I want to replace a sequence name in fasta file with another name

I have one fasta file and one text file fasta file contains sequences in fasta format and text file contains name of genes now I want to replace name of the sequences in fasta file after '>' sign with the gene names in text file I am new to perl though I have written a script but I don't know why its not working can anyone help me on that please following is my script:

print"Enter annotated file...";
$f1=<STDIN>;
print"Enter sequence file...";
$f2=<STDIN>;
open(FILE1,$f1) || die"Can't open $f1";
@annotfile=<FILE1>;
open(FILE2,$f2) || die"Can't open $f2";
@seqfile=<FILE2>;
@d=split('\t',@annotfile[0]);

for($i=0;$i<scalar(@annotfile);$i++)
{
@curr_all=split('\t',@annotfile[$i]);
@curr_id[$i]=@curr_all[0];
@gene_nm[$i]=@curr_all[1];
}
for($j=0;$j<scalar(@seqfile);$j++)
{   
$id=@curr_id[$j];
$gene=@gene_nm[$j];


@seqfile[$j]=~s/$id[$j]/$gene[$j]/g;
print @seqfile[$j];
}

my files looks like following:

annot.txt

pool75_contig_389 ubiquitin ligase e3a
pool75_contig_704 tumor susceptibility
pool75_contig_1977 serine threonine-protein phosphatase 4 catalytic subunit
pool75_contig_3064 bardet-biedl syndrome 2 protein P
pool75_contig_2499 succinyl- ligase

goat300.fasta

goat300.fasta


>pool75_contig_704
CCCTTTCTCCCTTCCCAACATTCAGAGATACTGAATCGAAACTCTTACTGTCTGTTAGAT
GACAAAGAGTTATCCATCCTACATACTCCAATTTCCTTCCGCAACTTGTGATTTCGCCGC
TTGAATCTTGACGCCGTGCGTCCACAGTTTGTTGTGTTTTATCAATCAAGGTCATTATCA
ACCGAAGACGCTATCTATTTTCTTGGCGAAGCTCTCGGAAAGGAGCCATCGAAATGGAAG
TATTTCTCAAGAAAGTCCGCGAGTTATCCCGGAAGCAGTTC
>pool75_contig_389
GACCTATACCGGACCGTCACTGAAAGNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
ACGATCCAGGCATGGAGTTGTGGTGACGAGTAGGAGGGTCACCGTGGTGAGCGGGAAGCC
TCGGGCGTGAGCCTGGGTGGAGCCGCCACGGGTGCAGATCTTGGTGGTAGTAGCAAATAT
TCAAGTGAGAACCTTGAAGGCCGAGGTGGAGAAGGNNNNNNNNNNNNNNNNNNNNNNNNN
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNTCATTTGTAT
CGCCCGGAAAACGTCACAAGAACGGGAGTTGCGTACAGAA
>pool75_contig_1977
AAGGGACACCGTTGGGTGAGGCGAGCTGCGTTCCTCGAACCATGGCTTCAAAAAGCGACT
TAGACCGTCAGATTGAACAGCTCAGGGCCTGCAAGCTCATTACAGAGGATGAGGTTAAGG
CACTCTGCGCTAAGGCGCGTGAGATTTTAATTGAAGAGAGTAATGTCCAGTGCGTGGACT
CACCTGTCACGGTTTGTGGCGATATCCACGGCCAGTTTTACGACTTGATTGAACTGTTTA
AAGTGGGCGGAGATGTTC
>pool75_contig_3064
TTACTATTTCTGGGCCTTAAGACTGGCTTAGTCGCTTACGACCCTTATAACAATGTAGAT
GTATATTATAAGGATCTTCCTGATGGTGCTAACGCTATGTTAATTTATTCAAACTCACCG
ACAAAGGAACAGAATATGCTTTGGCAGGTGGAAACTGTTCGATAATTGGATTGAACGACG
GCGGATGCGAGGTATTTTGGACAGTCACTGGCGACTCCGTTTGCTCTCTTTGCTCGATTA
AATCCGACAGCGATAAGTCAAGAGATTTTGTGGTTGGCTCTGAAGATTTTGACATCCGAA
TCTTCCATGGGGATGCCATAATATATGAAATCACGGAGTCTGATG
>pool75_contig_2499
AAGAGAAGAGGTGAGTTTGAGTATTGTTTGTGTGTGTGTGGTTGGGTGAGTGTGTGGTAT
GTGGTGTATGTGTGTGATGAATGTATGTGAAAGAGAGTGATGAATCTCATGGATATGTTC
GAGTTCGTGGTTTCCATTGATCGGTTATAGCCGAGATGATGGATGTGTTCCATGTGTCTG
ATTTCAGTTTAGGATTGTGTTGATGATGTTGATGATGAAAATTGTTGATGGTGATGACGA
TAGTGATGATGATGACGATGTTTCGGATAATGGTGATGATGATGATGGTTCCGACGATGA
TGTTTCGCTTGATGATGGTGATAATGATGACTCCGAAAATAACGTTGACTCGGATGAG

