Calcium-dependent lipolytic acyl-hydrolase activity in purified plant mitochondria

Bligny, Richard; Douce, Roland

doi:10.1016/0005-2760(78)90086-3

Cited by 32 publications

(12 citation statements)

References 21 publications

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“…The loss of mitochondrial integrity during aging has been ascribed to the release of free fatty acids (Douce and Lance 1972, Chan and Higgins 1978, Bligny and Douce 1978. In vitro aging experiments at 25°C reported in this paper also support these data.…”

Section: Discussionsupporting

confidence: 81%

Effect of bovine serum albumin on membrane potential in plant mitochondria

Diolez

Moreau

1983

Physiologia Plantarum

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The membrane potential in highly coupled potato (Solanum tuberosum L.) mitochondria, as measured by changes in safranine absorbance, was significantly increased by addition of bovine serum albumin. Purification of potato mitochondria on Percoll, in removing 50% of free unsaturated fatty acids, decreased the BSA‐de‐pendent membrane potential. The effect of added linoleic acid and of the natural accumulation of fatty acids during aging was studied. The response of membrane potential to addition of bovine serum albumin appeared to be directly correlated to the amount of free unsaturated fatty acids. Aging in vitro, in releasing free fatty acids, decreased respiratory control and ADP:O ratios and collapsed the membrane potential. During 2–3 h of incubation, addition of BSA completely restored membrane potential and oxidative phosphorylation. It is concluded that both in fresh and in aged potato mitochondria the effect of bovine serum albumin on oxidative phosphorylation can be ascribed to an effect on membrane permeability to ions. BSA, in binding free unsaturated fatty acids, restored maximal membrane potential. The bovine serum albumin‐dependent membrane potential appears to be a sensitive criterion of the functional integrity of the inner mitochondrial membrane.

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Section: Discussionsupporting

confidence: 81%

Effect of bovine serum albumin on membrane potential in plant mitochondria

Diolez

Moreau

1983

Physiologia Plantarum

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“…Phospholipid breakdown was measured using [U-'4C]phosphatidylcholine essentially as described earlier (6). The 1.5 Ci/mmol) in a final volume of 0.5 ml.…”

Section: Methodsmentioning

confidence: 99%

“…The aqueous 63 phase containing the radiolabeled choline was counted (0.5 ml of aqueous phase mixed with 5 ml of scintillation fluid, Scintiverse, Fisher) in a Beckman LS7500 Scintillation counter. Lipid components in the chloroform phase were separated by TLC and identified using authentic standards as described previously (6 (Table I). The release of free fatty acids can be attributed to lipolytic acyl hydrolase, phosphatidic acid and choline to phospholipase D, and diacylglycerol to phosphatidic acid phosphatase.…”

Section: Methodsmentioning

confidence: 99%

Calcium- and Calmodulin-Regulated Breakdown of Phospholipid by Microsomal Membranes from Bean Cotyledons

Paliyath¹,

Thompson²

1987

Plant Physiol.

