Human βB2-Crystallin Forms a Face-en-Face Dimer in Solution: An Integrated NMR and SAXS Study.
Human βB2-Crystallin Forms a Face-en-Face Dimer in Solution: An Integrated NMR and SAXS Study.
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人 βB2-晶状体蛋白在溶液中形成面对面二聚体：一项综合 NMR 和 SAXS 研究。
DOI：
10.1016/j.str.2017.02.001
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发表时间：
2017-03-07
期刊：
影响因子：
--
通讯作者：
Gronenborn AM
中科院分区：
文献类型：
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作者：
Xi Z;Whitley MJ;Gronenborn AM
βγ-晶状体蛋白是长寿命的眼睛透镜蛋白，其对于透镜透明度和屈光力是至关重要的。每个βγ-晶状体蛋白包含两个同源结构域，其通过短接头连接。γ-晶状体蛋白是单体，而β-晶状体蛋白结晶为二聚体和多聚体。在晶体中，人βB2-晶状体蛋白是结构域交换的二聚体，而N-末端截短的βB1-晶状体蛋白形成面-面-面二聚体。结合和整合来自溶液中全长和末端截短的人βB2-晶状体蛋白的多角度光散射、NMR和小角X射线散射的数据，我们表明这两种βB2-晶状体蛋白是二聚体，具有C2对称性，并且比结构域交换的二聚体更紧凑。重要的是，没有检测到与结构域交换相容的分子间顺磁弛豫增强效应。我们的集体实验结果明确表明，在溶液中，人βB2-晶状体蛋白不是结构域交换的，并且表现出与截短的βB1-晶状体蛋白的晶体结构相似的面-面-面二聚体结构。
βγ-crystallins are long-lived eye lens proteins that are crucial for lens transparency and refractive power. Each βγ-crystallin comprises two homologous domains, which are connected by a short linker. γ-crystallins are monomeric, while β-crystallins crystallize as dimers and multimers. In the crystal, human βB2-crystallin is a domain-swapped dimer, while the N-terminally truncated βB1-crystallin forms a face-en-face dimer. Combining and integrating data from multi-angle light scattering, NMR and small angle X-ray scattering of full-length and terminally truncated human βB2-crystallin in solution, we show that both these βB2-crystallin proteins are dimeric, possess C2 symmetry, and are more compact than domain-swapped dimers. Importantly, no intermolecular paramagnetic relaxation enhancement effects compatible with domain-swapping were detected. Our collective experimental results unambiguously demonstrate that, in solution, human βB2-crystallin is not domain-swapped and exhibits a face-en-face dimer structure similar to the crystal structure of truncated βB1-crystallin.