The Mycobacterium tuberculosis High-Affinity Iron Importer, IrtA, Contains an FAD-Binding Domain (cid:1) †

Iron is an essential nutrient not freely available to microorganisms infecting mammals. To overcome iron deficiency, bacteria have evolved various strategies including the synthesis and secretion of high-affinity iron chelators known as siderophores. The siderophores produced and secreted by Mycobacterium tuberculosis , exomycobactins, compete for iron with host iron-binding proteins and, together with the iron-regulated ABC transporter IrtAB, are required for the survival of M. tuberculosis in iron deficient conditions and for normal replication in macrophages and in mice. This study further characterizes the role of IrtAB in M. tuberculosis iron acquisition. Our results demonstrate a role for IrtAB in iron import and show that the amino terminus domain of IrtA is a flavin-adenine dinucleotide-binding domain essential for iron acquisition. These results suggest a model in which the amino terminus of IrtA functions to couple iron transport and assimilation.

[1]  S. Hasnain,et al.  Mechanistic Insights into a Novel Exporter-Importer System of Mycobacterium tuberculosis Unravel Its Role in Trafficking of Iron , 2008, PloS one.

[2]  G. M. Rodríguez,et al.  Utilization of Fe3+-acinetoferrin analogs as an iron source by Mycobacterium tuberculosis , 2008, BioMetals.

[3]  I. Smith,et al.  Structure of the DNA-binding domain of the response regulator PhoP from Mycobacterium tuberculosis. , 2007, Biochemistry.

[4]  M. Marahiel,et al.  Siderophore-Based Iron Acquisition and Pathogen Control , 2007, Microbiology and Molecular Biology Reviews.

[5]  H. Rubin,et al.  Steady-state Kinetics and Inhibitory Action of Antitubercular Phenothiazines on Mycobacterium tuberculosis Type-II NADH-Menaquinone Oxidoreductase (NDH-2)* , 2006, Journal of Biological Chemistry.

[6]  I. Smith,et al.  Identification of an ABC Transporter Required for Iron Acquisition and Virulence in Mycobacterium tuberculosis , 2006, Journal of bacteriology.

[7]  S. de Vries,et al.  Microbial ferric iron reductases. , 2003, FEMS microbiology reviews.

[8]  Jérôme Gouzy,et al.  ProDom: Automated Clustering of Homologous Domains , 2002, Briefings Bioinform..

[9]  Gary K. Schoolnik,et al.  ideR, an Essential Gene in Mycobacterium tuberculosis: Role of IdeR in Iron-Dependent Gene Expression, Iron Metabolism, and Oxidative Stress Response , 2002, Infection and Immunity.

[10]  O. Dym,et al.  Sequence‐structure analysis of FAD‐containing proteins , 2001, Protein science : a publication of the Protein Society.

[11]  J. Content,et al.  The ATP binding cassette (ABC) transport systems of Mycobacterium tuberculosis. , 2000, FEMS microbiology reviews.

[12]  M. S. Jorns,et al.  Structure of the flavocoenzyme of two homologous amine oxidases: monomeric sarcosine oxidase and N-methyltryptophan oxidase. , 1999, Biochemistry.

[13]  R. Perry,et al.  YbtP and YbtQ: two ABC transporters required for iron uptake in Yersinia pestis , 1999, Molecular microbiology.

[14]  G. Tusnády,et al.  Principles governing amino acid composition of integral membrane proteins: application to topology prediction. , 1998, Journal of molecular biology.

[15]  T. Parish,et al.  Regulation of the inducible acetamidase gene of Mycobacterium smegmatis. , 1997, Microbiology.

[16]  M. Horwitz,et al.  Exochelins of Mycobacterium tuberculosis remove iron from human iron- binding proteins and donate iron to mycobactins in the M. tuberculosis cell wall , 1996, The Journal of experimental medicine.

[17]  C. H. Moore,et al.  Iron acquisition by Mycobacterium tuberculosis: isolation and characterization of a family of iron-binding exochelins. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[18]  Juliano Timm,et al.  Identification of mycobacterium tuberculosis DNA sequences encoding exported proteins by using phoA gene fusions , 1995, Journal of bacteriology.

[19]  J. Thompson,et al.  CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. , 1994, Nucleic acids research.

[20]  Juliano Timm,et al.  Escherichia coli-mycobacteria shuttle vectors for operon and gene fusions to lacZ: the pJEM series , 1994, Journal of bacteriology.

[21]  S. Calderwood,et al.  Identification, cloning, and sequencing of a gene required for ferric vibriobactin utilization by Vibrio cholerae , 1994, Journal of bacteriology.

[22]  G J Barton,et al.  ALSCRIPT: a tool to format multiple sequence alignments. , 1993, Protein engineering.

[23]  W. Jacobs,et al.  New use of BCG for recombinant vaccines , 1991, Nature.

[24]  W. Jacobs,et al.  Genetic systems for mycobacteria. , 1991, Methods in enzymology.

[25]  C. Manoil,et al.  Chapter 3 Analysis of Membrane Protein Topology Using Alkaline Phosphatase and β-Galactosidase Gene Fusions , 1991 .

[26]  W. Jacobs,et al.  Isolation and characterization of efficient plasmid transformation mutants of Mycobacterium smegmatis , 1990, Molecular microbiology.

[27]  E. Weinberg.  Iron withholding: a defense against infection and neoplasia. , 1984, Physiological reviews.

[28]  J. Sambrook,et al.  Molecular Cloning: A Laboratory Manual , 2001 .

[29]  U. K. Laemmli,et al.  Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4 , 1970, Nature.

[30]  A. Boujnah.  [IRON METABOLISM]. , 1964, La Tunisie medicale.