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          Institute: MPI für molekulare Genetik     Collection: Sequencing Group     Display Documents

ID: 536194.0, MPI für molekulare Genetik / Sequencing Group
Cloning, tissue expression analysis, and functional characterization of two Δ6-desaturase variants of sea bass (Dicentrarchus labrax L.)
Authors:Santigosa, Ester; Geay, Florian; Tonon, Thierry; Le Delliou, Herve; Kuhl, Heiner; Reinhardt, Richard; Corcos, Laurent; Cahu, Chantal; Zambonino-Infante, José Luis; Mazurais, David
Date of Publication (YYYY-MM-DD):2010-03-23
Title of Journal:Marine Biotechnology
Journal Abbrev.:Mar Biotechnol
Start Page:epub
End Page:epub
Copyright:© Springer Science+Business Media, LLC 2010
Review Status:not specified
Audience:Experts Only
Abstract / Description: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.
Free Keywords:Sea bass (Dicentrarchus labrax); Desaturase; HUFA biosynthesis; Fish; EPA
Comment of the Author/Creator:Email: dmazurai@ifremer.fr
Electronic supplementary material The online version of this article (doi:10.1007/s10126-010-9264-4) contains supplementary material, which is available to authorized users.
External Publication Status:published
Document Type:Article
Communicated by:Richard Reinhardt
Affiliations:MPI für molekulare Genetik
External Affiliations:Ifremer Marine Fish Nutrition Team, Nutrition Aquaculture and Genomics Research Unit, UMR 1067, Ifremer, Technopole Brest-Iroise, BP 70, 29280 Plouzané, France
UPMC Univ Paris 6, UMR 7139 Végétaux marins et biomolécules, Station Biologique, 29682 Roscoff, France
CNRS, UMR 7139 Végétaux marins et biomolécules, Station Biologique, 29682 Roscoff, France
Université de Brest, INSERM, U613, ECLA, Brest, 29200, France
Faculté de Médecine, Université Européenne de Bretagne, Brest, 29200, France
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