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National Academy of Sciences, Proceedings of the National Academy of Sciences, 44(106), p. 18792-18797, 2009

DOI: 10.1073/pnas.0900589106

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Mycobacterial Esx-3 is required for mycobactin-mediated iron acquisition

Journal article published in 2009 by M. Sloan Siegrist, Meera Unnikrishnan, Matthew J. McConnell, Mark Borowsky, Tan-Yun Cheng, Noman Siddiqi, Sarah M. Fortune, D. Branch Moody, D. Branch Moody, Eric J. Rubin ORCID
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

The Esx secretion pathway is conserved across Gram-positive bacteria. Esx-1, the best-characterized system, is required for virulence of Mycobacterium tuberculosis , although its precise function during infection remains unclear. Esx-3, a paralogous system present in all mycobacterial species, is required for growth in vitro. Here, we demonstrate that mycobacteria lacking Esx-3 are defective in acquiring iron. To compete for the limited iron available in the host and the environment, these organisms use mycobactin, high-affinity iron-binding molecules. In the absence of Esx-3, mycobacteria synthesize mycobactin but are unable to use the bound iron and are impaired severely for growth during macrophage infection. Mycobacteria thus require a specialized secretion system for acquiring iron from siderophores.