Type II metacaspases Atmc4 and Atmc9 of Arabidopsis thaliana cleave substrates after arginine and lysine.
Nine potential caspase counterparts, designated metacaspases, were identified in the Arabidopsis thaliana genome. Sequence analysis revealed two types of metacaspases, one with (type I) and one without (type II) a proline- or glutamine-rich N-terminal extension, possibly representing a prodomain. Production of recombinant Arabidopsis type II metacaspases in Escherichia coli resulted in cysteine-dependent autocatalytic processing of the proform into large and small subunits, in analogy to animal caspases. A detailed biochemical characterization with a broad range of synthetic oligopeptides and several protease inhibitors of purified recombinant proteins of both metacaspase 4 and 9 showed that both metacaspases are arginine/lysine-specific cysteine proteases and did not cleave caspase-specific synthetic substrates. These findings suggest that type II metacaspases are not directly responsible for earlier reported caspase-like activities in plants.
Vercammen
Dominique
D
Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium.
van de Cotte
Brigitte
B
De Jaeger
Geert
G
Eeckhout
Dominique
D
Casteels
Peter
P
Vandepoele
Klaas
K
Vandenberghe
Isabel
I
Van Beeumen
Jozef
J
Inzé
Dirk
D
Van Breusegem
Frank
F
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001120:Arginine; D020169:Caspases / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D007527:Isoenzymes / Q000378:metabolism; D008239:Lysine; D008969:Molecular Sequence Data; D017385:Sequence Homology
D029681:Arabidopsis Proteins; D007527:Isoenzymes; D001120:Arginine; D020169:Caspases; D008239:Lysine