Spidroin
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| Spidroin, N-terminal | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | Spidroin_N | ||||||||
| Pfam | PF16763 | ||||||||
| InterPro | IPR031913 | ||||||||
| CATH | 2lpj | ||||||||
| |||||||||
| Spidroin, C-terminal | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | Spidroin_MaSp | ||||||||
| Pfam | PF11260 | ||||||||
| InterPro | IPR021001 | ||||||||
| CATH | 2m0m | ||||||||
| |||||||||
| Spidroin-1 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Organism | |||||||
| Symbol | ? | ||||||
UniProt | P19837 | ||||||
| |||||||
| Spidroin-2 | |||||||
|---|---|---|---|---|---|---|---|
| Identifiers | |||||||
| Organism | |||||||
| Symbol | ? | ||||||
UniProt | P46804 | ||||||
| |||||||
Spidroins are the main proteins in spider silk. Different types of spider silk contain different spidroins, all of which are members of a single protein family.[1] The most-researched type of spidroins are the major ampullate silk proteins (MaSp) used in the construction of dragline silk, the strongest type of spider silk. Dragline silk fiber is made up of two types of spidroins, spidroin-1 (MaSp1) and spidroin-2 (MaSp2).[2][3]
Spidroin is part of a large group of proteins called
A fiber of dragline spidroin is as thick and resistant as one of steel but is more flexible. It can be stretched to approximately 135% of its original length without breaking. Its properties make it an excellent candidate for use in various scientific fields.[4]
Structure
Major ampullate spidroins are large proteins with an extension of 250-350
On the other hand, spidroins have non-repetitive amino (N) and
Biological function
An individual spider spins a multitude of silk types, with each type emerging from its own distinctive set of abdominal silk glands. This complex silk machinery enables spiders to use task-specific silks (e.g., for web assembly, egg-case construction, prey wrapping, etc.).[9] The different types of silk (major ampullate silk, minor ampullate silk, flagelliform silk, aciniform silk, tubiliform silk, pyriform silk, and aggregate silk)[10] are composed of different types of proteins.
Dragline silk is mainly formed by spidroin proteins. It is a type of major ampullate silk and is produced in the major ampullate gland. Dragline silk is used not only to construct the outer frame and radii of the orb-shaped web but also as a hanging lifeline that allows the spider to evade and/or escape from predators.[11] The major ampullate gland that produces this silk is formed by three main sections: a central bag (B zone) flanked by a tail (A zone) and a duct heading towards the exit. The tail secretes most of the “spinning dope”, a solution which contains the protein molecules that will constitute the silk fiber. The sac is the main storage repository.
The epithelium of the A zone is composed of tall columns of secretory cells of a single type, packed with secretory granules. The major component of these cells which secrete the fibroin solution is a 275kDa protein containing the polypeptides spidroin I and spidroin II. The output of these cells is an aqueous and highly viscous solution of about 50% protein (mostly spidroin). The product secreted makes up the dragline silk, the main structure.
This highly viscous protein emulsion flows into the B zone, where it is covered by glycoproteins. After exiting this bag, the liquid is funneled into the narrow duct. As the gelatinous protein solution moves into the duct, the integral spidroins and glycoproteins are gradually distorted into long, thin, aligned figures with the direction of the flow. Then, they are stretched and lined up in a way that will eventually allow them to create strong intermolecular links. After different processes the silk is extended in the spinning channel to form an extremely tough thread.
Industrial and biomedical applications
In the last decade, much research has been done about spidroin protein and spider silk in order to take advantage of some of its properties, such as its elasticity and strength. Spider silk is used in different industries, and its range of applications in biomedicine is increasing every day. For example, the military and defense industries use bulletproof vests made from these fibers.
Recombinant spidroin has been successfully obtained in both eukaryotic and prokaryotic cells although there were some difficulties in the procedure due to the length of the gene sequence. Thanks to expression and the cloning work, it is possible to obtain large-scale production of spidroin which provides new opportunities for the manufacture of new biomaterials.[12] There have been attempts to generate transgenic tobacco and potato plants that express remarkable amounts of recombinant Nephila clavipes dragline proteins.[13]
Furthermore, fibers developed from spidroin are tolerated
The way spiders produce spidroin in micelles has inspired a method of mass-producing recombinant proteins. By fusing a pH-insensitive, charge-reversed mutant of spidroin N-terminal domain to the proteins to produce, much more soluble proteins can be produced in E. coli.[14]
Other silk types
| Tubuliform (egg case) silk strands structural domain | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | RP1-2 | ||||||||
| Pfam | PF12042 | ||||||||
| InterPro | IPR021915 | ||||||||
| CATH | 2mqa | ||||||||
| |||||||||
Silk proteins present in other spider silk types are also occasionally referred to as spidroin. These include tubuliform silk protein (TuSP), flagelliform silk protein (Flag; O44358-Q9NHW4-O44359), minor ampullate silk proteins (MiSp; K4MTL7), aciniform silk protein (AcSP), pyriform silk protein (PySp) and aggregate silk glue (ASG2/AgSp). These different silk proteins along with MaSP show some level of homology to each other, in protein domains, repeats, and in promoters, but also have their own unique features and variations on these parts to furfill their different functions.[15][16][17] These commonalities point at a common origin of proteins found in all these different types of silks.[1][9]
Artificial production
_artificial_spidroin.webp)
In July 2020 a team of
See also
- Spider silk
- Fibroin
- Scleroprotein
- BioSteel (fiber)
References
- ^ PMID 23155003.
- PMID 16283740.
- PMID 22364702.
- S2CID 4366005.
- PMID 2402494.
- PMID 15491167.
- PMID 16253207.
- PMID 17402782.
- ^ PMID 20696068.
- ^ Howorka S, ed. (2011). Progress in molecular biology and translational science. Vol. 103. London: Elsevier Science.
- PMID 18828837.
- ^ Rising A, Widhe M, Johansson J, Hedhammar M. Spider silk proteins: recent advances in recombinant production,structure–function relationships and biomedical applications. Cell. Mol. Life Sci. (2011) 68:169–184
- S2CID 517678.
- PMID 28534479.
- PMID 28735001.
- PMID 30279551.
- PMID 26875681.
- ^ "Spider silk made by photosynthetic bacteria". phys.org. Retrieved 16 August 2020.
- PMID 32641733..
Text and images are available under a Creative Commons Attribution 4.0 International License
Further reading
- Li V. "Spider Silk: Chemical Structure". Molecule of the Month. University of Bristol.
- Altairac S. "Spidroin". Protein Spotlight. SIB Swiss Institute of Bioinformatics.
- S2CID 4366005.