Denoising Autoencoder Trained on Simulation-Derived Structures for Noise Reduction in Chromatin Scanning Transmission Electron Microscopy

Walter Alvarado, Vasundhara Agrawal, Wing Shun Li, Vinayak P. Dravid, Vadim Backman*, Juan J. de Pablo*, Andrew L. Ferguson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Scanning transmission electron microscopy tomography with ChromEM staining (ChromSTEM), has allowed for the three-dimensional study of genome organization. By leveraging convolutional neural networks and molecular dynamics simulations, we have developed a denoising autoencoder (DAE) capable of postprocessing experimental ChromSTEM images to provide nucleosome-level resolution. Our DAE is trained on synthetic images generated from simulations of the chromatin fiber using the 1-cylinder per nucleosome (1CPN) model of chromatin. We find that our DAE is capable of removing noise commonly found in high-angle annular dark field (HAADF) STEM experiments and is able to learn structural features driven by the physics of chromatin folding. The DAE outperforms other well-known denoising algorithms without degradation of structural features and permits the resolution of α-tetrahedron tetranucleosome motifs that induce local chromatin compaction and mediate DNA accessibility. Notably, we find no evidence for the 30 nm fiber, which has been suggested to serve as the higher-order structure of the chromatin fiber. This approach provides high-resolution STEM images that allow for the resolution of single nucleosomes and organized domains within chromatin dense regions comprising of folding motifs that modulate the accessibility of DNA to external biological machinery.

Original languageEnglish (US)
Pages (from-to)1200-1212
Number of pages13
JournalACS Central Science
Volume9
Issue number6
DOIs
StatePublished - Jun 28 2023

Funding

We thank Dr. Yue Li, Eric Roth, and Dr. Reiner Bleher at the Biological-Cryogenic Electron Microscopy (BioCryo) facility at Northwestern University for their assistance in ChromSTEM staining, sectioning, and imaging. We also thank Dr. Tobin Sosnick, Dr. Rebecca Willett, Aria Coraor, Soren Kyhl, Eric Schultz, Yiheng Wu, Mike Jones, Fabian Bylehn, and Kirill Shmilovich for their helpful discussions. This study was primarily supported by NSF Grant EFRI CEE 1830969. The authors also gratefully acknowledge support from NSF grant EFMA-1830961, NIH grants U54CA268084, R01CA228272, and R01CA225002, and philanthropic support from Rob and Kristin Goldman. This work was completed in part with resources provided by the University of Chicago Research Computing Center. We gratefully acknowledge computing time on the University of Chicago high-performance GPU-based cyberinfrastructure supported by the National Science Foundation under Grant No. DMR-1828629. This work made use of the BioCryo facility of Northwestern University’s NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern’s MRSEC program (NSF DMR-1720139).

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering

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