Chlorosomes are light-har vesting complexes found in photosynthetic bacteria belonging t o three diverse phyla: Chlorobi , Chlorofl exi and Acidobacteria. They are composed of b a c teriochlorophylls with minor contributions from proteins, lipids, carotenoids and quinones.
Proteins are confi ned to the surf ace of the chlorosome while most bacteriochlorophyll m o l ecules are found within the interior where they assemble into agg regates. These agg regates consist of lamellar str uctures, in which bacteriochlorophylls for m cur ved layers while hydrophobic esterifying alcohols of bacteriochlorophylls from adjacent layers interdigitate and hold the system together.
Such an ar rangement suppor ts strong excitonic coupling between the pigments within a layer and enables effi cient excitation energy transfer. This chapter sur veys general features of the chlorosome, including str ucture, energy transfer, photoprotective mechanisms and assembly.