Metastable Dimeric Intermediate Drives Native-like Spidroin Fibrillogenesis, while Dehydration Promotes Cross-β Transition

A metastable dimeric intermediate drives native-like spidroin fibrillogenesis, producing ordered beta-structure nanofibrils, but dehydration triggers an effectively irreversible shift to amyloid-like cross-beta.

• Why it matters: Native-like hierarchical assembly of spidroin is hard to reproduce, and dehydration can scramble structure; this work targets the molecular factor and the dehydration-linked transition.
• What they did: Using SAXS and AFM, the study characterizes a compact core with solvent-excluded “dry interfaces” and exposed polyalanine segments, then tracks fibril growth after lowering denaturant concentration.
• The result: The resulting fibrils show parallel beta-structure matching native silk nanofibril architecture, yet XRD shows an effectively irreversible transition to amyloid-like cross-beta upon drying, implying dehydration decoupling strategies.

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