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Science  06 Oct 2000:
Vol. 290, Issue 5489, pp. 13e-15e

The construction of mechanical supports, such as cellulose in plants and collagen in animals, results from the conversion of small, soluble parts into a large, insoluble matrix. The difficulty in controlling this transition has contributed to the obstacles in identifying intermediates and determining their modes of assembly. One of the most tantalizing biomaterials in this regard is spider silk—effortlessly produced, remarkably strong, and extremely light.

Winkler et al. describe an approach aimed at introducing a switch with which the formation of the b-sheet structures observed in the final product might be regulated. They have engineered into a synthetic silk gene a recognition site for a protein kinase; adding bulky and anionic phosphoryl groups to the protein interferes with b-sheet formation, as assessed by circular dichroism and infrared spectroscopy, and increases its solubility four-fold. This technique, together with a previously described disulfide switch, may enable us to begin teasing apart the details of how spider silk is fabricated. — GJC

Biochemistry, in press.

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