I'm playing around with different aligners in Biopython. I initially used NeedleCommandline from Bio.Emboss.Application to align two sequences (JX205496.1, JX469991.1). Using the following settings, my optimal alignment score becomes 257 (which is my sought score):
NeedleCommandline(asequence="aseq.faa", bsequence="bseq.faa", gapopen=10, gapextend=1, \
endweight = True, endopen = 10, endextend = 1, outfile = "needle.txt")
I'd like to replicate this result using PairwiseAligner() from Bio.Align. Setting up my aligner as below I get an optimal alignment score of 534:
aligner = Bio.Align.PairwiseAligner()
aligner.mode = 'global'
aligner.open_gap_score = -10
aligner.extend_gap_score = -1
I get the same score with NeedleCommandline if I exclude endweight = True, endopen = 10, endextend = 1. I've tried adjusting the aligner.query/target_end_gap/extend_score settings, but I'm unable to replicate the result from NeedleCommandline.
Any ideas what I'm doing wrong, or what Bio.Align.PairwiseAligner() settings that are equivalent to the ones I used with NeedleCommandline?
2 answers
Have you tried adding:
aligner.end_open_gap_score = -10
aligner.end_extend_gap_score = -1
Yes I have, but that doesn't change the result. It looks like setting aligner.open_gap_score = -10 and aligner.extend_gap_score = -1 also sets the end_open and end_extend scores by default.
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