Structural highlights
Publication Abstract from PubMedStaphyloferrin B is a key siderophore secreted by Staphylococcus aureus to acquire ferric ions from a host during infection, and its biosynthetic pathway has been validated to develop efficient antibacterial agents. Herein, we report the crystal structure of AMP-bound SbnC from S. aureus (SaSbnC) as the first representative structure of type B synthetases in the biosynthesis of alpha-hydroxycarboxylate siderophores. While type B synthetases specifically use alpha-ketoglutarate (alpha-KG) as their carboxylic acid substrate, SaSbnC showed unique structural features in the substrate pocket compared with the type A and C synthetases. Screening of alpha-KG analogues suggested that the hydrogen-bonding interaction between the alpha-carbonyl group of alpha-KG and residue Lys552 is a key determinant for the substrate selectivity of type B synthetases. Interestingly, citrate, the product of the tricarboxylic acid cycle and the substrate of type A synthetases, was found to inhibit the activity of SaSbnC with an IC50 value of 83 muM by mimicking alpha-KG binding, suggesting a potential regulatory role of the tricarboxylic acid cycle, whose activity is under the control of the intracellular iron concentration, to SaSbnC and other type B synthetases. These results provide critical new information to understand the structure, function, and regulation of type B synthetases in the siderophore-based iron acquisition system employed by a large number of pathogenic microbes. Structural and Biochemical Characterization of SbnC as a Representative Type B Siderophore Synthetase.,Tang J, Ju Y, Zhou J, Guo J, Gu Q, Xu J, Zhou H ACS Chem Biol. 2020 Sep 18. doi: 10.1021/acschembio.0c00523. PMID:32880431[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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