This domain is found at the C-terminus of acetophenone carboxylase alpha subunit [1]. According to ECOD this domain adopts a reverse ferredoxin fold. This domain is found at the C-terminus of a wide range of related enzymes subunits.

1: Structure of the acetophenone carboxylase core complex: prototype of a new class of ATP-dependent carboxylases/hydrolases. Weidenweber S, Schuhle K, Demmer U, Warkentin E, Ermler U, Heider J; Sci Rep. 2017;7:39674. PMID:28054554

2: Structural Basis for the Mechanism of ATP-Dependent Acetone Carboxylation. Mus F, Eilers BJ, Alleman AB, Kabasakal BV, Wells JN, Murray JW, Nocek BP, DuBois JL, Peters JW; Sci Rep. 2017;7:7234. PMID:28775283