This domain is found in bacterial and plant proteins to the C-terminus of a Rieske 2Fe-2S domain (Pfam:PF00355). One of the proteins the domain is found in is Pheophorbide a oxygenase (PaO) which seems to be a key regulator of chlorophyll catabolism. Arabidopsis PaO (AtPaO) is a Rieske-type 2Fe-2S enzyme that is identical to Arabidopsis accelerated cell death 1 and homologous to lethal leaf spot 1 (LLS1) of maize [1], in which the domain described here is also found.

1: Chlorophyll breakdown: pheophorbide a oxygenase is a Rieske-type iron-sulfur protein, encoded by the accelerated cell death 1 gene. Pruzinska A, Tanner G, Anders I, Roca M, Hortensteiner S; Proc Natl Acad Sci U S A 2003;100:15259-15264. PMID:14657372