title: Major Cys protease activities are not essential for senescence in individually darkened Arabidopsis leaves.
abstract: Papain-like Cys Proteases (PLCPs) and Vacuolar Processing Enzymes (VPEs) are amongst the most highly expressed proteases during leaf senescence in Arabidopsis. Using activity-based protein profiling (ABPP), a method that enables detection of active enzymes within a complex sample using chemical probes, the activities of PLCPs and VPEs were investigated in individually darkened leaves of Arabidopsis, and their role in senescence was tested in null mutants.
  
  
  
  ABPP and mass spectrometry revealed an increased activity of several PLCPs, particularly RD21A and AALP. By contrast, despite increased VPE transcript levels, active VPE decreased in individually darkened leaves. Eight protease knock-out lines and two protease over expressing lines were subjected to senescence phenotype analysis to determine the importance of individual protease activities to senescence. Unexpectedly, despite the absence of dominating PLCP activities in these plants, the rubisco and chlorophyll decline in individually darkened leaves and the onset of whole plant senescence were unaltered. However, a significant delay in progression of whole plant senescence was observed in aalp-1 and rd21A-1/aalp-1 mutants, visible in the reduced number of senescent leaves.
  
  
  
  Major Cys protease activities are not essential for dark-induced and developmental senescence and only a knock out line lacking AALP shows a slight but significant delay in plant senescence.
authors.affiliation: The Plant Chemetics laboratory, Max Planck Institute for Plant Breeding Research, 50829, Cologne, Germany.|The Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, Australia.
authors.forename: Adriana
authors.initials: A
authors.lastname: Pružinská
authors.affiliation: The Plant Chemetics laboratory, Max Planck Institute for Plant Breeding Research, 50829, Cologne, Germany.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Shindo
authors.affiliation: The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Center for Physiological Proteomics, The Scripps Research Institute, La Jolla, 92037, California, USA.
authors.forename: Sherry
authors.initials: S
authors.lastname: Niessen
authors.affiliation: The Plant Chemetics laboratory, Max Planck Institute for Plant Breeding Research, 50829, Cologne, Germany.
authors.forename: Farnusch
authors.initials: F
authors.lastname: Kaschani
authors.affiliation: Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829, Cologne, Germany.
authors.forename: Réka
authors.initials: R
authors.lastname: Tóth
authors.affiliation: The Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, Perth, WA, Australia.
authors.forename: A Harvey
authors.initials: AH
authors.lastname: Millar
authors.affiliation: The Plant Chemetics laboratory, Max Planck Institute for Plant Breeding Research, 50829, Cologne, Germany. renier.vanderhoorn@plants.ox.ac.uk.|The Plant Chemetics Laboratory, Department of Plant Sciences, University of Oxford, OX1 3RB, Oxford, UK. renier.vanderhoorn@plants.ox.ac.uk.
authors.forename: Renier A L
authors.initials: RA
authors.lastname: van der Hoorn
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D057056:Cysteine Proteases / Q000235:genetics / Q000378:metabolism*; D003624:Darkness; D018515:Plant Leaves / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002734:Chlorophyll; D057056:Cysteine Proteases; D012273:Ribulose-Bisphosphate Carboxylase
keywords: Activity-based protein profiling; Papain-like proteases; Senescence; Vacuolar processing enzymes