Cu,Zn superoxide dismutases from Tetrahymena thermophila: molecular evolution and gene expression of the first line of antioxidant defenses

Diana Ferro; Rigers Bakiu; Cristiano De Pittà; Francesco Boldrin; Franco Cattalini; Sandra Pucciarelli; Cristina Miceli; Gianfranco Santovito

doi:10.1016/j.protis.2014.12.003

Cu,Zn superoxide dismutases from Tetrahymena thermophila: molecular evolution and gene expression of the first line of antioxidant defenses

Protist. 2015 Feb;166(1):131-45. doi: 10.1016/j.protis.2014.12.003. Epub 2014 Dec 16.

Authors

Diana Ferro¹, Rigers Bakiu², Cristiano De Pittà³, Francesco Boldrin³, Franco Cattalini³, Sandra Pucciarelli⁴, Cristina Miceli⁴, Gianfranco Santovito⁵

Affiliations

¹ Department of Biology, via U. Bassi 58/B, University of Padova, 35100 Padova, Italy; Institute for Evolution and Biodiversity, Westfälische Wilhelms-Universität, Münster, Germany.
² Department of Aquaculture and Fisheries, Agricultural University of Tirana, Tirana, Albania.
³ Department of Biology, via U. Bassi 58/B, University of Padova, 35100 Padova, Italy.
⁴ School of Biosciences and Veterinary Medicine, University of Camerino, Camerino, Italy.
⁵ Department of Biology, via U. Bassi 58/B, University of Padova, 35100 Padova, Italy. Electronic address: gianfranco.santovito@unipd.it.

PMID: 25681687
DOI: 10.1016/j.protis.2014.12.003

Abstract

In the present study, we describe the molecular and functional characterization of two Cu,Zn superoxide dismutase (SOD) genes, named tt-sod1a and tt-sod1b from Tetrahymena thermophila, a free-living ciliated protozoan widely used as model organism in biological research. The cDNAs and the putative amino acid sequences were compared with Cu,Zn SODs from other Alveolata. The primary sequences of T. thermophila Cu,Zn SODs are unusually long if compared to orthologous proteins, but the catalytically important residues are almost fully conserved. Both phylogenetic and preliminary homology modeling analyses provide some indications about the evolutionary relationships between the Cu,Zn SODs of Tetrahymena and the Alveolata orthologous enzymes. Copper-dependent regulation of Cu,Zn SODs expression was investigated by measuring mRNA accumulation and enzyme activity in response to chronic exposure to non-toxic doses of the metal. Our in silico analyses of the tt-sod1a and tt-sod1b promoter regions revealed putative consensus sequences similar to half Antioxidant Responsive Elements (hARE), suggesting that the transcription of these genes directly depends on ROS formation. These data emphasize the importance of complex metal regulation of tt-sod1a and tt-sod1b activation, as components of an efficient detoxification pathway allowing the survival of T. thermophila in continued, elevated presence of metals in the environment.

Keywords: Cu,Zn superoxide dismutase; Tetrahymena thermophila; ciliated protozoa; copper.; metal-induced oxidative stress.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Antioxidants / metabolism*
Copper / metabolism
DNA, Protozoan / chemistry
DNA, Protozoan / genetics
Evolution, Molecular*
Gene Expression Regulation, Enzymologic*
Molecular Sequence Data
Phylogeny
Reactive Oxygen Species / metabolism
Sequence Analysis, DNA
Sequence Homology
Superoxide Dismutase / genetics*
Superoxide Dismutase / metabolism*
Tetrahymena thermophila / enzymology*
Tetrahymena thermophila / genetics*

Substances

Antioxidants
DNA, Protozoan
Reactive Oxygen Species
Copper
Superoxide Dismutase

Associated data

GENBANK/KF740481
GENBANK/KF740482