This is a C-terminal domain found in 4-hydroxyphenylacetate decarboxylase small subunit (EC:4.1.1.83), which catalyzes the last reaction in the fermentative production of p-cresol from tyrosine. The C-terminal domain [4F-4S] cluster bears structural similarity to high-potential iron-sulfur proteins (HiPIPs). HiPIPs have an N-terminal extension of 20-40 residues, so the structural similarity is limited to their Fe/S cluster-binding scaffold. Furthermore, despite of the weak amino acid sequence identity, the cluster binding motifs are remarkably similar to H/CX2CX12-13CX16-17C for the gamma-subunit and CX2CX13-19CX14-19C for HiPIPs [1].

1: Structural basis for a Kolbe-type decarboxylation catalyzed by a glycyl radical enzyme. Martins BM, Blaser M, Feliks M, Ullmann GM, Buckel W, Selmer T; J Am Chem Soc. 2011;133:14666-14674. PMID:21823587