Peptide with both antimicrobial and neurotoxin activities. This toxin acts both on ERG potassium channels and sodium channels (PubMed:12815161,PubMed:16497878, PubMed:17473056, PubMed:22972919). It potently and reversibly inhibits human Kv11.1/KCNH2/ERG1 (IC(50)=34 nM) (PubMed:12815161, PubMed:16497878, PubMed:17473056), rat Kv11.1/KCNH2/ERG1 (PubMed:16497878) and Kv11.3/KCNH7/ERG3 (PubMed:17473056) voltage-gated potassium channels in a similar potency. It acts as a gating-modifier toxin that shifts the voltage-dependence of ERG activation in the positive direction and suppresses its current amplitudes elicited by strong depolarizing pulses (PubMed:12815161, PubMed:17473056). On sodium channels, it blocks Nav1.2/SCN2A (EC(50)=31 nM), Nav1.3/SCN3A, Nav1.4/SCN4A, Nav1.5/SCN5A, Nav1.6/SCN8A, Nav1.8/SCN10A (EC(50)=92 nM) (PubMed:22972919). It may act by binding at site 1 or close by, only when the pore is in an open configuration (PubMed:22972919). Shows antibacterial activity against the Gram-negative bacterium S.typhimurium, but not on the bacteria B.subtilis, S.aureus, and P.aeruginosa (PubMed:28796463). In vivo, this toxin does not induce neurotoxic symptoms when injected into mice (PubMed:12815161). Has the CSbeta/beta fold, which comprises anti-parallel beta-sheets stabilized by three or four disulfide bonds. Does not block Kv11.2/KCNH6/ERG2 (PubMed:17473056), Kv1.1/KCNA1, Kv1.2/KCNA2, Kv1.3/KCNA3, Kv1.5/KCNA5, Kv1.6/KCNA6, Kv2.1/KCNB1, Kv3.4/KCNC4, Kv4.2/KCND2, Kv7.1/KCNQ1, Kv7.2/KCNQ2, Kv7.3/KCNQ3, Kv10.1/EAG1/KCNH1 and Kv12.3/ELK1/KCNH4 (PubMed:12815161). Weakly inhibits Kv1.4 KCNA4 (27%) (PubMed:12815161). Does not inhibit Nav1.7/SCN9A and insect DmNav1 and BgNav1(PubMed:22972919). Belongs to the sea anemone type 3 (BDS) potassium channel toxin family.