Impact of natural variation in bacterial F17G adhesins on crystallization behaviour

Acta Crystallogr D Biol Crystallogr. 2005 Aug;61(Pt 8):1149-59. doi: 10.1107/S0907444905017038. Epub 2005 Jul 20.


Since the introduction of structural genomics, the protein has been recognized as the most important variable in crystallization. Recent strategies to modify a protein to improve crystal quality have included rationally engineered point mutations, truncations, deletions and fusions. Five naturally occurring variants, differing in 1-18 amino acids, of the 177-residue lectin domain of the F17G fimbrial adhesin were expressed and purified in identical ways. For four out of the five variants crystals were obtained, mostly in non-isomorphous space groups, with diffraction limits ranging between 2.4 and 1.1 A resolution. A comparative analysis of the crystal-packing contacts revealed that the variable amino acids are often involved in lattice contacts and a single amino-acid substitution can suffice to radically change crystal packing. A statistical approach proved reliable to estimate the compatibilities of the variant sequences with the observed crystal forms. In conclusion, natural variation, universally present within prokaryotic species, is a valuable genetic resource that can be favourably employed to enhance the crystallization success rate with considerably less effort than other strategies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adhesins, Bacterial / chemistry*
  • Adhesins, Bacterial / genetics*
  • Amino Acid Sequence
  • Crystallization / methods*
  • Crystallography, X-Ray
  • Disaccharides / chemistry
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / genetics*
  • Genetic Variation*
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Structure, Tertiary
  • Sequence Alignment


  • Adhesins, Bacterial
  • Disaccharides
  • Escherichia coli Proteins
  • F17-G adhesin protein, E coli