Abstract
The Bcl-2-family of proteins localize to intracellular membranes via a C-terminal hydrophobic membrane anchor (MA) domain, to exert their antiapoptotic or proapoptotic functions. In Drosophila, both Bcl-2 family members, DEBCL and BUFFY, contain an MA. In DEBCL the MA is necessary for the localization of protein to mitochondria and for its proapoptotic activity. BUFFY is highly similar to DEBCL but its localization and function are not clearly defined. Here, we report on comparative analysis of BUFFY and DEBCL to decipher the molecular basis for their subcellular localization. We show that these two proteins localize to distinct intracellular membranes, DEBCL predominantly to mitochondria and BUFFY to endoplasmic reticula (ER). Our results suggest that the MA-flanking residues in DEBCL, homologous to Bcl-XL, are required for the targeting of DEBCL to mitochondria. The C-terminal positively charged residues present in DEBCL are absent in BUFFY, which allows for its localization to ER. The MA in both proteins is required for the correct targeting and proapoptotic activities of these proteins. Interestingly, a functional nuclear localization signal was identified in the N-terminal region of BUFFY and in the absence of the MA, BUFFY accumulated in the nucleus. The functional implications of these findings are discussed.
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Abbreviations
- ER:
-
endoplasmic reticula
- MA:
-
membrane anchor
- NLS:
-
nuclear localization signal
- BH:
-
Bcl-2 homology
- TM:
-
transmembrane
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Acknowledgements
We are grateful to Christoph Borner for providing the Bcl-XL and Bcl-2 constructs used in this study. We thank the members of our laboratory for helpful comments. This work was supported by the National Health and Medical Council of Australia. JD was supported by a Royal Adelaide Hospital Dawes Postgraduate Award. LD is a Royal Adelaide Hospital Florey Fellow.
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Doumanis, J., Dorstyn, L. & Kumar, S. Molecular determinants of the subcellular localization of the Drosophila Bcl-2 homologues DEBCL and BUFFY. Cell Death Differ 14, 907–915 (2007). https://doi.org/10.1038/sj.cdd.4402082
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DOI: https://doi.org/10.1038/sj.cdd.4402082
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