Perica Tina, Kondo Yasushi, Tiwari Sandhya P, McLaughlin Stephen H, Kemplen Katherine R, Zhang Xiuwei, Steward Annette, Reuter Nathalie, Clarke Jane, Teichmann Sarah A
European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK. Medical Research Council (MRC) Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
Medical Research Council (MRC) Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK.
Science. 2014 Dec 19;346(6216):1254346. doi: 10.1126/science.1254346.
Evolution and design of protein complexes are almost always viewed through the lens of amino acid mutations at protein interfaces. We showed previously that residues not involved in the physical interaction between proteins make important contributions to oligomerization by acting indirectly or allosterically. In this work, we sought to investigate the mechanism by which allosteric mutations act, using the example of the PyrR family of pyrimidine operon attenuators. In this family, a perfectly sequence-conserved helix that forms a tetrameric interface is exposed as solvent-accessible surface in dimeric orthologs. This means that mutations must be acting from a distance to destabilize the interface. We identified 11 key mutations controlling oligomeric state, all distant from the interfaces and outside ligand-binding pockets. Finally, we show that the key mutations introduce conformational changes equivalent to the conformational shift between the free versus nucleotide-bound conformations of the proteins.
蛋白质复合物的进化和设计几乎总是通过蛋白质界面处氨基酸突变的视角来审视。我们之前表明，不参与蛋白质间物理相互作用的残基通过间接或变构作用对寡聚化做出重要贡献。在这项工作中，我们以嘧啶操纵子衰减子的PyrR家族为例，试图研究变构突变起作用的机制。在这个家族中，形成四聚体界面的一个序列完全保守的螺旋在二聚体直系同源物中作为溶剂可及表面暴露出来。这意味着突变必定是从远处起作用以使界面不稳定。我们鉴定出11个控制寡聚状态的关键突变，它们均远离界面且在配体结合口袋之外。最后，我们表明关键突变引入的构象变化等同于蛋白质在游离态与核苷酸结合态之间的构象转变。
