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The Ca2+-Regulation of the Mitochondrial External NADPH Dehydrogenase in Plants Is Controlled by Cytosolic pH.

Hao, Mengshu LU ; Jensen, Anna LU ; Boquist, Ann-Sofie LU ; Liu, Yunjun LU and Rasmusson, Allan LU (2015) In PLoS ONE 10(9).
Abstract
NADPH is a key reductant carrier that maintains internal redox and antioxidant status, and that links biosynthetic, catabolic and signalling pathways. Plants have a mitochondrial external NADPH oxidation pathway, which depends on Ca2+ and pH in vitro, but concentrations of Ca2+ needed are not known. We have determined the K0.5(Ca2+) of the external NADPH dehydrogenase from Solanum tuberosum mitochondria and membranes of E. coli expressing Arabidopsis thaliana NDB1 over the physiological pH range using O2 and decylubiquinone as electron acceptors. The K0.5(Ca2+) of NADPH oxidation was generally higher than for NADH oxidation, and unlike the latter, it depended on pH. At pH 7.5, K0.5(Ca2+) for NADPH oxidation was high (≈100 μM), yet 20-fold... (More)
NADPH is a key reductant carrier that maintains internal redox and antioxidant status, and that links biosynthetic, catabolic and signalling pathways. Plants have a mitochondrial external NADPH oxidation pathway, which depends on Ca2+ and pH in vitro, but concentrations of Ca2+ needed are not known. We have determined the K0.5(Ca2+) of the external NADPH dehydrogenase from Solanum tuberosum mitochondria and membranes of E. coli expressing Arabidopsis thaliana NDB1 over the physiological pH range using O2 and decylubiquinone as electron acceptors. The K0.5(Ca2+) of NADPH oxidation was generally higher than for NADH oxidation, and unlike the latter, it depended on pH. At pH 7.5, K0.5(Ca2+) for NADPH oxidation was high (≈100 μM), yet 20-fold lower K0.5(Ca2+) values were determined at pH 6.8. Lower K0.5(Ca2+) values were observed with decylubiquinone than with O2 as terminal electron acceptor. NADPH oxidation responded to changes in Ca2+ concentrations more rapidly than NADH oxidation did. Thus, cytosolic acidification is an important activator of external NADPH oxidation, by decreasing the Ca2+-requirements for NDB1. The results are discussed in relation to the present knowledge on how whole cell NADPH redox homeostasis is affected in plants modified for the NDB1 gene. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
PLoS ONE
volume
10
issue
9
publisher
Public Library of Science
external identifiers
  • pmid:26413894
  • wos:000362170700050
  • scopus:84946935131
ISSN
1932-6203
DOI
10.1371/journal.pone.0139224
language
English
LU publication?
yes
id
66cc5b81-19ad-4bde-a076-3efdd3c049d7 (old id 8034705)
date added to LUP
2015-11-11 14:20:52
date last changed
2017-09-03 04:24:20
@article{66cc5b81-19ad-4bde-a076-3efdd3c049d7,
  abstract     = {NADPH is a key reductant carrier that maintains internal redox and antioxidant status, and that links biosynthetic, catabolic and signalling pathways. Plants have a mitochondrial external NADPH oxidation pathway, which depends on Ca2+ and pH in vitro, but concentrations of Ca2+ needed are not known. We have determined the K0.5(Ca2+) of the external NADPH dehydrogenase from Solanum tuberosum mitochondria and membranes of E. coli expressing Arabidopsis thaliana NDB1 over the physiological pH range using O2 and decylubiquinone as electron acceptors. The K0.5(Ca2+) of NADPH oxidation was generally higher than for NADH oxidation, and unlike the latter, it depended on pH. At pH 7.5, K0.5(Ca2+) for NADPH oxidation was high (≈100 μM), yet 20-fold lower K0.5(Ca2+) values were determined at pH 6.8. Lower K0.5(Ca2+) values were observed with decylubiquinone than with O2 as terminal electron acceptor. NADPH oxidation responded to changes in Ca2+ concentrations more rapidly than NADH oxidation did. Thus, cytosolic acidification is an important activator of external NADPH oxidation, by decreasing the Ca2+-requirements for NDB1. The results are discussed in relation to the present knowledge on how whole cell NADPH redox homeostasis is affected in plants modified for the NDB1 gene.},
  articleno    = {e0139224},
  author       = {Hao, Mengshu and Jensen, Anna and Boquist, Ann-Sofie and Liu, Yunjun and Rasmusson, Allan},
  issn         = {1932-6203},
  language     = {eng},
  number       = {9},
  publisher    = {Public Library of Science},
  series       = {PLoS ONE},
  title        = {The Ca2+-Regulation of the Mitochondrial External NADPH Dehydrogenase in Plants Is Controlled by Cytosolic pH.},
  url          = {http://dx.doi.org/10.1371/journal.pone.0139224},
  volume       = {10},
  year         = {2015},
}