An easily reversible structural change underlies mechanisms enabling desert crust cyanobacteria to survive desiccation

Leeat Bar-Eyal, Ido Eisenberg, Adam Faust, Hagai Raanan, Reinat Nevo, Fabrice Rappaport, Anja Krieger-Liszkay, Pierre Sétif, Adrien Thurotte, Ziv Reich, Aaron Kaplan, Itzhak Ohad, Yossi Paltiel, Nir Keren*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

Abstract Biological desert sand crusts are the foundation of desert ecosystems, stabilizing the sands and allowing colonization by higher order organisms. The first colonizers of the desert sands are cyanobacteria. Facing the harsh conditions of the desert, these organisms must withstand frequent desiccation-hydration cycles, combined with high light intensities. Here, we characterize structural and functional modifications to the photosynthetic apparatus that enable a cyanobacterium, Leptolyngbya sp., to thrive under these conditions. Using multiple in vivo spectroscopic and imaging techniques, we identified two complementary mechanisms for dissipating absorbed energy in the desiccated state. The first mechanism involves the reorganization of the phycobilisome antenna system, increasing excitonic coupling between antenna components. This provides better energy dissipation in the antenna rather than directed exciton transfer to the reaction center. The second mechanism is driven by constriction of the thylakoid lumen which limits diffusion of plastocyanin to P700. The accumulation of P700+ not only prevents light-induced charge separation but also efficiently quenches excitation energy. These protection mechanisms employ existing components of the photosynthetic apparatus, forming two distinct functional modes. Small changes in the structure of the thylakoid membranes are sufficient for quenching of all absorbed energy in the desiccated state, protecting the photosynthetic apparatus from photoinhibitory damage. These changes can be easily reversed upon rehydration, returning the system to its high photosynthetic quantum efficiency.

Original languageAmerican English
Article number47505
Pages (from-to)1267-1273
Number of pages7
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1847
Issue number10
DOIs
StatePublished - 25 Jul 2015

Bibliographical note

Publisher Copyright:
© 2015 Elsevier B.V.

Keywords

  • Cyanobacteria
  • Desert
  • Desiccation tolerance
  • Photosynthesis

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