Edit : I know feature.type will give gene/CDS and feature.qualifiers will then give "db_xref"/"locus_tag"/"inference" etc. Is there a feature. object which will allow me to access the location (eg: [5240:7267](+) ) directly?
This URL give a bit more info, though I can't figure out how to use it for my purpose... http://biopython.org/DIST/docs/api/Bio.SeqFeature.SeqFeature-class.html#location_operator
Original Post:
I am trying to modify the location of features within a GenBank file. Essentially, I want to modify the following bit of a GenBank file:
gene 5240..7267
/db_xref="GeneID:887081"
/locus_tag="Rv0005"
/gene="gyrB"
CDS 5240..7267
/locus_tag="Rv0005"
/inference="protein motif:PROSITE:PS00177"
...........................
to
gene 5357..7267
/db_xref="GeneID:887081"
/locus_tag="Rv0005"
/gene="gyrB"
CDS 5357..7267
/locus_tag="Rv0005"
/inference="protein motif:PROSITE:PS00177"
.............................
Note the changes from 5240 to 5357
So far, from scouring the internet and Stackoverflow, I have:
from Bio import SeqIO
gb_file = "mtbtomod.gb"
gb_record = SeqIO.parse(open(gb_file, "r+"), "genbank")
rvnumber = 'Rv0005'
newstart = 5357
final_features = []
for record in gb_record:
for feature in record.features:
if feature.type == "gene":
if feature.qualifiers["locus_tag"][0] == rvnumber:
if feature.location.strand == 1:
feature.qualifiers["amend_position"] = "%s:%s" % (newstart, feature.location.end+1)
else:
# do the reverse for the complementary strand
final_features.append(feature)
record.features = final_features
with open("testest.gb","w") as testest:
SeqIO.write(record, testest, "genbank")
This basically creates a new qualifier called "amend_position".. however, what I would like to do is modify the location directly (with or without creating a new file...)
Rv0005 is just an example of a locus_tag I need to update. I have about 600 more locations to update, which explains the need for a script.. Help!
Ok, I have something which now fully works. I'll post the code in case anyone ever needs something similar
__author__ = 'Kavin'
from Bio import SeqIO
from Bio import SeqFeature
import xlrd
import sys
import re
workbook = xlrd.open_workbook(sys.argv[2])
sheet = workbook.sheet_by_index(0)
data = [[sheet.cell_value(r, c) for c in range(sheet.ncols)] for r in range(sheet.nrows)]
# Create dicts to store TSS data
TSS = {}
row = {}
# For each entry (row), store the startcodon and strand information
for i in range(2, sheet.nrows - 1):
if data[i][5] < -0.7: # Ensures BASS score is within significant range
Gene = data[i][0]
row['Direction'] = str(data[i][3])
row['StartCodon'] = int(data[i][4])
TSS[str(Gene)] = row
row = {}
else:
i += 1
# Create an output filename based on input filename
outfile_init = re.search('(.*)\.(\w*)', sys.argv[1])
outfile = str(outfile_init.group(1)) + '_modified.' + str(outfile_init.group(2))
final_features = []
for record in SeqIO.parse(open(sys.argv[1], "r"), "genbank"):
for feature in record.features:
if feature.type == "gene" or feature.type == "CDS":
if TSS.has_key(feature.qualifiers["locus_tag"][0]):
newstart = TSS[feature.qualifiers["locus_tag"][0]]['StartCodon']
if feature.location.strand == 1:
feature.location = SeqFeature.FeatureLocation(SeqFeature.ExactPosition(newstart - 1),
SeqFeature.ExactPosition(
feature.location.end.position),
feature.location.strand)
else:
feature.location = SeqFeature.FeatureLocation(
SeqFeature.ExactPosition(feature.location.start.position),
SeqFeature.ExactPosition(newstart), feature.location.strand)
final_features.append(feature) # Append final features
record.features = final_features
with open(outfile, "w") as new_gb:
SeqIO.write(record, new_gb, "genbank")
This assumes usage such as python program.py <genbankfile> <excel spreadsheet>
This also assumes a spreadsheet of the following format:
Gene Synonym Tuberculist_annotated_start Orientation Re-annotated_start BASS_score
Rv0005 gyrB 5240 + 5357 -1.782
Rv0012 Rv0012 14089 + 14134 -1.553
Rv0018c pstP 23181 - 23172 -2.077
Rv0032 bioF2 34295 + 34307 -0.842
Rv0037c Rv0037c 41202 - 41163 -0.554