title: Hemoglobin structure/function and globin-gene evolution in the Arctic fish Liparis tunicatus.
abstract: The importance of the Arctic, in contributing to the knowledge of the overall ensemble of adaptive processes influencing the evolution of marine organisms, calls for investigations on molecular adaptations in Arctic fish. Unlike the vast majority of Antarctic Notothenioidei, several Arctic species display high hemoglobin multiplicity. The blood of four species, the spotted wolffish of the family Anarhichadidae and three Gadidae, contains three functionally distinct major components. Similar to many Antarctic notothenioids, Arctic Liparis tunicatus (suborder Cottoidei, family Liparidae) has one major hemoglobin (Hb 1) accompanied by a minor component (Hb 2). This paper reports the structural and functional characterisation of Hb 1 of L. tunicatus. This hemoglobin shows low oxygen affinity, and pronounced Bohr and Root effects. The amino-acid sequence of the beta chain displays an unusual substitution in NA2 (beta2) at the phosphate-binding site, and the replacement of Val E11 (beta67) with Ile. Similar to some Antarctic fish Hbs, electron paramagnetic resonance spectra reveal the formation of a ferric penta-coordinated species even at physiological pH. The amino-acid sequences have also been used to gain insight into the evolutionary history of globins of polar fish. L. tunicatus globins appear close to the notothenioid clades as predicted by teleostean phylogenies. Close phylogenetic relationships between Cottoidei and Notothenioidei, together with their life style, seem to be the main factor driving the globin-sequence evolution.
authors.affiliation: Institute of Protein Biochemistry, CNR, Via Pietro Castellino 111, I-80131 Naples, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Giordano
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vergara
authors.forename: H Caroline
authors.initials: HC
authors.lastname: Lee
authors.forename: Jack
authors.initials: J
authors.lastname: Peisach
authors.forename: Marco
authors.initials: M
authors.lastname: Balestrieri
authors.forename: Lelio
authors.initials: L
authors.lastname: Mazzarella
authors.forename: Elio
authors.initials: E
authors.lastname: Parisi
authors.forename: Guido
authors.initials: G
authors.lastname: di Prisco
authors.forename: Cinzia
authors.initials: C
authors.lastname: Verde
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001110:Arctic Regions; D019143:Evolution, Molecular; D005399:Fishes / Q000235:genetics*; D005914:Globins / Q000235:genetics; D006454:Hemoglobins / Q000235:genetics*; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D006454:Hemoglobins; D005914:Globins; D010100:Oxygen