Expression of protein complexes and individual proteins upon transition of etioplasts to chloroplasts in pea (Pisum sativum) |
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Authors: | Kanervo Eira Singh Munna Suorsa Marjaana Paakkarinen Virpi Aro Eveliina Battchikova Natalia Aro Eva-Mari |
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Institution: | 1Department of Biology, University of Turku, FIN-20014 Turku, Finland
2Botany Department, Lucknow University, Lucknow-226 007 (U.P.), India |
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Abstract: | The protein complexes of pea (Pisum sativum L.) etioplasts,etio-chloroplasts and chloroplasts were examined using 2D BlueNative/SDS–PAGE. The most prominent protein complexesin etioplasts were the ATPase and the Clp and FtsH proteasecomplexes which probably have a crucial role in the biogenesisof etioplasts and chloroplasts. Also the cytochrome b6f (Cytb6f) complex was assembled in the etioplast membrane, as wellas Rubisco, at least partially, in the stroma. These complexesare composed of proteins encoded by both the plastid and nucleargenomes, indicating that a functional cross-talk exists betweenpea etioplasts and the nucleus. In contrast, the proteins andprotein complexes that bind chlorophyll, with the PetD subunitand the entire Cyt b6f complex as an exception, did not accumulatein etioplasts. Nevertheless, some PSII core components suchas PsbE and the luminal oxygen-evolvong complex (OEC) proteinsPsbO and PsbP accumulated efficiently in etioplasts. After 6h de-etiolation, a complete PSII core complex appeared with40% of the maximal photochemical efficiency, but a fully functionalPSII was recorded only after 24 h illumination. Similarly, thecore complex of PSI was assembled after 6 h illumination, whereasthe PSI–light-harvesting complex I was stably assembledonly in chloroplasts illuminated for 24 h. Moreover, a batteryof proteins responsible for defense against oxidative stressaccumulated particularly in etioplasts, including the stromaland thylakoidal forms of ascorbate peroxidase, glutathione reductaseand PsbS. |
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Keywords: | Chloroplast - Clp - Etioplast - FtsH - Pea - Protein complex assembly |
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