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.

令人意外的是，作为人体主要蛋白质构成单元的胶原蛋白（collagen），在体温下本质上是不稳定的。然而，它能组装成支撑组织的坚固支架。本研究探究胶原蛋白的热稳定性，尤其聚焦于IV型胶原蛋白（collagen type IV）。借助原子力显微镜（AFM），我们观察了体温下胶原蛋白的解折叠过程，并识别出增强其热韧性的序列特征。我们发现，链间二硫键（interchain disulfide bonds）——包括保守的胱氨酸结（conserved cystine knot）——可作为结构夹具，延长折叠结构的寿命，并促进沿N到C方向的再折叠，这与经典折叠途径（canonical folding pathway）相反。我们的研究结果有助于加深对天然胶原蛋白力学特性及亚稳性的理解，并对推进组织工程具有重要意义。