of binary and ternary complexes of serine hydroxymethyltransferase from Bacillus stearothermophilus: insights into the catalytic mechanism. J. Biol. Chem. 277, 17161-9
5. In vitro reconstituted biotransformation of 4-fluorothreonine from fluoride ion: application of the fluorinase. Chem. Biol. 15, 1268-76