Gene cloning and functional characterization of four novel antimicrobial-like peptides from scorpions of the family Vaejovidae

► We construct cDNA libraries from Vaejovis mexicanus smithi and Vaejovis subcristatus. ► We identify cDNAs coding for putative antimicrobial peptides from the libraries. ► We synthesize and characterize the activities of VmCT1, VmCT2, VsCT1 and VsCT2. ► VmCT1 and VmCT2 have broad-spectrum antibacterial activities with low hemolysis. From the cDNA libraries made from the venom glands of two scorpions belonging to the Vaejovidae family, four different putative non disulfide-bridged antimicrobial peptides were identified: VmCT1 and VmCT2 from Vaejovis mexicanus smithi plus VsCT1 and VsCT2 from Vaejovis subcristatus. These short peptides (with only 13 amino acid residues each) share important amino acid sequence similarities among themselves and with other reported antimicrobial peptides, but their biological activities vary dramatically. This communication reports the cloning, chemical synthesis and characterization of these peptides. Two peptides, VmCT1 and VmCT2 showed broad-spectrum antibacterial activity with minimum inhibitory concentrations MICs in the range of 5–25μM and 10–20μM respectively, whereas their hemolytic activity at these concentrations was low. Structure–function relationships that might determine the differences in activities are discussed.