Action of Calcium on Corn Mitochondria

Hanson, James A.; Malhotra, S. S.; Stoner, C. D.

doi:10.1104/pp.40.6.1033

Cited by 40 publications

(22 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The respiration data, presented as Arrhenius plots in Figure 1 1970 (22) for mitochondria from pears, the RC ratios shown in Table I fell within the range usually observed for succinate oxidation by plant mitochondria (1,3,5,23,26,27,30) and by rat liver mitochondria (6). Similarly, the ADP:O ratios, although exhibiting some variability, show no consistent pattern which can be related to temperature effects and approach the theoretical value of 2 for succinate oxidation.…”

Section: Resultsmentioning

confidence: 99%

Oxidative Activity of Mitochondria Isolated from Plant Tissues Sensitive and Resistant to Chilling Injury

1970

View full text Add to dashboard Cite

Arrhenius plots of the respiration rates of nmitochondria isolated from chilling sensitive plant tissuies (tonmato and cucumber fruit, and sweet potato roots) showed a linear decrease from 23 C to about 9 to 12 C (with Qio values of 1.3 to 1.6), at which point there was a marked deviation with an increased slope as temperatures were reduced to 1.5 C (Qio of 2.2 to 6.3). The phorylative activities (assayed at 25 C) of mitochondria, isolated from chilling sensitive sweet potato roots, were impaired as a result of chilling treatment. However, many factors, such as the polyphenol content of the parent tissue (4, 11), can markedly influence both oxidative rates and apparent phosphorylative ability of isolated plant mitochondria. Thus, where plant material is given a differential pretreatment, it is most difficult to ascertain whether the observed differences in activity represent a direct effect of the chilling treatment on the mitochondria or an indirect effect due to the release or activation of some components which might be operational during isolation. It has also been noted that the method of tissue disruption (8), the amount of mitochondrial protein in the assay mixture (20), and the time involved between tissue disruption and assay (18) influence the activity of isolated mitochondria but which may be of little significance in vivo.The experiments reported here were carried out with mitochondria from plant tissue not subjected to chilling treatment, with the aim of evaluating the influence of temperature on oxidation and phosphorylation of these isolated mitochondria. The results show that in mitochondria from chilling sensitive tissues there is a marked depression in the respiratory rates below the critical temperature for chilling injury (10 C) which is not observed with mitochondria from resistant tissues. It was also established that temperatures between 1.5 and 25 C do not influence the phosphorylative efficiency of mitochondria from either sensitive or resistant plant tissues.Mitochondria isolated from chilling resistant tissues show the capacity to swell to greater extent than the mitochondria from chilling sensitive tissues (14), indicating that the membranes of mitochondria from chilling sensitive tissues are less flexible than those from chilling resistant tissues. Furthermore, this difference in flexibility was related to the relative proportion of saturated and unsaturated fatty acids of the membrane lipids. A study of the temperature at which mixtures of the predominant saturated and unsaturated fatty acids, found in the membranes of plant mitochondria, solidify showed that a small increase in the proportion of unsaturated fatty acids causes a large decrease in the solidification temperature (13). Thus (Beta vulgaris L.).The mitochondria were prepared and respiratory activity was determined by the methods described in the preceding paper (20). Since it was shown (20) that the respiration of isolated mitochondria was greatly reduced and the mitochondria lost respiratory control when th...

show abstract

Section: Resultsmentioning

confidence: 99%

Oxidative Activity of Mitochondria Isolated from Plant Tissues Sensitive and Resistant to Chilling Injury

1970

View full text Add to dashboard Cite

show abstract

“…It ties in with a large body of work performed over the last decades on various plant species and tissues investigating the functional properties of Ca 2+ uptake into the matrix, mostly in vitro, i.e., in isolated mitochondria (Hanson et al, 1965;Dieter and Marmé, 1980;Akerman and Moore, 1983;Yamaya et al, 1984;Zottini and Zannoni, 1993). Convincing evidence has been provided for two different Ca 2+ uptake models, either by uniport or by exchange.…”

Section: Discussionmentioning

confidence: 99%

The EF-Hand Ca²⁺ Binding Protein MICU Choreographs Mitochondrial Ca²⁺ Dynamics in Arabidopsis

et al. 2015

View full text Add to dashboard Cite

Plant organelle function must constantly adjust to environmental conditions, which requires dynamic coordination. Ca 2+ signaling may play a central role in this process. Free Ca 2+ dynamics are tightly regulated and differ markedly between the cytosol, plastid stroma, and mitochondrial matrix. The mechanistic basis of compartment-specific Ca 2+ dynamics is poorly understood. Here, we studied the function of At-MICU, an EF-hand protein of Arabidopsis thaliana with homology to constituents of the mitochondrial Ca 2+ uniporter machinery in mammals. MICU binds Ca 2+ and localizes to the mitochondria in Arabidopsis. In vivo imaging of roots expressing a genetically encoded Ca 2+ sensor in the mitochondrial matrix revealed that lack of MICU increased resting concentrations of free Ca 2+ in the matrix. Furthermore, Ca 2+ elevations triggered by auxin and extracellular ATP occurred more rapidly and reached higher maximal concentrations in the mitochondria of micu mutants, whereas cytosolic Ca 2+ signatures remained unchanged. These findings support the idea that a conserved uniporter system, with composition and regulation distinct from the mammalian machinery, mediates mitochondrial Ca 2+ uptake in plants under in vivo conditions. They further suggest that MICU acts as a throttle that controls Ca 2+ uptake by moderating influx, thereby shaping Ca 2+ signatures in the matrix and preserving mitochondrial homeostasis. Our results open the door to genetic dissection of mitochondrial Ca 2+ signaling in plants.

