Duplication and concerted evolution of MiSp-encoding genes underlie the material properties of minor ampullate silks of cobweb weaving spiders

BMC Evolutionary Biology

Research Article

Jessica E. Garb¹  Evelyn E. Schwager¹  Cheryl Y. Hayashi²  Matthew A. Collin²  Sandra M. Correa-Garhwal²  Elizabeth R. Brassfield³  Nadia A. Ayoub³  Jannelle M. Vienneau-Hathaway³  Amanda Kelly Lane³  Thomas H. Clarke⁴ 

[1] Department of Biological Sciences, University of Massachusetts, Lowell, MA, USA;Department of Biology, University of California, Riverside, CA, USA;Department of Biology, Washington and Lee University, Lexington, VA, USA;Department of Biology, Washington and Lee University, Lexington, VA, USA;Department of Biology, University of California, Riverside, CA, USA;

关键词: Theridiidae;    Latrodectus;    Steatoda;    Silk glands;    Gene expression;    Silk proteins;    Spidroin gene family;   

DOI  :  10.1186/s12862-017-0927-x

 received in 2016-08-24, accepted in 2017-02-24,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundOrb-web weaving spiders and their relatives use multiple types of task-specific silks. The majority of spider silk studies have focused on the ultra-tough dragline silk synthesized in major ampullate glands, but other silk types have impressive material properties. For instance, minor ampullate silks of orb-web weaving spiders are as tough as draglines, due to their higher extensibility despite lower strength. Differences in material properties between silk types result from differences in their component proteins, particularly members of the spidroin (spider fibroin) gene family. However, the extent to which variation in material properties within a single silk type can be explained by variation in spidroin sequences is unknown. Here, we compare the minor ampullate spidroins (MiSp) of orb-weavers and cobweb weavers. Orb-web weavers use minor ampullate silk to form the auxiliary spiral of the orb-web while cobweb weavers use it to wrap prey, suggesting that selection pressures on minor ampullate spidroins (MiSp) may differ between the two groups.ResultsWe report complete or nearly complete MiSp sequences from five cobweb weaving spider species and measure material properties of minor ampullate silks in a subset of these species. We also compare MiSp sequences and silk properties of our cobweb weavers to published data for orb-web weavers. We demonstrate that all our cobweb weavers possess multiple MiSp loci and that one locus is more highly expressed in at least two species. We also find that the proportion of β-spiral-forming amino acid motifs in MiSp positively correlates with minor ampullate silk extensibility across orb-web and cobweb weavers.ConclusionsMiSp sequences vary dramatically within and among spider species, and have likely been subject to multiple rounds of gene duplication and concerted evolution, which have contributed to the diverse material properties of minor ampullate silks. Our sequences also provide templates for recombinant silk proteins with tailored properties.

【 授权许可】

CC BY   
© The Author(s). 2017