Identification of a novel antimicrobial peptide from Brazilian coast coral Phyllogorgia dilatata.

The marine ecosystem is able to provide enormous biomolecule diversity that could be used for treatment of various diseases. In this highly competitive environment, organisms need chemical barriers to reduce or avoid microorganism contamination. Among the molecules that protect these animals the antimicrobial peptides (AMPs) are included. In the present study, crude extracts of coral coral specimens Carijoa riisei, Muriceopsis sulphurea, Neospongodes atlantica, Palythoa caribeorum, Phyllogorgia dilatata and Plexaurella grandiflora were challenged against multiple Grampositive and -negative bacteria showing different activities. P. dilatata crude extract showed the antibacterial activity, and was ammonium-sulfate (0-40%) fractionated, being able to control the growth of K. pneumoniae, S. flexineri and S. aureus. Rich-fraction was further purified by using Amicon® Ultra Centrifugal 10 kDa associated with reversed-phase HPLC chromatography (C18), producing the peptide named Pd-AMP1. Pd-AMP1 was able to inhibit S. aureus development. Mass spectrometry analyses showed a monoisotopic mass of 5372.66 Da and N-terminal sequence showed no significant match with databank. In this view, the prospecting of protein biomolecules and biotechnological potential from marine animals is still little explored and may serve as an alternative to common antibiotics.

Deciphering the magainin resistance process of Escherichia coli strains in light of the cytosolic proteome.

Antimicrobial peptides (AMPs) are effective antibiotic agents commonly found in plants, animals, and microorganisms, and they have been suggested as the future of antimicrobial chemotherapies. It is vital to understand the molecular details that define the mechanism of action of resistance to AMPs for a rational planning of the next antibiotic generation and also to shed some light on the complex AMP mechanism of action. Here, the antibiotic resistance of Escherichia coli ATCC 8739 to magainin I was evaluated in the cytosolic subproteome. Magainin-resistant strains were selected after 10 subsequent spreads at subinhibitory concentrations of magainin I (37.5 mg · liter⁻¹), and their cytosolic proteomes were further compared to those of magainin-susceptible strains through two-dimensional electrophoresis analysis. As a result, 41 differentially expressed proteins were detected by in silico analysis and further identified by tandem mass spectrometry de novo sequencing. Functional categorization indicated an intense metabolic response mainly in energy and nitrogen uptake, stress response, amino acid conversion, and cell wall thickness. Indeed, data reported here show that resistance to cationic antimicrobial peptides possesses a greater molecular complexity than previously supposed, resulting in cell commitment to several metabolic pathways.