SPREAD

SPREAD performs automated end-to-end single-particle cryogenic electron microscopy (cryo-EM) data processing to generate three-dimensional reconstructions of biomacromolecules.

Key Features:

• Integration Across Processing Stages: Encompasses 2D image classification, 3D initial model generation, model selection, and 3D refinement within a single pipeline.
• Network-Based Image Classification (NCEM): Uses the NCEM network-based clustering algorithm for efficient and robust 2D image classification.
• Automatic Model Ranking and Selection (SRes): Implements the reference-free resolution measurement SRes to rank and select models automatically.
• Probabilistic Orientation Searching ("peak finding"): Applies a probabilistic orientation-searching method termed "peak finding" that leverages a network-based image similarity metric for projection orientation assignment.
• Mixture Image Network for Refinement: Constructs a mixture image network from peak-finding results to handle particle images and projection images during 3D refinement and recomputes node-pair similarities via a superposed random walk.
• Fully Automated Workflow: Executes the processing pipeline in a fully automated manner to minimize manual intervention during 2D classification, model selection, and 3D refinement.

Scientific Applications:

• 3D structure determination of biomacromolecules: Generates three-dimensional reconstructions of biomacromolecules from single-particle cryo-EM data for structural biology studies.
• Cryo-EM classification and refinement: Provides high-precision 2D classification, reference-free model ranking, and 3D refinement to support structural analysis and model selection.

Methodology:

Performs 2D image classification using NCEM; generates 3D initial models; ranks and selects models with SRes; assigns orientations via probabilistic "peak finding" using a network-based image similarity metric; constructs a mixture image network from peak-finding results and recomputes node-pair similarities through a superposed random walk for 3D refinement handling particle and projection images.