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，作为人体最主要的蛋白质构筑单元的胶原蛋白（collagen），在体温条件下本身存在固有不稳定性。然而它仍能组装成支撑机体组织的坚固支架结构。本研究围绕胶原蛋白的热稳定性展开探究，重点关注IV型胶原蛋白（collagen type IV）。研究借助原子力显微镜（Atomic Force Microscope, AFM），可视化观测了体温环境下胶原蛋白的解折叠过程，并鉴定出能够提升其热耐受能力的序列特征。研究发现，链间二硫键——包括保守的胱氨酸结结构——可作为结构钳，延长折叠结构的存续时长，并促进胶原蛋白以N端到C端的方向进行重折叠，这与经典的折叠路径方向相反。本研究结果有助于加深学界对天然胶原蛋白力学特性与亚稳态特性的理解，同时对组织工程领域的发展具有重要借鉴价值。