use strict;
use warnings;

my $s1 ='CCCATCTGTCCTTATTTGCTG';  my  @a1 = qw(ATCTG ATTTG);
my $s2 ='ACCCATCTGTCCTTGGCCAT';   my  @a2 = qw(CCATC);
my $s3 ='CCACCAGCACCTGTC';        my  @a3 = qw(CCACC CCAGC GCACC);
my $s4 ='CCCAACACCTGCTGCCT';      my  @a4 = qw(CCAAC ACACC);

put_bracket($s1, @a1);
put_bracket($s2, @a2);
put_bracket($s3, @a3);
put_bracket($s4, @a4);

sub put_bracket
{
    my $str = shift;
    $str =~ s/$_/[$&]/ for @_;
    return $str 
}