Exploring Force-Driven Stochastic Folding Dynamics in Mechano-Responsive Proteins and Implications in Phenotypic Variation

Abstract

Single-point mutations are pivotal in molecular zoology, shaping functions and influencing genetic diversity and evolution. Here we study three such genetic variants of a mechano-responsive gating-spring protein, cadherin-23, that uphold the structural integrity of the protein, but showcase distinct genotypes and phenotypes. All-atom simulations indicated marginal deviations in the transient intra-domain interactions among the variants leading to variations in the anti-cross correlated motions among constituent β-strands. In nature, the variants experience declining functions with aging at different rates. We expose these variants to constant and oscillatory forces using magnetic tweezer, and measure variations in stochastic folding dynamics. All variants exhibit multiple microstates under force. However, the protein variant with higher number of intra-domain contacts exhibits transitions among the heterogeneous microstates for larger extent of forces and persisted longer. Conversely, the protein variant with weaker inter-strand correlations exhibits greater unfolding cooperativity and faster intrinsic folding, although its folding-energy landscape is more susceptible to distortion under tension. Our study thus deciphers the molecular mechanisms underlying the variations in force-adaptations and propose a mechanical relation between genotype and phenotype.