cDNA Cloning and Analysis of the Chicken Homolog of E.coli Endonuclease Ⅲ

Abstract

We have cloned and analyzed the cDNA for the chicken homolog of E. coli endonuclease Ⅲ (chNthll; chicken homolog of E. coli endonuclease Ⅲ-like 1). The cDNA was isolated from a chicken embryonic cDNA library using cDNA of mouse endonuclease Ⅲ (mNthll) as a probe. The obtained　cDNA　was 1211 nucleotide long encoding a protein　consisting of 281 amino acids with a predicted molecular　mass of 32 kDa. The amino acid sequence exhibits 66% and 67%homologies with those of the human　and mouse homologs,　respectively, and the homologies are mostly concentrated　within the C-terminal, 2/3 region of the sequence. The two motifs consisting of a helix-hairpin-helix and an iron-sulphur [4Fe-4S] cluster were also preserved in the chicken homolog suggesting similar enzymatic function in chicken cells as that of endonuclease Ⅲ in E. coli.