Synthesis and properties of crosslinked recombinant pro-resilin

The elastic properties of the protein called resilin were discovered about 40 years ago during studies of the flight systems of locusts and dragonflies. It is used in repetitive tasks by most insects, including jumping fleas and chirping cicadas. Resilin is formed by crosslinking of a precursor protein, pro-resilin. The elastic region of pro-resilin has now been isolated in pure form in large quantities following expression of its gene in Escherichia coli. The recombinant pro-resilin can be photochemically crosslinked into a rubber-like material with many of the properties of natural resilin. The synthetic material can be cast into useful shapes, and its capacity to recover after deformation exceeds that of high-resilience rubber, making it a promising candidate for industrial and in situ biomedical applications. Resilin is a member of a family of elastic proteins that includes elastin, as well as gluten, gliadin, abductin and spider silks. Resilin is found in specialized regions of the cuticle of most insects, providing low stiffness, high strain and efficient energy storage1,2; it is best known for its roles in insect flight3,4 and the remarkable jumping ability of fleas5,6 and spittle bugs7. Previously, the Drosophila melanogaster CG15920 gene was tentatively identified as one encoding a resilin-like protein8,9 (pro-resilin). Here we report the cloning and expression of the first exon of the Drosophila CG15920 gene as a soluble protein in Escherichia coli. We show that this recombinant protein can be cast into a rubber-like biomaterial by rapid photochemical crosslinking. This observation validates the role of the putative elastic repeat motif in resilin function. The resilience (recovery after deformation) of crosslinked recombinant resilin was found to exceed that of unfilled synthetic polybutadiene, a high resilience rubber. We believe that our work will greatly facilitate structural investigations into the functional properties of resilin and shed light on more general aspects of the structure of elastomeric proteins. In addition, the ability to rapidly cast samples of this biomaterial may enable its use in situ for both industrial and biomedical applications.