Vacuolar proteases livening up programmed cell death

The molecular identity of the key executioners involved in controlling plant programmed cell death (PCD) has been elusive. In a recent paper published in Science, Hatsugai and coworkers reported that a well-characterized protease called VPE from the plant cell vacuole can cleave caspase-specific substrates and is required for cell death activation by tobacco mosaic virus. This work provides clear evidence for the importance of the vacuole in plant PCD and a novel regulatory function for this organelle as well as for VPE proteases.