A plant caspase-like protease activated during the hypersensitive response.
To test the hypothesis that caspase-like proteases exist and are critically involved in the implementation of programmed cell death (PCD) in plants, a search was undertaken for plant caspases activated during the N gene-mediated hypersensitive response (HR; a form of pathogen-induced PCD in plants) in tobacco plants infected with Tobacco mosaic virus (TMV). For detection, characterization, and partial purification of a tobacco caspase, the Agrobacterium tumefaciens VirD2 protein, shown here to be cleaved specifically at two sites (TATD and GEQD) by human caspase-3, was used as a target. In tobacco leaves, specific proteolytic processing of the ectopically produced VirD2 derivatives at these sites was found to occur early in the course of the HR triggered by TMV. A proteolytic activity capable of specifically cleaving the model substrate at TATD was partially purified from these leaves. A tetrapeptide aldehyde designed and synthesized on the basis of the elucidated plant caspase cleavage site prevented fragmentation of the substrate protein by plant and human caspases in vitro and counteracted TMV-triggered HR in vivo. Therefore, our data provide a characterization of caspase-specific protein fragmentation in apoptotic plant cells, with implications for the importance of such activity in the implementation of plant PCD.
Chichkova
Nina V
NV
Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119992, Russia.
Kim
Sang Hyon
SH
Titova
Elena S
ES
Kalkum
Markus
M
Morozov
Vasiliy S
VS
Rubtsov
Yuri P
YP
Kalinina
Natalia O
NO
Taliansky
Michael E
ME
Vartapetian
Andrey B
AB
D016960:Agrobacterium tumefaciens / Q000254:growth & development; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D049452:Green Fluorescent Proteins; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics / Q000502:physiology; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D010935:Plant Diseases / Q000235:genetics / Q000821:virology; D014026:Nicotiana / Q000201:enzymology* / Q000235:genetics / Q000821:virology; D014027:Tobacco Mosaic Virus / Q000187:drug effects / Q000254:growth & development
D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D010450:Endopeptidases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases