RAPID INTERCHANGE BETWEEN 2 DISTINCT FORMS OF CYANOBACTERIAL PHOTOSYSTEM-II REACTION-CENTER PROTEIN-D1 IN RESPONSE TO PHOTOINHIBITION
1993 (English)In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 90, no 21, 9973-9977 p.Article in journal (Refereed) Published
We have studied photoinhibition of photosynthesis in the cyanobacterium Synechococcus sp. PCC 7942, which possesses two distinct forms of the photosystem II reaction-center protein D1 (D1:1 and D1:2). We report here that when cells adapted to a growth irradiance of 50 mumol.m-2.s-1 are exposed to an irradiance of 500 mumol.m-2.s-1, the normally predominant D1 form (D1:1) is rapidly replaced with the alternative D1:2. This interchange is not only complete within the first hour of photoinhibition but is also fully reversible once cells are returned to 50 mumol.m-2.s-1. By using a mutant that synthesizes only D1:1, we show that the failure to replace D1:1 with D1:2 during photoinhibition results in severe loss of photosynthetic activity as well as a diminished capacity to recover after the stress period. We believe that this interchange between D1 forms may constitute an active component in a protection mechanism unique among photosynthetic organisms that enables cyanobacteria to effectively cope with and recover from photoinhibition.
Place, publisher, year, edition, pages
1993. Vol. 90, no 21, 9973-9977 p.
IdentifiersURN: urn:nbn:se:umu:diva-46839DOI: 10.1073/pnas.90.21.9973ISI: A1993MF29600048OAI: oai:DiVA.org:umu-46839DiVA: diva2:459063