An extracellular calcium-binding domain in bacteria with a distant relationship to EF-hands

FEMS Microbiol Lett. 2003 Apr 11;221(1):103-10. doi: 10.1016/S0378-1097(03)00160-5.

Abstract

Extracellular Ca(2+)-dependent nuclease YokF from Bacillus subtilis and several other surface-exposed proteins from diverse bacteria are encoded in the genomes in two paralogous forms that differ by a approximately 45 amino acid fragment, which comprises a novel conserved domain. Sequence analysis of this domain revealed a conserved DxDxDGxxCE motif, which is strikingly similar to the Ca(2+)-binding loop of the calmodulin-like EF-hand domains, suggesting an evolutionary relationship between them. Functions of many of the other proteins in which the novel domain, named Excalibur (extracellular calcium-binding region), is found, as well as a structural model of its conserved motif are consistent with the notion that the Excalibur domain binds calcium. This domain is but one more example of the diversity of structural contexts surrounding the EF-hand-like calcium-binding loop in bacteria. This loop is thus more widespread than hitherto recognized and the evolution of EF-hand-like domains is probably more complex than previously appreciated.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Bacteria / genetics*
  • Bacteria / metabolism
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Calcium / metabolism
  • Calcium-Binding Proteins / chemistry*
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Deoxyribonucleases / chemistry
  • Deoxyribonucleases / genetics
  • EF Hand Motifs / genetics*
  • Evolution, Molecular
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Molecular Sequence Data

Substances

  • Bacterial Proteins
  • Calcium-Binding Proteins
  • Membrane Proteins
  • Deoxyribonucleases
  • YokF protein, Bacillus subtilis
  • Calcium