Sequence analysis of a 212 kb defensin gene cluster on ECA 27q17

Defensins are a family of evolutionary ancient antimicrobial peptides consisting of three sub-families: α-, β- and θ-defensins. This investigation was focused on the genomic characterization of equine β-defensins and the investigation of the potential clustering of β-defensin genes in the equine genome. Six genomic BAC clones were isolated from the CHORI-241 library and one of these was mapped by FISH to ECA 27q17. This location was confirmed by RH-mapping. The contiguous 212 kb sequence of this clone was determined. Sequence analysis revealed the identification of ten pseudogenes and nine genes, six of which were highly homologous to human β-defensin DEFB4. Clustering of the β-defensin genes was confirmed and the order of the genes on the analyzed BAC was related to the corresponding defensin cluster on HSA 8. The knowledge about the sequence and the genomic structure of the equine β-defensin genes will improve the classification of different paralogous defensin genes and is a prerequisite for subsequent functional studies. Additionally, the first α-defensin-like sequence outside the groups of primates, lagomorphs and rodents (glires) was identified.