Date of Award


Degree Type


Degree Name

Master of Science


Microbiology and Immunology


Dr. David Heinrichs


In S. aureus, the iron-scavenging siderophores staphyloferrin A and staphyloferrin B are synthesized by enzymes encoded within the sfa and sbn gene clusters, respectively. This work details the in vitro functional characterization of the Sbn enzymes responsible for synthesizing staphyloferrin B. As demonstrated through UV-vis spectrophotometric enzymatic assays and LC-ESI-MS experiments, staphyloferrin B can be synthesized in vitro by incubating purified Sbn enzymes (SbnCEFH) with fundamental components of the siderophore such as L-2,3-diaminopropionic acid, citric acid, and alpha-ketoglutaric acid. Furthermore, a novel iron-regulated citrate synthase has been characterized and is named SbnG, which condenses acetyl-CoA with oxaloacetate to form the citric acid component o f staphyloferrin B. Finally, in vitro prepared staphyloferrin B was biologically active in that it was capable of binding and supplying iron, through the SirABC transporter, to S. aureus. With functional characterization of the Sbn enzymes and their corresponding reaction products, a biosynthetic pathway for staphyloferrin B is proposed.



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