Mycobacterial Esx-3 is Required for Mycobactin-mediated Iron Acquisition

Overview

Journal Proc Natl Acad Sci U S A

Specialty Science

Date 2009 Oct 23

PMID 19846780

Citations 186

Authors

M Sloan Siegrist

Meera Unnikrishnan

Matthew J McConnell

Mark Borowsky

Tan-Yun Cheng

Noman Siddiqi

Sarah M Fortune

D Branch Moody

Eric J Rubin

Affiliations

Soon will be listed here.

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.

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