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Titolo:
Oxygen-dependent electron flow influences photosystem II function and psbAgene expression in the cyanobacterium Synechococcus sp PCC 7942
Autore:
Campbell, D; Clarke, AK; Gustafsson, P; Oquist, G;
Indirizzi:
Mt Allison Univ, Dept Biol, Sackville, NB E4L 1G7, Canada Mt Allison UnivSackville NB Canada E4L 1G7 Sackville, NB E4L 1G7, Canada Umea Univ, Dept Plant Physiol, S-90187 Umea, Sweden Umea Univ Umea Sweden S-90187 , Dept Plant Physiol, S-90187 Umea, Sweden
Titolo Testata:
PHYSIOLOGIA PLANTARUM
fascicolo: 4, volume: 105, anno: 1999,
pagine: 746 - 755
SICI:
0031-9317(199904)105:4<746:OEFIPI>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
AIR-GROWN CELLS; INORGANIC CARBON ACCUMULATION; CYTOCHROME-C-OXIDASE; HIGH LIGHT-INTENSITY; CHLOROPHYLL FLUORESCENCE; 2 FORMS; ANACYSTIS-NIDULANS; SP PCC-7942; D1 PROTEIN; DISTINCT FORMS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
61
Recensione:
Indirizzi per estratti:
Indirizzo: Campbell, D Mt Allison Univ, Dept Biol, Sackville, NB E4L 1G7, Canada Mt Allison Univ Sackville NB Canada E4L 1G7 B E4L 1G7, Canada
Citazione:
D. Campbell et al., "Oxygen-dependent electron flow influences photosystem II function and psbAgene expression in the cyanobacterium Synechococcus sp PCC 7942", PHYSL PLANT, 105(4), 1999, pp. 746-755

Abstract

During acclimated growth in Synechococcus sp, PCC 7942 a substantial proportion of the electrons extracted from mater by photosystem II ultimately flow back to oxygen, This flow increases rapidly under high light, which allows Synechococcus to maintain photosystem II centers largely open, even under excessive excitation, The electron flow to oxygen with increasing light accounts for the progressive discrepancy between the light response curve ofmeasured oxygen evolution, and the light response curve of photosystem II activity estimated from fluorescence measures. In cells under anoxia this flexible electron sink is lost and photosystem II centers suffer partial closure at the growth light intensity, with closure becoming more severe underexcess light. As predicted from earlier work this PSII closure results in rapid loss of psbAI message, encoding the D1:1 protein of PSII, and induction of psbAII/AIII encoding the alternate D1:2 protein. The changes in the mRNA pool are not, however, reflected at the protein level, and D1:1 remainsin the thylakoid membranes. There is no accumulation of D1:2, despite somecontinued synthesis of other proteins. PSII closure, therefore, results inrepression of psbAI and induction psbAII/AIII expression, but D1:1/D1:2 exchange is blocked by anoxia, downstream from transcription. D1:1 protein and PSII activity are quite stable under anoxia and moderate illumination, Nevertheless, upon recovery under oxygenic conditions, the existing D1:1 is lost from the membranes, resulting in a transient drop in PSII activity. This suggests that under normal conditions the cells use oxygen to facilitate preemptive turnover of D1 proteins.

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Documento generato il 30/10/20 alle ore 09:51:01