use strict;
use warnings;

my @records;
my $currTail;
my $currField;

while (defined(my $line = <DATA>) or defined $currField) {
    my $field;
    my $tail;

    ($field, $tail) = $line =~ /^(.{10})  (.*)/ if defined $line;
    next if !defined $tail && !defined $currField;

    $field =~ tr/ //d if defined $field;
    $currField //= $field;

    if (! defined $field or (length $field && $currField ne $field)) {
        push @records, {} if $currField eq 'LOCUS';
        $records[-1]{$currField} = $currTail;
        $currField               = undef;
        $currTail                = undef;
        last if !defined $tail;
    }
    
    $currField = $field if length $field;
    push @$currTail, $tail if defined $tail;
}

for my $record (@records) {
    print "$_:\n", map{"   $_\n"} @{$record->{$_}} for sort keys %$record;
}


__DATA__
LOCUS       NM_001098209            3415 bp    mRNA    linear   PRI 27-APR-2014
DEFINITION  Homo sapiens catenin (cadherin-associated protein), beta 1, 88kDa
            (CTNNB1), transcript variant 2, mRNA.
ACCESSION   NM_001098209 XM_001133660 XM_001133664 XM_001133673 XM_001133675
VERSION     NM_001098209.1  GI:148233337
KEYWORDS    RefSeq.
SOURCE      Homo sapiens (human)
  ORGANISM  Homo sapiens
            Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
            Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini;
            Catarrhini; Hominidae; Homo.
     CDS             269..2614
                     /gene="CTNNB1"
                     /gene_synonym="armadillo; CTNNB; MRD19"
                     /codon_start=1
                     /product="catenin beta-1"
                     /protein_id="NP_001091679.1"
                     /db_xref="GI:148233338"
                     /db_xref="CCDS:CCDS2694.1"
                     /db_xref="GeneID:1499"
                     /db_xref="HGNC:HGNC:2514"
                     /db_xref="MIM:116806"
                     /translation="MATQADLMELDMAMEPDRKAAVSHWQQQSYLDSGIHSGATTTAP
                     SLSGKGNPEEEDVDTSQVLYEWEQGFSQSFTQEQVADIDGQYAMTRAQRVRAAMFPET
                     LDEGMQIPSTQFDAAHPTNVQRLAEPSQMLKHAVVNLINYQDDAELATRAIPELTKLL
//