Effect of polyamines on stabilization of molecular complexes in thylakoid membranes of osmotically stressed oat leaves

Abstract

Monocotyledonous leaves subjected to osmotica used for protoplast isolation accumulate a massive amount of putrescine (Put), lose chlorophyll and senesce rapidly. Treatment with spermidine (Spd) or spermine (Spm) prevents the loss of chlorophyll, indicating preservation of the thylakoid membranes at the site of the chlorophyll-protein complexes. Using several recently produced antibody probes, the effects on the stabilization of thylakoid membranes of applying either difluoromethylarginine (DFMA), a specific inhibitor of putrescine synthesis via arginine decarboxylase, or the polyamines Spd, Spm, or diaminopropane (Dap) to osmotically shocked oat leaves (Arena sativa L.) have been investigated. High protein levels were maintained in thylakoid membranes of leaf tissue incubated in the dark in the presence of 0.6 M sorbitol when pretreated with DFMA. After 48 h incubation, the level of the thylakoid protein D 1, at the core of photosystem II, was higher in the DFMA-pretreated leaves as was the stromal protein ribulose-l,5-bisphosphate carboxylase-oxygenase (Rubisco; as indicated by the level of large subunits). Applications of Spd, Spm or Dap were effective in retarding the loss of D1, D2 and cytochrome f from the thylakoid membranes as well as Rubisco large subunits and chlorophyll from the leaf tissue. The effects of polyamine applications may be mediated through Dap since most of the added Spd or Spm was converted to Dap within 6 h. The possible mechanisms of action of polyamine application s and DFMA-pretreatment on stabilizing the composition of the thylakoid membrane are also discussed.* To whom correspondence should be addressed; FAX: 44 (903) 72 67 80 Abbreviations : Cyt = cytochrorne; Dap = diaminopropane; DFMA = DL-cc-difluoromethylarginine ; LSU = large subunit (of Rubisco); Put=putrescine; Rubisco=ribulose-l,5-bisphosphate carboxylase-oxygenase; Spd = spermidine; Spin = spermine; SDS-PAGE = sodium dodecyl sulphate-polyacrylamide gel electrophoresis Key words: Polyamine -Ribulose-l,5-bisphosphate carboxylase/oxygenase (large subunit) -Thylakoid membrane (stabilization) -Thylakoid protein (D1, D2, cytochrome J)

Effect of nitric oxide and putrescine on antioxidative responses under NaCl stress in chickpea plants

“…Their ability to decrease lipid peroxidation, under stress conditions has been attributed to their supposed ability to stabilize membranes by association with negatively charged phospholipids (Besford et al, 1973).…”

Sorbitol and NaCl stresses affect free, microsome-associated and thylakoid-associated polyamine content in Zea mays and Phaseolus vulgaris

“…The importance of chloroplast PAs in the function of photosynthetic membranes in tobacco leaves recently has been described by Ioannidis and Kotzabasis (2007). Also exogenous Spd was effective in stabilization of thylakoid membranes under stress conditions and during senescence (Besford et al 1993;Legocka and Zajchert 1999).…”

“…Plant PA metabolism is extremely sensitive to adverse environmental conditions, so PAs are considered as stress markers in plants (Kumar et al 1993;Bouchereau et al 1999;Liu et al 2007;Kusano et al 2008;Takahashi and Kakehi 2010). The function of PAs is presumed to be protective, as they act as free radical scavengers, stabilize cellular membranes, and maintain cellular balance (Bors et al 1989;Besford et al 1993). However, the precise role and mode of action of PAs in plant stress have long been a matter of debate.…”

Constitutively Elevated Levels of Putrescine and Putrescine-Generating Enzymes Correlated with Oxidant Stress Resistance in Conyza bonariensis and Wheat

“…(c) Putrescine and other polyamines might interact with membranes, either by inhibiting transbilayer movement of phospholipids (Bratton, 1994), or by stabilizing molecular complexes of thylakoid membranes (Popovic et al, 1979;Besford et al, 1993).…”