LHPP, the light-harvesting NADPH:protochlorophyllide (Pchlide) oxido¬reductase:Pchlide complex of etiolated plants, is developmentally expressed across the barley leaf gradient
| Autor: | Erwin Beck, Stephan Pollmann, Steffen Reinbothe, Martina Weigele, Claire Desvignes, Christiane Reinbothe |
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| Rok vydání: | 2004 |
| Předmět: |
0106 biological sciences
2. Zero hunger 0303 health sciences Biología food and beverages Plant Science General Medicine Biology Photosynthesis 01 natural sciences Chloroplast 03 medical and health sciences Protochlorophyllide Biochemistry Protochlorophyllide reductase Thylakoid Etiolation Genetics Photosynthetic membrane Hordeum vulgare Agronomy and Crop Science 030304 developmental biology 010606 plant biology & botany |
| Zdroj: | Plant Science, ISSN 0168-9452, 2004, Vol. 167, No. 5 Archivo Digital UPM Universidad Politécnica de Madrid |
| Popis: | NADPH:protochlorophyllide oxidoreductase is a key enzyme for the light-induced greening of etiolated angiosperm plants. In barley, two POR proteins exist termed PORA and PORB that have previously been proposed to structurally and functionally cooperate in terms of a higher molecular mass light-harvesting complex named LHPP, in the prolamellar body of etioplasts [Nature 397 (1999) 80]. In this study we examined the expression pattern of LHPP during seedling etiolation and de-etiolation under different experimental conditions. Our results show that LHPP is developmentally expressed across the barley leaf gradient. We further provide evidence that LHPP operates both in plants that etiolate completely before being exposed to white light and in plants that etiolate only partially and begin light-harvesting as soon as traces of light become available in the uppermost parts of the soil. As a result of light absorption, in either case LHPP converts Pchlide a to chlorophyllide (Chlide) a and in turn disintegrates. The released Chlide a, as well as Chlide b produced upon LHPP’s light-dependent dissociation, which leads to the activation of the PORA as a Pchlide b-reducing enzyme, then bind to homologs of water-soluble chlorophyll proteins of Brassicaceae. We propose that these proteins transfer Chlide a and Chlide b to the thylakoids, where their esterification with phytol and assembly into the photosynthetic membrane complexes ultimately takes place. Presumably due to the tight coupling of LHPP synthesis and degradation, as well as WSCP formation and photosynthetic membrane assembly, efficient photo-protection is conferred onto the plant. |
| Databáze: | OpenAIRE |
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