ISOLATION AND SEQUENCE ANALYSIS OF A cDNA ENCODING A NOVEL PUTATIVE ESTERASE FROM THE MARINE MICROALGA ISOCHRYSIS GALBANA (PRYMNESIOPHYCEAE, HAPTOPHYTA)

Authors

  • Stéphanie Godet,

    1. EA 2160, Mer Molécules Santé, Département Génie Biologique, Institut Universitaire de Technologie de Laval, Université du Maine, 52 rue des Docteurs Calmette et Guérin, BP 2045, 53020 Laval Cedex 09, France
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    • Present address: EA 2106, Biomolécules et Biotechnologies Végétales, Département de Physiologie et Biologie Végétales, Parc Grandmont, Université de Tours, 37000 Tours, France.

  • Céline Loiseau,

    1. EA 2160, Mer Molécules Santé, Département Génie Biologique, Institut Universitaire de Technologie de Laval, Université du Maine, 52 rue des Docteurs Calmette et Guérin, BP 2045, 53020 Laval Cedex 09, France
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  • Gaëlle Pencreac’h,

    1. EA 2160, Mer Molécules Santé, Département Génie Biologique, Institut Universitaire de Technologie de Laval, Université du Maine, 52 rue des Docteurs Calmette et Guérin, BP 2045, 53020 Laval Cedex 09, France
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  • Françoise Ergan,

    1. EA 2160, Mer Molécules Santé, Département Génie Biologique, Institut Universitaire de Technologie de Laval, Université du Maine, 52 rue des Docteurs Calmette et Guérin, BP 2045, 53020 Laval Cedex 09, France
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  • Josiane Hérault

    1. EA 2160, Mer Molécules Santé, Département Génie Biologique, Institut Universitaire de Technologie de Laval, Université du Maine, 52 rue des Docteurs Calmette et Guérin, BP 2045, 53020 Laval Cedex 09, France
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  • Received 3 April 2009. Accepted 28 January 2010.

Abstract

Microalgae constitute an interesting novel study area for characterizing new esterases, and so we decided to isolate a complete cDNA encoding a new putative microalgal esterase from the haptophyte Isochrysis galbana Parke. Rapid amplifications of both the 5′ and 3′ cDNA ends (RACE) were performed with specific primers, designed using an incomplete candidate gene from the I. galbana expressed sequence tag (EST) database. The full-length cDNA obtained was designated IgEst1. The coding sequence was 828 bp long, and the deduced amino acid sequence revealed a polypeptide of 275 amino acids with a predicted signal peptide of 23 residues in the N-terminal region. The following 252 amino acids formed, after in silico analysis, a mature protein with a molecular mass of ∼26.92 kDa and had a theoretical pI of 5.87. Alignment analyses revealed slight but significant identity and similarity with carboxylesterases, phospholipases, and lysophospholipases from various organisms including fungi, plants, and animals. The new sequence IgEst1 enclosed the catalytic triad Ser/Asp/His and the consensus pentapeptide Gly-X-Ser-X-Gly, two highly conserved patterns found in serine hydrolases. Phylogenetic analyses established a close relationship with putative esterases identified in microalgae genomes.

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