Marine Biotechnology

, Volume 13, Issue 1, pp 22–31

Cloning, Tissue Expression Analysis, and Functional Characterization of Two Δ6-Desaturase Variants of Sea Bass (Dicentrarchus labrax L.)

  • Ester Santigosa
  • Florian Geay
  • Thierry Tonon
  • Herve Le Delliou
  • Heiner Kuhl
  • Richard Reinhardt
  • Laurent Corcos
  • Chantal Cahu
  • José Luis Zambonino-Infante
  • David Mazurais
Original Article

Abstract

Fish are the main source of the n-3 highly unsaturated fatty acids, which are crucial for human health. Their synthesis from C18 precursors is mediated by desaturases and elongases, but the activity of these enzymes has not been conclusively established in marine fish species. This study reports the cloning, tissue expression, and functional characterization of a sea bass (Dicentrarchus labrax L.) Δ6-desaturase and one of its splicing variants. Two cDNAs with open reading frames of 1,346 and 1,354 bp were cloned and named D6D and D6D-V, respectively. Both deduced protein sequences (445 and 387 amino acids, respectively) contained two transmembrane regions and the N-terminal cytochrome b5 domain with the HPGG motif characteristic of microsomal desaturases. D6D presents three histidine-rich regions, whereas in D6D-V, an insertion of eight nucleotides in the boundaries of exons 10 and 11 modified the third histidine-rich domain and led to insertion of a premature STOP codon, resulting in a shorter predicted protein. Quantitative real-time polymerase chain reaction assay of gene expression showed that D6D was highly expressed in the brain and intestine, and to a lesser extent, in muscle and liver; meanwhile, D6D-V was expressed in all tissues tested, but at level at least 200-fold lower than D6D. Functional analysis in yeast showed that sea bass D6D encodes a fully functional Δ6-desaturase with no residual Δ5-desaturase activity. This desaturase does not exhibit a clear preference for n-3 versus n-6 C18 substrates. Interestingly, D6D-V is a nonfunctional protein, suggesting that the C-terminal end is indispensable for protein activity.

Keywords

Sea bass (Dicentrarchus labraxDesaturase HUFA biosynthesis Fish EPA 

Supplementary material

10126_2010_9264_MOESM1_ESM.doc (40 kb)
Supplementary Table 1(DOC 40 kb)
10126_2010_9264_MOESM2_ESM.doc (39 kb)
Supplementary Table 2(DOC 39 kb)
10126_2010_9264_MOESM3_ESM.doc (104 kb)
Supplementary Fig. 1(DOC 104 kb)

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Ester Santigosa
    • 1
  • Florian Geay
    • 1
  • Thierry Tonon
    • 2
    • 3
  • Herve Le Delliou
    • 1
  • Heiner Kuhl
    • 4
  • Richard Reinhardt
    • 4
  • Laurent Corcos
    • 5
    • 6
  • Chantal Cahu
    • 1
  • José Luis Zambonino-Infante
    • 1
  • David Mazurais
    • 1
  1. 1.Ifremer Marine Fish Nutrition Team, Nutrition Aquaculture and Genomics Research UnitUMR 1067, Ifremer, Technopole Brest-IroisePlouzanéFrance
  2. 2.UPMC Univ Paris 6, UMR 7139 Végétaux marins et biomolécules, Station BiologiqueRoscoffFrance
  3. 3.CNRS, UMR 7139 Végétaux marins et biomolécules, Station BiologiqueRoscoffFrance
  4. 4.Max-Planck-Institute Molecular GeneticsBerlin-DahlemGermany
  5. 5.Université de Brest, INSERM, U613, ECLABrestFrance
  6. 6.Faculté de MédecineUniversité Européenne de BretagneBrestFrance

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