Ama1p-activated anaphase-promoting complex regulates the destruction of Cdc20p during meiosis II

Department of Biochemistry and Molecular Biology, Drexel Medical School, Philadelphia, PA 19102, USA.
Molecular biology of the cell (Impact Factor: 4.47). 02/2011; 22(3):315-26. DOI: 10.1091/mbc.E10-04-0360
Source: PubMed


The execution of meiotic divisions in Saccharomyces cerevisiae is regulated by anaphase-promoting complex/cyclosome (APC/C)-mediated protein degradation. During meiosis, the APC/C is activated by association with Cdc20p or the meiosis-specific activator Ama1p. We present evidence that, as cells exit from meiosis II, APC/C(Ama1) mediates Cdc20p destruction. APC/C(Ama1) recognizes two degrons on Cdc20p, the destruction box and destruction degron, with either domain being sufficient to mediate Cdc20p destruction. Cdc20p does not need to associate with the APC/C to bind Ama1p or be destroyed. Coimmunoprecipitation analyses showed that the diverged amino-terminal region of Ama1p recognizes both Cdc20p and Clb1p, a previously identified substrate of APC/C(Ama1). Domain swap experiments revealed that the C-terminal WD region of Cdh1p, when fused to the N-terminal region of Ama1p, could direct most of Ama1p functions, although at a reduced level. In addition, this fusion protein cannot complement the spore wall defect in ama1Δ strains, indicating that substrate specificity is also derived from the WD repeat domain. These findings provide a mechanism to temporally down-regulate APC/C(Cdc20) activity as the cells complete meiosis II and form spores.

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    • "To determine whether Cdh1p plays a role in Ama1p proteolysis during meiosis, Ama1p protein levels were monitored in cdh1∆ cells during meiosis. The results show that cdh1∆ cells both progress through meiosis (Additional file 2: Figure S2A, S2B and S2C) and degrade Ama1p with the same kinetics as wild type (Additional file 2: Figure S2D and see Tan et al. [12] for Northern analysis). Interestingly, dissection of the resulting cdh1∆ tetrads revealed that, different to previously published results [16], cdh1∆ spores exhibit a significant reduction in their ability to form colonies (Additional file 2: Figure S2E). "
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    ABSTRACT: The execution of meiotic nuclear divisions in S. cerevisiae is regulated by protein degradation mediated by the anaphase promoting complex/cyclosome (APC/C) ubiquitin ligase. The correct timing of APC/C activity is essential for normal chromosome segregation. During meiosis, the APC/C is activated by the association of either Cdc20p or the meiosis-specific factor Ama1p. Both Ama1p and Cdc20p are targeted for degradation as cells exit meiosis II with Cdc20p being destroyed by APC/CAma1. In this study we investigated how Ama1p is down regulated at the completion of meiosis. Here we show that Ama1p is a substrate of APC/CCdc20 but not APC/CCdh1 in meiotic cells. Cdc20p binds Ama1p in vivo and APC/CCdc20 ubiquitylates Ama1p in vitro. Ama1p ubiquitylation requires one of two degradation motifs, a D-box and a "KEN-box" like motif called GxEN. Finally, Ama1p degradation does not require its association with the APC/C via its conserved APC/C binding motifs (C-box and IR) and occurs simultaneously with APC/CAma1-mediated Cdc20p degradation. Unlike the cyclical nature of mitotic cell division, meiosis is a linear pathway leading to the production of quiescent spores. This raises the question of how the APC/C is reset prior to spore germination. This and a previous study revealed that Cdc20p and Ama1p direct each others degradation via APC/C-dependent degradation. These findings suggest a model that the APC/C is inactivated by mutual degradation of the activators. In addition, these results support a model in which Ama1p and Cdc20p relocate to the substrate address within the APC/C cavity prior to degradation.
    Cell Division 07/2013; 8(1):9. DOI:10.1186/1747-1028-8-9 · 3.53 Impact Factor
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    • "For example, Rec8 replaces Mcd1 to maintain sister centromere cohesion during meiosis I [4]. In addition, Ama1 is a meiosis-specific activator of the anaphase promoting complex/cyclosome (APC/C) ubiquitin ligase and is required for exit from meiosis II [5-8]. The second approach utilizes mitotic regulators that take on new meiotic functions. "
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    ABSTRACT: ABSTRACT: The anaphase promoting complex is a highly conserved E3 ligase complex that mediates the destruction of key regulatory proteins during both mitotic and meiotic divisions. In order to maintain ploidy, this destruction must occur after the regulatory proteins have executed their function. Thus, the regulation of APC/C activity itself is critical for maintaining ploidy during all types of cell divisions. During mitotic cell division, two conserved activator proteins called Cdc20 and Cdh1 are required for both APC/C activation and substrate selection. However, significantly less is known about how these proteins regulate APC/C activity during the specialized meiotic nuclear divisions. In addition, both budding yeast and flies utilize a third meiosis-specific activator. In Saccharomyces cerevisiae, this meiosis-specific activator is called Ama1. This review summarizes our knowledge of how Cdc20 and Ama1 coordinate APC/C activity to regulate the meiotic nuclear divisions in yeast.
    Cell Division 08/2011; 6(1):16. DOI:10.1186/1747-1028-6-16 · 3.53 Impact Factor
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    ABSTRACT: In response to nitrogen starvation in the presence of a poor carbon source, diploid cells of the yeast Saccharomyces cerevisiae undergo meiosis and package the haploid nuclei produced in meiosis into spores. The formation of spores requires an unusual cell division event in which daughter cells are formed within the cytoplasm of the mother cell. This process involves the de novo generation of two different cellular structures: novel membrane compartments within the cell cytoplasm that give rise to the spore plasma membrane and an extensive spore wall that protects the spore from environmental insults. This article summarizes what is known about the molecular mechanisms controlling spore assembly with particular attention to how constitutive cellular functions are modified to create novel behaviors during this developmental process. Key regulatory points on the sporulation pathway are also discussed as well as the possible role of sporulation in the natural ecology of S. cerevisiae.
    Genetics 11/2011; 189(3):737-65. DOI:10.1534/genetics.111.127126 · 5.96 Impact Factor
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