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

Author:
  • Mengshu Hao
  • Anna Jensen
  • Ann-Sofie Boquist
  • Yunjun Liu
  • Allan G. Rasmusson
Publishing year: 2015
Language: English
Publication/Series: PLoS ONE
Volume: 10
Issue: 9
Document type: Journal article
Publisher: Public Library of Science
Additional info: The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Molecular Cell Biology (432112241), Biology building (Closed 2011) (011008000)

Abstract english

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.

Keywords

  • Botany
  • Cell Biology

Other

Published
  • ISSN: 1932-6203
Allan Rasmusson
E-mail: allan [dot] rasmusson [at] biol [dot] lu [dot] se

Professor

Molecular Cell Biology

+46 46 222 93 81

B-A329A

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