LOCALIZATION AND GENOMIC ORGANIZATION OF SHEEP ANTIMICROBIAL PEPTIDE GENES

Antimicrobial peptides are an abundant and diverse component of animal innate immunity. Within mammalian species, defensins and cathelicidin s are the two principal antimicrobial peptide families. We identified and sequenced ten new sheep genes which encode potential antimicrobial peptides including two beta-defensins and eight cathelicidins. We map ped the two-exon beta-defensin genes to sheep chromosome 26 and the fo ur-exon cathelicidin genes to sheep chromosome 19 using sheep-hamster somatic cell hybrids in conjunction with flow-sorted sheep chromosomes . These assignments confirm homology between sheep, cattle, mouse, and human antimicrobial peptide gene families. Contig construction for th e sheep cathelicidin gene family demonstrates that three genes, OaDode A, OaDodeB, and OaMAP-34, are present head-to-tail in a 14.5 kb region , and that four proline/arginine-rich genes, OaBac5, OaBac7.5, OaBac11 , and OaBac6, are arranged head-to-tail in a region covering 30.5 kb. This richly diverse family of sheep cathelicidin peptides is encoded i n a gene array which may reflect the mechanism of its evolution. (C) 1 997 Elsevier Science B.V.