| 1. |
- Hernández-Prieto, Miguel Angel, 1975-, et al.
(författare)
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Imbalance in tetrapyrrole metabolites caused by deletion of scp genes in the cyanobacterium Synechocystis sp. PCC 6803 results in dramatic cellular effects
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Light-harvsting like (Lil) proteins contain a chlorophyll-binding domain similar to the chlorophyll a/b binding antenna proteins of plants. The five small Cab-like proteins (SCPs) of the cyanobacterium Synechocystis sp. PCC 6803 belong to the Lil family. They have been shown to stabilize chlorophyll and to play a role in the tetrapyrrole biosynthesis pathway (Xu, H., Vavilin, D., Funk, C. and Vermaas, W. (2004) J. Biol. Chem. 279, 27971-27979). Here we show that deletion of the five scp genes in a PSI-less mutant results in a decrease of Photosystem II amount in the thylakoid membrane. This reduction of Photosystem II leads to increased cell volume, disorganized thylakoid membranes in the cell, and metabolic imbalance. We conclude that the lack of SCPs alters the assembly/repair of Photosystem II, causing an imbalance in the energetic level of the mutant cells.
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| 2. |
- Hernández-Prieto, Miguel Angel, 1975-
(författare)
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The Small Cab-like Proteins in the cyanobacterium Synechocystis sp. PCC 6803
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Small Cab-like Proteins (SCPs) in the cyanobacterium Synechocystis sp. PCC 6803 accumulate in cells grown under different stress conditions. Genes coding for SCPs have been found in all sequenced organisms performing oxygenic photosynthesis and even in the genomes of cyanophages. Deletion of multiple scp genes in Synechocystis resulted in mutants with severely impaired growth and altered pigment content. These findings indicate the importance of SCPs in photosynthesis; however, their specific function is not well understood. SCPs share a chlorophyll-binding motif with the plant light harvesting complex, suggesting that they bind chlorophyll. Here I describe my findings, which unambiguously show that SCPs are able to bind chlorophyll in vitro. Although they affect both the stoichiometric ratio of Photosystem I to II and chlorophyll stability, they do not seem to be directly involved in non-photochemical quenching. I was able to reveal the location of the SCPs within the cyanobacterial cell: in stressed cells they attach to Photosystem II in the thylakoid membrane. Furthermore, I revealed the presence of another light-harvesting like (Lil)/SCP protein in Synechocystis sp. PCC 6803. The gene, slr1544, codifying for this newly characterised LilA protein, co-transcribes together with scpD and also appears to bind to Photosystem II during stress.
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| 3. |
- Kufryk, Galyna, et al.
(författare)
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Association of small CAB-like proteins (SCPs) of Synechocystis sp. PCC 6803 with Photosystem II
- 2008
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Ingår i: Photosynthesis Research. - : SpringerLink. - 0166-8595 .- 1573-5079. ; 95:2/3, s. 135-145
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Tidskriftsartikel (refereegranskat)abstract
- The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267-276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD; Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA.
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| 4. |
- Storm, Patrik, et al.
(författare)
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The small CAB-like proteins of Synechocystis sp. PCC 6803 bind chlorophyll : In vitro pigment reconstitution studies on one-helix light-harvesting-like proteins.
- 2008
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Ingår i: Photosynthesis Research. - : SpringerLink. - 0166-8595 .- 1573-5079. ; 98:1/3, s. 479-488
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Tidskriftsartikel (refereegranskat)abstract
- The large family of light-harvesting-like proteins contains members with one to four membrane spanning helices with significant homology to the chlorophyll a/b-binding antenna proteins of plants. From structural as well as evolutionary perspective, it is likely that the members of this family bind chlorophylls and carotenoids. However, undisputable evidence is still lacking. The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of LHCII (LHCIIb) including the chlorophyll-binding motifs. They have been proposed to act as chlorophyll-carrier proteins. Here, we analyze the in vivo absorption spectra of single scp deletion mutants in Synechocystis sp. PCC 6803 and compare the in vitro pigment binding ability of the SCP pairs ScpC/D and ScpB/E with the one of LHCII and a synthetic peptide containing the chlorophyll-binding motif (Eggink LL, Hoober JK (2000) J Biol Chem 275:9087–9090). We demonstrate that deletion of scpB alters the pigmentation in the cyanobacterial cell. Furthermore, we are able to show that chlorophylls and carotenoids interact in vitro with the pairs of ScpC/D and ScpB/E, demonstrated by fluorescence resonance energy transfer and circular dichroism.
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| 5. |
- Yao, Danny, et al.
(författare)
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Localization of the small CAB-like proteins in photosystem II
- 2007
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 282:1, s. 267-276
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Tidskriftsartikel (refereegranskat)abstract
- The cyanobacterial small CAB-like proteins (SCPs) consist of one-helix proteins that resemble transmembrane regions of the light-harvesting proteins of plants. To determine whether these proteins are associated with protein complexes in the thylakoid membrane, an abundant member of the SCP family, ScpD, was marked with a His tag, and proteins co-isolating with His-tagged ScpD were identified. These proteins included the major Photosystem (PS) II components as well as FtsH, which is involved in degradation of the PSII complex. To ascertain specific interaction between ScpD and the PSII complex, the His-tagged protein fraction was subjected to two-dimensional blue native/SDS-PAGE. Again, PSII components were co-isolated with ScpD-His, and ScpD-His was found to interact most strongly with CP47. ScpD association was most prominent with the monomeric form of PSII, suggesting ScpD association with PSII that is repaired. Using antibodies that recognize both ScpC and ScpD, we found the ScpC protein, which is very similar in primary structure to ScpD, to also co-isolate with the PSII complex. In contrast, ScpE did not co-isolate with a major protein complex in thylakoids. A fourth member of the SCP family, ScpB, could not be immunodetected, but was found by mass spectrometry in samples co-isolating with ScpD-His. Therefore, ScpB may be associated with ScpD as well. No association between SCPs and PSI could be demonstrated. On the basis of these and other data presented, we suggest that members of the SCP family can associate with damaged PSII and can serve as a temporary pigment reservoir while PSII components are being replaced.
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