Gold_2001_Mol.Microbiol_42_851

Reference

Title : The Mycobacterium tuberculosis IdeR is a dual functional regulator that controls transcription of genes involved in iron acquisition, iron storage and survival in macrophages - Gold_2001_Mol.Microbiol_42_851
Author(s) : Gold B , Rodriguez GM , Marras SA , Pentecost M , Smith I
Ref : Molecular Microbiology , 42 :851 , 2001
Abstract :

In this work, we characterize genes in Mycobacterium tuberculosis that are regulated by IdeR (iron-dependent regulator), an iron-responsive DNA-binding protein of the DtxR family that has been shown to regulate iron acquisition in Mycobacterium smegmatis. To identify some of the genes that constitute the IdeR regulon, we searched the M. tuberculosis genome for promoter regions containing the consensus IdeR/DxR binding sequence. Genes preceded by IdeR boxes included a set encoding proteins necessary for iron acquisition, such as the biosynthesis of siderophores (mbtA, mbtB, mbtI), aromatic amino acids (pheA, hisE, hisB-like) and others annotated to be involved in the synthesis of iron-storage proteins (bfrA, bfrB). Some putative IdeR-regulated genes identified in this search encoded proteins predicted to be engaged in the biosynthesis of lipopolysaccharide (LPS)-like molecules (rv3402c), lipids (acpP) and peptidoglycan (murB). We analysed four promoter regions containing putative IdeR boxes, mbtA-mbtB, mbI, rv3402c and bfrA-bfd, for interaction with IdeR and for iron-dependent expression. Gel retardation experiments and DNase footprinting analyses with purified IdeR showed that IdeR binds to these IdeR boxes in vitro. Analysis of the promoters by primer extension indicated that the IdeR boxes are located near the -10 position of each promoter, suggesting that IdeR acts as a transcriptional repressor by blocking RNA polymerase binding. Using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) coupled to molecular beacons, we showed that mRNA levels of mbtA, mbtB, mbtI, rv3402c and bfd are induced 14- to 49-fold in cultures of M. tuberculosis starved for iron, whereas mRNA levels of bfrA decreased about threefold. We present evidence that IdeR not only acts as a transcriptional repressor but also functions as an activator of bfrA. Three of the IdeR- and iron-repressed genes, mbtB, mbtI and rv3402c, were induced during M. tuberculosis infection of human THP-1 macrophages.

PubMedSearch : Gold_2001_Mol.Microbiol_42_851
PubMedID: 11722747
Gene_locus related to this paper: myctu-MBTB

Related information

Gene_locus myctu-MBTB

Citations formats

Gold B, Rodriguez GM, Marras SA, Pentecost M, Smith I (2001)
The Mycobacterium tuberculosis IdeR is a dual functional regulator that controls transcription of genes involved in iron acquisition, iron storage and survival in macrophages
Molecular Microbiology 42 :851

Gold B, Rodriguez GM, Marras SA, Pentecost M, Smith I (2001)
Molecular Microbiology 42 :851