title: CsmA Protein is Associated with BChl a in the Baseplate Subantenna of Chlorosomes of the Photosynthetic Green Filamentous Bacterium Oscillochloris trichoides belonging to the Family Oscillochloridaceae.
abstract: The baseplate subantenna in chlorosomes of green anoxygenic photosynthetic bacteria, belonging to the families Chloroflexaceae and Chlorobiaceae, is known to represent a complex of bacteriochlorophyll (BChl) a with the ~6 kDa CsmA proteins. Earlier, we showed the existence of a similar BChl a subantenna in chlorosomes of the photosynthetic green bacterium Oscillochloris trichoides, member of Oscillochloridaceae, the third family of green photosynthetic bacteria. However, this BChl a subantenna was not visually identified in absorption spectra of isolated Osc. trichoides chlorosomes in contrast to those of Chloroflexaceae and Chlorobiaceae. In this work, using room and low-temperature absorbance and fluorescence spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis of alkaline-treated and untreated chlorosomes of Osc. trichoides, we showed that the baseplate BChl a subantenna does exist in Oscillochloridaceae chlorosomes as a complex of BChl a with the 5.7 kDa CsmA protein. The present results support the idea that the baseplate subantenna, representing a complex of BChl a with a ~6 kDa CsmA protein, is a universal interface between the BChl c subantenna of chlorosomes and the nearest light-harvesting BChl a subantenna in all three known families of green anoxygenic photosynthetic bacteria.
authors.affiliation: A.N. Belozersky Institute of Physico-Chemical Biology, Building A, M.V. Lomonosov Moscow State University, Moscow 119991, Russia.
authors.forename: Anastasiya
authors.initials: A
authors.lastname: Zobova
authors.forename: Alexandra
authors.initials: A
authors.lastname: Taisova
authors.forename: Eugeny
authors.initials: E
authors.lastname: Lukashev
authors.forename: Nataliya
authors.initials: N
authors.lastname: Fedorova
authors.forename: Ludmila
authors.initials: L
authors.lastname: Baratova
authors.forename: Zoya
authors.initials: Z
authors.lastname: Fetisova