PNAS_2024-collagen.zip

Surprisingly, collagen – the predominant protein building block of our bodies – is inherently unstable at body temperature. Yet, it assembles into robust scaffolds that support tissues. This study investigates collagen’s thermal stability, with a particular focus on collagen type IV. Using AFM, we visualize unfolding of collagen at body temperature and identify sequence features that enhance its thermal resilience. We find that interchain disulfide bonds, including a conserved cystine knot, act as structural clamps that prolong the lifetime of folded structures and facilitate refolding in the N-to-C direction, opposite to the canonical folding pathway. Our findings contribute to our understanding of native collagen mechanics and metastability and have implications for advancing tissue engineering.