Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.
Plant Physiol, August 2002, Vol. 129, pp. 1829-1842
Induction of Mitochondrial Alternative Oxidase in Response to a
Cell Signal Pathway Down-Regulating the Cytochrome Pathway Prevents
Programmed Cell Death1
Division of Life Sciences and Department of Botany, University of
Toronto at Scarborough, 1265 Military Trail, Scarborough, Ontario,
Canada M1C 1A4
Treatment of tobacco (Nicotiana tabacum L. cv Petit
Havana SR1) cells with cysteine (Cys) triggers a signal pathway
culminatingin a large loss of mitochondrial cytochrome (cyt) pathway
capacity.This down-regulation of the cyt path likely requires events
outsidethe mitochondrion and is effectively blocked by cantharidin orendothall, indicating that protein dephosphorylation is one criticalprocess involved. Generation of reactive oxygen species, cytosolicprotein synthesis, and Ca2+ flux from organelles also
appear to be involved. Accompanyingthe loss of cyt path is a large
induction of alternative oxidase(AOX) protein and capacity. Induction
of AOX allows the cellsto maintain high rates of respiration,
indicating that the lesiontriggered by Cys is in the cyt path
downstream of ubiquinone.Consistent with this, transgenic (AS8) cells
unable to induceAOX (due to the presence of an antisense transgene)
lose all respiratorycapacity upon Cys treatment. This initiates in AS8
a programmedcell death pathway, as evidenced by the accumulation of
oligonucleosomalfragments of DNA as the culture dies. Alternatively,
wild-typecells remain viable and eventually recover their cyt path.
Inductionof AOX in response to a chemical inhibition of the cyt path
(byantimycin A) is also dependent upon protein dephosphorylationand
the generation of reactive oxygen species. Common events requiredfor
both down-regulation of the cyt path and induction of AOXmay represent
a mechanism to coordinate the biogenesis of thesetwo electron
transport paths. Such coordinate regulation may benecessary, not only
to satisfy metabolic demands, but also tomodulate the initiation of a
programmed cell death pathway responsiveto mitochondrial respiratorystatus.
The Metabolic Response of Arabidopsis Roots to Oxidative Stress is Distinct from that of Heterotrophic Cells in Culture and Highlights a Complex Relationship between the Levels of Transcripts, Metabolites, and Flux.
M. Lehmann, M. Schwarzlander, T. Obata, S. Sirikantaramas, M. Burow, C. E. Olsen, T. Tohge, M. D. Fricker, B. L. Moller, A. R. Fernie, et al. (2009)
|Abstract »|Full Text »|PDF »
The Arabidopsis onset of leaf death5 Mutation of Quinolinate Synthase Affects Nicotinamide Adenine Dinucleotide Biosynthesis and Causes Early Ageing.
J. H.M. Schippers, A. Nunes-Nesi, R. Apetrei, J. Hille, A. R. Fernie, and P. P. Dijkwel (2008)
|Abstract »|Full Text »|PDF »
The hypersensitive response; the centenary is upon us but how much do we know?.