ANTIMICROBIAL ACTIVITY OF A 13 AMINO-ACID TRYPTOPHAN-RICH PEPTIDE DERIVED FROM A PUTATIVE PORCINE PRECURSOR PROTEIN OF A NOVEL FAMILY OF ANTIBACTERIAL PEPTIDES

It has long been speculated that porcine cathelin is an N-terminal fra gment of a longer precursor protein which possesses antimicrobial acti vity, In an attempt to find such a precursor, a cDNA clone was recentl y isolated and sequenced by screening a cDNA library from porcine bone marrow, In order to identify the functional activity of the putative protein encoded by an open reading frame, we have synthesized various lengths of peptides that correspond to the C-terminal region of the pr otein and examined them for their antimicrobial activities, We found t hat a 13 amino acid tryptophan-rich region with the sequence of VRRFPW WWPFLRR had strong antimicrobial activity with a wide spectrum, It sho wed potency against Escherichia coli, Pseudomonas aeruginosa, Klebsiel la pneumonia, Staphylococcus epidermidis, Proteus mirabilis, and Strep tococcus group D as well as Aspergillus fumigatus. The action of this peptide is bactericidal rather than bacteriostatic and this activity i s completely inhibited by 2 mM MgCl2. Our results indicate that the pr eviously identified putative precursor encoded by the isolated cDNA in deed possesses a potent antimicrobial activity and that this 13 amino acid synthetic peptide is considered to be a potentially effective dru g against various infectious agents.