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Mysore VP, Zhou ZW, Ambrogio C, Li L, Kapp JN, Lu C, Wang Q, Tucker MR, Okoro JJ, Nagy-Davidescu G, Bai X, Plückthun A, Jänne PA, Westover KD, Shan Y, Shaw DE. A structural model of a Ras-Raf signalosome. Nat Struct Mol Biol 2021; 28:847-857. [PMID: 34625747 PMCID: PMC8643099 DOI: 10.1038/s41594-021-00667-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 08/25/2021] [Indexed: 01/29/2023]
Abstract
The protein K-Ras functions as a molecular switch in signaling pathways regulating cell growth. In the human mitogen-activated protein kinase (MAPK) pathway, which is implicated in many cancers, multiple K-Ras proteins are thought to assemble at the cell membrane with Ras effector proteins from the Raf family. Here we propose an atomistic structural model for such an assembly. Our starting point was an asymmetric guanosine triphosphate-mediated K-Ras dimer model, which we generated using unbiased molecular dynamics simulations and verified with mutagenesis experiments. Adding further K-Ras monomers in a head-to-tail fashion led to a compact helical assembly, a model we validated using electron microscopy and cell-based experiments. This assembly stabilizes K-Ras in its active state and presents composite interfaces to facilitate Raf binding. Guided by existing experimental data, we then positioned C-Raf, the downstream kinase MEK1 and accessory proteins (Galectin-3 and 14-3-3σ) on and around the helical assembly. The resulting Ras-Raf signalosome model offers an explanation for a large body of data on MAPK signaling.
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Affiliation(s)
| | - Zhi-Wei Zhou
- Departments of Biochemistry and Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Chiara Ambrogio
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin, Turin, Italy
| | - Lianbo Li
- Departments of Biochemistry and Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jonas N Kapp
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Chunya Lu
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Respiratory Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Qi Wang
- D. E. Shaw Research, New York, NY, USA
| | | | - Jeffrey J Okoro
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | | | - Xiaochen Bai
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Andreas Plückthun
- Department of Biochemistry, University of Zürich, Zürich, Switzerland
| | - Pasi A Jänne
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
- Belfer Center for Applied Cancer Science, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Kenneth D Westover
- Departments of Biochemistry and Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | - David E Shaw
- D. E. Shaw Research, New York, NY, USA.
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA.
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