Distinctive Roles of Two Acinetobactin Isomers in Challenging Host Nutritional Immunity
Mingi Kim, Do Young Kim, Woon Song, So Eun Park, Simone Harrison, Walter Chazin, Man Hwan Oh, Hak Joong Kim
Abstract
Acinetobacter baumannii has acquired antibiotic resistance at an alarming rate, and it is becoming a serious threat to society, particularly due to the paucity of effective treatment options. Acinetobactin is a siderophore of Acinetobacter baumannii, responsible for active iron supply, and it serves as a key virulence factor to counter host nutritional immunity during infection. While two acinetobactin isomers were identified, their distinctive roles for successful infection of Acinetobacter baumannii remained unsettled. This study clearly identified the isomer containing an oxazoline core as the principal siderophore based on comparative analysis of the specificity of the acinetobactin uptake machinery, the stability of the corresponding iron complexes, and the iron scavenging activity against the host iron sequestering proteins. Our findings are anticipated to stimulate efforts to discover a potent antivirulence agent against Acinetobacter baumannii that exploits the acinetobactin-based iron assimilation mechanism.