Role of the ubiquitin-proteasome pathway and some peptidases during seed germination and copper stress in bean cotyledons.
The role of the ubiquitin (Ub)-proteasome pathway and some endo- and aminopeptidases (EPs and APs, respectively) was studied in cotyledons of germinating bean seeds (Phaseolus vulgaris L.). The Ub system appeared to be important both in the early (3 days) and late (9 days) phases of germination. In the presence of copper, an increase in protein carbonylation and a decrease in reduced -SH pool occurred, indicating protein damage. This was associated with an enhancement in accumulation of malondialdehyde, a major product of lipid peroxidation, and an increase in content of hydrogen peroxide (H2O2), showing oxidative stress generation. Moreover, copper induced inactivation of the Ub-proteasome (EC 3.4.25) pathway and inhibition of leucine and proline aminopeptidase activities (EC 3.4.11.1 and EC 3.4.11.5, respectively), thus limiting their role in modulating essential metabolic processes, such as the removal of regulatory and oxidatively-damaged proteins. By contrast, total trypsin and chymotrypsin-like activities (EC 3.4.21.4 and EC 3.4.21.1, respectively) increased after copper exposure, in parallel with a decrease in their inhibitor capacities (i.e. trypsin inhibitor and chymotrypsin inhibitor activity), suggesting that these endoproteases are part of the protective mechanisms against copper stress.
Plant Toxicology and Molecular Biology of Microorganisms, Faculty of Sciences of Bizerta, 7021 Zarzouna, Tunisia. Electronic address: ines.karmous@yahoo.fr.
Inès
I
Karmous
Plant Toxicology and Molecular Biology of Microorganisms, Faculty of Sciences of Bizerta, 7021 Zarzouna, Tunisia. Electronic address: cabdelilah1@yahoo.fr.
Abdelilah
A
Chaoui
Plant Toxicology and Molecular Biology of Microorganisms, Faculty of Sciences of Bizerta, 7021 Zarzouna, Tunisia. Electronic address: j.dayja@yahoo.fr.
Khadija
K
Jaouani
Proteomics Research Group, Department of Biochemistry and Environmental Research Institute University College Cork, Lee Maltings, Prospect Row, Mardyke, Cork, Ireland. Electronic address: d.sheehan@ucc.ie.
David
D
Sheehan
Plant Toxicology and Molecular Biology of Microorganisms, Faculty of Sciences of Bizerta, 7021 Zarzouna, Tunisia. Electronic address: ezzferjani2002@yahoo.fr.
Ezzedine
E
El Ferjani
Dipartimento di Scienze della Terra, della Vita e dell'Ambiente, Sezione di Biologia Vegetale, Università di Urbino "Carlo Bo", Via Bramante 28, 61029 Urbino, Italy. Electronic address: valeria.scoccianti@uniurb.it.
Valeria
V
Scoccianti
Dipartimento di Scienze Biomolecolari, Sezione di Biochimica e Biologia Molecolare, Università di Urbino "Carlo Bo", Via Saffi 2, 61029 Urbino, Italy. Electronic address: rita.crinelli@uniurb.it.
Rita
R
Crinelli
D000626:Aminopeptidases / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D002918:Chymotrypsin / Q000378:metabolism; D003300:Copper / Q000737:chemistry*; D018548:Cotyledon / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development; D018525:Germination / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation; D018384:Oxidative Stress; D010447:Peptide Hydrolases / Q000378:metabolism*; D027805:Phaseolus / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D012639:Seeds / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D014357:Trypsin / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*
D025801:Ubiquitin; D002244:Carbon; D003300:Copper; D010447:Peptide Hydrolases; D000626:Aminopeptidases; D002918:Chymotrypsin; D014357:Trypsin; D046988:Proteasome Endopeptidase Complex
Aminopeptidase; Chymotrypsin; Copper; Germination; Proteasome; Trypsin; Ubiquitin