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The small CAB-like proteins of the cyanobacterium Synechocystis sp. PCC 6803: Their involvement in chlorophyll biogenesis for Photosystem II
Umeå University, Faculty of Science and Technology, Department of Chemistry. (Centre for Molecular and Structural Biomedicine, Institute for Biotechnology and Bioengineering (Laboratório Associado), Universidade do Algarve, 8005-139 Faro, Portugal)
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Institute of Plant Biology, Biological Research Center, Szeged, Hungary.
Commissariat à l'Energie Atomique (CEA), Institut de Biologie et Technologies de Saclay (iBiTec-S), France. (Centre National de la Recherche Scientifique (CNRS), 91191 Gif sur Yvette, France)
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2011 (English)In: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1807, no 9, 1143-1151 p.Article in journal (Refereed) Published
Abstract [en]

The five small CAB-like proteins (ScpA-E) of the cyanobacterium Synechocystis sp. PCC 6803 belong to the family of stress-induced light-harvesting-like proteins, but are constitutively expressed in a mutant deficient of Photosystem I (PSI). Using absorption, fluorescence and thermoluminescence measurements this PSI-less strain was compared with a mutant, in which all SCPs were additionally deleted. Depletion of SCPs led to structural rearrangements in Photosystem II (PSII): less photosystems were assembled; and in these, the Q(B) site was modified. Despite the lower amount of PSII, the SCP-deficient cells contained the same amount of phycobilisomes (PBS) as the control. Although, the excess PBS were functionally disconnected, their fluorescence was quenched under high irradiance by the activated Orange Carotenoid Protein (OCP). Additionally the amount of OCP, but not of the iron-stress induced protein (isiA), was higher in this SCP-depleted mutant compared with the control. As previously described, the lack of SCPs affects the chlorophyll biosynthesis (Vavilin, D., Brune, D. C., Vermaas, W. (2005) Biochim Biophys Acta 1708, 91-101). We demonstrate that chlorophyll synthesis is required for efficient PSII repair and that it is partly impaired in the absence of SCPs. At the same time, the amount of chlorophyll also seems to influence the expression of ScpC and ScpD.

Place, publisher, year, edition, pages
Elsevier, 2011. Vol. 1807, no 9, 1143-1151 p.
Keyword [en]
photosystem II, non-photochemical quenching, light-harvesting-like proteins, synechocystis sp. PCC 6803, high-light inducible proteins, chlorophyll
National Category
Chemical Sciences
URN: urn:nbn:se:umu:diva-44584DOI: 10.1016/j.bbabio.2011.05.002PubMedID: 21605542OAI: diva2:421699
Available from: 2011-06-09 Created: 2011-06-09 Last updated: 2012-09-27Bibliographically approved
In thesis
1. Functional studies on the Light-harvesting-Like (LiL) Proteins in Cyanobacteria and Cryptophytes
Open this publication in new window or tab >>Functional studies on the Light-harvesting-Like (LiL) Proteins in Cyanobacteria and Cryptophytes
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The light-harvesting like (LiL) proteins are a widely spread group of proteins within photosynthetic organisms. They are membrane proteins composed of one to four transmembrane helices and – in homology to the light-harvesting complexes of algae and higher plants – at least one of these transmembrane helices contains the chlorophyll a/b-binding (CAB) domain. Opposite to the light-harvesting antenna complexes, LiL proteins are stress induced and they have been shown to be involved in protection of the photosynthetic apparatus. The work presented in this thesis is focused on understanding the function of one-helical LiL proteins of the cryptophyte algae Guillardia theta and the cyanobacterium Synechocystis sp. PCC 6803. G. theta contains two genes encoding LiL proteins, one is localized in the plastid (hlipP), the other in the nucleomorph (HlipNm). Both genes are expressed in normal growth condition, but they are not induced by high light. Immunostaining indicated that HlipNm is translated, but not light-induced. These proteins therefore seem not to be involved in photoprotective mechanisms of G. theta. In the cyanobacterium Synechocystis sp. PCC 6803 four one-helical LiL proteins were identified, they are called Small CAB-like Proteins (SCPs); a fifth LiL (ScpA) is fused with the ferrochelatase (FC), an enzyme involved in the heme synthesis. Our analysis revealed that SCPs are involved in the de novo assembly/repair cycle of Photosystem II, stabilizing the chlorophyll pigments at their protein scaffold. The in vitro characterization of the recombinant FC showed that ScpA is involved in the product-release of the catalytic domain of the enzyme, thereby regulating substrate availability for chlorophyll- or heme- biosynthesis. Finally, using a transcriptomic and metabolomic approaches, I was able to show that deletion of all SCP genes has profound impact on the cell organization and metabolism. In SCP-depleted cells, production of reactive oxygen species (ROS) is increased, while the amount of Photosystem II per cell volume is decreased, causing a macronutrient-deficient phenotype. Therefore, SCPs are important for stress protection and help to maintain a metabolic equilibrium within the cell.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2012. 67 p.
Photosynthesis, cyanobacteria, Guillardia theta, photosystem II, chlorophyll-binding proteins, onehelix LiL proteins, photoprotection
National Category
Natural Sciences
Research subject
urn:nbn:se:umu:diva-59801 (URN)978-91-7459-486-7 (ISBN)
Public defence
2012-10-26, KBC-huset, KB3A9, Umeå University, Umeå, 10:00 (English)
Available from: 2012-10-05 Created: 2012-09-26 Last updated: 2012-09-26Bibliographically approved

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