Structural and functional characteristics of xenavidin, the first frog avidin from Xenopus tropicalis
Structural and functional characteristics of xenavidin, the first frog avidin from Xenopus tropicalis
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DOI：
10.1186/1472-6807-9-63
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发表时间：
2009-09-29
影响因子：
--
通讯作者：
Nordlund, Henri R.
中科院分区：
文献类型：
--
作者：
Maatta, Juha A. E.;Helppolainen, Satu H.;Nordlund, Henri R.
背景：Avidins是一种具有极高的配体结合亲和力的蛋白质，这一特性在生命科学的广泛应用中被使用。尽管对生物技术和纳米技术很有用，但亲和素的生物学功能还没有被完全理解。在这里，我们从结构和功能上鉴定了一种新的亲和素，命名为Xenavidin，据我们所知，它是第一个从青蛙中报道的亲和素。结果：Xenavidin是从热带非洲爪哇EST序列数据库中鉴定出来的，并利用杆状病毒表达系统在昆虫细胞中表达。凝胶过滤分析表明，重组Xenavidin为同源四聚体。用Biacore传感器分析、荧光标记生物素和放射性生物素评价了Xenavidin的生物素结合特性--它与生物素的结合亲和力很高，但不如鸡的亲和素和细菌的链霉亲和素紧密。X射线结晶学显示配体结合部位周围的结构保守，而一些环区有独特的设计。结构水分子在入口处和/或配体结合部位的位置可能在决定Xenaviine的生物素结合特性方面起作用。结论：这里报道的新数据提供了关于生物素结合的生化和结构上重要的决定因素的信息。这些信息可能有助于发现生物技术的新工具。
Background: Avidins are proteins with extraordinarily high ligand-binding affinity, a property which is used in a wide array of life science applications. Even though useful for biotechnology and nanotechnology, the biological function of avidins is not fully understood. Here we structurally and functionally characterise a novel avidin named xenavidin, which is to our knowledge the first reported avidin from a frog.Results: Xenavidin was identified from an EST sequence database for Xenopus tropicalis and produced in insect cells using a baculovirus expression system. The recombinant xenavidin was found to be homotetrameric based on gel filtration analysis. Biacore sensor analysis, fluorescently labelled biotin and radioactive biotin were used to evaluate the biotin-binding properties of xenavidin - it binds biotin with high affinity though less tightly than do chicken avidin and bacterial streptavidin. X-ray crystallography revealed structural conservation around the ligand-binding site, while some of the loop regions have a unique design. The location of structural water molecules at the entrance and/or within the ligand-binding site may have a role in determining the characteristic biotin-binding properties of xenavidin.Conclusion: The novel data reported here provide information about the biochemically and structurally important determinants of biotin binding. This information may facilitate the discovery of novel tools for biotechnology.