Extract multiple sequences on ncbi by gene symbol

[Giorgio C]

Hi all,

I have a lot of gene symbols belonging to the same organism and I need to extract the corresponding sequences on ncbi.

The gene symbol are all like: NMB0001, NMB0010, NMB0015...

Is there any automated way (scripts, tools,..) in order to obtain the fasta sequences?

Thanks in advance,
Giorgio

[Richard Finney]

Download gene_info and gene2accession from NCBI.

run these :
"wget -nc ftp://ftp.ncbi.nlm.nih.gov/gene/DATA/gene_info.gz"
"wget -nc ftp://ftp.ncbi.nlm.nih.gov/gene/DATA/gene2accession.gz"
Run gunzip to get these two files uncompressed and readable.

Get your genename(s) converted to entrez gene ids (second column), make sure taxonomy id is 122586 (. in your case).
Convert the gene names to GIs (gene info identifiers) or accessions.

Like this ...

bash-3.00# grep NMB0001 gene_info
122586 902103 NMB0001 NMB0001 - - - - acetyltransferase protein-coding - - - - 20120121

bash-3.00# grep "122586.902103" gene2accession
122586 902103 - - - AAF40480.1 7225226 AE002098.2 66731897 - - ? -
122586 902103 PROVISIONAL - - NP_273067.1 15675949 NC_003112.2 77358697 6 497 - -

Cut out the the accession(s) you want, either RNA or Protein. Put them into a flat text file as a list.
You'll want to program using bash/perl/c/command line utilities, whatever to automate the two basic commands above. Be careful.

There's supposedly "batch entrez" : http://www.ncbi.nlm.nih.gov/sites/batchentrez

But I've found it to be unreliable. It drops some accessions. Sad but true. You're welcome to try it.

The absolute best utility for batch downloading is "idfetch" : http://man.cx/idfetch%281%29 . It's command line, takes parameters, you can give it a file of your accessions or GIs and crank it up. ....downloading ... downloading ... downloading ... wahlah ... your file appears ...just like you asked for. I keep an old copy from an old NCBI C toolkit around and ... apparently it's still available in ncbi-tools-bin package ...

I run this on Linux/Unix command line ...
sudo apt-get install ncbi-tools-bin
and idfetch is there !!! So you can install the ncbi-tools-bin package and get it.
___
sudo apt-get install ncbi-tools-bin

$ man idfetch | head
IDFETCH(1) NCBI Tools User's Manual IDFETCH(1)



NAME
idfetch - retrieve biological data from the NCBI ID1 server

SYNOPSIS
idfetch [-] [-F str] [-G filename] [-Q filename] [-c N] [-d str] [-e N]
[-f str] [-g N] [-i N] [-l filename] [-n] [-o filename] [-q str] [-s str]
....

[Giorgio C]

Thank you so much for your time and suggestions. Actually I tried 'batch entrez' and as you reported, it's not so good; so you're right about that.

I really like your last option and I'm gonna try that.

Thanks again.

Cheers,
Giorgio

[dexterslab]

hi,
you might also wanna look into the BiomaRt package for R.