A NEW BETA DEFENSIN FROM SIKA DEER: MOLECULAR CLONING AND SEQUENCE CHARACTERIZATION

The beta-defensins are small, well-characterized peptides with broad antimicrobial activities. Here we report the identification of a novel beta-defensin, sika deer beta-defensin-1 (siBD-1), from sika deer tissues with a pair of PCR primers according to the conserved cDNA sequences of known ruminant beta-defensins. Total RNA was extracted from the tongue epithelia of a sika deer and the 418 bp cDNA encoding siBD-1 was amplified by the reverse transcription PCR (RT-PCR), 5'- and 3'-RACE. The cDNA contained an open reading frame (ORF) of 192 bases which encoded a 64 amino acid prepro-peptide. The prepro-peptide contained six invariantly spaced cysteine residues, which is the beta defensin consensus sequence. The putative mature peptide of the siBD-1 contained nine positively charged residues (5 arginine-R, 3 lysine-K, and 1 histidine-H). The sequence homology shows that siBD-1 has 73.0-90.6% amino-acid identity and 74.6-90.6% cDNA identity with other ruminant beta-defensins, sharing the greatest identity with buffalo enteric beta-defensin in both amino acid and nucleotide sequences.