title: Expression, purification, and in vitro comparative characterization of avian beta-defensin-2, -6, and -12.
abstract: The mature peptides of avian β-defensin-2 (AvBD-2), AvBD-6, and AvBD-12 were expressed as 6xHis-tagged recombinant proteins using the Escherichia coli BL21(DE3)pLysS system. The yields of rAvBD-2, rAvBD-6, and rAvBD-12 were approximately 0.92 mg/L, 1.24 mg/L, and 1.52 mg/L, respectively, of bacterial culture. The antimicrobial activities of rAvBDs were characterized under different salt, nutrient, and pH conditions. At concentrations of 8 μg/ml, 16 μg/ml, and 32 μg/ml, rAvBDs inhibited the growth of Staphylococcus aureus, E. coli, and Salmonella enterica serovar Typhimurium. While no synergistic inhibitory activity was found, a significant antagonistic effect was detected between rAvBD-2 and rAvBD-12. Treatment of E. coli and Salmonella Typhimurium with rAvBDs diminished their natural resistance to bile salts. Under the nonreplicating low-nutrient condition, rAvBDs at a concentration of 16 μg/ml were able to kill E. coli and S. aureus within 30 min of contact. The antimicrobial activities of rAvBDs were enhanced by lowering salt concentration and pH from 7 to 6. The antimicrobial potency against S. aureus and E. coli could be characterized as rAvBD-6 > rAvBD-2 > rAvBD-12, which coincided with the net positive charges of these peptides. In conclusion, data from the current study warrant the investigation of the potential use of rAvBD-2, -6, and -12 as therapeutic and prophylactic antimicrobial agents against common bacterial pathogens.
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.forename: Michael
authors.initials: M
authors.lastname: Zhang
authors.forename: Shuping
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects*; D002645:Chickens; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology*; D010057:Oviducts / Q000166:cytology; D023083:beta-Defensins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D023083:beta-Defensins