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Indian Journal of Biochemistry and Biophysics (IJBB) >
IJBB Vol.45 [2008] >
IJBB Vol.45(2) [April 2008] >
| Title: | Mitochondrial complex I impairment and differential carbon monoxide sensitivity of cytochrome c oxidase in wild type and CMS II mutants of Nicotiana sylvestris |
| Authors: | Naik, R M |
| Keywords: | Nicotiana sylvestris
Cytochrome oxidase
Alternative oxidase
Carbon monoxide sensitivity
Nitrate reductase induction
Mitochondrial complex I |
| Issue Date: | Apr-2008 |
| Publisher: | CSIR |
| Abstract: | Plant mitochondria unlike their animal counterpart have some
unique features with highly branched respiratory chain. The
present work was undertaken in order to investigate the effect of
loss/dysfunction of plant mitochondrial complex I on the relative
flux of electrons through alternative oxidase (AOX) and
cytochrome oxidase. Loss of a major subunit of mitochondrial
complex I in cytoplasmic male sterile II (CMS II) mutant of
Nicotiana sylvestris caused respiratory redox perturbations, as
evident from the differential CO sensitivity of cytochrome
oxidase. The leaf segments of CMS II mutant when exposed to
CO under dark aerobic condition were insensitive to the inhibition
of cytochrome oxidase, as against the wild type (WT). The
differential CO response of WT and CMS II mutants appeared to
be due to differences in the redox state of cytochrome a3 (cyt a3),
the terminal electron acceptor during in situ respiration. Cyt a3
appeared to be more in its oxidized form in CMS II and hence
unable to form cyt a3-CO complex. Pre-treatment of CMS II
leaves with 2,4-dinitrophenol, an uncoupler of oxidative
phosphorylation increased the CO response. The slight increase in
rotenone-insensitive respiration of CMS II could be attributed
partly to enhanced flux of electrons through cytochrome pathway
to compensate for the loss of phosphorylation site and partly
through AOX, which was induced by nitrate. |
| Page(s): | 126-129 |
| ISSN: | 0301-1208 |
| Source: | IJBB Vol.45(2) [April 2008]
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