Analiza strukturalna i funkcjonalna podjednostek kompleksu γ-sekretazy u Arabidopsis thaliana
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2012-06-27T09:37:11Z
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Structural and functional analysis of γ-secretase complex subunits in Arabidopsis thaliana
Abstract
Gamma-sekretaza jest kompleksem transbłonowym o aktywności proteazy, zdolnym do cięcia substratów w obrębie błon biologicznych. Odkryto go w trakcie badań nad chorobą Alzheimera. Jego substratem jest między innymi białko prekursorowe amyloidu oraz receptor Notch. W skład kompleksu wchodzą 4 białka: presenilina, nikastryna, oraz APH-1 i PEN-2. Jedną z funkcji gamma-sekretazy u zwierząt jest udział w regulowanej proteolizie wewnątrzbłonowej wielu białek sygnałowych. Pewne dane wskazują, że u zwierząt kompleks może być także zaangażowany w proces krążenia pęcherzyków. U roślin istnienie oraz funkcja kompleksu gamma-sekretazy są całkowicie nieznane.
W rozprawie doktorskiej przedstawiono analizę strukturalną oraz funkcjonalną kompleksu gamma-sekretazy u Arabidopsis thaliana. Na podstawie danych bioinformatycznych ustalono, że w genomie roślin obecne są homologi wszystkich podjednostek kompleksu. Wykorzystując techniki mikroskopii fluorescencyjnej stwierdzono, że wszystkie podjednostki kompleksu gamma-sekretazy są zlokalizowane w obrębie systemu błon wewnętrznych. Analiza kolokalizacji, połączona z oceną oddziaływań metodą FLIM-FRET, pozwoliła zaproponować model składania i organizacji kompleksu gamma-sekretazy u roślin. Analiza funkcjonalna wykazała, że rośliny pozbawione presenilin wykazują zaburzenia rozwojowe. Poznanie dokładnego mechanizmu tych zmian wymaga dalszych badań.
Gamma-secretase is an intramembrane protease complex that carries out proteolysis inside diverse membranes. It was discovered though the genetic linkage with an Alzheimer disease. It is involved in the Notch signaling pathway. The complex consists of 4 proteins: presenilin, nicastrin, PEN-2 and APH-1. In animals gamma-secretase is involved in Regulated Intramembrane Proteolysis of many proteins. It might also play a role in endocytosis and vesicle trafficking regulation. In plants the existence and function of the gamma-secretase complex is completely unknown. The aim of research was to investigate structural and functional aspects of gamma-secretase complex in plants. Sequence analyses indicated that all four components of gamma-secretase complex are present in Arabidopsis genome. Confocal microscopy approach was used to determine the sub-cellular localization of distinct gamma-secretase components in plants. It was revealed that all subunits localize to endomembrane system. Colocalization studies, combined with FLIM-FRET analyses, have proven that gamma-secretase subunits interact with each other. These data were sufficient, to propose a simplified model of gamma-secretase assembly and maturation. Functional analyses showed that plants devoid of presenilins exhibit developmental abnormalities. However, the mechanism of these changes needs to be further investigated.
Gamma-secretase is an intramembrane protease complex that carries out proteolysis inside diverse membranes. It was discovered though the genetic linkage with an Alzheimer disease. It is involved in the Notch signaling pathway. The complex consists of 4 proteins: presenilin, nicastrin, PEN-2 and APH-1. In animals gamma-secretase is involved in Regulated Intramembrane Proteolysis of many proteins. It might also play a role in endocytosis and vesicle trafficking regulation. In plants the existence and function of the gamma-secretase complex is completely unknown. The aim of research was to investigate structural and functional aspects of gamma-secretase complex in plants. Sequence analyses indicated that all four components of gamma-secretase complex are present in Arabidopsis genome. Confocal microscopy approach was used to determine the sub-cellular localization of distinct gamma-secretase components in plants. It was revealed that all subunits localize to endomembrane system. Colocalization studies, combined with FLIM-FRET analyses, have proven that gamma-secretase subunits interact with each other. These data were sufficient, to propose a simplified model of gamma-secretase assembly and maturation. Functional analyses showed that plants devoid of presenilins exhibit developmental abnormalities. However, the mechanism of these changes needs to be further investigated.
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Wydział Biologii: Instytut Biologii Molekularnej i Biotechnologii
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Keywords
γ-sekretaza, γ-secretase, Presenilina, Presenilin, Proteaza wewnątrzbłonowa, Intramembrane protease, Arabidopsis thaliana, Arabidopsis thaliana