The amino acid sequence and oxygen-binding properties of the single hemoglobin of the cold-adapted Antarctic teleost Gymnodraco acuticeps.
ABSTRACT The complete amino acid sequence of the single hemoglobin of the Antarctic teleost Gymnodraco acuticeps has been determined. The alpha chain contains 142 amino acid residues; an acetylated seryl residue is at the amino terminal. The beta chain contains 146 residues. A very high degree of sequence identity has been found with hemoglobins of other Antarctic fishes. Oxygen binding is not modulated by pH and allosteric effectors. The Bohr and Root effects are absent, although specific amino acid residues, considered responsible of most of these functions, are conserved in the sequence, thus posing new questions about the molecular basis of these mechanisms. The low heat of oxygenation may be interpreted as one of the mechanisms involved in the process of cold adaptation.
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ABSTRACT: Cathepsin S is a lysosomal cysteine endopeptidase of the papain family. Our preliminary results showed the up-regulation of cathepsin S (CTSS) transcript during the early stage of Edwardsiella ictaluri infection, leading us to speculate that CTSS may play a role in infection. In this report, we identified, sequenced and characterized the channel catfish CTSS cDNA. Total RNA from tissues was isolated and cDNA libraries were constructed by the rapid amplification cDNA end (RACE) method. The gene-specific primers in conjunction with the RACE primers were used to PCR amplify 5'- and 3'-ends of the CTSS transcript. The complete channel catfish CTSS cDNA comprised 1530 nucleotides including a 96-nucleotide 5'-untranslated region (UTR), a 990-nucleotide open reading frame and a 444-nucleotide 3'-UTR. The open reading frame appears to encode a protein of 329 amino-acid residues with calculated molecular mass of 36.7kDa and pI of 5.96. The degree of conservation of the channel catfish CTSS amino-acid sequence in comparison to other species ranged from 56.6 to 68.5%. These results provide important information for further exploring the roles of channel catfish CTSS in antigen processing.Veterinary Immunology and Immunopathology 09/2008; 126(3-4):382-7. DOI:10.1016/j.vetimm.2008.07.014 · 1.75 Impact Factor
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ABSTRACT: Because hemoglobins (Hbs) of all animal species have the same heme group, differences in their properties, including oxygen affinity, electrophoretic mobility, and pH sensitivity, must result from the interaction of the prosthetic group with specific amino acid residues in the primary structure. For this reason, fish globins have been the object of extensive studies in the past few years, not only for their structural characteristics but also because they offer the possibility to investigate the evolutionary history of Hbs in marine and freshwater species living in a large variety of environmental conditions. For such a purpose, phylogenetic analysis of globin sequences can be combined with knowledge of the phylogenetic relationships between species. In addition, Type I functional-divergence analysis is aimed toward predicting the amino acid residues that are more likely responsible for biochemical diversification of different Hb families. These residues, mapped on the three-dimensional Hb structure, can provide insights into functional and structural divergence.Methods in Enzymology 02/2008; 436:539-70. DOI:10.1016/S0076-6879(08)36030-3 · 2.19 Impact Factor
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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.Gene 01/2008; 406(1-2):58-68. DOI:10.1016/j.gene.2007.06.002 · 2.08 Impact Factor