Abstract: 【Objective】 The purpose of this study is to clarify the structural features of artiodactyl PrP gene, relationships of the sequence variations with its structure-function and the species barrier of prion disease transmission, and molecular phylogeny among the PrP genes.【Method】 The identity analysis and multiple alignment of 43 complete PrP gene sequences of 22 artiodactyls were undertaken, and phylogenetic trees were reconstructed, respectively, by using the DNAstar and Clustalx packages, and treev32 program.【Results】PrP gene sequences in different artiodactyls showed the entire ORFs size range from 768 bp to 795 bp, which could encode PrPs with 255 to 264 amino acids. The homology of these nucleotide and amino acid sequences were greater than or equal to 88.6% and greater than or equal to 93.3% among artiodactyls, and were greater than or equal to 95.4% and greater than or equal to 96.5% between ruminants, respectively.A total of 40 point mutations and two variable regions were found. The major mutations in the N-terminal flexible disordered"tail"region (25～135) were the octarepeat deletion, while those in the globular domain region (136～241) were the point mutations. The most of point mutations clustered in the C-terminal portion of the flexible disordered region before S1 -sheet and within HC -helix. There were eight high-frequency mutation positions in the regions of amino acid residues 104～135 and the globular domain. The known motifs and functional positions of PrP, such as the aromatic hydrocarbon palindrome motif, the two N-linked glycosylation sites, the two threonine residues phosphorylation sites, the tyrosine residue sulfurization site, the two cysteine residues forming the disulfide bond, and the serine residue at position 242 where the GPI anchor is attached, were mutual for all interspecies variations of artiodactyls. It was showed that the interspecies variations were in good agreement with structural model. According to the phylogenetic relationship analysis of PrP genes, the PrP genes of artiodactyls could be obviously separated into three super-kinds, the PrP genes of ruminants could be further divided into three distinct kinds of genes. It was surprised that the PrP gene phylogenesis of two bactrian camels was homologous with the bovine genus animals.【Conclusion】PrP gene in artiodactyls is a conservative gene. The eight high-frequency mutation positions within the regions of amino acid residues 104-135 and the globular domain seem to be the major positions affecting intermolecular interactions and forming the species barrier of prion disease transmission, and the amino acid variations in these species do not affect the key structures and functions of PrPs.

Key words: artiodactyls, prion protein gene, structural characteristic, molecular phylogeny, structure-function relationship, species barrier