Novel mechanism for high-altitude adaptation in hemoglobin of the Andean frog Telmatobius peruvianus.
In contrast to birds and mammals, no information appears to be available on the molecular adaptations for O(2) transport in high-altitude ectothermic vertebrates. We investigated Hb of the aquatic Andean frog Telmatobius peruvianus from 3,800-m altitude as regards isoform differentiation, sensitivity to allosteric cofactors, and primary structures of the alpha- and beta-chains, and we carried out comparative O(2)-binding measurements on Hb of lowland Xenopus laevis. The three T. peruvianus isoHbs show similar functional properties. The high O(2) affinity of the major component results from an almost complete obliteration of chloride sensitivity, which correlates with two alpha-chain modifications: blockage of the NH(2)-terminal residues and replacement by nonpolar Ala of polar residues Ser and Thr found at position alpha131(H14) in human and X. leavis Hbs, respectively. The data indicate adaptive significance of alpha-chain chloride-binding sites in amphibians, in contrast to human Hb where chloride appears mainly to bind in the cavity between the beta-chains. The findings are discussed in relation to other strategies for high-altitude adaptations in amphibians.
Weber
Roy E
RE
Department of Zoophysiology, University of Aarhus, 131 C. F. Møllers Alle, DK 8000 Aarhus C, Denmark. roy.weber@biology.au.dk
Ostojic
Hrvoj
H
Fago
Angela
A
Dewilde
Sylvia
S
Van Hauwaert
Marie-Louise
ML
Moens
Luc
L
Monge
Carlos
C
D000222:Adaptation, Physiological / Q000502:physiology*; D000531:Altitude; D000595:Amino Acid Sequence; D000818:Animals; D001001:Anura / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006454:Hemoglobins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D010101:Oxygen Consumption / Q000502:physiology; D013045:Species Specificity; D013329:Structure-Activity Relationship; D014982:Xenopus laevis
D006454:Hemoglobins