InterPro domain: IPR008990

The electron transport accessory proteins adopt the beta topology of an SH3 domain, with a partly opened beta barrel and a 3-10 helical turn interrupting the last strand. Other proteins displaying this topology include R67 dihydrofolate reductase, which catalyses the hydration of nitriles to amides [ 1 ], photosystem I accessory proteins (PsaE), which participate in cyclic electron transport and modulate the interaction of photosystem I with ferrodoxin [ 2 ], the alpha chain of ferrodoxin thioredoxin reductase (FTR), which is involved in the regulation of the activity of chloroplast enzymes [ 3 ], and the beta chain of nitrile hydratase, which confers trimethoprim-resistance to R67-expressing bacteria [ 4 ].

1. Crystal structure of nitrile hydratase reveals a novel iron centre in a novel fold. Structure 5, 691-9
2. The solution structure of photosystem I accessory protein E from the cyanobacterium Nostoc sp. strain PCC 8009. Biochemistry 38, 13736-46
3. Redox signaling in chloroplasts: cleavage of disulfides by an iron-sulfur cluster. Science 287, 655-8
4. Breaking symmetry: mutations engineered into R67 dihydrofolate reductase, a D2 symmetric homotetramer possessing a single active site pore. Biochemistry 41, 15664-75