Clustering support vector machines for protein local structure prediction

摘要

Understanding the sequence-to-structure relationship is a central task in bioinformatics research. Adequate knowledge about this relationship can potentially improve accuracy for local protein structure prediction. One of approaches for protein local structure prediction uses the conventional clustering algorithms to capture the sequence-to-structure relationship. The cluster membership function defined by conventional clustering algorithms may not reveal the complex nonlinear relationship adequately. Compared with the conventional clustering algorithms, Support Vector Machine (SVM) can capture the nonlinear sequence-to-structure relationship by mapping the input space into another higher dimensional feature space. However, SVM is not favorable for huge datasets including millions of samples. Therefore, we propose a novel computational model called Clustering Support Vector Machines (CSVMs). Taking advantage of both theory of granular computing and advanced statistical learning methodology, CSVMs are built specifically for each information granule partitioned intelligently by the clustering algorithm. This feature makes learning tasks for each CSVM more specific and simpler. CSVMs modeled for each granule can be easily parallelized so that CSVMs can be used to handle complex classification problems for huge datasets. Average accuracy for CSVMs is over 80%, which indicates that the generalization power for CSVMs is strong enough to recognize the complicated pattern of sequence-to-structure relationships. Compared with the conventional clustering algorithm, our experimental results show that accuracy for local structure prediction has been improved noticeably when CSVMs are applied.