A Space Efficient Algorithm for Sequence Alignment with Inversions

A dynamic programming algorithm to find an optimal alignment for a pair of DNA sequences has been described by Schöniger and Waterman. The alignments use not only substitutions, insertions, and deletions of single nucleotides, but also inversions, which are the reversed complements, of substrings of the sequences. With the restriction that the inversions are non-intersecting each other, their proposed algorithm runs in O(nm) time and consumes O(nm) space, where n and m are the lengths of the input sequences respectively. We develop a space efficient algorithm to compute such an optimal alignment which consumes only O(nm) space within the same amount of time. Our algorithm enables the computation for a pair of DNA sequences of length up to 10,000 to be carried out on an ordinary desktop computer. Simulation study is conducted to verify some biological facts about gene shuffling across species.