Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/15826
Title: Characterization of Candida Albicans cyclase-associated protein CAP1 and its roles in morphogenesis - G-actin associates with the Adenylyl cyclase Cyr1 through Cap1 and regulates cAMP synthesis in Candida Albicans Hyphal Morphogenesis
Authors: ZOU HAO
Keywords: Candida Albicans, CAP1, Hyphae, cAMP, Cyr1, actin
Issue Date: 24-Apr-2009
Source: ZOU HAO (2009-04-24). Characterization of Candida Albicans cyclase-associated protein CAP1 and its roles in morphogenesis - G-actin associates with the Adenylyl cyclase Cyr1 through Cap1 and regulates cAMP synthesis in Candida Albicans Hyphal Morphogenesis. ScholarBank@NUS Repository.
Abstract: The yeast-to-hyphal growth switch is a key virulence trait of C. albicans. It is induced by certain environmental signals and primarily mediated by the cAMP/PKA pathway. Actin cytoskeleton plays a central role in the hyphal growth. However, the mechanisms of interaction between the cAMP/PKA pathway and the actin cytoskeleton remain unclear. The aim of this study is to test the hypothesis that the Cyclase Associated Protein, Cap1 of C. albicans, which has the capacity to interact with both actin and the adenylyl cyclase Cyr1, may play an important role in linking the actin cytoskeleton and the cAMP/PKA pathway. We have found that Cyr1, Cap1 and actin can indeed form a ternary complex in which Cap1 acts as a bridge, and this complex is sufficient for producing cAMP in vitro under hyphal-inducing conditions. Since the C-terminus of Cap1 contains the G-actin binding site and is required for the formation of the ternary complex, it is reasonable to speculate that G-actin might be able to influence Cyr1 activity through its interaction with Cap1. Consistent with this view, cells expressing a Cap1 mutant lacking the G-actin binding site exhibited delayed and reduced cAMP production and defects in hyphal morphogenesis. Consistently, while wild-type cells exhibited suppressed adenylyl cyclase activity when treated with actin depolymerization drugs, the mutant cells were resistant. These results for the first time demonstrate that G-actin plays an active role in directly regulating cAMP synthesis by forming a ternary complex with Cyr1 and Cap1, revealing a mechanistic link for regulation of the cAMP/PKA pathway by cellular actin status.
URI: http://scholarbank.nus.edu.sg/handle/10635/15826
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