Regulation of glyceraldehyde-3-phosphate dehydrogenase in the eustigmatophyte Pseudocharaciopsis ovalis is intermediate between a chlorophyte and a diatom

Avilan, Luisana; Maberly, Stephen C.; Mekhalfi, Malika; Plateau, Julia; Puppo, Carine; Gontero, Brigitte. 2012 Regulation of glyceraldehyde-3-phosphate dehydrogenase in the eustigmatophyte Pseudocharaciopsis ovalis is intermediate between a chlorophyte and a diatom. European Journal of Phycology, 47 (3). 207-215. 10.1080/09670262.2012.687459

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Abstract/Summary

The regulation of NADPH-dependent GAPDH was analysed in the chromalveolate (eustigmatophyte) Pseudocharaciopsis ovalis and compared with the well-studied chlorophyte Chlamydomonas reinhardtii and with another chromalveolate(diatom), Asterionella formosa. Optimal pH for GAPDH activity in P. ovalis and C. reinhardtii ranged between 8 and 9, but in A. formosa ranged between 6.2 and 8.1. Assuming dark pH values of about 7 in the plastids of all three species, GAPDH would be down-regulated in the dark in C. reinhardtii and P. ovalis, but fully active in A. formosa. The time required for halfmaximal GAPDH activity on transfer to reducing conditions, was significantly different in each species: 1.4, 4.0 and 5.9 min in A. formosa, P. ovalis and C. reinhardtii respectively. Under oxidized conditions in P. ovalis and A. formosa, NADPH caused a large inhibition in GAPDH activity even at very low concentrations (10 to 20 mM) unlike in C. reinhardtii. This inhibition was relieved by addition of a reducing agent suggesting that NADPH can control GAPDH activity under dark-light transitions. A small increase of GAPDH activity with NADP at concentrations higher than 0.5mM was observed with P. ovalis and C. reinhardtii, while a greater than 1.5-fold stimulation was observed in A. formosa. Regulation of GAPDH in P. ovalis was intermediate between the diatom and the chlorophyte and the possible evolutionary reasons for this are discussed.

Item Type:	Article
Identification Number/DOI:	10.1080/09670262.2012.687459
Programmes:	CEH Topics & Objectives 2009 onwards > Water > WA Topic 2 - Ecohydrological Processes > WA - 2.3 - Assess the responses of river, lake and wetland ecosystems to ecohydrological drivers
CEH Sections:	Parr
ISSN:	0967-0262
Additional Keywords:	Asterionella formosa, Bacillariophyceae, Calvin cycle, Chlamydomonas reinhardtii, Chlorophyta, chromalveolates, CP12, enzyme regulation, Eustigmatophyceae, GAPDH, Plantae, regulation by pH
NORA Subject Terms:	Ecology and Environment Biology and Microbiology Botany
Date made live:	03 Aug 2012 13:24
URI:	http://nora.nerc.ac.uk/id/eprint/19054

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