Discovering almost any hidden motif from multiple sequences

Bin Fu*, Ming-Yang Kao, Lusheng Wang

*Corresponding author for this work

Research output: Contribution to journalArticle

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Abstract

We study a natural probabilistic model for motif discovery. In this model, there are k background sequences, and each character in a background sequence is a random character from an alphabet ∑. A motif G = g1g 2 ⋯ gm is a string of m characters. Each background sequence is implanted with a probabilistically generated approximate copy of G. For a probabilistically generated approximate copy b1b2 ⋯ bm of G, every character is probabilistically generated such that the probability for bi ≠ gi is at most α. In this article, we develop an efficient algorithm that can discover a hidden motif from a set of sequences for any alphabet ∑ with |∑| ≥ 2 and is applicable to DNA motif discovery. We prove that for α < 1/8 (1 - 1/|∑| ), there exist positive constants c0, ε, and δ2 such that if there are at least c0 logn input sequences, then in O( n2/h (log n)O(1)) time this algorithm finds the motif with probability at least 3/4 for every G ε ∑p - ψp,h,ε (∑), where n the length of longest sequences, p is the length of the motif, h is a parameter with p ≥ 4h ≥ δ2 log n, and εp,h,ε (∑) is a small subset of at most 2-Θ(ε2h) fraction of the sequences in ∑p .

Original languageEnglish (US)
Article number26
JournalACM Transactions on Algorithms
Volume7
Issue number2
DOIs
StatePublished - Mar 1 2011

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Keywords

  • Complexity
  • Motif detection
  • Probabilistic analysis
  • Probability

ASJC Scopus subject areas

  • Mathematics (miscellaneous)

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