Bocharov Eduard V, Sobol Alexander G, Pavlov Konstantin V, Korzhnev Dmitry M, Jaravine Victor A, Gudkov Anatoly T, Arseniev Alexander S
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya, 16/10, Moscow 117997, Russia.
J Biol Chem. 2004 Apr 23;279(17):17697-706. doi: 10.1074/jbc.M313384200. Epub 2004 Feb 11.
Based on the (1)H-(15)N NMR spectroscopy data, the three-dimensional structure and internal dynamic properties of ribosomal protein L7 from Escherichia coli were derived. The structure of L7 dimer in solution can be described as a set of three distinct domains, tumbling rather independently and linked via flexible hinge regions. The dimeric N-terminal domain (residues 1-32) consists of two antiparallel alpha-alpha-hairpins forming a symmetrical four-helical bundle, whereas the two identical C-terminal domains (residues 52-120) adopt a compact alpha/beta-fold. There is an indirect evidence of the existence of transitory helical structures at least in the first part (residues 33-43) of the hinge region. Combining structural data for the ribosomal protein L7/L12 from NMR spectroscopy and x-ray crystallography, it was suggested that its hinge region acts as a molecular switch, initiating "ratchet-like" motions of the L7/L12 stalk with respect to the ribosomal surface in response to elongation factor binding and GTP hydrolysis. This hypothesis allows an explanation of events observed during the translation cycle and provides useful insights into the role of protein L7/L12 in the functioning of the ribosome.
基于氢-氮核磁共振波谱数据，推导了来自大肠杆菌的核糖体蛋白L7的三维结构和内部动力学性质。溶液中L7二聚体的结构可描述为一组三个不同的结构域，它们相当独立地翻滚，并通过柔性铰链区相连。二聚体的N端结构域（第1至32位氨基酸残基）由两个反平行的α-α-发夹结构组成，形成一个对称的四螺旋束，而两个相同的C端结构域（第52至120位氨基酸残基）则呈现出紧密的α/β折叠结构。至少在铰链区的第一部分（第33至43位氨基酸残基）存在瞬时螺旋结构有间接证据。结合来自核磁共振波谱和X射线晶体学的核糖体蛋白L7/L12的结构数据，有人提出其铰链区充当分子开关，响应延伸因子结合和GTP水解，启动L7/L12柄相对于核糖体表面的“棘轮样”运动。这一假设能够解释翻译循环中观察到的事件，并为蛋白L7/L12在核糖体功能中的作用提供有用的见解。
