Translocation of a Bak C-terminus mutant from cytosol to mitochondria to mediate cytochrome C release: implications for Bak and Bax apoptotic function.
<h4>Background</h4>One of two proapoptotic Bcl-2 proteins, Bak or Bax, is required to permeabilize the mitochondrial outer membrane during apoptosis. While Bax is mostly cytosolic and translocates to mitochondria following an apoptotic stimulus, Bak is constitutively integrated within th...
Saved in:
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2012-01-01
|
| Series: | PLoS ONE |
| Online Access: | https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0031510&type=printable |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1849727623973830656 |
|---|---|
| author | Pedro Eitz Ferrer Paul Frederick Jacqueline M Gulbis Grant Dewson Ruth M Kluck |
| author_facet | Pedro Eitz Ferrer Paul Frederick Jacqueline M Gulbis Grant Dewson Ruth M Kluck |
| author_sort | Pedro Eitz Ferrer |
| collection | DOAJ |
| description | <h4>Background</h4>One of two proapoptotic Bcl-2 proteins, Bak or Bax, is required to permeabilize the mitochondrial outer membrane during apoptosis. While Bax is mostly cytosolic and translocates to mitochondria following an apoptotic stimulus, Bak is constitutively integrated within the outer membrane. Membrane anchorage occurs via a C-terminal transmembrane domain that has been studied in Bax but not in Bak, therefore what governs their distinct subcellular distribution is uncertain. In addition, whether the distinct subcellular distributions of Bak and Bax contributes to their differential regulation during apoptosis remains unclear.<h4>Methodology/principal findings</h4>To gain insight into Bak and Bax targeting to mitochondria, elements of the Bak C-terminus were mutated, or swapped with those of Bax. Truncation of the C-terminal six residues (C-segment) or substitution of three basic residues within the C-segment destabilized Bak. Replacing the Bak C-segment with that from Bax rescued stability and function, but unexpectedly resulted in a semi-cytosolic protein, termed Bak/BaxCS. When in the cytosol, both Bax and Bak/BaxCS sequestered their hydrophobic transmembrane domains in their hydrophobic surface groove. Upon apoptotic signalling, Bak/BaxCS translocated to the mitochondrial outer membrane, inserted its transmembrane domain, oligomerized, and released cytochrome c. Despite this Bax-like subcellular distribution, Bak/BaxCS retained Bak-like regulation following targeting of Mcl-1.<h4>Conclusions/significance</h4>Residues in the C-segment of Bak and of Bax contribute to their distinct subcellular localizations. That a semi-cytosolic form of Bak, Bak/BaxCS, could translocate to mitochondria and release cytochrome c indicates that Bak and Bax share a conserved mode of activation. In addition, the differential regulation of Bak and Bax by Mcl-1 is predominantly independent of the initial subcellular localizations of Bak and Bax. |
| format | Article |
| id | doaj-art-69db642ec54f42a48bf048af56a7c4ee |
| institution | DOAJ |
| issn | 1932-6203 |
| language | English |
| publishDate | 2012-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj-art-69db642ec54f42a48bf048af56a7c4ee2025-08-20T03:09:48ZengPublic Library of Science (PLoS)PLoS ONE1932-62032012-01-0173e3151010.1371/journal.pone.0031510Translocation of a Bak C-terminus mutant from cytosol to mitochondria to mediate cytochrome C release: implications for Bak and Bax apoptotic function.Pedro Eitz FerrerPaul FrederickJacqueline M GulbisGrant DewsonRuth M Kluck<h4>Background</h4>One of two proapoptotic Bcl-2 proteins, Bak or Bax, is required to permeabilize the mitochondrial outer membrane during apoptosis. While Bax is mostly cytosolic and translocates to mitochondria following an apoptotic stimulus, Bak is constitutively integrated within the outer membrane. Membrane anchorage occurs via a C-terminal transmembrane domain that has been studied in Bax but not in Bak, therefore what governs their distinct subcellular distribution is uncertain. In addition, whether the distinct subcellular distributions of Bak and Bax contributes to their differential regulation during apoptosis remains unclear.<h4>Methodology/principal findings</h4>To gain insight into Bak and Bax targeting to mitochondria, elements of the Bak C-terminus were mutated, or swapped with those of Bax. Truncation of the C-terminal six residues (C-segment) or substitution of three basic residues within the C-segment destabilized Bak. Replacing the Bak C-segment with that from Bax rescued stability and function, but unexpectedly resulted in a semi-cytosolic protein, termed Bak/BaxCS. When in the cytosol, both Bax and Bak/BaxCS sequestered their hydrophobic transmembrane domains in their hydrophobic surface groove. Upon apoptotic signalling, Bak/BaxCS translocated to the mitochondrial outer membrane, inserted its transmembrane domain, oligomerized, and released cytochrome c. Despite this Bax-like subcellular distribution, Bak/BaxCS retained Bak-like regulation following targeting of Mcl-1.<h4>Conclusions/significance</h4>Residues in the C-segment of Bak and of Bax contribute to their distinct subcellular localizations. That a semi-cytosolic form of Bak, Bak/BaxCS, could translocate to mitochondria and release cytochrome c indicates that Bak and Bax share a conserved mode of activation. In addition, the differential regulation of Bak and Bax by Mcl-1 is predominantly independent of the initial subcellular localizations of Bak and Bax.https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0031510&type=printable |
| spellingShingle | Pedro Eitz Ferrer Paul Frederick Jacqueline M Gulbis Grant Dewson Ruth M Kluck Translocation of a Bak C-terminus mutant from cytosol to mitochondria to mediate cytochrome C release: implications for Bak and Bax apoptotic function. PLoS ONE |
| title | Translocation of a Bak C-terminus mutant from cytosol to mitochondria to mediate cytochrome C release: implications for Bak and Bax apoptotic function. |
| title_full | Translocation of a Bak C-terminus mutant from cytosol to mitochondria to mediate cytochrome C release: implications for Bak and Bax apoptotic function. |
| title_fullStr | Translocation of a Bak C-terminus mutant from cytosol to mitochondria to mediate cytochrome C release: implications for Bak and Bax apoptotic function. |
| title_full_unstemmed | Translocation of a Bak C-terminus mutant from cytosol to mitochondria to mediate cytochrome C release: implications for Bak and Bax apoptotic function. |
| title_short | Translocation of a Bak C-terminus mutant from cytosol to mitochondria to mediate cytochrome C release: implications for Bak and Bax apoptotic function. |
| title_sort | translocation of a bak c terminus mutant from cytosol to mitochondria to mediate cytochrome c release implications for bak and bax apoptotic function |
| url | https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0031510&type=printable |
| work_keys_str_mv | AT pedroeitzferrer translocationofabakcterminusmutantfromcytosoltomitochondriatomediatecytochromecreleaseimplicationsforbakandbaxapoptoticfunction AT paulfrederick translocationofabakcterminusmutantfromcytosoltomitochondriatomediatecytochromecreleaseimplicationsforbakandbaxapoptoticfunction AT jacquelinemgulbis translocationofabakcterminusmutantfromcytosoltomitochondriatomediatecytochromecreleaseimplicationsforbakandbaxapoptoticfunction AT grantdewson translocationofabakcterminusmutantfromcytosoltomitochondriatomediatecytochromecreleaseimplicationsforbakandbaxapoptoticfunction AT ruthmkluck translocationofabakcterminusmutantfromcytosoltomitochondriatomediatecytochromecreleaseimplicationsforbakandbaxapoptoticfunction |