A major focus of the wwPDB is maintaining consistency and accuracy across the archive. As the PDB grows, developments in structure determination methods and technologies can challenge how all structures are represented. The wwPDB addresses these challenges with regular reviews of data processing procedures and coordinates remediation efforts to improve data representation.
The wwPDB and the EMDataBank/Unified Data Resource for 3DEM Project have collaborated to update the experimental methods descriptions of all electron microscopy and electron crystallography-derived structures in the PDB archive. With this work now completed, all 3DEM-derived entries have better-organized content and conform to the revised data model developed by the EMDataBank team for use within the wwPDB OneDep System. The OneDep System has supported deposition, annotation, and validation of 3DEM structures and fully integrates deposition of 3DEM maps and model coordinates since January 2016.
Examples of 3DEM model files (both remediated and from the OneDep system) are provided in a new wwPDB ftp directory (ftp://ftp.wwpdb.org/pub/pdb/test_data/EM/). A data-item level description of the changes made during remediation is provided here. 3DEM terms in the updated PDBx/mmCIF dictionary can be reviewed here.
Files in the current PDB ftp archive will be replaced with new files corresponding to the updated PDBx/mmCIF dictionary in 2017. Users are encouraged to review and test the example data files.
Large structures (containing >62 chains and/or 99999 ATOM lines) represented as single files in both PDBx/mmCIF and PDBML formats were fully
integrated into the main PDB FTP archive. Previously, large structures were represented in multiple "SPLIT" entries, which have now been
removed (obsoleted). Users searching for ID codes of "SPLIT" entries at wwPDB member websites will be automatically redirected to the combined
entry. The file large_split_mapping.tsv
lists the single large structure IDs created during this remediation and the corresponding obsoleted
SPLIT entries. Following this remediation, large structures will only be distributed in the main PDB FTP directory in PDBx/mmCIF and PDBML
formats, including biological assembly files. In addition, a separate directory in the PDB FTP archive provides access to a TAR file containing
a collection of minimal PDB format files that represent all large structures.
In 2012, the wwPDB reviewed structure factor files in the archive for format consistency and correspondence with coordinate data. As a result, around 43,800 structure factor files were updated to standardize the format and to incorporate data corrections. Changes made are described in the audit.details record of the structure factor file. These modified entries were released throughout 2013 in weekly batches of 1000.
The July 2011 release of Version 4.0 of the PDB archive involved remediating complex problems, including the representation of biological assemblies, residual B factors, peptide inhibitors and antibiotics, and entries in nonstandard crystal frames. A description of the review and resulting changes and corrections is available in a PDF document. Any changes made to the data are recorded in the PDBX_VERSION data category and in a revision log created for this release (XLS and CSV).
The March 2009 release of Version 3.2 of the PDB archive includes improvements and enhancements to the data,
including details about the chemistry of the polymer and the ligands bound to it, biological assemblies, and
binding sites of ligands and metal ions. An overview (PDF) is provided.
In August 2007, the wwPDB released remediated files for all PDB entries to ensure the uniformity of the
data across the archive. As a part of this project, many entries in the archive were updated and made consistent,
with a focus on sequences (references to databases and taxonomies, plus differences between chemical and
macromolecular sequences); primary citations; and assembly and virus information. In the Chemical Component
Dictionary, the chemistry and nomenclature in monomers and ligands was standardized. This release of remediated
data greatly improved searching and reporting capabilities across the PDB archive.
The details of this project have been described in
K. Henrick, Z. Feng, W. Bluhm, D. Dimitropoulos, J.F. Doreleijers, S. Dutta, J.L. Flippen-Anderson, J. Ionides, C. Kamada, E. Krissinel, C.L. Lawson, J.L. Markley, H. Nakamura, R. Newman, Y. Shimizu, J. Swaminathan, S. Velankar, J. Ory, E.L. Ulrich, W. Vranken, J. Westbrook, R. Yamashita, H. Yang, J. Young, M. Yousufuddin, and H. Berman (2008) Remediation of the Protein Data Bank Archive. Nucleic Acids Res. 36(Database issue): D426-D433.
C.L. Lawson, S. Dutta, J.D. Westbrook, K. Henrick, and H.M. Berman (2008) Representation of viruses in the remediated PDB archive. Acta Cryst. D64: 874-882.
The full scope of the remediation project is also available an
Overview Document (PDF).