The hemoglobins of the sub-antartic fish Cottoperca gobio, a phyletically basal species. Oxygen binding equilibria, kinetics, and molecular dynamics

D. GIORDANO; L. BOECHI; A. VERGARA; M.A. MARTI; U. SUMUNI; D. DANTSKER; L. GRASSI; D.A. ESTRIN; J. FRIEDMAN; L. MAZZARELLA; G. DI PRISCO; C. VERDE

FEBS JOURNAL

Wiley

Año: 2009 vol. 276 p. 2266 - 2277

1742-464X

The dominant perciform suborder Notothenioidei is an excellent studygroup for assessing the evolution and functional importance of biochemical adaptations to temperature. The availability of notothenioid taxa in a wide range of latitudes (Antarctic and non-Antarctic) provides a tool to enable identification of physiological and biochemical characteristics gained and lost during evolutionary history. Non-Antarctic notothenioids belonging to the most basal families are a crucial source for understanding the evolution of hemoglobin in high-Antarctic cold-adapted fish. This paper focuses on the structure, function and evolution of the oxygen-transport system of Cottoperca gobio, a sub-Antarctic notothenioid fish of the family Bovichtidae, probably derived from ancestral species that evolved in the Antarctic region and later migrated to lower latitudes. Unlike most high-Antarctic notothenioids, but similar to many other acanthomorph teleosts, C. gobio has two major hemoglobins having the b chain in common. The oxygen-binding equilibria and kinetics of the two hemoglobins have been measured.Hb1 and Hb2 show strong modulation of oxygen-binding equilibria andkinetics by heterotropic effectors, with marked Bohr and Root effects. InHb1 and Hb2, oxygen affinity and subunit cooperativity are slightly higherthan in most high-Antarctic notothenioid hemoglobins. Hb1 and Hb2show similar rebinding rates, but also show significant dynamic differencesthat are likely to have functional consequences. Molecular dynamic simula-tions of C. gobio Hb1 were performed on the dimeric protein in order toobtain a better understanding of the molecular basis of structure ⁄ function relationships.