Determining the Chemical Structure of Brucebactin: The Sole Complex Siderophore Utilized by the Pathogenic Bacterium Brucella Abortus

Abstract

Brucellosis is a zoonotic bacterial disease that affects many around the world. There are over half a million new cases each year and prevalence rates in some areas of the world exceed 10 new cases per 100,000 in the population. It is one of the world’s most common zoonotic diseases. In cattle, brucellosis can result in spontaneous abortion in females and sterility in males. In humans, brucellosis causes the disease Undulant fever. Undulant fever is characterized by a cyclic fever, and can include other symptoms such as headaches, malaise, sweats, and muscle pains. The causative agent of brucellosis is Brucella abortus which is a Gram negative coccobacillus bacterium. Because this pathogen persists in an iron-limited environment within the host, it must produce iron capturing molecules called siderophores, to meet its metabolic needs. The structure of the major siderophore produced by the brucellae, called brucebactin, is currently not known, and the goal for this project was to determine its structure. Using thin layer chromatography (TLC), Mass Spectrometry, and NMR, new information about the compound was determined. TLC separation followed by Electron Impact Mass Spec analysis identified an iron-binding compound consisting of two molecules of 2,3-DHBA bound by a spermidine polyamine linker. A compound with the hypothesized structure of brucebactin was prepared by organic chemical synthesis, and found to have the same HPLC properties and mass spectral profile as the material isolated from bacterial culture.