A novel class of bifunctional acylpeptide hydrolases – potential role in the antioxidant defense systems of the Antarctic fish Trematomus bernacchii

Authors

  • Marta Gogliettino,

    1. Institute of Protein Biochemistry and Institute of Biosciences and BioResources, National Research Council (CNR-IBP and CNR-IBBR), Naples, Italy
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    • These authors equally contributed to this work.
  • Alessia Riccio,

    1. Institute of Protein Biochemistry and Institute of Biosciences and BioResources, National Research Council (CNR-IBP and CNR-IBBR), Naples, Italy
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    • These authors equally contributed to this work.
  • Marco Balestrieri,

    1. Institute of Protein Biochemistry and Institute of Biosciences and BioResources, National Research Council (CNR-IBP and CNR-IBBR), Naples, Italy
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  • Ennio Cocca,

    Corresponding author
    1. Institute of Protein Biochemistry and Institute of Biosciences and BioResources, National Research Council (CNR-IBP and CNR-IBBR), Naples, Italy
    • Correspondence

      E. Cocca, IBP and IBBR, Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131 Napoli, Italy

      Fax: +39 0816132277

      Tel: +39 0816132552

      E-mail: ennio.cocca@ibbr.cnr.it

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  • Angelo Facchiano,

    1. Institute of Food Sciences, National Research Council (CNR-ISA), Avellino, Italy
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  • Teresa M. D'Arco,

    1. Institute of Protein Biochemistry and Institute of Biosciences and BioResources, National Research Council (CNR-IBP and CNR-IBBR), Naples, Italy
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  • Clara Tesoro,

    1. Institute of Protein Biochemistry and Institute of Biosciences and BioResources, National Research Council (CNR-IBP and CNR-IBBR), Naples, Italy
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  • Mosè Rossi,

    1. Institute of Protein Biochemistry and Institute of Biosciences and BioResources, National Research Council (CNR-IBP and CNR-IBBR), Naples, Italy
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  • Gianna Palmieri

    1. Institute of Protein Biochemistry and Institute of Biosciences and BioResources, National Research Council (CNR-IBP and CNR-IBBR), Naples, Italy
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Abstract

Oxidative challenge is an important factor affecting the adaptive strategies of Antarctic fish, but data on antioxidant defenses in these organisms remain scarce. In this context, a key role could be played by acylpeptide hydrolase (APEH), which was recently hypothesized to participate in the degradation of oxidized and cytotoxic proteins, although its physiological function is still not fully clarified. This study represents the first report on piscine members of this enzyme family, specifically from the Antarctic teleost Trematomus bernacchii. The cDNAs corresponding to two apeh genes were isolated, and the respective proteins were functionally and structurally characterized with the aim of understanding the biological significance of these proteases in Antarctic fish. Both APEH isoforms (APEH-1Tb and APEH-2Tb) showed distinct temperature-kinetic behavior, with significant differences in the Km values. Moreover, beside the typical acylpeptide hydrolase activity, APEH-2Tb showed remarkable oxidized protein endohydrolase activity towards oxidized BSA, suggesting that this isoform could play a homeostatic role in removing oxidatively damaged proteins, sustaining the antioxidant defense systems. The 3D structures of both APEHs were predicted, and a possible relationship was found between the substrate specificity/affinity and the marked changes in the number of charged residues and hydrophobicity properties surrounding their catalytic sites. Our results demonstrated the occurrence of two APEH isoforms in T. bernacchii, belonging to different phylogenetic clusters, identified for the first time, and showing distinct molecular and temperature–kinetic behaviors. In addition, we suggest that the members of the new cluster ‘APEH-2’ could participate in reactive oxygen species detoxification as phase 3 antioxidant enzymes, enhancing the protein degradation machinery.

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