101

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Evidence for the involvement of Ca2" and calmodulin in the regulation of phospholipid breakdown by microsomal membranes from bean cotyledons has been obtained by following the formation of radiolabeled degradation products from IU-'4Cjphosphatidylcholine. Three membraneassociated enzymes were found to mediate the breakdown of IU-`4C1 phosphatidylcholine, viz. phospholipase D (EC 3.1.4.4), phosphatidic acid phosphatase (EC 3.1.3.4), and lipolytic acyl hydrolase. Phospholipase D and phosphatidic acid phosphatase were both stimulated by physiological levels of free Ca", whereas lipolytic acyl hydrolase proved to be insensitive to Ca2". Phospholipase D was unaffected by calmodulin, but the activity of phosphatidic acid phosphatase was additionally stimulated by nanomolar levels ofcalmodulin in the presence of 15 micromolar free Ca2. Calmidazolium, a calmodulin antagonist, inhibited phosphatidic acid phosphatase activity at IC5. values ranging from 10 to 15 micromolar. Thus the Ca2"-induced stimulation of phosphatidic acid phosphatase appears to be mediated through calmodulin, whereas the effect of Ca2" on phospholipase D is independent of calmodulin. The role of Ca2" as a second messenger in the initiation of membrane lipid degradation is discussed.A variety of enzymes are able to degrade phospholipids. Phospholipase A2 and phospholipase C are the major phospholipiddegrading enzymes in animal tissue (11,26), but the enzymes responsible for phospholipid breakdown in plants are less well characterized. Phospholipase A2 and phospholipase C are apparently not present in plant tissues (13). Rather, the breakdown of plant phospholipids appears to be mediated by phospholipase D, which has been purified to apparent homogeneity (15), and nonspecific lipolytic acyl hydrolase (13,17 deesterification of arachidonic acid, a precursor of prostaglandin synthesis, by promoting phospholipase A2-mediated hydrolysis of membrane phospholipids (11,26). In the present study, we have examined the breakdown of phospholipids by microsomal membranes from senescing bean cotyledons and have obtained evidence that metabolism of phospholipid in plant membranes is also subject to regulation by calcium and calmodulin. MATERIALS AND METHODSBean seeds (Phaseolus vulgaris L. cv Kinghorn wax, Ontario Seed Co., Waterloo, Ontario, Canada) were germinated in vermiculite in darkness at 29°C. Microsomal membranes were prepared from the cotyledons of 5-d-old seedlings. The tissue was suspended (0.5 g/ml) in buffer (50 mM Hepes, 2 mM EGTA, 150 mm KCI, 0.5 mm DTE, 0.5 mM phenylmethylsulfonyl fluoride, and 0.25 mm sucrose, pH 7.0) and homogenized at 4°C in a Sorvall Omnimixer for 30 s and again in a Polytron homogenizer for 40 s. The homogenate was filtered through four layers of cheesecloth and centrifuged at 10,000g for 20 min. The supernatant was recentrifuged at 105,000g for 60 min to yield a pellet of microsomal membranes. The microsomes were washed once by resuspension in wash buffer (50 mM Hepes, 0.2 mM EGTA, 150 mm KCI, and 0.25 M sucrose, pH 7...

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“…Cytochrome aa3 measurements were carried out in whole cell homogenates obtained by sonication and in isolated mitochondria, according to the procedure described by Bligny and Douce [16]. Cytochrome aa3 was measured from the difference spectra between dithionite-reduced minus oxidized preparations.…”

Section: Cytochrome Oxidase Measurementsmentioning

confidence: 99%

Arrest of mitochondrial biogenesis in copper‐treated sycamore cells

et al. 1996

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Sycamore suspension cells (Acer pseudoplatanus L.) were grown in the presence of sublethal concentrations of copper (50 BM). During the first 5-6 days of treatment, growth was not affected, but cell respiration (coupled and uncoupled) declined to 60% of its normal value. This decline of respiration was attributed to a progressive diminution of the number of mitochondria in copper-treated cells, based on the demonstration of the concomitant decline of (1) cardiolipin (diphosphatidylglycerol) and cytochrome aa3 (cytochrome oxidase), two specific markers of mitochondrial inner membrane, and (2) fumarase activity, a specific marker of mitochondrial matrix space. In addition, the mitochondria extracted from copper-treated cells presented the same properties as those from control cells, concerning substrate oxidation, cardiolipin and cytochrome aa3 contents, and fumarase activity. These results strongly suggest that copper triggered an arrest of mitochondrial biogenesis, which preceded cell division arrest.

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Calcium-dependent lipolytic acyl-hydrolase activity in purified plant mitochondria

Cited by 32 publications

References 21 publications

Effect of bovine serum albumin on membrane potential in plant mitochondria

Effect of bovine serum albumin on membrane potential in plant mitochondria

Calcium- and Calmodulin-Regulated Breakdown of Phospholipid by Microsomal Membranes from Bean Cotyledons

Arrest of mitochondrial biogenesis in copper‐treated sycamore cells

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