Analysis of repetitive amino acid motifs reveals the essential features of spider dragline silk proteins

Abstract

The extraordinary mechanical properties of spider dragline silk are dependent on the highly repetitive sequences of the component proteins, major ampullate spidroin 1 and 2 (MaSp2 and MaSp2). MaSp sequences are dominated by repetitive modules composed of short amino acid motifs; however, the patterns of motif conservation through evolution and their relevance to silk characteristics are not well understood. We performed a systematic analysis of MaSp sequences encompassing infraorder Araneomorphae based on the conservation of explicitly defined motifs, with the aim of elucidating the essential elements of MaSp1 and MaSp2. The results show that the GGY motif is nearly ubiquitous in the two types of MaSp, while MaSp2 is invariably associated with GP and di-glutamine (QQ) motifs. Further analysis revealed an extended MaSp2 consensus sequence in family Araneidae, with implications for the classification of the archetypal spidroins ADF3 and ADF4. Additionally, the analysis of RNA-seq data showed the expression of a set of distinct MaSp-like variants in genus Tetragnatha. Finally, an apparent association was uncovered between web architecture and the abundance of GP, QQ, and GGY motifs in MaSp2, which suggests a co-expansion of these motifs in response to the evolution of spiders' prey capture strategy.

Chemoenzymatic synthesis of polypeptides consisting of periodic di- and tri-peptide motifs similar to elastin

“…This was due to the bent structure of the proline units in poly (GlyProGly), as seen in the amorphous sequence of spider silk proteins showing an elastic nature. 8 The CD spectra of poly (GlyProGly-co-ValGly) and poly(ValProGly-co-ValGly) also showed a negative Cotton effect. Poly(GlyProGly-co-ValGly) adopted more β-strand structure than poly(GlyProGly).…”

“…6,7 Structural proteins obtain their mechanical properties from certain important amino acids, such as proline in spider silk, collagen, and elastin. Proline exists in repetitive short peptide motifs in these structural proteins, such as glycine-proline-glycine (GlyProGly), in the major ampullate spidroin (MaSp) protein of spider silk 8 and glycine-proline-hydroxyproline (GlyProHyp) in collagen. 9 On the other hand, elastin contains valine-proline-glycine-valine-glycine (ValProGlyValGly) in its hydrophobic region, and its high elastic properties arise from the tandem sequence of ValProGlyValGly.…”

Novel In Silico Analyses of Repetitive Spider Silk Sequences to Understand the Evolution and Mechanical Properties of Fibrous Protein Materials

“…In the results of the RTA clade (orange), glutamine (Q) newly appeared. It is known that the extremely high abundance of Q further differentiates spider silk proteins from other extracellular and structural proteins such as collagen and that the QQ‐motif in spider silk forms intermolecular hydrogen bonding . In the Orbiculae (purple) and Argiope (yellow) groups, trimer motifs containing P and V were first extracted.…”

“…Because pre‐established bioinformatical tools were not designed for groups of sequences that have imbalanced lengths and harbor ITR, simple sequence alignment and phylogenetic analyses of spider silk sequences cannot output meaningful results. In fact, because some previous trials simply used the naked eye or basic tools in finding tandem repeats or motifs and aligning sequences to investigate groups of spider silk sequences, they have low versatility and managing ability for exceptional cases of other types of repetitive proteins.…”

Towards Spider Glue: Long-read scaffolding for extreme length and repetitious silk family genes AgSp1 and AgSp2 with insights into functional adaptation

“…Orb web glue is much more extensible than cobweb glue (Sahni et al, 2011a), and, interestingly, the tail region of orb web AgSp1 repeats contains a higher proportion of short motifs similar to those that contribute to the extensibility of major ampullate (MaSp) and flagelliform (FLAG) silks (Gosline et al, 1999;Hayashi et al, 1999;Adrianos et al, 2013;Malay et al, 2017). Similar to MaSp1 and FLAG, orb weaver AgSp1 repeat tails contain GGQ groups, and share PGG, GPG, and QGP groups in common with MaSp2 ( Fig.…”