Multiple protein sequence alignment using double-dynamic programming.

A method of multiple sequence alignment is described based on the double dynamic programming (DDP) algorithm previously used for treating structural constraints encountered in structure comparison and threading. Following these applications, the inconsistencies that emerge when trying to combine pair-wise alignments into a multiple alignment are reconciled by summing all the, possibly inconsistent, paths (low-level alignments) into a matrix which is then used to provide a final (high-level) alignment. This process is applied to all sequence pairs and the pair-wise results combined in a simple multiple sequence alignment program. From this alignment, further constraints are selected to bias the low-level alignments in the DDP algorithm and the process iterated. The results, however, showed that this overall iteration was not needed and one-pass gave results at least as good as the 'standard' progressive method of multiple sequence alignment. Further applications of the method are discussed.