Molecular cloning of cDNAs and structural model analysis of two gonadotropin beta-subunits of snakehead fish (Channa maculata).
The cDNAs encoding beta-subunits of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) have been cloned from the pituitary of snakehead fish, Channa maculata, and the three-dimensional structural models of the encoded FSH and LH were investigated. The cloned cDNAs, including 5'-untranslated region (UTR), open-reading frame, and 3'-UTR followed by a poly(A) tail, were obtained by reverse transcription-polymerase chain reaction and rapid amplification of cDNA end methods. The open-reading frames of FSH-beta cDNA encodes a 120-amino acid protein with a signal peptide of 18 amino acids and a mature protein of 102 amino acids; while LH-beta cDNA encodes a 140-amino acid protein with a signal peptide of 33 amino acids and a mature protein of 115 amino acids. The amino acid sequence identities of snakehead fish FSH-beta and LH-beta in comparison with other fish are 27.8-81.9% and 45.2-88.8%, respectively; while in comparison with tetrapods are 26.2-28.9% and 37.5-51.2%, respectively. Both FSH-beta and LH-beta of snakehead fish resemble most to those of Perciformes, implying their closer phylogenetic relationship. All 12 cysteine residues are conserved in snakehead fish LH-beta; while 11 cysteine residues are conserved in its FSH-beta. The third cysteine is absent in snakehead fish FSH-beta; instead, a positionally shifted cysteine residue is present at the N-terminus, as found in some phylogenetic related fish. The structure models of snakehead fish FSH and LH, constructed by using the crystal structures of human FSH and human chorionic gonadotropin as respective template, showed that the positionally shifted N-terminal cysteine residue of snakehead fish FSH-beta likely can substitute the third cysteine to form a disulfide bond with the 12th cysteine.
Chatterjee
Abhijit
A
Endocrinology Laboratory, Institute of Zoology, Academia Sinica, 128 Academia Road, Section II, Taipei 115, Taiwan, ROC.
Shen
San-Tai
ST
Yu
John Yuh-Lin
JY
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics*; D037201:Follicle Stimulating Hormone, beta Subunit / Q000737:chemistry / Q000235:genetics*; D037101:Luteinizing Hormone, beta Subunit / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics*; D010802:Phylogeny; D017434:Protein Structure, Tertiary
D018076:DNA, Complementary; D037201:Follicle Stimulating Hormone, beta Subunit; D037101:Luteinizing Hormone, beta Subunit