Antimicrobial peptide that potently acts against several species of Gram-positive bacteria (PubMed:16222292, PubMed:19472324). It selectively inhibits peptidoglycan biosynthesis through complex formation with the cell wall precursor lipid II (1:1 molar ratio) thus inhibiting cell wall synthesis (PubMed:20508130). It does not disrupt cell membranes (PubMed:20508130). Is especially active against numerous clinical isolates of S.pneumoniae, including all 90 different serotypes and isolates resistant to clinically used antibiotics (PubMed:16222292). In vitro, shows considerable selectivity for bacteria over mammalian cells (PubMed:16222292). The peptide synthesized in D-amino acids does not show antibacterial activity (PubMed:19472324). In vitro, acts on voltage-gated potassium channels by moderately inhibiting mammalian Kv1.3/KCNA3 (IC(50)=2.8 uM), and moderately inhibiting others potassium channels (PubMed:25568977). Plectasin could be used as a possible antibiotic, especially against S.pneumoniae infections. An improved derivative NZ2114 can be used as an antibiotic for the methicillin-resistant S.aureus (MRSA). In mice infected by S.pneumoniae, it has an efficacy comparable to vancomycin in the peritoneal model and to penicillin in the pneumonia model. Belongs to the invertebrate defensin family. Type 2 subfamily.