Structural organization of the bovine cathelicidin gene family and identification of a novel member.

Cathelicidins are a group of myeloid antimicrobial peptide precursors found in a variety of mammalian species. Transcripts of this family show a highly conserved 5' region corresponding to the 5' untranslated region, signal peptide and propiece, and diverse 3' regions encoding structurally varied C-terminal sequences that correspond to mature antimicrobial peptides after proteolytic release from the precursors. To establish the size of the bovine gene family encoding these proteins, lambda genomic clones were isolated by screening a bovine library with a probe based on the conserved cDNA region of bovine members. Restriction mapping, hybridization studies and sequence analysis identified 11 distinct genes that based on the intergenic distances of contiguous genes appear to be in close physical proximity. Among these, a novel gene encoding the precursor of a putative alpha-helical antimicrobial peptide was recognized and sequenced. The novel gene appears to be expressed in bovine bone marrow myeloid cells, spleen and testis.