Planta

, Volume 233, Issue 2, pp 261–273

Mannitol-1-phosphate dehydrogenase activity in Ectocarpus siliculosus, a key role for mannitol synthesis in brown algae

  • Sylvie Rousvoal
  • Agnès Groisillier
  • Simon M. Dittami
  • Gurvan Michel
  • Catherine Boyen
  • Thierry Tonon
Original Article

DOI: 10.1007/s00425-010-1295-6

Cite this article as:
Rousvoal, S., Groisillier, A., Dittami, S.M. et al. Planta (2011) 233: 261. doi:10.1007/s00425-010-1295-6

Abstract

Mannitol represents a major end product of photosynthesis in brown algae (Phaeophyceae), and is, with the β-1,3-glucan laminarin, the main form of carbon storage for these organisms. Despite its importance, little is known about the genes and enzymes responsible for the metabolism of mannitol in these seaweeds. Taking benefit of the sequencing of the Ectocarpus siliculosus genome, we focussed our attention on the first step of the synthesis of mannitol (reduction of the photo-assimilate fructose-6-phosphate), catalysed by the mannitol-1-phosphate dehydrogenase (M1PDH). This activity was measured in algal extracts, and was shown to be regulated by NaCl concentration in the reaction medium. Genomic analysis revealed the presence of three putative M1PDH genes (named EsM1PHD1, EsM1PDH2 and EsM1PDH3). Sequence comparison with orthologs demonstrates the modular architecture of EsM1PHD1 and EsM1PDH2, with an additional N-terminal domain of unknown function. In addition, gene expression experiments carried out on samples harvested through the diurnal cycle, and after several short-term saline and oxidative stress treatments, showed that EsM1PDH1 is the most highly expressed of these genes, whatever the conditions tested. In order to assess the activity of the corresponding protein, this gene was expressed in Escherichia coli. Cell-free extracts prepared from bacteria containing EsM1PDH1 displayed higher M1PDH activity than bacteria transformed with an empty plasmid. Further characterisation of recombinant EsM1PDH1 activity revealed its very narrow substrate specificity, salt regulation, and sensitivity towards an inhibitor of SH-enzymes.

Keywords

Brown algaeEctocarpusEnzymatic activityMannitolPrimary metabolism

Abbreviations

ANOVA

Analysis of variance

ASW

Artificial seawater

CCAP

Culture collection of algae and protozoa

dbEST

Database of expressed sequence tags

DTT

Dithiothreitol

EDTA

Ethylenediaminetetraacetic acid

EGTA

Ethylene glycol tetraacetic acid

F6P

Fructose-6-phosphate

HCA

Hydrophobic cluster analysis

Hepes

4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid

HK

Hexokinase

H2O2

Hydrogen peroxide

LB

Luria–Bertani medium

M1P

Mannitol-1-phosphate

M1Pase

Mannitol-1-phosphatase

M1PDH

Mannitol-1-phosphate dehydrogenase

M2DH

Mannitol-2-dehydrogenase

MOPS

3-(N-morpholino)propanesulfonic acid

NCBI

National Center for Biotechnology Information

pHMB

p-Hydroxymercuribenzoate

PSU

Practical salinity unit

PVP

Polyvinylpyrrolidone

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Sylvie Rousvoal
    • 1
    • 2
  • Agnès Groisillier
    • 1
    • 2
  • Simon M. Dittami
    • 1
    • 2
  • Gurvan Michel
    • 1
    • 2
  • Catherine Boyen
    • 1
    • 2
  • Thierry Tonon
    • 1
    • 2
    • 3
  1. 1.UPMC Univ Paris 6, UMR 7139 Marine Plants and BiomoleculesRoscoffFrance
  2. 2.CNRS, UMR 7139 Marine Plants and BiomoleculesRoscoffFrance
  3. 3.UMR 7139 CNRS-UPMCRoscoffFrance