Carotenoids are essential for the assembly of cyanobacterial photosynthetic complexes

T.N. Tóth*, Volha Chukhutsina, Ildikó Domonkos, Jana Knoppová, Josef Komenda, Mihály Kis, Zsófia Lénárt, Gyozo Garab, László Kovács, Zoltán Gombos, Herbert Van Amerongen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

23 Citations (Scopus)

Abstract

In photosynthetic organisms, carotenoids (carotenes and xanthophylls) are important for light harvesting, photoprotection and structural stability of a variety of pigment-protein complexes. Here, we investigated the consequences of altered carotenoid composition for the functional organization of photosynthetic complexes in wild-type and various mutant strains of the cyanobacterium Synechocystis sp. PCC 6803. Although it is generally accepted that xanthophylls do not play a role in cyanobacterial photosynthesis in low-light conditions, we have found that the absence of xanthophylls leads to reduced oligomerization of photosystems I and II. This is remarkable because these complexes do not bind xanthophylls. Oligomerization is even more disturbed in crtH mutant cells, which show limited carotenoid synthesis; in these cells also the phycobilisomes are distorted despite the fact that these extramembranous light-harvesting complexes do not contain carotenoids. The number of phycocyanin rods connected to the phycobilisome core is strongly reduced leading to high amounts of unattached phycocyanin units. In the absence of carotenoids the overall organization of the thylakoid membranes is disturbed: Photosystem II is not formed, photosystem I hardly oligomerizes and the assembly of phycobilisomes remains incomplete. These data underline the importance of carotenoids in the structural and functional organization of the cyanobacterial photosynthetic machinery.

Original languageEnglish
Pages (from-to)1153-1165
JournalBiochimica et Biophysica Acta. B, Bioenergetics
Volume1847
Issue number10
DOIs
Publication statusPublished - 29 Jun 2015

Keywords

  • Carotenoid deficiency
  • Cyanobacterial photosynthesis
  • Photosynthetic complexes
  • Phycobilisome
  • Time-resolved fluorescence

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