Surpassing the physical Nyquist limit to produce super-resolution cryo-EM reconstructions

The resolution of cryo-EM reconstructions is fundamentally limited by the Nyquist frequency, which is half the sampling frequency of the detector and depends upon the magnification used. In principle, super-resolution imaging should enable reconstructions to surpass the physical Nyquist limit by increasing sampling frequency, yet there are no reports of reconstructions that do so. Here we report the use of super-resolution imaging with the K3 direct electron detector to produce super-resolution single-particle cryo-EM reconstructions significantly surpassing the physical Nyquist limit. We also present a comparative analysis of a sample imaged at four different magnifications. This analysis demonstrates that lower magnifications can be beneficial, despite the loss of higher resolution signal, due to the increased particle numbers imaged. To highlight the potential utility of lower magnification data collection, we produced a 3.5 [A] reconstruction of jack bean urease with particles from a single micrograph. O_FIG O_LINKSMALLFIG WIDTH=111 HEIGHT=200 SRC="FIGDIR/small/675397v3_ufig1.gif" ALT="Figure 1"> View larger version (23K): org.highwire.dtl.DTLVardef@1579481org.highwire.dtl.DTLVardef@d6bf96org.highwire.dtl.DTLVardef@bc4bc0org.highwire.dtl.DTLVardef@116412_HPS_FORMAT_FIGEXP M_FIG C_FIG