Developmental regulation of a VEIDase caspase-like proteolytic activity in barley caryopsis.
Caspases are essential in animal programmed cell death both as initiator and executioner proteases. Plants do not have close caspase homologues, but several instances of caspase-like proteolytic activity have been demonstrated in connection with programmed cell death in plants. It was asked if caspase-like proteases are involved during development of the barley caryopsis. The presence of a caspase-6-like proteolytic activity that preferentially cleaved the sequence VEID was demonstrated. A range of protease inhibitors was tested and only caspase-specific inhibitors showed major inhibitory effects. The profile of VEIDase activity in developing starchy endosperm, embryo, and whole caryopsis was measured and showed a general trend of higher activity in young, rapidly developing tissues. The VEIDase activity was localized in vivo to vesicles, shown to be autophagosomes, in randomly distributed cells of the starchy endosperm. The VEIDase activity detected in barley caryopsis is similar to activities described previously in mammals, spruce, yeast, and thale cress. In mammals, spruce, and yeast, VEIDase activity has been shown to be positively correlated with the occurrence of programmed cell death. Several manifestations of programmed cell death exist in developing barley caryopsis, indicating a connection between VEIDase activity and developmental programmed cell death in barley.
Borén
Mats
M
Department of Plant Biology and Forestry Genetics, Swedish University of Agricultural Sciences, PO Box 7080, SE-75007, Uppsala, Sweden.
Höglund
Anna-Stina
AS
Bozhkov
Peter
P
Jansson
Christer
C
D017209:Apoptosis; D020169:Caspases / Q000235:genetics / Q000378:metabolism*; D053938:DNA Fragmentation; D018506:Gene Expression Regulation, Plant; D001467:Hordeum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012639:Seeds / Q000201:enzymology / Q000235:genetics / Q000254:growth & development
D010940:Plant Proteins; D020169:Caspases