Open AccessAn extracellular calcium‐binding domain in bacteria with a distant relationship to EF‐hands
Author(s) -
Rigden Daniel J.,
Jedrzejas Mark J.,
Galperin Michael Y.
Publication year - 2003
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/s0378-1097(03)00160-5
Subject(s) - extracellular , calmodulin , ef hand , bacillus subtilis , biology , calcium binding protein , bacteria , conserved sequence , binding site , calcium , sequence alignment , nuclease , peptide sequence , genetics , biochemistry , microbiology and biotechnology , dna , gene , chemistry , enzyme , organic chemistry
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 ∼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 ( ex tracellular cal cium‐ b inding r egion), 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.