The cyanobacterial cytochrome b6f subunit PetP adopts an SH3 fold in solution

PetP is a peripheral subunit of the cytochrome b6f complex (b6f) present in both, cyanobacteria and red algae. It is bound to the cytoplasmic surface of this membrane protein complex where it greatly affects the efficiency of the linear photosynthetic electron flow although it is not directly involved in the electron transfer reactions.