Functional sub-states link conformational landscapes and protein evolution

The intrinsic conformational flexibility of proteins creates structural heterogeneity, giving rise to conformational ensembles within the energy landscape. When conformational ensembles harbor distinct functional sub-states, mutations can reshape the conformational landscape, thereby altering the distribution of functional sub-states and driving the evolution of novel functions. In this review, we provide a conceptual framework that elucidates the importance of functional sub-states and how evolution can select them. We highlight key studies that have uncovered functional sub-states and discuss recent insights into the transitions of functional sub-states during evolutionary trajectories. Finally, we outline critical techniques for studying functional sub-states, address the challenges faced in analyzing these sub-states, and explore future advancements in the field of protein evolution.