Photosynthetic system in Blastochloris viridis revisited

Marina Konorty, Vlad Brumfeld, Andre Vermeglio, Nava Kahana, Ohad Medalia, Abraham Minsky

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


The bacterium Blastochloris viridis carries one of the simplest photosynthetic systems, which includes a single light-harvesting complex that surrounds the reaction center, membrane soluble quinones, and a soluble periplasmic protein cytochrome c2 that shuttle between the reaction center and the bc1 complex and act as electron carriers, as well as the ATP synthase. The close arrangement of the photosynthetic membranes in Bl. viridis, along with the extremely tight arrangement of the photosystems within these membranes, raises a fundamental question about the diffusion of the electron carriers. To address this issue, we analyzed the structure and response of the Bl. viridis photosynthetic system to various light conditions, by using a combination of electron microscopy, whole-cell cryotomography, and spectroscopic methods. We demonstrate that in response to high light intensities, the ratio of both cytochrome c2 and bc1 complexes to the reaction centers is increased. The shorter membrane stacks, along with the notion that the bc1 complex is located at the highly curved edges of these stacks, result in a smaller average distance between the reaction centers and the bc1 complexes, leading to shorter pathways of cytochrome c2 between the two complexes. Under anaerobic conditions, the slow diffusion rate is further mitigated by keeping most of the quinone pool reduced, resulting in a concentration gradient of quinols that allows for a constant supply of theses electron carriers to the bc1 complex.

Original languageEnglish
Pages (from-to)4753-4761
Number of pages9
Issue number22
StatePublished - 9 Jun 2009

ASJC Scopus subject areas

  • Biochemistry


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