Has potent antibacterial activity against some Gram-positive bacteria (PubMed:19400806). Has good antistreptococcal activity. Inhibits cell wall biosynthesis by binding to lipid II and blocking transglycosylation (PubMed:9449277). Maturation of lantibiotics involves the enzymatic conversion of Thr, and Ser into dehydrated AA by the enzyme garM and the formation of thioether bonds with cysteine (Probable). The 59-64 beta-methyllanthionine thioether bond is oxidized to a sulfoxide by the monooxygenase GarO (PubMed:19400806). This is followed by membrane translocation and cleavage of the modified precursor (Probable). The sulfoxide group of the 59-64 beta-methyllanthionine thioether bond is mildly important for activity, since the antibacterial activity of deoxyactagardine is marginally lower compared with oxidized actagardine. Belongs to the type B lantibiotic family.