These findings come from recent publications in Science. Silk genes, which code for extremely large proteins with stretches of amino acids that repeat many times, are themselves long and full of repetitive DNA that's hard to decipher. But the velvet spider genome, together with that of the orb weaver and the house spider, has exposed an unexpected variety of silk genes—“a lot more than we thought,” Coddington says. Researchers had already identified two genes for the class of silk known as major ampullate, which forms the superstrong dragline threads that anchor webs and are the inspiration for a major effort to make spider silk commercially. The social velvet spider's genome, however, revealed 10 genes just for that one kind of silk and nine other genes for additional silk proteins.
The newly deciphered genes help explain the molecular basis
of spider silk properties. The silk genes contain short stretches of
DNA called motifs that vary between species in number and in their exact
sequence. By comparing the genetic differences with differences in silk
properties, Hayashi's team has found that those motifs appear to
influence strength, elasticity, and other features.
Sorting
out this complexity may help bioengineers better understand and,
ultimately, harness silk's remarkable strength and flexibility. For example, silk glands contain nonsilk proteins that may
serve as molecular chaperones to help with production of the fiber. For researchers trying to make artificial silks, these findings are a gold mine.
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