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NO-Mediated [Ca2+]cyt Increases Depend on ADP-Ribosyl Cyclase Activity in Arabidopsis.

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Peer-reviewed

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Article

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Authors

Hotta, Carlos T 
Davey, Matthew P 
Dodd, Antony N 

Abstract

Cyclic ADP ribose (cADPR) is a Ca(2+)-mobilizing intracellular second messenger synthesized from NAD by ADP-ribosyl cyclases (ADPR cyclases). In animals, cADPR targets the ryanodine receptor present in the sarcoplasmic/endoplasmic reticulum to promote Ca(2+) release from intracellular stores to increase the concentration of cytosolic free Ca(2+) in Arabidopsis (Arabidopsis thaliana), and cADPR has been proposed to play a central role in signal transduction pathways evoked by the drought and stress hormone, abscisic acid, and the circadian clock. Despite evidence for the action of cADPR in Arabidopsis, no predicted proteins with significant similarity to the known ADPR cyclases have been reported in any plant genome database, suggesting either that there is a unique route for cADPR synthesis or that a homolog of ADPR cyclase with low similarity might exist in plants. We sought to determine whether the low levels of ADPR cyclase activity reported in Arabidopsis are indicative of a bona fide activity that can be associated with the regulation of Ca(2+) signaling. We adapted two different fluorescence-based assays to measure ADPR cyclase activity in Arabidopsis and found that this activity has the characteristics of a nucleotide cyclase that is activated by nitric oxide to increase cADPR and mobilize Ca(2.)

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Keywords

ADP-ribosyl Cyclase, Arabidopsis, Arabidopsis Proteins, Calcium, Cytosol, Guanine Nucleotides, NAD, Niacinamide, Nitric Oxide, Signal Transduction

Journal Title

Plant Physiol

Conference Name

Journal ISSN

0032-0889
1532-2548

Volume Title

171

Publisher

Oxford University Press (OUP)
Sponsorship
Biotechnology and Biological Sciences Research Council (BB/D017904/1)
This work was supported by the Islamic Development Bank and the Cambridge Commonwealth Trust (SMA-A), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CTH) and BBSRC UK grant BB/D017904/1 (AND) awarded to AARW.