show abstract

“…3) (17). The transport is competitive with ATP formation (7,8), and the increase in respiration can be viewed as coupling of electron transport to work, much as when ATP is formed. Table II shows that oxidation of all substrates was accelerated with Ca2+, Sr2+, and Ba2+, but not detectably so with the other cations.…”

Section: Methodsmentioning

confidence: 99%

“…The oxidation of NADH by corn mitochondria is stimulated by Ca2+ (17), but this is not true for malate-pyruvate or succinate oxidation (7). Only in the presence of inorganic phosphate is organic acid oxidation promoted and this can be attributed to the coupling of respiration to phosphate transport (10,16).…”

mentioning

confidence: 99%

Divalent Cation Stimulation of Substrate Oxidation by Corn Mitochondria

et al. 1970

Self Cite

View full text Add to dashboard Cite

The oxidation of reduced nicotinamide adenine dinucleotide, malate-pyruvate, and succinate by corn mitochondria in buffered 0.2 M KCl was determined as a function of divalent cations. Ni2+, Mg2+, Co2+, Ca2+, Mn2+, Sr2+, and Ba2+ stimulated reduced nicotinamide adenine dinucleotide oxidation in the absence of inorganic phosphate, with Ca2+ and Sr2+ having the greatest effect. Malate-pyruvate and succinate oxidation was stimulated by Ca2+, Ba2+, and Sr2+, but only in the presence of inorganic phosphate. Ca2+, Sr2+, and Ba2+ produced a simulated state 4 to state 3 transition with all three substrates, but only with malate-pyruvate and succinate was there a return to state 4. The order of divalent cation effectiveness suggests that the rate of water substitution from the cation inner coordination hydration sphere may be a rate-limiting step in certain mitochondrial reactions involving electron transport and phosphorylation.Plant mitochondria readily oxidize exogenous reduced nicotinamide adenine dinucleotide by a pathway stimulated by salts in general and by divalent cations in particular (6, 9). Hackett (6) found that the divalent cation stimulation was greater than that due to the ionic strength effect of monovalent salts. Associated with the respiratory stimulation was a light absorbancy increase, indicative of structural changes. Hackett suggested that the stimulation was due to either a greater NADH permeability or a release of some limiting step in the respiratory chain which might be the breakdown of high energy intermediates.The oxidation of NADH by corn mitochondria is stimulated by Ca2+ (17), but this is not true for malate-pyruvate or succinate oxidation (7). Only in the presence of inorganic phosphate is organic acid oxidation promoted and this can be attributed to the coupling of respiration to phosphate transport (10, 16). Hence, if Ca2+ is enhancing substrate permeability, it does so only for NADH. It seems likely that Hackett's second alternative is more probable; divalent cations release some rate-limiting step of the NADH oxidation pathway.The Ca2+-stimulated oxidation of NADH is accompanied by extra Ca2+ binding (10). When respiration ceases, the Ca2+ is released. Hanson and Miller (8) METHODSIsolation of Mitochondria. Mitochondria were isolated from 3-day-old corn shoots (Zea mays L., WF9 X M14) by a procedure similar to that used by Kenefick and Hanson (10). Corn seedlings were grown on paper toweling saturated with a 0.1 mm CaCl2 solution. Approximately 100 g of corn shoots were ground in an ice-cold mortar with 200 ml of 0.5 M sucrose, 50 mM tris-HCl (pH 7.5), 50 mm KH2PO4, and 5 mm disodium EDTA (pH 7.5). The homogenate was strained through four layers of cheesecloth and cleared of cell debris by centrifuging at 1,500g for 10 min, and the mitochondria were collected by centrifugation at 28,00g for 5 min. The mitochondria were then resuspended in a total of 50 ml of 0.4 M sucrose and again centrifuged at 1 ,500g for 10 min. The supernatant was decanted into clean tubes and 10 ml o...

show abstract

Action of Calcium on Corn Mitochondria

Cited by 40 publications

References 17 publications

Oxidative Activity of Mitochondria Isolated from Plant Tissues Sensitive and Resistant to Chilling Injury

Oxidative Activity of Mitochondria Isolated from Plant Tissues Sensitive and Resistant to Chilling Injury

The EF-Hand Ca²⁺ Binding Protein MICU Choreographs Mitochondrial Ca²⁺ Dynamics in Arabidopsis

Divalent Cation Stimulation of Substrate Oxidation by Corn Mitochondria

Contact Info

Product

Resources

About

Action of Calcium on Corn Mitochondria

Cited by 40 publications

References 17 publications

Oxidative Activity of Mitochondria Isolated from Plant Tissues Sensitive and Resistant to Chilling Injury

Oxidative Activity of Mitochondria Isolated from Plant Tissues Sensitive and Resistant to Chilling Injury

The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis

Divalent Cation Stimulation of Substrate Oxidation by Corn Mitochondria

Contact Info

Product

Resources

About

The EF-Hand Ca²⁺ Binding Protein MICU Choreographs Mitochondrial Ca²⁺ Dynamics in Arabidopsis