Effects of the Oncogenic V664E Mutation on Membrane Insertion, Structure, and Sequence-Dependent Interactions of the Neu Transmembrane Domain in Micelles and Model Membranes: An Integrated

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• 作者：Andrew J. Beevers ; Anthony Nash ; Martha Salazar-Cancino ; David J. Scott ; Rebecca Notman ; Ann M. Dixon
• 刊名：Biochemistry
• 出版年：2012
• 出版时间：March 27, 2012
• 年：2012
• 卷：51
• 期：12
• 页码：2558-2568
• 全文大小：452K
• 年卷期：v.51,no.12(March 27, 2012)
• ISSN：1520-4995

文摘

Receptor tyrosine kinases bind ligands such as cytokines, hormones, and growth factors and regulate key cellular processes, including cell division. They are also implicated in the development of many types of cancer. One such example is the Neu receptor tyrosine kinase found in rats (homologous to the human ErbB2 protein), which can undergo a valine to glutamic acid (V₆₆₄E) mutation at the center of its 伪-helical transmembrane domain. This substitution results in receptor activation and oncogenesis. The molecular basis of this dramatic change in behavior upon introduction of the V₆₆₄E mutation has been difficult to pin down, with conflicting results reported in the literature. Here we report the first quantitative, thermodynamic analysis of dimerization and biophysical characterization of the rat Neu transmembrane domain and several mutants in a range of chemical environments. These data have allowed us to identify the effects of the V₆₆₄E mutation in the isolated TM domain with respect to protein鈥損rotein and protein鈥搇ipid interactions, membrane insertion, and secondary structure. We also report the results from a 100 ns atomistic molecular dynamics simulation of the Neu transmembrane domain in a model membrane bilayer (dipalmitoylphosphatidylcholine). The results from simulation and experiment are in close agreement and suggest that, in the model systems investigated, the V₆₆₄E mutation leads to a weakening of the TM dimer and a change in sequence-dependent interactions. These results are contrary to recent results obtained in mammalian membranes, and the implications of this are discussed.