Roseiflexus(Rfl.) castenholziiis a niche-adapted,filamentous anoxygenic phototroph (FAP) that lacks chlorosomes, the primary lightharvesting architecture in green bacteria[1]. Light-harvesting is realized
only in the membrane antenna (B800–880) complex which is in close
association with a RC. Bacteriochlorophyll (BChl) and carotenoids
within the antenna complex are organized in a similar manner to the
B808–866 complex fromChloroflexus(Cfl.)aurantiacusbut also share
many spectroscopic and functional similarities to light-harvesting 1 and
light-harvesting 2 complexes from purple bacteria[2–4].
Excitation captured by the antenna complex is rapidly and efficiently
transferred to a photochemical RC. The RC is an integral membrane,