4-Hydroxyphenylacetate decarboxylase (4-HPAD) is a heterotetramer consisting of catalytic beta-subunit harboring the putative glycyl/thiyl dyad and a distinct small gamma-subunit with two [4Fe-4S] clusters (EC:4.1.1.83). The gamma-subunit is proposed to be involved in the regulation of the oligomeric state and catalytic activity of the enzyme and it comprises two domains with some amino acid sequence identity that are structurally related by a pseudo-2-fold symmetry indicating a gene duplication origin. This entry represents the N-terminal domain which binds one [4Fe-4S] cluster through His3, Cys6, Cys19, and Cys36 [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