An integrative computational framework based on a two-step random forest algorithm improves prediction of zinc-binding sites in proteins

PLoS One. 2012;7(11):e49716. doi: 10.1371/journal.pone.0049716. Epub 2012 Nov 14.

Abstract

Zinc-binding proteins are the most abundant metalloproteins in the Protein Data Bank where the zinc ions usually have catalytic, regulatory or structural roles critical for the function of the protein. Accurate prediction of zinc-binding sites is not only useful for the inference of protein function but also important for the prediction of 3D structure. Here, we present a new integrative framework that combines multiple sequence and structural properties and graph-theoretic network features, followed by an efficient feature selection to improve prediction of zinc-binding sites. We investigate what information can be retrieved from the sequence, structure and network levels that is relevant to zinc-binding site prediction. We perform a two-step feature selection using random forest to remove redundant features and quantify the relative importance of the retrieved features. Benchmarking on a high-quality structural dataset containing 1,103 protein chains and 484 zinc-binding residues, our method achieved >80% recall at a precision of 75% for the zinc-binding residues Cys, His, Glu and Asp on 5-fold cross-validation tests, which is a 10%-28% higher recall at the 75% equal precision compared to SitePredict and zincfinder at residue level using the same dataset. The independent test also indicates that our method has achieved recall of 0.790 and 0.759 at residue and protein levels, respectively, which is a performance better than the other two methods. Moreover, AUC (the Area Under the Curve) and AURPC (the Area Under the Recall-Precision Curve) by our method are also respectively better than those of the other two methods. Our method can not only be applied to large-scale identification of zinc-binding sites when structural information of the target is available, but also give valuable insights into important features arising from different levels that collectively characterize the zinc-binding sites. The scripts and datasets are available at http://protein.cau.edu.cn/zincidentifier/.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Amino Acids / chemistry
  • Amino Acids / metabolism
  • Apoproteins / chemistry
  • Apoproteins / metabolism
  • Binding Sites*
  • Computational Biology / methods*
  • Internet
  • Metalloproteins / chemistry*
  • Metalloproteins / metabolism
  • Models, Biological
  • Protein Binding
  • ROC Curve
  • Reproducibility of Results
  • Zinc / chemistry*
  • Zinc / metabolism

Substances

  • Amino Acids
  • Apoproteins
  • Metalloproteins
  • Zinc

Grants and funding

This work was supported by grants from the National Key Basic Research Project of China (2009CB918802), the Hundred Talents Program of the Chinese Academy of Sciences (CAS), the National Natural Science Foundation of China (No. 61202167), Tianjin Municipal Science & Technology Commission (No. 10ZCKFSY05600) and the National Health and Medical Research Council of Australia (NHMRC) (No. 490989). JS is an NHMRC Peter Doherty Fellow and a Recipient of the Hundred Talents Program of CAS and the Japan Society for the Promotion of Science (JSPS) Short-term Invitation Fellowship to the Bioinformatics Center, Kyoto University, Japan. TA was supported by the Chinese Academy of Sciences Visiting Professorship for Senior International Scientists (No. 2011T2S34). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.