diff --git a/src/exabiome/gtdb/prepare_data.py b/src/exabiome/gtdb/prepare_data.py
index d3db8b2..bc993b8 100644
--- a/src/exabiome/gtdb/prepare_data.py
+++ b/src/exabiome/gtdb/prepare_data.py
@@ -87,11 +87,13 @@ def prepare_data(argv=None):
 
     parser = argparse.ArgumentParser()
     parser.add_argument('accessions', type=str, help='file of the NCBI accessions of the genomes to convert')
+
     parser.add_argument('fadir', type=str, help='directory with NCBI sequence files')
     parser.add_argument('metadata', type=str, help='metadata file from GTDB')
     parser.add_argument('tree', type=str, help='the distances file')
     parser.add_argument('out', type=str, help='output HDF5')
     grp = parser.add_mutually_exclusive_group()
+    parser.add_argument('--locus_tags', type=str, help='file of the NCBI locus tags of the genes to convert', default=None)
     parser.add_argument('-e', '--emb', type=str, help='embedding file', default=None)
     grp.add_argument('-P', '--protein', action='store_true', default=False, help='get paths for protein files')
     grp.add_argument('-C', '--cds', action='store_true', default=False, help='get paths for CDS files')
@@ -118,6 +120,11 @@ def prepare_data(argv=None):
     with open(args.accessions, 'r') as f:
         taxa_ids = [l[:-1] for l in f.readlines()]
 
+    # read locus tags
+    logger.info('reading locus tags %s' % args.locus_tags)
+    with open(args.locus_tags, 'r') as f:
+        locus_ids = set([l[:-1] for l in f.readlines()])
+
     # get paths to Fasta Files
     fa_path_func = get_genomic_path
     if args.cds:
@@ -214,7 +221,7 @@ def func(row):
             SeqTable = DNATable
             if args.cds:
                 logger.info("reading and writing CDS sequences")
-                seqit = DNAVocabGeneIterator(fapaths, logger=logger, min_seq_len=args.min_len)
+                seqit = DNAVocabGeneIterator(fapaths, locus_ids=locus_ids, logger=logger, min_seq_len=args.min_len)
             else:
                 seqit = DNAVocabIterator(fapaths, logger=logger, min_seq_len=args.min_len)
     else:
diff --git a/src/exabiome/sequence/convert.py b/src/exabiome/sequence/convert.py
index 56463df..09c936d 100644
--- a/src/exabiome/sequence/convert.py
+++ b/src/exabiome/sequence/convert.py
@@ -362,7 +362,9 @@ class DNAVocabIterator(VocabIterator):
     chars, basemap = _get_DNA_map()
 
 class DNAVocabGeneIterator(VocabIterator):
-
+    def __init__(self, paths, locus_ids=None, logger=None, min_seq_len=None):
+        super().__init__(paths, logger=logger, min_seq_len=min_seq_len)
+        self.locus_ids = locus_ids
     chars, basemap = _get_DNA_map()
 
     def _read_seq(self, path):
@@ -370,7 +372,8 @@ def _read_seq(self, path):
         kwargs = {'format': 'fasta', 'constructor': self.skbio_cls, 'validate': False}
         for seq in skbio.io.read(path, **kwargs):
             ltag = re.findall("\[locus_tag=([^[\]]*)\]", seq.metadata['description'])[0]
-            yield seq, ltag
+            if ltag in self.locus_ids:
+                yield seq, ltag
 
 def _get_AA_map():
     chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'