Bioinformatics Advance Access published online on March 18, 2008
Bioinformatics, doi:10.1093/bioinformatics/btn104
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Combining Statistical Alignment and Phylogenetic Footprinting to Detect Regulatory Elements
1Department of Statistics, Oxford University, Oxford UK
2Department of Mathematics, Univeristy of California, Berkeley, CA USA
*To whom correspondence should be addressed. Rahul Satija, E-mail: satija{at}stats.ox.ac.uk
| Abstract |
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Motivation: Traditional alignment-based phylogenetic footprinting approaches make predictions on the basis of a single assumed alignment. The predictions are therefore highly sensitive to alignment errors or regions of alignment uncertainty. Alternatively, statistical alignment methods provide a framework for performing phylogenetic analyses by examining a distribution of alignments.
Results: We developed a novel algorithm for predicting functional elements by combining statistical alignment and phylogenetic footprinting (SAPF). SAPF simultaneously performs both alignment and annotation by combining phylogenetic footprinting techniques with an HMM transducer-based multiple alignment model, and can analyze sequence data from multiple sequences. We assessed SAPF's predictive performance on two simulated datasets and three well-annotated cis-regulatory modules from newly sequenced Drosophila genomes. The results demonstrate that removing the traditional dependence on a single alignment can significantly augment the predictive performance, especially when there is uncertainty in the alignment of functional regions.
Availability: SAPF is freely available to download online at http://www.stats.ox.ac.uk/~satija/SAPF/
Contact: satija{at}stats.ox.ac.uk
Associate Editor: Dr. Limsoon Wong
Received on January 21, 2008; revised on February 21, 2008; accepted on March 17, 2008