Scotty: lattice coincidences in the Protein Data Bank

The application Scotty, implemented within the Phasertng codebase, was used to perform a PDB-wide analysis of lattice coincidences. Using a broad definition of lattice coincidence, the number of distinct lattice clusters is approximately half the total number of crystallographic PDB entries. In over one thousand lattice clusters entries are reported in different space groups, consistent with pseudo-symmetric variation within a common lattice framework. Space-group frequencies computed at the lattice-coincidence level update those obtained by entry-based counting, and more accurately reflect priors for novel crystal forms. Combining lattice clustering with sequence identity and deposited oligomeric annotations reveals multiple cases of inconsistent biological assembly assignments among structures sharing near-identical lattices, suggesting an opportunity to improve annotations. The survey also identifies a range of protein systems forming extended in cellulo paracrystalline arrays, including storage, sequestration, toxin and membrane-associated proteins, an understudied area of structural biology. Overall, the results demonstrate that lattice-level analysis provides a valuable perspective on macromolecular self-association.