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.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-25886 |
| Date | January 2009 |
| Creators | Hernández-Prieto, Miguel Angel |
| Publisher | Umeå universitet, Kemi, Umeå : Umeå universitet |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, info:eu-repo/semantics/doctoralThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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