Thank you so much for your advice! I am now trying to create a set of new index files with the NONCODE file using bowtie2-build as follows:
bowtie2-build –f genome.fa genome
Where genome.fa is the NONCODE2016_mouse.fa I downloaded from http://www.noncode.org/download.php. I was able to successfully create six index files (genome.2.bt2, genome.4.bt2, genome.rev.1.bt2, genome.1.bt2, genome.3.bt2, genome.rev.2.bt2). However, when I rerun tophat2 with these new index files, I still get: “Error: Couldn't build bowtie2 index with err = 1” at the "Building Bowtie index" step.
When I used:
bowtie2-inspect -n genome
the output I got was very large, and the following is a small portion:
NONMMUT000001.2
NONMMUT000009.2
NONMMUT000015.2
NONMMUT000018.2
It doesn't seem to match the first column of the NONCODE mouse mm10 gtf file, rather it seems to match the transcript_id instead. The following is a small portion of my gtf file:
chr1 Cufflinks transcript 3063334 3064403 0 + . gene_id "NONMMUG000001.1"; transcript_id "NONMMUT000001.1"; FPKM "0"; exon_number 1;
chr1 Cufflinks exon 3063334 3064403 0 + . gene_id "NONMMUG000001.1"; transcript_id "NONMMUT000001.1"; FPKM "0"; exon_number 1;
chr1 Cufflinks transcript 3456668 3503634 0 + . gene_id "NONMMUG000008.1"; transcript_id "NONMMUT000009.1"; FPKM "0"; exon_number 2;
chr1 Cufflinks exon 3456668 3456768 0 + . gene_id "NONMMUG000008.1"; transcript_id "NONMMUT000009.1"; FPKM "0"; exon_number 2;
chr1 Cufflinks exon 3503486 3503634 0 + . gene_id "NONMMUG000008.1"; transcript_id "NONMMUT000009.1"; FPKM "0"; exon_number 2;
chr1 Cufflinks transcript 3670236 3671869 0 + . gene_id "NONMMUG000012.1"; transcript_id "NONMMUT000015.1"; FPKM "0"; exon_number 1;
chr1 Cufflinks exon 3670236 3671869 0 + . gene_id "NONMMUG000012.1"; transcript_id "NONMMUT000015.1"; FPKM "0"; exon_number 1;
chr1 Cufflinks transcript 3869653 3898640 0 + . gene_id "NONMMUG000014.1"; transcript_id "NONMMUT000018.1"; FPKM "0"; exon_number 2;
chr1 Cufflinks exon 3869653 3869781 0 + . gene_id "NONMMUG000014.1"; transcript_id "NONMMUT000018.1"; FPKM "0"; exon_number 2;
I am wondering if I produced the bowtie2 index files correctly? Do I need to add some command line options to bowtie2-build, or do I need to do some pre-processing with the original fasta file? I would really appreciate your help.
Thank you very much!