PetG and PetN, but not PetL, are essential subunits of the cytochrome b6f complex from Synechocystis PCC 6803

The cytochrome b6f complex consists of four large core subunits and an additional four low molecular weight subunits, the function of which is elusive thus far. Here we sought to determine whether small subunits PetG, PetL, and PetN are essential for a cyanobacterial cytochrome b6f complex. We found that only PetL is dispensable, whereas PetG and PetN appear to be essential. Possible roles of the small cytochrome b6f complex subunits are discussed, and observations from our study are compared with previous findings.