title: Bacterial calpains and the evolution of the calpain (C2) family of peptidases.
abstract: Homologues of calpain, often thought to be an essential, cytoplasmic, calcium-dependent cysteine endopeptidase found exclusively in eukaryotes, have been found in bacterial proteomes. The homologues lack calcium-binding sites, have differing domain architectures, and can be secreted or membrane-associated. Homologues are rare and occur in a minority of bacterial phyla and often in a minority of species in a genus. However, the differences in domain architecture argue against a recent, horizontal gene transfer from a eukaryote. From analysis of a phylogenetic tree and absence of homologues in archaea, calpains in eukaryotes may be derived from genes horizontally transferred from a bacterium.
authors.affiliation: Wellcome Trust Sanger Institute and the EMBL-European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridgeshire, CB10 1SA, UK. ndr@sanger.ac.uk.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Rawlings
mesh_terms: D001419:Bacteria / Q000201:enzymology* / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002154:Calpain / Q000235:genetics* / Q000378:metabolism; D056890:Eukaryota / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D010802:Phylogeny
chemical_list: D001426:Bacterial Proteins; D002154:Calpain