Moore Sean D, Baker Tania A, Sauer Robert T
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Proc Natl Acad Sci U S A. 2008 Aug 19;105(33):11685-90. doi: 10.1073/pnas.0805633105. Epub 2008 Aug 11.
When individual protein components of supramolecular complexes are required for assembly, determining whether they play additional structural or functional roles can be difficult. Removing a protein from the complex after assembly can circumvent this problem. Here, we show that an AAA+ unfoldase/protease can extract an essential assembly protein from the ribosome. Specifically, Mg(2+) depletion allowed ClpXP to remove an ssrA-tagged variant of ribosomal protein L22 from the 50S subunit of E. coli ribosomes without disrupting either the structural integrity or hydrodynamic properties of the modified particle. Forced extraction using AAA+ enzymes and targeted component proteins should be broadly applicable to the study of macromolecular complexes.
当超分子复合物的各个蛋白质组分对组装是必需的时候，确定它们是否发挥额外的结构或功能作用可能会很困难。在组装后从复合物中去除一种蛋白质可以规避这个问题。在这里，我们表明一种AAA+解折叠酶/蛋白酶可以从核糖体中提取一种必需的组装蛋白。具体来说，Mg(2+)的消耗使ClpXP能够从大肠杆菌核糖体的50S亚基中去除核糖体蛋白L22的一个带有ssrA标签的变体，而不会破坏修饰颗粒的结构完整性或流体动力学性质。使用AAA+酶和靶向组分蛋白进行强制提取应该广泛适用于大分子复合物的研究。
