Cloning and sequence analysis of 5' fragment of Hoxa-11 gene in Latimeria chalumnae.
Hoxa-11 gene is essential for the development of fish fins and tetrapod limbs. Based on the published nucleotide sequences of human and mouse Hoxa-11 genes, two degenerate primers were designed. Latimeria Hoxa-11 gene fragment was amplified by PCR, cloned and sequenced. The acquired Hox gene fragment, which encodes 204 amino acids, is comprised of 2,065 bp, including most exon 1, intron and partial exon 2. The homology of latimeria Hoxa-11 protein is 66.0% to human, 67.6% to mouse, 74.4% to chick, 72.8% to frog, and 59.7% to zebrafish, respectively. The exon 2 region including the homeobox and the splice site are highly conserved. However, the exon 1 region has increased in size by 16% from latimeria to human. Sequence analysis further revealed that exon 1 of latimeria Hoxa-11 could be divided into four regions: two highly conserved regions, a moderately conserved region, and a variable region adjacent to the intron. The size variation is primarily caused by the accumulation of alanine repeats and of flanking segments rich in glycine and serine in the variable region. It implies that the variable region might be related to acquisition of new functions in the fin-limb transition and vertebrate evolution. Besides the homeobox, two highly conserved regions in exon 1 and two phylogenetic footprints in the intro were found. The strong sequence conservation suggests an important functional role of these regions.
Xue
L Y
LY
College of Life Sciences, Zhejiang University, Hangzhou 310027, China. xue315@mail.nbptt.zj.cn
Qian
K X
KX
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005399:Fishes / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017385:Sequence Homology
C484298:HOXA11 protein, human; D018398:Homeodomain Proteins; C094041:Hoxa11 protein, mouse