eLife assessment
This is a valuable analysis of the structure of Roseiflexus castenholzii native and carotenoid-depleted light harvesting complexes. The authors have investigated the relationship between Carotenoid pigment depletion in the photosynthesis-related light harvesting complex, the assembly of the prokaryotic reaction center LH complex, and quinone exchange in Roseiflexus castenholzii, a chlorosome-less filamentous anoxygenic phototroph that forms the deepest branch of photosynthetic bacteria. The evidence supporting the claims is solid, with application of rigorous biochemical and biophysical techniques, including cryo-electron microscopy of the purified of the RC-LH complexes with or depleted of carotenoids. This study will be of interest to biologists working on the evolution and diversity of prokaryotic photosynthetic apparatus.