HOw to merge multifasta sequence into a single sequence having only one header?

Question

[majeedaasim]

I have a multifasta sequence file. I want to merge all the sequences together to create a single sequence file. I men that the ">IDs" in the sequences be removed to create a super sequence. THis would take much time doing mannualy.

how can it be done in linux

THanks

[Santosh Anand]

If I may ask, for what need?

[mittu1602]

@majeedaasim please choose the accept answer option if it works for you, It will help us motivated. Good Luck!

Answer 1

[Charles Plessy]

Using the union command from the EMBOSS package:

$ cat test.fasta 
>seq1
AAAATTGGG
>seq2
GGCCCTTTT
>seq3
AAATGGGG

$ union -filter test.fasta
>seq1
AAAATTGGGGGCCCTTTTAAATGGGG

Answer 2

[mittu1602]

grep -v "^>" test.fasta | awk 'BEGIN { ORS=""; print ">My_New_Sequence_name\n" } { print }' > new​.fasta

test.fasta
>seq1
AAAATTGGG
>seq2
GGCCCTTTT
>seq3
AAATGGGG

new.fasta
>My_New_Sequence_name
AAAATTGGGGGCCCTTTTAAATGGGG

[cssulliv]

Hi,

Would this work on a mac osx?

[Joe]

Not necessarily. MacOS ships with a non standard version of grep (I.e. not GNU coreutils). Consequently, the syntax often isn't 100% transferable. It may work, but that's not something you can rely on. You can however download and install the 'proper' coreutils via HomeBrew or MacPorts.

Answer 3

[Joe]

cat multifasta.fa | sed -e '1!{/^>.*/d;}' | sed  ':a;N;$!ba;s/\n//2g' > output.fa

E.g:

$ cat ~/test/seqs.fasta
>tpg|Magnaporthiopsis_incrustans|JF414846
ACTGTAGTAGCTACGATCGATCAGATGATCACGTAGCATCGATCGATCATCGACTAGTAGATCACTCGACATAGATCCACATCAATAGATCATCATCATCATAATCGATCACTAGCAGCNNNNNN
>tpg|Pyricularia_pennisetigena|AB818016
NNNNNNGCAAGNTTCATGACGATGTAGAATGGCTTATCGAAGGGAGCAGGCCAGGGATTGAGGTCCGTCTCACGGGTTGGCTTCACTCCCCCACTGCCAGCCCTCTTGCTGCAACTCCACCAGAA
>tpg|Inocybe_sororia|EU525947
NNNAACCANGCCGCGACGGCGGTGCGATCGGGAAACGCGGCGGTGGCGGAGGAATCGGCCATCCTTCACCATATCGGCCAAGGATTGTGGTTCCTGTAGGGCTCGCGCAGCCCAGGACGCGCNNN


$ cat ~/test/seqs.fasta | sed -e '1!{/^>.*/d;}' | sed  ':a;N;$!ba;s/\n//2g'
>tpg|Magnaporthiopsis_incrustans|JF414846
ACTGTAGTAGCTACGATCGATCAGATGATCACGTAGCATCGATCGATCATCGACTAGTAGATCACTCGACATAGATCCACATCAATAGATCATCATCATCATAATCGATCACTAGCAGCNNNNNNNNNNNNGCAAGNTTCATGACGATGTAGAATGGCTTATCGAAGGGAGCAGGCCAGGGATTGAGGTCCGTCTCACGGGTTGGCTTCACTCCCCCACTGCCAGCCCTCTTGCTGCAACTCCACCAGAANNNAACCANGCCGCGACGGCGGTGCGATCGGGAAACGCGGCGGTGGCGGAGGAATCGGCCATCCTTCACCATATCGGCCAAGGATTGTGGTTCCTGTAGGGCTCGCGCAGCCCAGGACGCGCNNN

(retains just the header of the first seq in the multifasta)

Bonus:

If you also want to hard line-wrap the fasta to 80 chars (or whatever), the command becomes;

cat $1 | sed -e '1!{/^>.*/d;}' | sed ':a;N;$!ba;s/\n//2g' | sed '1!s/.\{80\}/&\n/g'

[psschlogl]

Can you keep it the last file .gz? Thanks

[Joe]

You can pipe the output of the command to gzip - just tell it to use STDIN as the data source.

Answer 4

[yhoogstrate]

grep -v '^>' in.fa > out.fa

if in.fa =

>chr1
ttttccccaaaagggg
>chr2
ACTGACTGnnnnACTG
>chr3.1
ACTGACTGaaaac
>chr3.2
ACTGACTGaaaacc
>chr3.3
ACTGACTGaaaaccc
>chr4
ACTGnnnn
>chr5
nnACTG

then out.fa becomes:

ttttccccaaaagggg
ACTGACTGnnnnACTG
ACTGACTGaaaac
ACTGACTGaaaacc
ACTGACTGaaaaccc
ACTGnnnn
nnACTG