Additional file 1: of Duplication and concerted evolution of MiSp-encoding genes underlie the material properties of minor ampullate silks of cobweb weaving spiders (original) (raw)
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BMC evolutionary biology, 2017
Orb-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 mi...
Intragenic homogenization and multiple copies of prey-wrapping silk genes in Argiope garden spiders
BMC Evolutionary Biology, 2014
Background: Spider silks are spectacular examples of phenotypic diversity arising from adaptive molecular evolution. An individual spider can produce an array of specialized silks, with the majority of constituent silk proteins encoded by members of the spidroin gene family. Spidroins are dominated by tandem repeats flanked by short, non-repetitive N-and C-terminal coding regions. The remarkable mechanical properties of spider silks have been largely attributed to the repeat sequences. However, the molecular evolutionary processes acting on spidroin terminal and repetitive regions remain unclear due to a paucity of complete gene sequences and sampling of genetic variation among individuals. To better understand spider silk evolution, we characterize a complete aciniform spidroin gene from an Argiope orb-weaving spider and survey aciniform gene fragments from congeneric individuals.
Inter-specific sequence conservation and intra-individual sequence variation in a spider silk gene
International Journal of Biological Macromolecules, 2004
Currently, studies on major ampullate spidroin 1 (MaSp1) genes of non-orb weaving spiders are few, and it is not clear whether genes of these organisms exhibit the same characteristics as those of orb-weavers. In addition, many studies have proposed that MaSp1 might be a single gene with allelic variants, but supporting evidence is still lacking. In this study, we compared partial DNA and amino acid sequences of MaSp1 cloned from different spider guilds. We also cloned partial MaSp1 sequences from genomic DNA and cDNA of the same individuals of spiders using the same primer combination to see if different molecular forms existed. In the repetitive region of partial MaSp1 sequences obtained, GGX, GA and poly-A motifs were present in all Araneomorphae and Mygalomorpae species examined. An extreme similarity in MaSp1 non-repetitive portions was found in sequences of ecribellate, cribellate and Mygalomorphae web-builders and such a result suggested that this sequence might exhibit an important function. A comparison of sequences amplified from the same individual showed that substitutions in amino acids occurred in both repetitive and non-repetitive regions, with a much higher variation in the former. These results suggest that the MaSp1 of Araneomorphae spiders exhibits several forms in an individual spider and it might be either a multiple gene or a single gene with a multiple exon/intron organization.
Meta-analysis reveals materiomic relationships in major ampullate silk across the spider phylogeny
Journal of The Royal Society Interface, 2020
Spider major ampullate (MA) silk, with its combination of strength and extensibility, outperforms any synthetic equivalents. There is thus much interest in understanding its underlying materiome. While the expression of the different silk proteins (spidroins) appears an integral component of silk performance, our understanding of the nature of the relationship between the spidroins, their constituent amino acids and MA silk mechanics is ambiguous. To provide clarity on these relationships across spider species, we performed a meta-analysis using phylogenetic comparative methods. These showed that glycine and proline, both of which are indicators of differential spidroin expression, had effects on MA silk mechanics across the phylogeny. We also found serine to correlate with silk mechanics, probably via its presence within the carboxyl and amino-terminal domains of the spidroins. From our analyses, we concluded that the spidroin expression shifts across the phylogeny from predominant...
Protein Science, 1998
Spider minor ampullate silk is a strong non-elastic deformably stretchable silk used in web formation. This silk from Nephila clavipes is composed of two proteins, MiSp 1 and 2, whose transcripts are 9.5 and 7.5 kb, respectively, as determined by northern blots. Both MiSp proteins are organized into a predominantly repetitive region and a small nonrepetitive carboxy terminal region. These highly repetitive regions are composed mainly of glycine and alanine, but also contain tyrosine, glutamine, and arginine. The sequences are mainly GGX and GA repeats. The repetitive regions are interrupted by nonrepetitive serine-rich spacer regions. Although the sequences of the spacer regions differ from the repetitive regions, sequences of the spacers from different regions of the proteins are nearly identical. The sequence differences between major and minor ampullate silks may explain the differing mechanical properties of the fibers.
Web building and silk properties functionally covary among species of wolf spider
Journal of evolutionary biology, 2018
While phylogenetic studies have shown covariation between the properties of spider major ampullate (MA) silk and web building, both spider webs and silks are highly plastic so we cannot be sure whether these traits functionally co-vary or just vary across environments that the spiders occupy. Since MaSp2-like proteins provide MA silk with greater extensibility, their presence is considered necessary for spider webs to effectively capture prey. Wolf spiders (Lycosidae) are predominantly non-web building, but a select few species build webs. We accordingly collected MA silk from two web building and six non-web building species found in semi-rural ecosystems in Uruguay to test whether the presence of MaSp2-like proteins (indicated by amino acid composition), silk mechanical properties, and silk nanostructures, were associated with web building across the group. The web building and non-web building species were from disparate subfamilies so we estimated a genetic phylogeny to perform ...
