Monteith William B, Cohen Rachel D, Smith Austin E, Guzman-Cisneros Emilio, Pielak Gary J
Departments of Chemistry and.
Departments of Chemistry and Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
Proc Natl Acad Sci U S A. 2015 Feb 10;112(6):1739-42. doi: 10.1073/pnas.1417415112. Epub 2015 Jan 26.
Protein quinary interactions organize the cellular interior and its metabolism. Although the interactions stabilizing secondary, tertiary, and quaternary protein structure are well defined, details about the protein-matrix contacts that comprise quinary structure remain elusive. This gap exists because proteins function in the crowded cellular environment, but are traditionally studied in simple buffered solutions. We use NMR-detected H/D exchange to quantify quinary interactions between the B1 domain of protein G and the cytosol of Escherichia coli. We demonstrate that a surface mutation in this protein is 10-fold more destabilizing in cells than in buffer, a surprising result that firmly establishes the significance of quinary interactions. Remarkably, the energy involved in these interactions can be as large as the energies that stabilize specific protein complexes. These results will drive the critical task of implementing quinary structure into models for understanding the proteome.
蛋白质五元相互作用构建细胞内部结构并调控其新陈代谢。虽然稳定蛋白质二级、三级和四级结构的相互作用已被明确界定，但构成五元结构的蛋白质与基质接触的细节仍不清楚。之所以存在这一差距，是因为蛋白质在拥挤的细胞环境中发挥功能，但传统上是在简单的缓冲溶液中进行研究的。我们利用核磁共振检测的氢/氘交换来量化蛋白质G的B1结构域与大肠杆菌细胞质之间的五元相互作用。我们证明，该蛋白的一个表面突变在细胞中的去稳定作用比在缓冲液中强10倍，这一惊人结果有力地证明了五元相互作用的重要性。值得注意的是，这些相互作用所涉及的能量可与稳定特定蛋白质复合物的能量一样大。这些结果将推动在理解蛋白质组的模型中纳入五元结构这一关键任务。
