Cellulases catalyze the hydrolysis of cellulose. Improving their catalytic efficiency is a long-standing goal in biotechnology given the interest in lignocellulosic biomass decomposition. Although methods based on sequence alteration exist, improving cellulases is still a challenge. Here we show that Ancestral Sequence Reconstruction can “resurrect” efficient cellulases. This technique reconstructs enzymes from extinct organisms that lived in the harsh environments of ancient Earth. We obtain ancestral bacterial endoglucanases from the late Archean eon that efficiently work in a broad range of temperatures (30–90 °C), pH values (4–10). The oldest enzyme (~2800 million years) processes different lignocellulosic substrates, showing processive activity and doubling the activity of modern enzymes in some conditions. We solve its crystal structure to 1.45 Å which, together with molecular dynamics simulations, uncovers key features underlying its activity. This ancestral endoglucanase shows good synergy in combination with other lignocellulosic enzymes as well as when integrated into a bacterial cellulosome.

纤维素酶催化纤维素的水解。考虑到对木质纤维素生物质分解的兴趣，提高它们的催化效率是生物技术中的长期目标。尽管存在基于序列改变的方法，但是改善纤维素酶仍然是一个挑战。在这里，我们表明祖先序列重建可以“复活”有效的纤维素酶。这项技术从生活在古代地球恶劣环境中的灭绝生物中重建酶。我们从太古宙晚期获得祖先细菌内切葡聚糖酶，可在广泛的温度范围（30–90°C），pH值（4–10）中有效地起作用。最古老的酶（约28亿年）处理不同的木质纤维素底物，在某些条件下显示出连续的活性，并使现代酶的活性加倍。我们将其晶体结构解析为1。45Å结合分子动力学模拟，揭示了其活性的关键特征。这种祖先内切葡聚糖酶与其他木质纤维素酶结合以及整合到细菌纤维素体中时均显示出良好的协同作用。