The functionally distinct hemoglobins of the Arctic spotted wolffish Anarhichas minor.
The Arctic fish Anarhichas minor, a benthic sedentary species, displays high hemoglobin multiplicity. The three major hemoglobins (Hb 1, Hb 2, and Hb 3) show important functional differences in pH and organophosphate regulation, subunit cooperativity, and response of oxygen binding to temperature. Hb 1 and Hb 2 display a low, effector-enhanced Bohr effect and no Root effect. In contrast, Hb 3 displays pronounced Bohr and Root effects, accompanied by strong organophosphate regulation. Hb 1 has the beta (beta(1)) chain in common with Hb 2; Hb 3 and Hb 2 share the alpha (alpha(2)) chain. The amino acid sequences have been established. Several substitutions in crucial positions were observed, such as Cys in place of C-terminal His in the beta(1) chain of Hb 1 and Hb 2. In Hb 3, Val E11 of the beta(2) chain is replaced by Ile. Homology modeling revealed an unusual structure of the Hb 3 binding site of inositol hexakisphoshate. Phylogenetic analysis indicated that only Hb 2 displays higher overall similarity with the major Antarctic hemoglobins. The oxygen transport system of A. minor differs remarkably from those of Antarctic Notothenioidei, indicating distinct evolutionary pathways in the regulatory mechanisms of the fish respiratory system in the two polar environments.
Institute of Protein Biochemistry, Consiglio Nazionale delle Ricerche, Via Marconi 12, I-80125 Naples, Italy.
Cinzia
C
Verde
Vito
V
Carratore
Antonio
A
Riccio
Maurizio
M
Tamburrini
Elio
E
Parisi
Guido
G
Di Prisco
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003545:Cysteine / Q000737:chemistry; D005786:Gene Expression Regulation; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009943:Organophosphorus Compounds / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010473:Perciformes / Q000378:metabolism*; D010802:Phylogeny; D010833:Phytic Acid / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D013696:Temperature; D013997:Time Factors
D006454:Hemoglobins; D009943:Organophosphorus Compounds; D010833:Phytic Acid; D000255:Adenosine Triphosphate; D003545:Cysteine; D010100:Oxygen