- Investigation of the Anti-apoptotic Function and Regulation of Vaccinia Virus F1L
- Campbell, Stephanie D
- Jan 4, 2012 10:57 AM
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- Apoptosis, an evolutionarily conserved cell death programme, is a potent barrier against virus infection. Central to this process are mitochondria, which harbour cytochrome c and other apoptosis-inducing factors. Once released, these factors activate a caspase cascade that culminates in cell death. Mitochondrial integrity is tightly regulated by the Bcl-2 family of proteins, which are united by the presence of one or more conserved Bcl-2 homology, or BH, domains that are critical for protein interactions and function. Bak and Bax are the key pro-apoptotic members that engage the mitochondrial death machinery to release cytochrome c. These proteins are activated by pro-apoptotic BH3-only proteins and inhibited by anti-apoptotic family members, such as Mcl-1. Due to the importance of Bak and Bax, many viruses, including poxviruses, have adapted strategies to interfere with the activation of these two proteins. In the prototypic poxvirus vaccinia virus, this is accomplished by a unique anti-apoptotic protein, F1L. F1L localizes to mitochondria and prevents apoptosis induced by a variety of stimuli. This is achieved by direct binding to Bak, while Bax inhibition is believed to occur by the binding of F1L to the BH3-only protein, BimL. However, the way in which F1L binds Bak and BimL is unknown, since F1L lacks sequence homology to Bcl-2 proteins. Here, we show that F1L functions in a manner that resembles Mcl-1, the major cellular regulator of Bak. Moreover, we have identified divergent BH domains within F1L that are critical for Bak binding and anti-apoptotic activity. Given the importance of the Bcl-2 family of proteins, many members are regulated by ubiquitination, which targets the proteins for proteasomal degradation. Similarly, we have discovered that F1L is tightly regulated by the ubiquitin-proteasome system. Our studies on F1L ubiquitination have also revealed a potential role for F1L in the regulation of mitochondrial morphology. Thus, despite divergence at the sequence level, F1L interacts with Bak in a manner nearly identical to cellular Bcl-2 family members, and, additionally, F1L is governed by the same regulatory mechanisms that control members of the Bcl-2 family.
- Campbell, S., B. Hazes, M. Kvansakul, P. Colman, and M. Barry. 2010. Vaccinia virus F1L interacts with Bak using highly divergent Bcl-2 homology domains and replaces the function of Mcl-1. Journal of Biological Chemistry 285:4695-4708.
- Doctor of Philosophy
- Department of Medical Microbiology and Immunology
- Spring 2012
- Barry, Michele (Medical Microbiology and Immunology)
Barry, Michele (Medical Microbiology and Immunology)
Berthiaume, Luc (Cell Biology)
Ingham, Rob (Medical Microbiology and Immunology)
Evans, David (Medical Microbiology and Immunology)
Fruh, Klaus (Vaccine and Gene Therapy Institute)
Theses and Dissertations Spring 2009 to present
Department of Medical Microbiology and Immunology
Apr 28, 2014 3:35 PM
Mar 17, 2014 10:17 AM
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