CP43 ', the isiA gene product, functions as an excitation energy dissipator in the cyanobacterium Synechococcus sp PCC 7942
2001 (English)In: Photochemistry and Photobiology, ISSN 0031-8655, E-ISSN 1751-1097, Vol. 74, no 3, 431-437 p.Article in journal (Refereed) Published
Under conditions of iron deficiency certain cyanobacteria induce a chlorophyll (Chl)-binding protein, CP43 ', which is encoded by the isiA gene. We have previously suggested that CP43' functions as a nonradiative dissipator of light energy. To further substantiate its functional role an isiA overexpression construct was introduced into the genome of a cyanobacterium Synechococcus sp. PCC 7942 (giving isiA(oe) cells). The presence of functional CP43' in isiA(oe) cells was confirmed by Western blot as well as by the presence of a characteristic blueshift of the red Chi a absorption peak and a notable increase in the 77 K fluorescence peak at 685 nm. Compared to wildtype cells isiA(oe) cells, with induced CP43', had both smaller functional antenna size and decreased yields of room temperature Chi fluorescence at various light irradiances. These observations strongly suggest that isiA(oe) cells, with induced CP43', have an increased capacity for dissipating light energy as heat. In agreement with this hypothesis isiA(oe) cells were also more resistant to photoinhibition of photosynthesis than wild-type cells. Based on these results we have further strengthened the hypothesis that CP43 ' functions as a nonradiative dissipator of light energy, thus protecting photosystem II from excessive excitation under iron-deficient conditions.
Place, publisher, year, edition, pages
2001. Vol. 74, no 3, 431-437 p.
IdentifiersURN: urn:nbn:se:umu:diva-44705ISI: 000171359900010OAI: oai:DiVA.org:umu-44705DiVA: diva2:428141