Der Blaulicht-Photorezeptor Cryptochrom 2 aus Arabidopsis thaliana: Lichtabhängige Phosphorylierung und Interaktionspartner in der Signaltransduktion
Obwohl über die physiologische Bedeutung der pflanzlichen Cryptochrome bereits viel bekannt ist, und deren nahe Verwandte, die Photolyasen auch molekular sehr detailliert, einschließlich der Struktur auf atomarer Ebene, charakterisiert sind, sind die Mechanismen der Signalwe...
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| Format: | Doctoral Thesis |
| Language: | German |
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Philipps-Universität Marburg
2003
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| Online Access: | PDF Full Text |
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Althougth the physiological functions of plant cryptochromes have been thoroughly investigated and their near relatives, the photolyases have been studied on the molecular level in very detail, the knowledge about the signal transduction of the cryptochromes however is relatively poor. Following the aim to find out more about these molecular processes, this work presents insights into some aspects, using Arabidopsis cry2 as a model. In this thesis, a light dependent posphorylation of cry2 has been discovered and further investigated. The recorded action-spectrum of this phosphorylation shows clear characteristics of a flavin-spectrum. Attempts to identifiy the responsible kinase have not been finished so far. A potential autophosphorylation activity connected with cry2 has been discussed, but could not be proven, finally. Further experiments with heterologouesly expressed cry2 in yeast resulted in data that suggest a role of cry2 as light dependent transcription activator. Also a DNA-binding activity of in vitro-transcribed and -translated cry2 has been demonstrated. Furthermore, the subcellular localization of two putative interaction partners of cry2 ? At5g26280 and At2g02230 - has been described. At2g02230 has been identified as functional F-box protein. Studies to elucidate the degradation pathway of cry2 could not strengthen the model of a proteasomal degradation.Althougth the physiological functions of plant cryptochromes have been thoroughly investigated and their near relatives, the photolyases have been studied on the molecular level in very detail, the knowledge about the signal transduction of the cryptochromes however is relatively poor. Following the aim to find out more about these molecular processes, this work presents insights into some aspects, using Arabidopsis cry2 as a model. In this thesis, a light dependent posphorylation of cry2 has been discovered and further investigated. The recorded action-spectrum of this phosphorylation shows clear characteristics of a flavin-spectrum. Attempts to identifiy the responsible kinase have not been finished so far. A potential autophosphorylation activity connected with cry2 has been discussed, but could not be proven, finally. Further experiments with heterologouesly expressed cry2 in yeast resulted in data that suggest a role of cry2 as light dependent transcription activator. Also a DNA-binding activity of in vitro-transcribed and -translated cry2 has been demonstrated. Furthermore, the subcellular localization of two putative interaction partners of cry2 ? At5g26280 and At2g02230 - has been described. At2g02230 has been identified as functional F-box protein. Studies to elucidate the degradation pathway of cry2 could not strengthen the model of a proteasomal degradation.