The inhibition of plant aconitate hydratase (aconitase) by fluorocitrate

Treble, D.H.; Lamport, Derek T. A.; Peters, Rudolph

doi:10.1042/bj0850113

Cited by 33 publications

(11 citation statements)

References 14 publications

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“…In plants however, it is not as potent an inhibitor as it is in animals. There are at least three possible reasons for this: (a) insensitivity of plant aconitase to fluorocitrate (31,32,45,49,50); (b) inability of either the thiokinase or citrate synthase to accept the fluoroderivative (16); and (c) defluorination of fluoroacetate (39,40,49,50). Plants, however, are capable of forming fluorocitrate, (32,49,50,55) and citrate does accumulate though to a lesser extent than in animal tissues (16,49, and this paper).…”

Section: Methodsmentioning

confidence: 99%

The Effect of Light on the Tricarboxylic Acid Cycle in Green Leaves

Chapman

Graham²

1974

Plant Physiol.

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Excised green leaves of mung bean (Phaseolus aureus L. var. Mungo) were used to determine the effect of light on the rate of endogenous respiration via the tricarboxylic acid cycle. ILlumination with white light at an intensity of 0.043 gram calories cm'minn (approximately 8600 lux) of visible radiation (400-700 nm) gave a rate of apparent photosynthesis, measured as net C02 uptake, of 21 mg CO2 dm-2hr-' which was about 11-fold greater than the rate of dark respiration. The feeding of '4CO2 or 14C-labeled acids of the tricarboxylic acid cycle in the dark for 2 hours was established as a suitable method for labeling mitochondrial pools of cycle intermediates.At a concentration of 0.1 mM 3-(3,4-dichlorophenyl)-1,1-dimethylurea, apparent photosynthesis was inhibited 82%, and the refixation of 14CO2 derived internally from endogenous respiration was largely prevented. In the presence of this inhibitor endogenous respiration, measured as "CO2 evolution, continued in the light at a rate comparable to that in the dark. Consequently, under these conditions light-induced nonphotosynthetic processes have no significant effect on endogenous dark respiration. Inhibitors of the tricarboxylic acid cycle, malonate and fluoroacetate, were used to determine the relative rates of carbon flux through the cycle in the dark and in the light by measuring the rate of accumulation of 4(C in either succinate or citrate. Results were interpreted to indicate that the tricarboxylic acid cycle functions in the light at a rate similar to that in the dark except for a brief initial inhibition on transition from dark to light. Evidence was obtained that succinate dehydrogenase as well as aconitase, was inhibited in the presence of fluoroacetate.Controversy has surrounded the question of the effect of light on endogenous aerobic respiration via glycolysis and the tricarboxylic acid cycle in algae and green leaves of higher plants. Reports have included stimulation, inhibition, or no effect of light on respiration. For example, physiological studies, using the mass spectrometer to measure respiratory and photosynthetic gas exchange simultaneously, showed that relatively low light intensities had little or no effect on rate of respiratory oxygen uptake in barley leaves or in suspensions of the alga Chiorella (8). With the green alga Ankistrodesmus braunii (9) or the algal flagellate Ochromonas malhamensis (52) it was found that respiratory CO2 evolution was almost independent of light intensity, and that respiratory oxygen consumption was not affected by low light although it was enhanced at high light intensities. Hoch et al. (24) concluded from their results obtained with the mass spectrometer that low light intensities inhibited endogenous respiration in Anacystis, a blue-green alga, but not in Scenedesmus, a green alga, whereas higher light intensities promoted oxygen uptake in both organisms. The total oxygen consumption or CO2 evolution cannot be separated, however, into dark endogenous respiratory and light-induced photorespirator...

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Section: Methodsmentioning

confidence: 99%

The Effect of Light on the Tricarboxylic Acid Cycle in Green Leaves

Chapman

Graham²

1974

Plant Physiol.

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“…Naturally, I offered sycamore cell suspensions as a test. Judging from sycamore, plant aconitase is simply much more resistant to inhibition [28]. And so the work went on.…”

Section: The University 1955mentioning

confidence: 99%

“…27 At that time dissertation seminars were treated as part of the normal seminar (tea club) schedule, so the whole department was likely to turn up, at least for the free tea. 28 In those pre-VCR days I used 8 mm film with a (poorly) synchronized tape recorder soundtrack. sycamore log, was just too much for F. G. Young 29 (nothing was ever unofficial), who subsequently vetoed my application to work with the Nobel Laureate Luis Leloir in Argentina.…”

Section: The University 1955mentioning

confidence: 99%

“…Curiously, apart from brief forays into cell wall enzymes [9,14,28,89], my Cambridge training had left me relatively unprepared for this. With the notable exception of Marjorie Stephenson [90], no one ever seemed to discover new enzymes at Cambridge despite the presence of the great gurus Malcolm Dixon and Edwin Webb, who taught the fundamentals with a rigor that stood the test of time [91].…”

Section: Extensin Peroxidasementioning

confidence: 99%

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Life behind cell walls: paradigm lost, paradigm regained

Lamport

2001

CMLS, Cell. Mol. Life Sci.

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This review of the living cell wall and its protein components is in two parts. The first is anecdotal. A personal account spanning over 40 years research may perhaps be an antidote to one stereotypical view of scientists as detached and humorless. The second part deals with the meaning of function, particularly as it applies to hydroxyproline-rich glycoproteins. Function is a difficult word to define objectively. However, with help from such luminaries as Humpty Dumpty: "A word means what I want it to mean, neither more nor less," and Wittgenstein: "Giving examples of usage ... is the only way to talk about meaning," it is possible to construct a ziggurat representing increasingly complex levels of organization from molecular structure to ecology. Forty years ago I suggested that hydroxyproline-rich structural proteins played a key role in cell wall functioning. But because the bulk of the wall is carbohydrate, there has been an understandable resistance to paradigm change. Expansins, paradoxically, contribute greatly to this resistance because their modus operandi as cell-wall-loosening proteins is based on the idea that they break hydrogen bonds between polysaccharide chains allowing slippage. However, this view is not consistent with the recent discovery [Grobe et al. (1999) Eur. J. Biochem 263: 33-40] that beta-expansins may be proteases, as it implies that the extensin network is not a straightjacket but a substrate for expansin in muro. Such a direct role for extensins in both negative and positive regulation of cell expansion and elongation may constitute a major morphogenetic mechanism operating at all levels of plant growth and development.

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“…Mutations other than in citrate synthase may prevent the generation of fluorocitrate, and there may also be an inability to take up fluoroacetate into the cell. In other cases citrate synthase may not utilise fluoroacetyl-CoA as effectively as acetyl-CoA [21] or the aconitase may be relatively insensitive to fluorocitrate inhibition [22,23]. Ano.ther possibility is that the organism may be able to hydrolyse fluoroacetate to glycollate (e.g.…”

Section: Resultsmentioning

confidence: 99%