Orb weaver aggregate glue protein composition as a mechanism for rapid evolution of material properties
Orb weaver aggregate glue protein composition as a mechanism for rapid evolution of material properties
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DOI：
10.3389/fevo.2023.1099481
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发表时间：
2023-04-18
影响因子：
3
通讯作者：
Opell, Brent D.
中科院分区：
文献类型：
--
作者：
Ayoub, Nadia A.;DuMez, Lucas;Opell, Brent D.
蜘蛛总科的圆网蜘蛛和蛛网蜘蛛的区别在于它们能够在特化的聚集丝腺中产生化学粘性的水胶。聚合胶是一种对环境敏感的材料，它已经进化到在蜘蛛觅食的湿度周围表现最佳。蛋白质成分及其翻译后修饰赋予胶水粘性，但这些蛋白质的身份尚未被描述为圆网编织者。方法使用生物力学，基因表达数据和蛋白质组学，我们的特点是胶水的物理性质和分子组成的两个同源物，生活在不同的环境中，Argiope argentata（干燥的美国西南部）和Argiope trifasciata（潮湿的美国东南部）。结果A. argentata比A. trifasciata，并且具有比例较小的粘弹性蛋白质核心，随着湿度增加，其包含较小百分比的吸收水。Argiope argentata蛋白质核心比A. trifasciata蛋白核心。每个种的胶包含30个相似的聚集表达蛋白，其中大部分是同源的两个物种之间，具有高度的序列同一性。然而，每个同源组的基因家族成员的相对贡献和数量不同。例如，聚集的蛛丝蛋白（AgSp 1和AgSp 2）占A中检测到的胶成分的近一半。argentata，而A.三带的此外，具有高度负电荷区域的AgSp 1的丰度类似于A中带正电的AgSp 2的2倍。argentata，但与A.三带的作为另一个例子，A. argentata glue包括一个新发现的富含半胱氨酸基因家族的11个成员，而A.三带的讨论半胱氨酸形成二硫键，结合AgSp 1和AgSp 2之间更高的静电相互作用电位，可能有助于A的更大刚度。银胶选择性表达不同的胶蛋白基因和/或以不同速率挤出其产物的能力提供了比单独的序列进化更快的进化材料性质的机制。
IntroductionOrb web and cobweb weaving spiders in the superfamily Araneoidea are distinguished by their ability to make a chemically sticky aqueous glue in specialized aggregate silk glands. Aggregate glue is an environmentally responsive material that has evolved to perform optimally around the humidity at which a spider forages. Protein components and their post-translational modifications confer stickiness to the glue, but the identities of these proteins have not been described for orb web weavers. MethodsUsing biomechanics, gene expression data, and proteomics, we characterized the glue's physical properties and molecular components in two congeners that live in different environments, Argiope argentata (dry southwest US) and Argiope trifasciata (humid southeast US). ResultsThe droplets of A. argentata are less hygroscopic than those of A. trifasciata and have proportionately smaller viscoelastic protein cores, which incorporate a smaller percentage of absorbed water as humidity increases. Argiope argentata protein cores were many times stiffer and tougher than A. trifasciata protein cores. Each species' glue included similar to 30 aggregate-expressed proteins, most of which were homologous between the two species, with high sequence identity. However, the relative contribution and number of gene family members of each homologous group differed. For instance, the aggregate spidroins (AgSp1 and AgSp2) accounted for nearly half of the detected glue composition in A. argentata, but only 38% in A. trifasciata. Additionally, AgSp1, which has highly negatively charged regions, was similar to 2X as abundant as the positively charged AgSp2 in A. argentata, but similar to 3X as abundant in A. trifasciata. As another example, A. argentata glue included 11 members of a newly discovered cysteine-rich gene family, versus 7 members in A. trifasciata. DiscussionCysteines form disulfide bonds that, combined with the higher potential for electrostatic interactions between AgSp1 and AgSp2, could contribute to the greater stiffness of A. argentata glue. The ability to selectively express different glue protein genes and/or to extrude their products at different rates provides a faster mechanism to evolve material properties than sequence evolution alone.