Study of new antimicrobial peptides in chromaffin granules from bovine adrenal medulla: new aspects of innate immunity

Secretory granules of chromaffin cells contain with catecholamines several antimicrobial peptides, which are secreted in the extracellular medium following exocytosis. In this report we decided to focus on three active peptides Chromofungin (chromogranin A 47-66), Enkelytin (proenkephalin-A 209-237 and Ubifungin (ubiquitin 65-76). Using confocal laser microscopy we have shown that Chromofungin and Ubifungin are able to cross the cell membranes and penetrate into fungi and yeasts, whereas the Nterminal fragment ubiquitin 1-34 was stopped at the fungal cell wall level. At the intracellular level Chromofungin and Ubifungin are able to inhibit calmodulin-dependent calcineurin, a crucial enzyme for fungal growth. Finally, all together these peptides constitute a mixture of potent antimicrobial peptides, which might represent molecules useful for the development of new therapeutic agents.