School of Life Sciences, University of Nottingham, Nottingham, NG7 2RD, UK.
Centre for Biomolecular Sciences, School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, UK.
Heredity (Edinb). 2018 Jun;120(6):574-580. doi: 10.1038/s41437-018-0050-9. Epub 2018 Feb 15.
Spiders produce multiple silks with different physical properties that allow them to occupy a diverse range of ecological niches, including the underwater environment. Despite this functional diversity, past molecular analyses show a high degree of amino acid sequence similarity between C-terminal regions of silk genes that appear to be independent of the physical properties of the resulting silks; instead, this domain is crucial to the formation of silk fibers. Here, we present an analysis of the C-terminal domain of all known types of spider silk and include silk sequences from the spider Argyroneta aquatica, which spins the majority of its silk underwater. Our work indicates that spiders have retained a highly conserved mechanism of silk assembly, despite the extraordinary diversification of species, silk types and applications of silk over 350 million years. Sequence analysis of the silk C-terminal domain across the entire gene family shows the conservation of two uncommon amino acids that are implicated in the formation of a salt bridge, a functional bond essential to protein assembly. This conservation extends to the novel sequences isolated from A. aquatica. This finding is relevant to research regarding the artificial synthesis of spider silk, suggesting that synthesis of all silk types will be possible using a single process.
蜘蛛能产生多种具有不同物理性质的丝，这使它们能够占据包括水下环境在内的各种生态位。尽管具有这种功能多样性，但过去的分子分析表明，丝基因 C 末端区域的氨基酸序列高度相似，这些区域似乎与丝的物理性质无关；相反，这个结构域对丝纤维的形成至关重要。在这里，我们分析了所有已知类型蜘蛛丝的 C 末端结构域，并包括了来自水生蜘蛛 Argyroneta aquatica 的丝序列，该蜘蛛在水下吐出大部分丝。我们的工作表明，尽管蜘蛛物种、丝类型和丝的应用已经经历了 3.5 亿多年的非凡多样化，但它们仍然保留了一种高度保守的丝组装机制。对整个基因家族的丝 C 末端结构域进行序列分析表明，两种不常见的氨基酸得到了保守，这两种氨基酸参与形成盐桥，盐桥是蛋白质组装所必需的功能键。这种保守性延伸到从 A. aquatica 中分离出来的新序列。这一发现与关于人工合成蜘蛛丝的研究有关，这表明使用单一工艺就有可能合成所有类型的丝。
