title: The cry-DASH cryptochrome encoded by the sll1629 gene in the cyanobacterium Synechocystis PCC 6803 is required for Photosystem II repair.
abstract: The role of the Syn-CRY cryptochrome from the cyanobacterium Synechocystis sp. PCC 6803 has been a subject of research for more than a decade. Recently we have shown that photolyase, showing strong homology with Syn-CRY is required for Photosystem II repair by preventing accumulation of DNA lesions under UV-B (Vass et al. 2013). Here we investigated if Syn-CRY is also involved in PSII repair, either via removal of DNA lesions or other mechanism? The Δsll1629 mutant lacking Syn-CRY lost faster the PSII activity and D1 protein during UV-B or PAR than the WT. However, no detectable damages in the genomic DNA were observed. The transcript levels of the UV-B and light stress indicator gene psbA3, encoding D1, are comparable in the two strains showing that Δsll1629 cells are not defective at the transcriptional level. Nevertheless 2D protein analysis in combination with mass spectrometry showed a decreased accumulation of several, mostly cytoplasmic, proteins including PilA1 and bicarbonate transporter SbtA. Δsll1629 cells exposed to high light also showed a limitation in de novo assembly of PSII. It is concluded that Syn-CRY is required for efficient restoration of Photosystem II activity following UV-B and PAR induced photodamage. This effect is not caused by retardation of DNA repair, instead the synthesis of new D1 (and D2) subunit(s) and/or the assembly of the Photosystem II reaction center complex is likely affected due to the lack of intracellular CO2, or via a so far unidentified pathway that possibly includes the PilA1 protein.
authors.affiliation: Institute of Plant Biology, Biological Research Center of the Hungarian Academy of Sciences, P. O. Box 521, H-6701 Szeged, Hungary.
authors.forename: István-Zoltán
authors.initials: IZ
authors.lastname: Vass
authors.affiliation: Institute of Plant Biology, Biological Research Center of the Hungarian Academy of Sciences, P. O. Box 521, H-6701 Szeged, Hungary.
authors.forename: Péter B
authors.initials: PB
authors.lastname: Kós
authors.affiliation: Faculty of Science, University of South Bohemia, Branisovska 31, Ceske Budejovice, Czech Republic.
authors.forename: Jana
authors.initials: J
authors.lastname: Knoppová
authors.affiliation: Institute of Microbiology, Academy of Sciences, Opatovicky Mlyn, 379 81 Trebon, Czech Republic.
authors.forename: Josef
authors.initials: J
authors.lastname: Komenda
authors.affiliation: Institute of Plant Biology, Biological Research Center of the Hungarian Academy of Sciences, P. O. Box 521, H-6701 Szeged, Hungary. Electronic address: vass.imre@brc.mta.hu.
authors.forename: Imre
authors.initials: I
authors.lastname: Vass
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D056931:Cryptochromes / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D008027:Light; D045332:Photosystem II Protein Complex / Q000235:genetics / Q000378:metabolism*; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D001426:Bacterial Proteins; D056931:Cryptochromes; D004269:DNA, Bacterial; D045332:Photosystem II Protein Complex
keywords: Chryptochrome; Photolyase; Photosystem II repair; Synechocystis PCC 6803; UV-B radiation