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RAPID INTERCHANGE BETWEEN 2 DISTINCT FORMS OF CYANOBACTERIAL PHOTOSYSTEM-II REACTION-CENTER PROTEIN-D1 IN RESPONSE TO PHOTOINHIBITION
Tekijät: CLARKE AK, SOITAMO A, GUSTAFSSON P, OQUIST G
Kustantaja: NATL ACAD SCIENCES
Julkaisuvuosi: 1993
Lehti:: Proceedings of the National Academy of Sciences of the United States of America
Tietokannassa oleva lehden nimi: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Lehden akronyymi: P NATL ACAD SCI USA
Vuosikerta: 90
Numero: 21
Aloitussivu: 9973
Lopetussivu: 9977
Sivujen määrä: 5
ISSN: 0027-8424
DOI: https://doi.org/10.1073/pnas.90.21.9973
Tiivistelmä
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.
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.
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