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Ancient properties of spider silks revealed by the complete gene sequence of the prey-wrapping silk protein (AcSp1).
Mol Biol Evol. 2013 Mar; 30(3):589-601.MB

Abstract

Spider silk fibers have impressive mechanical properties and are primarily composed of highly repetitive structural proteins (termed spidroins) encoded by a single gene family. Most characterized spidroin genes are incompletely known because of their extreme size (typically >9 kb) and repetitiveness, limiting understanding of the evolutionary processes that gave rise to their unusual gene architectures. The only complete spidroin genes characterized thus far form the dragline in the Western black widow, Latrodectus hesperus. Here, we describe the first complete gene sequence encoding the aciniform spidroin AcSp1, the primary component of spider prey-wrapping fibers. L. hesperus AcSp1 contains a single enormous (∼19 kb) exon. The AcSp1 repeat sequence is exceptionally conserved between two widow species (∼94% identity) and between widows and distantly related orb-weavers (∼30% identity), consistent with a history of strong purifying selection on its amino acid sequence. Furthermore, the 16 repeats (each 371-375 amino acids long) found in black widow AcSp1 are, on average, >99% identical at the nucleotide level. A combination of stabilizing selection on amino acid sequence, selection on silent sites, and intragenic recombination likely explains the extreme homogenization of AcSp1 repeats. In addition, phylogenetic analyses of spidroin paralogs support a gene duplication event occurring concomitantly with specialization of the aciniform glands and the tubuliform glands, which synthesize egg-case silk. With repeats that are dramatically different in length and amino acid composition from dragline spidroins, our L. hesperus AcSp1 expands the knowledge base for developing silk-based biomimetic technologies.

Authors+Show Affiliations

Department of Biology, Washington and Lee University, USA. ayoubn@wlu.eduNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

23155003

Citation

Ayoub, Nadia A., et al. "Ancient Properties of Spider Silks Revealed By the Complete Gene Sequence of the Prey-wrapping Silk Protein (AcSp1)." Molecular Biology and Evolution, vol. 30, no. 3, 2013, pp. 589-601.
Ayoub NA, Garb JE, Kuelbs A, et al. Ancient properties of spider silks revealed by the complete gene sequence of the prey-wrapping silk protein (AcSp1). Mol Biol Evol. 2013;30(3):589-601.
Ayoub, N. A., Garb, J. E., Kuelbs, A., & Hayashi, C. Y. (2013). Ancient properties of spider silks revealed by the complete gene sequence of the prey-wrapping silk protein (AcSp1). Molecular Biology and Evolution, 30(3), 589-601. https://doi.org/10.1093/molbev/mss254
Ayoub NA, et al. Ancient Properties of Spider Silks Revealed By the Complete Gene Sequence of the Prey-wrapping Silk Protein (AcSp1). Mol Biol Evol. 2013;30(3):589-601. PubMed PMID: 23155003.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ancient properties of spider silks revealed by the complete gene sequence of the prey-wrapping silk protein (AcSp1). AU - Ayoub,Nadia A, AU - Garb,Jessica E, AU - Kuelbs,Amanda, AU - Hayashi,Cheryl Y, Y1 - 2012/11/15/ PY - 2012/11/17/entrez PY - 2012/11/17/pubmed PY - 2013/7/17/medline SP - 589 EP - 601 JF - Molecular biology and evolution JO - Mol. Biol. Evol. VL - 30 IS - 3 N2 - Spider silk fibers have impressive mechanical properties and are primarily composed of highly repetitive structural proteins (termed spidroins) encoded by a single gene family. Most characterized spidroin genes are incompletely known because of their extreme size (typically >9 kb) and repetitiveness, limiting understanding of the evolutionary processes that gave rise to their unusual gene architectures. The only complete spidroin genes characterized thus far form the dragline in the Western black widow, Latrodectus hesperus. Here, we describe the first complete gene sequence encoding the aciniform spidroin AcSp1, the primary component of spider prey-wrapping fibers. L. hesperus AcSp1 contains a single enormous (∼19 kb) exon. The AcSp1 repeat sequence is exceptionally conserved between two widow species (∼94% identity) and between widows and distantly related orb-weavers (∼30% identity), consistent with a history of strong purifying selection on its amino acid sequence. Furthermore, the 16 repeats (each 371-375 amino acids long) found in black widow AcSp1 are, on average, >99% identical at the nucleotide level. A combination of stabilizing selection on amino acid sequence, selection on silent sites, and intragenic recombination likely explains the extreme homogenization of AcSp1 repeats. In addition, phylogenetic analyses of spidroin paralogs support a gene duplication event occurring concomitantly with specialization of the aciniform glands and the tubuliform glands, which synthesize egg-case silk. With repeats that are dramatically different in length and amino acid composition from dragline spidroins, our L. hesperus AcSp1 expands the knowledge base for developing silk-based biomimetic technologies. SN - 1537-1719 UR - https://www.unboundmedicine.com/medline/citation/23155003/Ancient_properties_of_spider_silks_revealed_by_the_complete_gene_sequence_of_the_prey_wrapping_silk_protein__AcSp1__ L2 - https://academic.oup.com/mbe/article-lookup/doi/10.1093/molbev/mss254 DB - PRIME DP - Unbound Medicine ER -