酵母菌第三腺嘌呤核苷二磷酸核醣化因子於侵入性生長之功能性探討
Other Title
Functional Characterization of Arf3p-mediated Invasive Growth in Saccharomyces cerevisiae
Start Page
1
End Page
97
Date Issued
2013
Author(s)
Advisor
李芳仁
Abstract
真菌類的侵入性生長會影響其致病能力，其調控機制在過去已被研究的相當廣泛。Bud2p可以幫助Bud1p/Rsr1p之鳥糞嘌呤核苷三磷酸水解能力，Bud2p在過去的研究中指出會參與在酵母菌出芽生殖及侵入性生長的過程中，但是詳細的分子機制目前還尚未了解。本研究指出：在酵母菌侵入性生長的過程中Arf3p可以調控Bud2p的活性。我們發現Arf3p藉由直接作用於Bud2p的胺基端來促進其酵素活性，透過遺傳學及生化分析也發現Bud1p的活化態及不活化態可以影響酵母菌侵入性生長，且當細胞中缺乏Arf3p或是Bud2p都會讓細胞中累積過多的活化態Bud1p。此外，我們也發現當葡萄糖缺乏所引發的酵母菌侵入性生長中，會增加活化態Arf3p，且此過程與其鳥糞嘌呤核苷酸交換因子Yel1p無關。因此我們提出一個機制，那就是當酵母菌遭遇到葡萄糖缺乏時，其會促進Arf3p活化，並會與Bud2p直接作用來調控Bud2p對於提升Bud1p之鳥糞嘌呤核苷三磷酸水解能力，進而影響酵母菌的侵入性生長。
The regulation and signaling pathways involved in the invasive growth of yeast have been studied extensively because of their general applicability to fungal pathogenesis. Bud2p, which functions as a GTPase-activating protein (GAP) for Bud1p/Rsr1p, is required for appropriate budding patterns and filamentous growth. However, the regulatory mechanisms leading to Bud2p activation are poorly understood. In this study, we report that Arf3p acts as a regulator of Bud2p activation during invasive growth. Arf3p binds directly to the N-terminal region of Bud2p and promotes its GAP activity both in vitro and in vivo. Genetic analysis shows that deletion of BUD1 suppresses the defect of invasive growth in arf3 or bud2 cells. Lack of Arf3p, like that of Bud2p, causes the intracellular accumulation of Bud1p-GTP. The Arf3p-Bud2p interaction is important for invasive growth and facilitates the Bud2p-Bud1p association in vivo. Finally, we show that under glucose depletion-induced invasion conditions in yeast, more Arf3p is activated to the GTP-bound state and the activation is independent of Arf3p guanine nucleotide-exchange factor (GEF) Yel1p. Thus, we demonstrate that a novel spatial activation of Arf3p plays a role in regulating Bud2p activation during glucose-depletion-induced invasive growth.
Subjects
侵入性生長
細胞極性
鳥糞嘌呤核苷三磷酸酶
鳥糞嘌呤核苷三磷酸酶活化蛋白
鳥糞嘌呤核苷酸交換因子
ARF
BUD2
GAP
GEF
GTPase
invasion
polarity
Publisher
國立臺灣大學
Type
doctoral thesis