Sequence analysis and tissue expression of a non-Bohr beta-globin cDNA from Atlantic salmon

The presence of a haemoglobin protein which does not exhibit a Bohr effect has been found only in fish living in fast flowing waters. We report the cloning of the first non-Bohr effect beta-globin cDNA from an adult Atlantic salmon kidney bank. Nucleotide sequence analysis of this cDNA shows that the predicted beta-globin peptide comprises 147 amino acids with a calculated molecular mass of 15 975 Da and an overall amino acid homology of 40 to 50% to higher vertebrates and 60–90% to fish sequences. This sequence confirms the important amino acid residues which are changed thus causing loss of the Bohr effect [Powers, D.A. and Edmunson, A.B. (1972) Multiple hemoglobins of catostomid fish. J. Biol. Chem. 247, 6686–6693; Brunori, M. (1975) Molecular adaptation to physiological requirements: the hemoglobin system of trout. Curr. Topics Cell. Regul. 9, 1–39]. This loss allows the haemoglobin protein to have a higher oxygen affinity, as it does not release oxygen when the pH of the surrounding environment decreases, which is an important ability for the fish in times of stress.