Something like this will work, it depends how yuo are storing the info. I like hashes, so I put it in a hash.
open (SEQ, "proteinfile.fasta") or die "Dang!";
my $name = <SEQ>;
($genename, $species) = $name =~ /some regex/;
while (<SEQ>) {
if (/>/) {
$genomes{$genename_species}{'genename'} =...