title: Recognizing metal and acid radical ion-binding sites by integrating ab initio modeling with template-based transferals.
abstract: More than half of proteins require binding of metal and acid radical ions for their structure and function. Identification of the ion-binding locations is important for understanding the biological functions of proteins. Due to the small size and high versatility of the metal and acid radical ions, however, computational prediction of their binding sites remains difficult.
  
  
  
  We proposed a new ligand-specific approach devoted to the binding site prediction of 13 metal ions (Zn2+, Cu2+, Fe2+, Fe3+, Ca2+, Mg2+, Mn2+, Na+, K+) and acid radical ion ligands (CO32-, NO2-, SO42-, PO43-) that are most frequently seen in protein databases. A sequence-based ab initio model is first trained on sequence profiles, where a modified AdaBoost algorithm is extended to balance binding and non-binding residue samples. A composite method IonCom is then developed to combine the ab initio model with multiple threading alignments for further improving the robustness of the binding site predictions. The pipeline was tested using 5-fold cross validations on a comprehensive set of 2,100 non-redundant proteins bound with 3,075 small ion ligands. Significant advantage was demonstrated compared with the state of the art ligand-binding methods including COACH and TargetS for high-accuracy ion-binding site identification. Detailed data analyses show that the major advantage of IonCom lies at the integration of complementary ab initio and template-based components. Ion-specific feature design and binding library selection also contribute to the improvement of small ion ligand binding predictions.
  
  
  
  http://zhanglab.ccmb.med.umich.edu/IonCom CONTACT: hxz@imut.edu.cn or zhng@umich.eduSupplementary information: Supplementary data are available at Bioinformatics online.
authors.affiliation: Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, USA College of Sciences, Inner Mongolia University of Technology, Hohhot 010051, China.
authors.forename: Xiuzhen
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, USA Institute for Data Science and Engineering, East China Normal University, Shanghai 200062, China.
authors.forename: Qiwen
authors.initials: Q
authors.lastname: Dong
authors.affiliation: Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, USA School of Mathematical Sciences, Nankai University, Tianjin 300071, China.
authors.forename: Jianyi
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, USA Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000465:Algorithms; D001665:Binding Sites; D030562:Databases, Protein; D008024:Ligands; D008670:Metals; D008958:Models, Molecular; D011506:Proteins
chemical_list: D008024:Ligands; D008670:Metals; D011506:Proteins