1. Pattern matching through Chaos Game Representation: bridging numerical and discrete data structures for biological sequence analysis
- Author
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Jonas S. Almeida, Alexandre P. Francisco, Susana Vinga, Alexandra M. Carvalho, Luís M. S. Russo, and NOVA Medical School|Faculdade de Ciências Médicas (NMS|FCM)
- Subjects
Theoretical computer science ,lcsh:QH426-470 ,Matching (graph theory) ,TANDEM REPEATS ,Computer science ,0206 medical engineering ,02 engineering and technology ,ULTRAFAST ,Rolling hash ,CLASSIFICATION ,03 medical and health sciences ,Structural Biology ,SHORT READ ALIGNMENT ,SEARCH ,ALGORITHM ,Pattern matching ,lcsh:QH301-705.5 ,Molecular Biology ,030304 developmental biology ,GENOMIC SIGNATURE ,0303 health sciences ,Research ,Applied Mathematics ,String (computer science) ,Approximate string matching ,Data structure ,DNA-SEQUENCES ,Substring ,lcsh:Genetics ,lcsh:Biology (General) ,Computational Theory and Mathematics ,TREES ,Graph (abstract data type) ,EFFICIENT ALIGNMENT ,Algorithm ,020602 bioinformatics - Abstract
This work was partially supported by FCT through the PIDDAC Program funds (INESC-ID multiannual funding) and under grant PEst-OE/EEI/LA0008/2011 (IT multiannual funding). In addition, it was also partially funded by projects HIVCONTROL (PTDC/EEA-CRO/100128/2008, S. Vinga, PI), TAGS (PTDC/EIA-EIA/112283/2009) and NEUROCLINOMICS (PTDC/EIA-EIA/111239/2009) from FCT (Portugal). Background: Chaos Game Representation (CGR) is an iterated function that bijectively maps discrete sequences into a continuous domain. As a result, discrete sequences can be object of statistical and topological analyses otherwise reserved to numerical systems. Characteristically, CGR coordinates of substrings sharing an L-long suffix will be located within 2(-L) distance of each other. In the two decades since its original proposal, CGR has been generalized beyond its original focus on genomic sequences and has been successfully applied to a wide range of problems in bioinformatics. This report explores the possibility that it can be further extended to approach algorithms that rely on discrete, graph-based representations. Results: The exploratory analysis described here consisted of selecting foundational string problems and refactoring them using CGR-based algorithms. We found that CGR can take the role of suffix trees and emulate sophisticated string algorithms, efficiently solving exact and approximate string matching problems such as finding all palindromes and tandem repeats, and matching with mismatches. The common feature of these problems is that they use longest common extension (LCE) queries as subtasks of their procedures, which we show to have a constant time solution with CGR. Additionally, we show that CGR can be used as a rolling hash function within the Rabin-Karp algorithm. Conclusions: The analysis of biological sequences relies on algorithmic foundations facing mounting challenges, both logistic (performance) and analytical (lack of unifying mathematical framework). CGR is found to provide the latter and to promise the former: graph-based data structures for sequence analysis operations are entailed by numerical-based data structures produced by CGR maps, providing a unifying analytical framework for a diversity of pattern matching problems. publishersversion published
- Published
- 2012