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Open Access Highly Accessed Research article

A discriminative method for family-based protein remote homology detection that combines inductive logic programming and propositional models

Juliana S Bernardes12*, Alessandra Carbone23 and Gerson Zaverucha1

Author Affiliations

1 COPPE, Programa de Engenharia de Sistemas e Computação, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil

2 Université Pierre et Marie Curie, UMR7238, Génomique Analytique, 15 rue de l'Ecole de Médecine, F-75006 Paris, France

3 CNRS, UMR7238, Laboratoire de Génomique des Microorganismes, F-75006 Paris, France

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BMC Bioinformatics 2011, 12:83  doi:10.1186/1471-2105-12-83

Published: 23 March 2011

Abstract

Background

Remote homology detection is a hard computational problem. Most approaches have trained computational models by using either full protein sequences or multiple sequence alignments (MSA), including all positions. However, when we deal with proteins in the "twilight zone" we can observe that only some segments of sequences (motifs) are conserved. We introduce a novel logical representation that allows us to represent physico-chemical properties of sequences, conserved amino acid positions and conserved physico-chemical positions in the MSA. From this, Inductive Logic Programming (ILP) finds the most frequent patterns (motifs) and uses them to train propositional models, such as decision trees and support vector machines (SVM).

Results

We use the SCOP database to perform our experiments by evaluating protein recognition within the same superfamily. Our results show that our methodology when using SVM performs significantly better than some of the state of the art methods, and comparable to other. However, our method provides a comprehensible set of logical rules that can help to understand what determines a protein function.

Conclusions

The strategy of selecting only the most frequent patterns is effective for the remote homology detection. This is possible through a suitable first-order logical representation of homologous properties, and through a set of frequent patterns, found by an ILP system, that summarizes essential features of protein functions.