ABSTRACT
Secretory granules of chromaffin cells from the adrenal medulla store catecholamines and a variety of peptides that are secreted in the extracellular medium during exocytosis. Among these fragments, several natural peptides displaying antimicrobial activities at the micromolar range have been isolated and characterized. We have shown that these peptides, derived from the natural processing of chromogranins (CGs), proenkephalin-A (PEA) and free ubiquitin (Ub), are released into the circulation and display antibacterial and antifungal activities. In this review we focus on three naturally secreted antimicrobial peptides corresponding to CGA1-76 (vasostatin-I), the bisphosphorylated form of PEA209-237 (enkelytin) and Ub. In addition, the antimicrobial properties of the synthetic active domains of vasostatin-I (CGA47-66 or chromofungin) and Ub (Ub65-76 or ubifungin) are reported.
Subject(s)
Anti-Infective Agents , Chromogranins , Enkephalins , Immunity, Innate , Neuropeptides , Peptide Fragments , Ubiquitin , Amino Acid Sequence , Animals , Anti-Infective Agents/chemistry , Anti-Infective Agents/metabolism , Anti-Infective Agents/pharmacology , Bacteria/drug effects , Chromogranin A , Chromogranins/chemistry , Chromogranins/metabolism , Chromogranins/pharmacology , Enkephalins/chemistry , Enkephalins/metabolism , Enkephalins/pharmacology , Fungi/drug effects , Models, Molecular , Molecular Sequence Data , Neuropeptides/chemistry , Neuropeptides/metabolism , Neuropeptides/pharmacology , Peptide Fragments/chemistry , Peptide Fragments/metabolism , Peptide Fragments/pharmacology , Ubiquitin/chemistry , Ubiquitin/metabolism , Ubiquitin/pharmacologyABSTRACT
The antifungal peptide named chromofungin is the most active vasostatin-I-derived peptide, corresponding to the sequence 47-66 of chromogranin A. (1)H-NMR analysis revealed that it adopts a helical structure. The mechanism implicated in the interaction of chromofungin with fungi and yeast cells was studied by penetration of monolayers and confocal laser microscopy. Chromofungin is able to interact with the cell wall, to cross the plasma membrane, to accumulate in the microorganism, and to inhibit calcineurin activity.
Subject(s)
Chromogranins/chemistry , Chromogranins/pharmacology , Peptide Fragments/chemistry , Peptide Fragments/pharmacology , Peptides/chemistry , Alternaria/metabolism , Antifungal Agents/chemistry , Aspergillus fumigatus/metabolism , Calcineurin Inhibitors , Calcium-Binding Proteins/metabolism , Calreticulin , Candida albicans/metabolism , Cell Membrane/metabolism , Chromogranin A , Chromogranins/metabolism , Humans , Magnetic Resonance Spectroscopy , Peptide Fragments/metabolism , Peptides/pharmacology , Protein Structure, Tertiary , Ribonucleoproteins/metabolismABSTRACT
Vasostatin-I, the natural fragment of chromogranin A-(1-76), is a neuropeptide able to kill a large variety of fungi and yeast cells in the micromolar range. We have examined the antifungal properties of synthetic vasostatin-I-related peptides. The most active shortest peptide, named chromofungin, corresponds to the sequence Arg(47)-Leu(66). Extensive (1)H NMR analysis revealed that it adopts a helical structure. The biophysical mechanism implicated in the interaction of chromofungin with fungi and yeast cells was studied, showing the penetration of this peptide with different lipid monolayers. In order to examine thoroughly the antifungal activity of chromofungin, confocal laser microscopy was used to demonstrate the ability of the rhodamine-labeled peptide to interact with the fungal cell wall, to cross the plasma membrane, and to accumulate in Aspergillus fumigatus, Alternaria brassicola, and Candida albicans. Our present data reveal that chromofungin inhibits calcineurin activity, extending a previous observation that the N-terminal region of chromogranin A interacts with calmodulin in the presence of calcium. Therefore, the destabilization of fungal wall and plasma membrane, together with the possible intracellular inhibition of calmodulin-dependent enzymes, is likely to represent the mechanism by which vasostatin-I and chromofungin exert antifungal activity.
