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.
Department of Plant Systems Biology, Flanders Interuniversity Institute for Biotechnology, Ghent University, Technologiepark 927, B-9052 Ghent, Belgium.
Dominique
D
Vercammen
Brigitte
B
van de Cotte
Geert
G
De Jaeger
Dominique
D
Eeckhout
Peter
P
Casteels
Klaas
K
Vandepoele
Isabel
I
Vandenberghe
Jozef
J
Van Beeumen
Dirk
D
Inzé
Frank
F
Van Breusegem
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