title: Metacaspase 2 of Trypanosoma brucei is a calcium-dependent cysteine peptidase active without processing.
abstract: Metacaspases are cysteine peptidases that are distantly related to the caspases, for which proteolytic processing is central to their activation. Here, we show that recombinant metacaspase 2 (MCA2) from Trypanosoma brucei has arginine/lysine-specific, Ca(2+)-dependent proteolytic activity. Autocatalytic processing of MCA2 occurred after Lys55 and Lys268; however, this was shown not to be required for the enzyme to be proteolytically active. The necessity of Ca(2+), but not processing, for MCA2 enzymatic activity clearly distinguishes MCA2 from the caspases and would be consistent with different physiological roles.
authors.affiliation: Wellcome Centre for Molecular Parasitology and Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Catherine X
authors.initials: CX
authors.lastname: Moss
authors.forename: Gareth D
authors.initials: GD
authors.lastname: Westrop
authors.forename: Luiz
authors.initials: L
authors.lastname: Juliano
authors.forename: Graham H
authors.initials: GH
authors.lastname: Coombs
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Mottram
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D015800:Protozoan Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000378:metabolism
chemical_list: D015800:Protozoan Proteins; D011994:Recombinant Proteins; D001120:Arginine; D020169:Caspases; D003546:Cysteine Endopeptidases; D008239:Lysine; D002118:Calcium