InterPro domain: IPR024185

This superfamily represents a domain found in 5-formyltetrahydrofolate cyclo-ligase, also known as 5,10-methenyltetrahydrofolate synthetase. This enzyme is involved in folate metabolism. It is a single-domain alpha/beta protein. The central core of the protein is a four-stranded parallel beta-strand flanked by three helices on one side and a single helix on the other side [ 1 ]. This domain is also found in LutC/YkgG. The Escherichia coli ykgEFG operon is a clear homologue of the Bacillus subtilis lutABC operon. This operon is involved in lactate catabolism in B. subtilis, though its role in E. coli is not clear. LutB and LutC probably act as electron transporters during oxidation of L-lactate [ 2 ].

1. Crystal structure of methenyltetrahydrofolate synthetase from Mycoplasma pneumoniae (GI: 13508087) at 2.2 A resolution. Proteins 56, 839-43
2. A widely conserved gene cluster required for lactate utilization in Bacillus subtilis and its involvement in biofilm formation. J. Bacteriol. 191, 2423-30