Solution

Consider using Bio::SeqIO to parse your Fasta dataset, instead of doing it yourself. Bio::SeqIO lives for this task, and is well developed for it. Additionally, if you're in bioinformatics, it would serve you well to get to know Bio::SeqIO. Given this, consider the following:

use strict;
use warnings;
use Bio::SeqIO;

open my $fh, '<', 'annot.txt' or die $!;
my %annot = map { /(\S+)\s+(.+)/; $1 => $2 } <$fh>;
close $fh;

my $in = Bio::SeqIO->new( -file => 'goat300.fasta', -format => 'Fasta' );

while ( my $seq = $in->next_seq() ) {
    my $seqID = $annot{ $seq->id } // $seq->id;
    print "$seqID\n" . $seq->seq . "\n";
}

Output on your datasets:

tumor susceptibility
CCCTTTCTCCCTTCCCAACATTCAGAGATACTGAATCGAAACTCTTACTGTCTGTTAGATGACAAAGAGTTATCCATCCTACATACTCCAATTTCCTTCCGCAACTTGTGATTTCGCCGCTTGAATCTTGACGCCGTGCGTCCACAGTTTGTTGTGTTTTATCAATCAAGGTCATTATCAACCGAAGACGCTATCTATTTTCTTGGCGAAGCTCTCGGAAAGGAGCCATCGAAATGGAAGTATTTCTCAAGAAAGTCCGCGAGTTATCCCGGAAGCAGTTC
ubiquitin ligase e3a
GACCTATACCGGACCGTCACTGAAAGNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNACGATCCAGGCATGGAGTTGTGGTGACGAGTAGGAGGGTCACCGTGGTGAGCGGGAAGCCTCGGGCGTGAGCCTGGGTGGAGCCGCCACGGGTGCAGATCTTGGTGGTAGTAGCAAATATTCAAGTGAGAACCTTGAAGGCCGAGGTGGAGAAGGNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNTCATTTGTATCGCCCGGAAAACGTCACAAGAACGGGAGTTGCGTACAGAA
serine threonine-protein phosphatase 4 catalytic subunit
AAGGGACACCGTTGGGTGAGGCGAGCTGCGTTCCTCGAACCATGGCTTCAAAAAGCGACTTAGACCGTCAGATTGAACAGCTCAGGGCCTGCAAGCTCATTACAGAGGATGAGGTTAAGGCACTCTGCGCTAAGGCGCGTGAGATTTTAATTGAAGAGAGTAATGTCCAGTGCGTGGACTCACCTGTCACGGTTTGTGGCGATATCCACGGCCAGTTTTACGACTTGATTGAACTGTTTAAAGTGGGCGGAGATGTTC
bardet-biedl syndrome 2 protein P
TTACTATTTCTGGGCCTTAAGACTGGCTTAGTCGCTTACGACCCTTATAACAATGTAGATGTATATTATAAGGATCTTCCTGATGGTGCTAACGCTATGTTAATTTATTCAAACTCACCGACAAAGGAACAGAATATGCTTTGGCAGGTGGAAACTGTTCGATAATTGGATTGAACGACGGCGGATGCGAGGTATTTTGGACAGTCACTGGCGACTCCGTTTGCTCTCTTTGCTCGATTAAATCCGACAGCGATAAGTCAAGAGATTTTGTGGTTGGCTCTGAAGATTTTGACATCCGAATCTTCCATGGGGATGCCATAATATATGAAATCACGGAGTCTGATG
succinyl- ligase
AAGAGAAGAGGTGAGTTTGAGTATTGTTTGTGTGTGTGTGGTTGGGTGAGTGTGTGGTATGTGGTGTATGTGTGTGATGAATGTATGTGAAAGAGAGTGATGAATCTCATGGATATGTTCGAGTTCGTGGTTTCCATTGATCGGTTATAGCCGAGATGATGGATGTGTTCCATGTGTCTGATTTCAGTTTAGGATTGTGTTGATGATGTTGATGATGAAAATTGTTGATGGTGATGACGATAGTGATGATGATGACGATGTTTCGGATAATGGTGATGATGATGATGGTTCCGACGATGATGTTTCGCTTGATGATGGTGATAATGATGACTCCGAAAATAACGTTGACTCGGATGAG

The hash %annot is initialized by reading and capturing the contents of your annot.txt data. A Bio::SeqIO object is created using your goat300.fasta file data. The while loop iterates through your fasta sequences. The variable $seqID either takes the associated value of the key in the %annot hash or it keeps the current sequence ID (the // notation means defined or, so that insures $seqID will be defined). Finally, the Fasta record is printed.

Hope this helps!