Integrated conformational and lipid-sensing regulation of endosomal ArfGEF BRAG2.
The mechanisms whereby guanine nucleotide exchange factors (GEFs) coordinate their subcellular targeting to their activation of small GTPases remain poorly understood. Here we analyzed how membranes control the efficiency of human BRAG2, an ArfGEF involved in receptor endocytosis, Wnt signaling, and...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2013-09-01
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| Series: | PLoS Biology |
| Online Access: | http://europepmc.org/articles/PMC3769224?pdf=render |
| _version_ | 1819129891490103296 |
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| author | Kaheina Aizel Valérie Biou Jorge Navaza Lionel V Duarte Valérie Campanacci Jacqueline Cherfils Mahel Zeghouf |
| author_facet | Kaheina Aizel Valérie Biou Jorge Navaza Lionel V Duarte Valérie Campanacci Jacqueline Cherfils Mahel Zeghouf |
| author_sort | Kaheina Aizel |
| collection | DOAJ |
| description | The mechanisms whereby guanine nucleotide exchange factors (GEFs) coordinate their subcellular targeting to their activation of small GTPases remain poorly understood. Here we analyzed how membranes control the efficiency of human BRAG2, an ArfGEF involved in receptor endocytosis, Wnt signaling, and tumor invasion. The crystal structure of an Arf1-BRAG2 complex that mimics a membrane-bound intermediate revealed an atypical PH domain that is constitutively anchored to the catalytic Sec7 domain and interacts with Arf. Combined with the quantitative analysis of BRAG2 exchange activity reconstituted on membranes, we find that this PH domain potentiates nucleotide exchange by about 2,000-fold by cumulative conformational and membrane-targeting contributions. Furthermore, it restricts BRAG2 activity to negatively charged membranes without phosphoinositide specificity, using a positively charged surface peripheral to but excluding the canonical lipid-binding pocket. This suggests a model of BRAG2 regulation along the early endosomal pathway that expands the repertoire of GEF regulatory mechanisms. Notably, it departs from the auto-inhibitory and feedback loop paradigm emerging from studies of SOS and cytohesins. It also uncovers a novel mechanism of unspecific lipid-sensing by PH domains that may allow sustained binding to maturating membranes. |
| first_indexed | 2024-12-22T08:50:55Z |
| format | Article |
| id | doaj.art-ed65405052864a3b8fe0a1123aecc0b7 |
| institution | Directory Open Access Journal |
| issn | 1544-9173 1545-7885 |
| language | English |
| last_indexed | 2024-12-22T08:50:55Z |
| publishDate | 2013-09-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Biology |
| spelling | doaj.art-ed65405052864a3b8fe0a1123aecc0b72022-12-21T18:31:59ZengPublic Library of Science (PLoS)PLoS Biology1544-91731545-78852013-09-01119e100165210.1371/journal.pbio.1001652Integrated conformational and lipid-sensing regulation of endosomal ArfGEF BRAG2.Kaheina AizelValérie BiouJorge NavazaLionel V DuarteValérie CampanacciJacqueline CherfilsMahel ZeghoufThe mechanisms whereby guanine nucleotide exchange factors (GEFs) coordinate their subcellular targeting to their activation of small GTPases remain poorly understood. Here we analyzed how membranes control the efficiency of human BRAG2, an ArfGEF involved in receptor endocytosis, Wnt signaling, and tumor invasion. The crystal structure of an Arf1-BRAG2 complex that mimics a membrane-bound intermediate revealed an atypical PH domain that is constitutively anchored to the catalytic Sec7 domain and interacts with Arf. Combined with the quantitative analysis of BRAG2 exchange activity reconstituted on membranes, we find that this PH domain potentiates nucleotide exchange by about 2,000-fold by cumulative conformational and membrane-targeting contributions. Furthermore, it restricts BRAG2 activity to negatively charged membranes without phosphoinositide specificity, using a positively charged surface peripheral to but excluding the canonical lipid-binding pocket. This suggests a model of BRAG2 regulation along the early endosomal pathway that expands the repertoire of GEF regulatory mechanisms. Notably, it departs from the auto-inhibitory and feedback loop paradigm emerging from studies of SOS and cytohesins. It also uncovers a novel mechanism of unspecific lipid-sensing by PH domains that may allow sustained binding to maturating membranes.http://europepmc.org/articles/PMC3769224?pdf=render |
| spellingShingle | Kaheina Aizel Valérie Biou Jorge Navaza Lionel V Duarte Valérie Campanacci Jacqueline Cherfils Mahel Zeghouf Integrated conformational and lipid-sensing regulation of endosomal ArfGEF BRAG2. PLoS Biology |
| title | Integrated conformational and lipid-sensing regulation of endosomal ArfGEF BRAG2. |
| title_full | Integrated conformational and lipid-sensing regulation of endosomal ArfGEF BRAG2. |
| title_fullStr | Integrated conformational and lipid-sensing regulation of endosomal ArfGEF BRAG2. |
| title_full_unstemmed | Integrated conformational and lipid-sensing regulation of endosomal ArfGEF BRAG2. |
| title_short | Integrated conformational and lipid-sensing regulation of endosomal ArfGEF BRAG2. |
| title_sort | integrated conformational and lipid sensing regulation of endosomal arfgef brag2 |
| url | http://europepmc.org/articles/PMC3769224?pdf=render |
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