文章基本信息

标题：Natural hybrid silica/protein superstructure at atomic resolution
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作者：Stefan Görlich ; Abisheik John Samuel ; Richard Johannes Best 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2020
卷号：117
期号：49
页码：31088-31093
DOI：10.1073/pnas.2019140117
出版社：The National Academy of Sciences of the United States of America
摘要：Formation of highly symmetric skeletal elements in demosponges, called spicules, follows a unique biomineralization mechanism in which polycondensation of an inherently disordered amorphous silica is guided by a highly ordered proteinaceous scaffold, the axial filament. The enzymatically active proteins, silicateins, are assembled into a slender hybrid silica/protein crystalline superstructure that directs the morphogenesis of the spicules. Furthermore, silicateins are known to catalyze the formation of a large variety of other technologically relevant organic and inorganic materials. However, despite the biological and biotechnological importance of this macromolecule, its tertiary structure was never determined. Here we report the atomic structure of silicatein and the entire mineral/organic hybrid assembly with a resolution of 2.4 Å. In this work, the serial X-ray crystallography method was successfully adopted to probe the 2-µm-thick filaments in situ, being embedded inside the skeletal elements. In combination with imaging and chemical analysis using high-resolution transmission electron microscopy, we provide detailed information on the enzymatic activity of silicatein, its crystallization, and the emergence of a functional three-dimensional silica/protein superstructure in vivo. Ultimately, we describe a naturally occurring mineral/protein crystalline assembly at atomic resolution.
关键词：biomineralization ; sponges ; protein crystallography ; silica