ISOLATION AND SEQUENCE ANALYSIS ON HMG1 GENE FROM THE CHINESE SOFT-SHELL TURTLE(PELODISCUS SINENSIS)

In order to understand sequence information about turtle HMG1, a cDNA encoding HMG1 protein of the Chinese sof-t shell turtle( Pelodiscus sinensis)was amplified by RT-PCR from liver total RNA, and was cloned, sequenced and analyzed. The results revealed that the open reading frame ( ORF) of turtle HMG1 cDNA is 606 bp long. The ORF encodes 202 amino acid residues. Turtle HMG1 protein contains three conserved regions: two HMG- box domains and one polyacidic region. From the Nterminus, HMG box1 domain(residues 9-80) and HMG box2 domain(residues 89-162) are tandemly arranged.Beginning at position residue 163,the polyacidic region consists of two portions:the first portion(residues 163-181) and the last portion (residues 182-202).The last portion contains a consecutive run of 7 Asp and 14 Glu residues that ends at the C-terminus.Two HMG- box domains of turtleHMG1 protein share higher amino acid identity with homologues sequences of chicken(96.5%) and human(74%) than homologues sequence of rainbow trout( 67%).Length of the polyacidic region from different HMG1 gene is variable,implying that selective forces may play a role in the polyacidic region in HMG1 gene.But,selective forces involved in the evolutionary development of the polyacidic region have not discriminated between Glu and Asp residues.Phylogenetic analysis suggests that HMG box1 and box2 present in vertebrate HMG1 gene form two separate subgroups.To our knowledge,this is the first report of HMG1cDNA sequence in any reptilian.