Estimation of Local Heterogeneity of Cryo-EM Maps in Direct Space for Type I Pilus from E. coli

The accuracy of resolution estimation of an experimental cryo-EM scattering density map has a decisive effect on the accuracy of determining the uncertainty parameters of atomic positions (ADP parameters), when refined in direct space. The previously developed methodology for local resolution estimation of cryo-EM maps using direct space methods was applied to the study of maps for type I pilus from E. coli. A study of four maps obtained by three groups of researchers showed that, for each of the three standard maps, the resolution can be considered constant and is about 2.6–2.7 Å, while for the sharpened map, the resolution is higher and is equal to 2.3 Å.