Goodbye, GenBank is a package for use with Biopython that gives feature annotations from GenBank records a new and better life.
Project description
Goodbye, GenBank converts SeqFeature sequence annotations from NCBI GenBank records to a common and simplified format. GenBank feature annotations have a feature key and reasonably well defined qualifiers, but non-standard and discontinued feature types and qualifiers are commonly used and often the feature key is something someone made up and not a valid GenBank feature key. And even when a valid GenBank feature key is used, it is often incomplete and useless without additional details in the qualifiers.
This package converts most feature keys to appropriate Sequence Ontology terms used by GFF3 and SBOL. Non-standard qualifiers are repaired or removed.
Goodbye, GenBank is intended for those who wish to clean-up their GenBank files and then transition to a different format. The philosophy of this project is to salvage what is salvageable and to discard what is not. GenBank feature types are translated to Sequence Ontology terms; qualifiers are converted into a reduced set that contains only the parts that are not broken. Qualifiers are also converted to their correct type: int for integers, list only for qualifiers that can appear multiple times, bool for flags.
Moreover, different options are available to configure what is kept and what is thrown away.
Installation
pip install gbgb
Example
>>> feature
SeqFeature(FeatureLocation(ExactPosition(2931), ExactPosition(2936), strand=1), type='-10_signal')
>>> feature.qualifiers
{'ApEinfo_fwdcolor': ['pink'],
'ApEinfo_graphicformat': ['arrow_data {{0 1 2 0 0 -1} {} 0} width 5 offset 0'],
'ApEinfo_revcolor': ['pink'],
'label': ['RNAII Promoter (-10 signal)']}
>>>
>>> from gbgb import convert_feature
>>> feature = convert_feature(feature)
>>> feature
SeqFeature(FeatureLocation(ExactPosition(2931), ExactPosition(2936), strand=1), type='minus_10_signal')
>>> feature.qualifiers
{'note': 'RNAII Promoter (-10 signal)'}
>>>
>>> from gbgb import genbank_feature_key
>>> genbank_feature_key('minus_10_signal')
'regulatory'
Design considerations
For the most part, Goodbye, GenBank attempts to be idempotent, i.e. features and their types/keys and qualifiers can be safely transformed any number times with the same settings. The apparent mismatch between the conversion to Sequence Ontology feature terms and valid/fixed GenBank qualifiers is to simplify downstream processing. It is up to the users which qualifiers they wish to keep, but at least the choices they are given are reasonable.
Contributing
If you have any questions or suggestions or if you have found a unique new specimen of GenBank files that you would like to convert, please open an issue.
Issues
SO Term: “regulatory” feature type with /regulatory_class=”enhancer_blocking_element”
There is apparently no matching Sequence Ontology term. An enhancer blocking element behaves like an insulator, but is not an insulator. It is a transcriptional cis regulatory region, but that description is too broad.
SO Term: “misc_structure” feature type
GenBank uses this feature type for secondary and tertiary nucleotide structures. There appears to be no matching Sequence Ontology term.
SO Term: “assembly_gap” feature type
GenBank has both “gap” and “assembly_gap” feature types, which appear to have slightly different meanings. However, SO only has a “gap” term, which refers to assembly gaps.
GFF3 export
There is no good GFF3 exporter out there, so why not write one?
Skeleton code in gbgb.export.gff3
Reduction of SO terms
Allow users to specify a set of Sequence Ontology terms (inheriting from “sequence_feature”). Feature types will be reduced to the nearest Ontology term. This is to simplify downstream analysis.
/pseudo qualifier without /pseudogene=””
There is no matching Sequence Ontology term for this. Several GenBank files contain /pseudo without /pseudogene=”” to mean pseudogene.
Mandatory qualifiers
These should be filled in using a reasonable guess or errors should be thrown when trying to convert a feature without its mandatory qualifiers.
Materials
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