title: A New APEH Cluster with Antioxidant Functions in the Antarctic Hemoglobinless Icefish Chionodraco hamatus.
abstract: Acylpeptide hydrolase (APEH) is a ubiquitous cytosolic protease that plays an important role in the detoxification of oxidised proteins. In this work, to further explore the physiological role of this enzyme, two apeh cDNAs were isolated from the Chionodraco hamatus icefish, which lives in the highly oxygenated Antarctic marine environment. The encoded proteins (APEH-1(Ch) and APEH-2(Ch)) were characterised in comparison with the uniquely expressed isoform from the temperate fish Dicentrarchus labrax (APEH-1Dl) and the two APEHs from the red-blooded Antarctic fish Trematomus bernacchii (APEH-1(Tb) and APEH-2(Tb)). Homology modelling and kinetic characterisation of the APEH isoforms provided new insights into their structure/function properties. APEH-2 isoforms were the only ones capable of hydrolysing oxidised proteins, with APEH-2(Ch) being more efficient than APEH-2(Tb) at this specific function. Therefore, this ability of APEH-2 isoforms is the result of an evolutionary adaptation due to the pressure of a richly oxygenated environment. The lack of expression of APEH-2 in the tissues of the temperate fish used as the controls further supported this hypothesis. In addition, analysis of gene expression showed a significant discrepancy between the levels of transcripts and those of proteins, especially for apeh-2 genes, which suggests the presence of post-transcriptional regulation mechanisms, triggered by cold-induced oxidative stress, that produce high basal levels of APEH-2 mRNA as a reserve that is ready to use in case of the accumulation of oxidised proteins.
authors.affiliation: National Research Council, Institute of Biosciences and BioResources (CNR-IBBR), Napoli, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Riccio
authors.affiliation: National Research Council, Institute of Biosciences and BioResources (CNR-IBBR), Napoli, Italy.
authors.forename: Marta
authors.initials: M
authors.lastname: Gogliettino
authors.affiliation: National Research Council, Institute of Biosciences and BioResources (CNR-IBBR), Napoli, Italy.
authors.forename: Gianna
authors.initials: G
authors.lastname: Palmieri
authors.affiliation: National Research Council, Institute of Biosciences and BioResources (CNR-IBBR), Napoli, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Balestrieri
authors.affiliation: National Research Council, Institute of Food Sciences (CNR-ISA), Avellino, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Facchiano
authors.affiliation: National Research Council, Institute of Biosciences and BioResources (CNR-IBBR), Napoli, Italy.
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.affiliation: National Research Council, Institute of Biosciences and BioResources (CNR-IBBR), Napoli, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Palumbo
authors.affiliation: Ittica Literno srl, Caserta, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Monti
authors.affiliation: National Research Council, Institute of Biosciences and BioResources (CNR-IBBR), Napoli, Italy.
authors.forename: Ennio
authors.initials: E
authors.lastname: Cocca
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000818:Animals; D000864:Antarctic Regions; D000975:Antioxidants / Q000378:metabolism*; D001483:Base Sequence; D005075:Biological Evolution; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D008958:Models, Molecular; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010100:Oxygen; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D010473:Perciformes / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D000975:Antioxidants; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D010447:Peptide Hydrolases; C038220:acylaminoacyl-peptidase; D010100:Oxygen