Activation of NADPH-recycling Systems in Leaves and Roots of Arabidopsis Thaliana Under Arsenic-Induced Stress Conditions Is Accelerated by Knock-Out of Nudix Hydrolase 19 (AtNUDX19) Gene

J Plant Physiol. 2016 Mar 15;192:81-9. doi: 10.1016/j.jplph.2016.01.010. Epub 2016 Feb 3.

Abstract

NADPH is an important cofactor in cell growth, proliferation and detoxification. Arabidopsis thaliana Nudix hydrolase 19 (AtNUDX19) belongs to a family of proteins defined by the conserved amino-acid sequence GX5-EX7REUXEEXGU which has the capacity to hydrolyze NADPH as a physiological substrate in vivo. Given the importance of NADPH in the cellular redox homeostasis of plants, the present study compares the responses of the main NADPH-recycling systems including NADP-isocitrate dehydrogenase (ICDH), glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase (6PGDH) and NADP-malic enzyme (ME) in the leaves and roots of Arabidopsis wild-type (Wt) and knock-out (KO) AtNUDX19 mutant (Atnudx19) plants under physiological and arsenic-induced stress conditions. Two major features were observed in the behavior of the main NADPH-recycling systems: (i) under optimal conditions in both organs, the levels of these activities were higher in nudx19 mutants than in Wt plants; and, (ii) under 500μM AsV conditions, these activities increase, especially in nudx19 mutant plants. Moreover, G6PDH activity in roots was the most affected enzyme in both Wt and nudx19 mutant plants, with a 4.6-fold and 5.0-fold increase, respectively. In summary, the data reveals a connection between the absence of chloroplastic AtNUDX19 and the rise in all NADP-dehydrogenase activities under physiological and arsenic-induced stress conditions, particularly in roots. This suggests that AtNUDX19 could be a key factor in modulating the NADPH pool in plants and consequently in redox homeostasis.

Keywords: 6PGDH; Arsenic; AtNUDX19; G6PDH; NADP-ICDH; NADP-ME; NADPH; Oxidative stress.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / drug effects
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics
  • Arabidopsis / physiology*
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism
  • Arsenic / adverse effects
  • Gene Knockout Techniques
  • Glucosephosphate Dehydrogenase / genetics
  • Glucosephosphate Dehydrogenase / metabolism
  • Homeostasis
  • Isocitrate Dehydrogenase / genetics
  • Isocitrate Dehydrogenase / metabolism
  • Malate Dehydrogenase / genetics
  • Malate Dehydrogenase / metabolism
  • Mutation
  • NADP / metabolism*
  • NADPH Dehydrogenase / genetics
  • NADPH Dehydrogenase / metabolism
  • Oxidation-Reduction
  • Oxidative Stress
  • Phosphogluconate Dehydrogenase / genetics
  • Phosphogluconate Dehydrogenase / metabolism
  • Plant Leaves / enzymology
  • Plant Leaves / genetics
  • Plant Leaves / physiology
  • Plant Roots / enzymology
  • Plant Roots / genetics
  • Plant Roots / metabolism
  • Plant Roots / physiology
  • Pyrophosphatases / genetics*
  • Pyrophosphatases / metabolism
  • Stress, Physiological / drug effects

Substances

  • Arabidopsis Proteins
  • NADP
  • Malate Dehydrogenase
  • malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)
  • Isocitrate Dehydrogenase
  • isocitrate dehydrogenase (NADP+)
  • Phosphogluconate Dehydrogenase
  • Glucosephosphate Dehydrogenase
  • NADPH Dehydrogenase
  • Pyrophosphatases
  • nudix hydrolases
  • Arsenic