Exploring the Potential of AlphaFold Distograms for Flexibility Assignment in Cryo-EM Maps

AlphaFold (AF) models are widely used in cryo-EM workflows, but their static structure predictions limit the interpretation of flexible or unresolved regions. To address this, we investigate whether AF-generated distance probability distributions (distograms) can reveal conformational flexibility, using the AIFM1/AK2 complex as a test case. Molecular dynamics simulations identified a hinge-driven motion in AK2 upon AIFM1 binding, which was accurately reflected in distograms from AF2.3 and AF3, though not in their predicted structures. Enhanced sampling and MSA perturbations did not improve flexibility detection in earlier AF2 versions. So, by analyzing a key metabolic complex, we demonstrate that distograms might offer a promising approach for structure-free identification of flexible protein regionsl for interpreting dynamic signals in cryo-EM maps.