title: Molecular cloning and sequencing of hemoglobin-beta gene of channel catfish, Ictalurus punctatus Rafinesque.
abstract: The hemoglobin-beta gene of channel catfish, Ictalurus punctatus, was cloned and sequenced. Total RNA from head kidneys was isolated, reverse transcribed and amplified. The sequence of the channel catfish hemoglobin-beta gene consists of 600 nucleotides. Analysis of the nucleotide sequence reveals one open reading frame and 5'- as well as 3'-untranslated regions. The open reading frame of the sequence potentially encodes 148 amino acids with a calculated molecular mass of 16.3 kDa. The pI and charge at pH 7.0 of the deduced hemoglobin-beta protein were 7.28 and 0.47, respectively. Overall, 22 amino acid residues were conserved throughout the sequences, including His64 and His93, the sites for heme-binding. Unlike the counterpart of other common cultured fish such as Salmo salar, Oncorhynchus nerka, Oncorhynchus mykiss, Cyprinus carpio and Ctenopharyngodon idella, the hemoglobin-beta of channel catfish did not have cysteine. The amino acid sequence of channel catfish hemoglobin-beta shows 84% homology with that of Silurus asotus (both are in the order Siluriformes). However, comparison with those of other fish species shows homology ranging from 53 to 68%. Structural analysis by the 3D-PSSM program displays that channel catfish hemoglobin-beta has eight alpha-helices, A-H.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Unit, 990 Wire Road, P.O. Box 952, Auburn, AL, 36831-0952, USA, yyeh@ars.usda.gov.
authors.forename: Hung-Yueh
authors.initials: HY
authors.lastname: Yeh
authors.forename: Craig A
authors.initials: CA
authors.lastname: Shoemaker
authors.forename: Phillip H
authors.initials: PH
authors.lastname: Klesius