SPIDER DRAGLINE SILK: CORRELATED AND MOSAIC EVOLUTION IN HIGH-PERFORMANCE BIOLOGICAL MATERIALS
Evolution, 2006
The evolution of biological materials is a critical, yet poorly understood, component in the generation of biodiversity. For example, the diversification of spiders is correlated with evolutionary changes in the way they use silk, and the material properties of these fibers, such as strength, toughness, extensibility, and stiffness, have profound effects on ecological function. Here, we examine the evolution of the material properties of dragline silk across a phylogenetically diverse sample of species in the Araneomorphae (true spiders). The silks we studied are generally stronger than other biological materials and tougher than most biological or man-made fibers, but their material properties are highly variable; for example, strength and toughness vary more than fourfold among the 21 species we investigated. Furthermore, associations between different properties are complex. Some traits, such as strength and extensibility, seem to evolve independently and show no evidence of correlation or trade-off across species, even though trade-offs between these properties are observed within species. Material properties retain different levels of phylogenetic signal, suggesting that traits such as extensibility and toughness may be subject to different types or intensities of selection in several spider lineages. The picture that emerges is complex, with a mosaic pattern of trait evolution producing a diverse set of materials across spider species. These results show that the properties of biological materials are the target of selection, and that these changes can produce evolutionarily and ecologically important diversity.
Molecular Biology and Evolution, 2004
Araneoid spiders use specialized abdominal glands to produce up to seven different proteinbased silks/glues that have diverse physical properties. The fibroin sequences that encode aciniform fibers (wrapping silk) and the mechanical properties of these fibers have not been characterized previously. In order to gain a better understanding of the molecular radiation of spider silk fibroin genes, cDNA libraries derived from aciniform glands of the banded garden spider, Argiope trifasciata, were constructed, and unique silk transcripts were sequenced. There was evidence for a single silk fibroin gene that was expressed in the aciniform glands, and the inferred amino acid composition of the novel fibroin closely matched the amino acid contents of these glands. The inferred protein, aciniform spidroin 1 (AcSp1), is composed of highly homogenized repeats that are 200 amino acids in length. The long stretches of poly-alanine and glycine-alanine subrepeats, that are thought to account for the crystalline regions of minor ampullate and major ampullate fibers, are very poorly represented in AcSp1. The AcSp1 repeat unit is iterated minimally fourteen times and does not display substantial sequence similarity to any previously described genes or proteins. Database searches, however, showed that the non-repetitive carboxy-terminus contains stretches of matches to known spider fibroin sequences, suggesting that the AcSp1 gene is a highly divergent member of the spider silk gene family. In phylogenetic analyses of carboxy-terminal sequences from araneid spiders, the aciniform sequence did not group strongly with clusters of fibroins from the flagelliform, minor ampullate, or major ampullate silk glands. Comparisons of stress/strain curves for major ampullate, minor ampullate, and aciniform silks from Argiope trifasciata showed significant differences in ultimate strength, extensibility, and toughness. Remarkably, the toughness of aciniform silk was 50% greater than the highest values typically recorded for major ampullate silk. These differences in performance, in combination with the radical divergence at the sequence level among fibroin paralogues, suggest a possible linkage between silk fibroin sequences and performance that should be explored in future structural/functional studies of aciniform silk.
Chromosome Mapping of Dragline Silk Genes in the Genomes of Widow Spiders (Araneae, Theridiidae)
PLoS ONE, 2010
With its incredible strength and toughness, spider dragline silk is widely lauded for its impressive material properties. Dragline silk is composed of two structural proteins, MaSp1 and MaSp2, which are encoded by members of the spidroin gene family. While previous studies have characterized the genes that encode the constituent proteins of spider silks, nothing is known about the physical location of these genes. We determined karyotypes and sex chromosome organization for the widow spiders, Latrodectus hesperus and L. geometricus (Araneae, Theridiidae). We then used fluorescence in situ hybridization to map the genomic locations of the genes for the silk proteins that compose the remarkable spider dragline. These genes included three loci for the MaSp1 protein and the single locus for the MaSp2 protein. In addition, we mapped a MaSp1 pseudogene. All the MaSp1 gene copies and pseudogene localized to a single chromosomal region while MaSp2 was located on a different chromosome of L. hesperus. Using probes derived from L. hesperus, we comparatively mapped all three MaSp1 loci to a single region of a L. geometricus chromosome. As with L. hesperus, MaSp2 was found on a separate L. geometricus chromosome, thus again unlinked to the MaSp1 loci. These results indicate orthology of the corresponding chromosomal regions in the two widow genomes. Moreover, the occurrence of multiple MaSp1 loci in a conserved gene cluster across species suggests that MaSp1 proliferated by tandem duplication in a common ancestor of L. geometricus and L. hesperus. Unequal crossover events during recombination could have given rise to the gene copies and could also maintain sequence similarity among gene copies over time. Further comparative mapping with taxa of increasing divergence from Latrodectus will pinpoint when the MaSp1 duplication events occurred and the phylogenetic distribution of silk gene linkage patterns.