Department of Biological Sciences, UNC Charlotte, 9201 University City Blvd, NC 28223, USA.
Department of Biological Sciences, University of Maryland, Baltimore County, 1000 Hilltop Circle, MD 21250, USA.
Integr Comp Biol. 2021 Oct 14;61(4):1450-1458. doi: 10.1093/icb/icab048.
Many species of spider use a modified silk adhesive, called aggregate glue, to aid in prey capture. Aggregate spidroins (spider fibroins) are modified members of the spider silk family; however, they are not spun into fibers as are their solid silk relatives. The genes that encode for aggregate spidroins are the largest of the known spidroin genes and are similarly highly repetitive. In this study, we used long read sequencing to discover the aggregate spidroin genes of the toad-like bolas spider, Mastophora phrynosoma, which employs the glue in a unique way, using only a single, large droplet to capture moths. While Aggregate Spidroin 1 (AgSp1) remains incomplete, AgSp2 is more than an extraordinary 62 kb of coding sequence, 20 kb longer than the longest spidroin on record. The structure of repeats from both aggregate silk proteins follows a similar pattern seen in other species, with the same strict conservation of amino acid residue number for much of the repeats' lengths. Interestingly, AgSp2 lacks the elevated number and groupings of glutamine residues seen in the other reported AgSp2 of a classic orb weaving species. The role of gene length in glue functionality remains a mystery, and thus discovering length differences across species will allow understanding and harnessing of this attribute for the next generation of bio-inspired adhesives.
许多蜘蛛物种使用一种改良的丝胶，称为聚集胶，以帮助捕捉猎物。聚集丝蛋白（蜘蛛丝纤维蛋白）是蜘蛛丝家族的改良成员；然而，它们不像其固体丝纤维的近亲那样被纺成纤维。编码聚集丝蛋白的基因是已知丝蛋白基因中最大的，同样具有高度的重复。在这项研究中，我们使用长读测序技术发现了蟾蛛状球蛛（Mastophora phrynosoma）的聚集丝蛋白基因，这种蜘蛛以独特的方式使用这种胶，只用一滴大的胶滴来捕捉飞蛾。虽然 Aggregate Spidroin 1（AgSp1）仍然不完整，但 AgSp2 的编码序列超过了 62kb，比记录中最长的丝蛋白长 20kb。两种聚集丝蛋白的重复结构遵循与其他物种相似的模式，大部分重复长度的氨基酸残基数量保持严格保守。有趣的是，AgSp2 缺乏在经典圆形织网物种中报道的其他 AgSp2 中看到的大量和分组的谷氨酰胺残基。基因长度在胶功能中的作用仍然是个谜，因此发现不同物种之间的长度差异将有助于理解和利用这一特性，为下一代仿生胶粘剂的发展提供帮助。
