Selvita Platform tools overview
 
Selvita Platform technology is based on the CABS model, extensively tested, state-of-the-art approach to protein structure prediction. The modeling process is divided into two stages: fold assembly (by the CABS model in a simplified representation) followed by an automated model selection and refinement procedure.

Fold assembly can be done in a framework of a standard comparative modeling procedure, where spatial restraints are derived from alternative sequence alignments with a template/ templates. Preferentially in more difficult modeling cases, a new approach to comparative modeling can be used, which does not require the prior alignment.

The protein-protein docking is realized by a combination of rigid-body and flexible-backbone docking. In the first stage thousands of models are produced by rigid docking systematic search. The next filtering step reduces the number of models to hundred or less by automated structural clustering or filtering out models due to user provided data on binding site residues. The last modeling stage includes fully flexible docking (CABS) followed by the model refinement.

Selvita Platform provide an integrated tool-kit for automated protein structure predictions and protein-protein docking. However, like blind prediction experiments show, due to high complexity of prediction tasks, fully automated approach often doesn't guarantee the highest possible performance. Therefore, human intervention is made possible at all modeling stages.
 
The SPMP technology (CABS) enables the structure prediction and dynamics studies of large biomolecular systems beyond the capabilities of state-of-the-art tools. Multiple CABS trajectories led to description of N-terminal domain of the FecA complex conformational transitions, suggesting signaling mechanism in response to the binding of ferric citrate. Shown above is the simulation snapshot of the N-terminal domain (in blue) of the FecA complex. Simulation studies performed by research scientists at Warsaw University (Sen TZ et al. Biophys J, 94:7, 2008)

 

Selvita Protein Modeling Platform 2.0 includes:

  • [NEW!] Protein-protein docking (FTDOCK rigid-body fast Fourier docking, fully flexible CABS Monte Carlo docking, optional structural filtering according to user-provided data on interface residues)
  • Protein structure prediction (homology CABS Monte Carlo simulations)
  • Loop modeling (de novo CABS Monte Carlo simulations)
  • Protein structure optimization – all-atom Molecular Mechanics (GROMACS independent module)
  • Protein sequence homology search (BLAST)
  • Secondary structure prediction (Psi-Pred algorithm)
  • Alignments editor and external alignments & templates verification tool
  • Toolkit set of tools for conversion between various sequence & structure files formats, calculating protein structure properties, protein database files visualization in the text format
  • 3D Visualiser (OpenAstexViewer)
  • 3D Threading (Genetic algorithm search of the structure-sequence alignment space)

 
RAR (retinoic acid receptor ) and RXR (retinoid X receptor ) unbound structures (2LBD and 1LBD) were docked together using SPMP 2.0 protein-protein docking procedure and compared to RAR-RXR experimental complex structure (1DKF). Both molecules undergo serious conformational changes upon binding - RMSD’s between bound and unbound structures are: 2.42 (RAR) and 8.28 (RXR). RMSD between the model (in gray) and experimental structure 1DKF (in blue) of RAR-RXR complex is 4.4 A, interface RMSD 1.37 A.