The role of the PsbU subunit in the light sensitivity of PSII in the cyanobacterium Synechococcus 7942

Leyla Abasova, Z. Deák, Rakefet Schwarz, I. Vass

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

In the present study we investigated the role of the PsbU subunit in the electron transport characteristics and light sensitivity of the Photosystem II complex. The experiments were performed by using an earlier characterized PsbU-less mutant of the cyanobacterium Synechococcus PCC 7942, which has enhanced antioxidant capacity (Balint et al. FEBS Lett. 580 (2006) 2117-2122). Flash induced Chl fluorescence measurements in the presence and absence of the electron transport inhibitor DCMU showed that both the S 2QA- and the S 2QB- recombination is slowed down in the PsbU mutant relative to the WT strain. Thermoluminescence measurements confirmed the increased stability of the S 2QA- and S 2QB- charge pairs by showing an increased peak temperature of Q and B bands, which were measured in the presence and absence of DCMU, respectively. In addition, the intensity of the TL bands is also increased in the PsbU mutant (≈1.7 times for the B band), as compared to the WT. The PsbU mutant shows enhanced loss of Photosystem II activity under exposure to high light intensity both in the absence and presence of the protein synthesis inhibitor lincomycin. It is concluded from the data that the lack of the PsbU subunit in Synechococcus PCC 7942 affects the energetic stability of the S 2QA- and S 2QB- charge pairs by modifying both the PSII donor and acceptor side components. This effect is most likely caused by structural changes in the vicinity of the Mn cluster and in the inner part of the PSII complex, which are induced by the lack of the PsbU subunit from the lumenal part of the complex. The light sensitivity of Photosystem II in Synechococcus 7942 in the absence of the PsbU subunit is likely due to reactive oxygen species, which are produced as a consequence of disturbed donor side structure and/or due to the modified energetic properties of the primary radical pair.

Original languageEnglish
Pages (from-to)149-156
Number of pages8
JournalJournal of Photochemistry and Photobiology, B: Biology
Volume105
Issue number2
DOIs
Publication statusPublished - Nov 3 2011

Fingerprint

Synechococcus
Photophobia
Photosystem II Protein Complex
Cyanobacteria
Diuron
Electron Transport
inhibitors
sensitivity
protein synthesis
Lincomycin
Protein Synthesis Inhibitors
antioxidants
thermoluminescence
luminous intensity
Genetic Recombination
flash
Reactive Oxygen Species
electrons
Antioxidants
Fluorescence

Keywords

  • Cyanobacterium
  • Photoinactivation
  • PsbU subunit
  • Reactive oxygen species
  • Synechococcus 7942

ASJC Scopus subject areas

  • Radiation
  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology
  • Biophysics

Cite this

The role of the PsbU subunit in the light sensitivity of PSII in the cyanobacterium Synechococcus 7942. / Abasova, Leyla; Deák, Z.; Schwarz, Rakefet; Vass, I.

In: Journal of Photochemistry and Photobiology, B: Biology, Vol. 105, No. 2, 03.11.2011, p. 149-156.

Research output: Contribution to journalArticle

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