Semi-supervised prediction of SH2-peptide interactions from imbalanced high-throughput data

PLoS One. 2013 May 17;8(5):e62732. doi: 10.1371/journal.pone.0062732. Print 2013.

Abstract

Src homology 2 (SH2) domains are the largest family of the peptide-recognition modules (PRMs) that bind to phosphotyrosine containing peptides. Knowledge about binding partners of SH2-domains is key for a deeper understanding of different cellular processes. Given the high binding specificity of SH2, in-silico ligand peptide prediction is of great interest. Currently however, only a few approaches have been published for the prediction of SH2-peptide interactions. Their main shortcomings range from limited coverage, to restrictive modeling assumptions (they are mainly based on position specific scoring matrices and do not take into consideration complex amino acids inter-dependencies) and high computational complexity. We propose a simple yet effective machine learning approach for a large set of known human SH2 domains. We used comprehensive data from micro-array and peptide-array experiments on 51 human SH2 domains. In order to deal with the high data imbalance problem and the high signal-to-noise ration, we casted the problem in a semi-supervised setting. We report competitive predictive performance w.r.t. state-of-the-art. Specifically we obtain 0.83 AUC ROC and 0.93 AUC PR in comparison to 0.71 AUC ROC and 0.87 AUC PR previously achieved by the position specific scoring matrices (PSSMs) based SMALI approach. Our work provides three main contributions. First, we showed that better models can be obtained when the information on the non-interacting peptides (negative examples) is also used. Second, we improve performance when considering high order correlations between the ligand positions employing regularization techniques to effectively avoid overfitting issues. Third, we developed an approach to tackle the data imbalance problem using a semi-supervised strategy. Finally, we performed a genome-wide prediction of human SH2-peptide binding, uncovering several findings of biological relevance. We make our models and genome-wide predictions, for all the 51 SH2-domains, freely available to the scientific community under the following URLs: http://www.bioinf.uni-freiburg.de/Software/SH2PepInt/SH2PepInt.tar.gz and http://www.bioinf.uni-freiburg.de/Software/SH2PepInt/Genome-wide-predictions.tar.gz, respectively.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Area Under Curve
  • Artificial Intelligence
  • Humans
  • Ligands
  • Models, Biological*
  • Predictive Value of Tests
  • Protein Array Analysis / methods
  • Protein Binding
  • Protein Interaction Domains and Motifs / genetics*
  • Protein Interaction Mapping / methods*
  • ROC Curve
  • src Homology Domains / genetics*
  • src Homology Domains / physiology

Substances

  • Ligands

Grants and funding

This work was funded by Centre for Biological Signalling Studies (BIOSS), University of Freiburg, Germany, and the Excellence Initiative of the German Federal and State Governments (EXC 294 to RB). RB and FC were partially supported by the German Research Foundation (BA 2168/3-1 and BA 2168/4-1 to RB). MH was supported by the German Research Foundation (Hu799/5-1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.