Processing site and gene structure for the murine antimicrobial peptide CRAMP.

Cathelicidins are a mammalian gene family notable for the presence of an antibiotic peptide encoded at the carboxy-terminal domain of the nascent pre-pro-protein. Following proteolytic release, this peptide has direct antimicrobial activity. To understand the function and regulation of cathelicidin we investigated the peptide processing site and gene structure of the mouse cathelicidin CRAMP. Amino acid sequencing of the purified native 5 kDa peptide identified the functionally critical amino terminal sequence of mature CRAMP. Characterization of the CRAMP gene (Cnlp) showed homology in structure and sequence identity in several potential transcription factors binding sites found in the human cathelicidin LL-37. Overall, CRAMP shows striking similarities with LL-37, making it a useful model for study of human cathelicidin function and regulation.