Genderen, E. v. | bioRxiv Science

bioRxiv2026

Narrow-beam geometry improves the efficiency of cryo-EM

Cryo-electron microscopy (cryo-EM) of biological specimens is limited by radiation damage and a low signal-to-noise ratio (SNR). Here, we show that reducing the illuminated area substantially slows the observed diffraction decay in protein microcrystals. We further show that narrow parallel-beam electron diffraction from thin non-crystalline biological specimens provides substantially higher reciprocal-space SNR than conventional cryo-EM imaging. We developed a multimodal scanning workflow, 4D-para-STEM, that records narrow-beam diffraction patterns together with corresponding images. Using viruses, peptide assemblies, and microtubules, we demonstrate interpretable diffraction signals from both crystalline and non-crystalline biological specimens. Together, these results show that narrow parallel-beam scanning reduces observed radiation damage and improves the SNR in cryo-EM.

biophysics↗

bioRxiv2024

DiffGAN: a conditional generative adversarial network for phasing single molecule diffraction data to atomic resolution

IntroductionProteins that adopt multiple conformations pose significant challenges in structural biology research and pharmaceutical development, as structure determination via single particle cryo-electron microscopy (cryo-EM) is often impeded by data heterogeneity. In this context, the enhanced signal-to-noise ratio of single molecule cryo-electron diffraction (simED) offers a promising alternative. However, a significant challenge in diffraction methods is the loss of phase information, which is crucial for accurate structure determination. MethodsHere, we present DiffGAN, a conditional generative adversarial network (cGAN) that estimates the missing phases at high resolution from a combination of high-resolution single particle diffraction data and low-resolution image data. ResultsFor simulated datasets, DiffGAN allows effectively determine protein structures at atomic resolution from diffraction patterns and noisy low-resolution images. DiscussionOur findings suggest that combining single particle cryo-electron diffraction with advanced generative modeling, as in DiffGAN, could revolutionize the way protein structures are determined, offering a more accurate and efficient alternative to existing methods.

biophysics↗