151
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Gauglitz JM, Zhou H, Butler A. A suite of citrate-derived siderophores from a marine Vibrio species isolated following the Deepwater Horizon oil spill. J Inorg Biochem 2011; 107:90-5. [PMID: 22178670 DOI: 10.1016/j.jinorgbio.2011.10.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2011] [Revised: 10/20/2011] [Accepted: 10/27/2011] [Indexed: 02/01/2023]
Abstract
Nearly all microbes require iron for growth. The low concentration of iron found in the ocean makes iron acquisition a particularly difficult task. In response to these low iron conditions, many bacteria produce low-molecular-weight iron-binding molecules called siderophores to aid in iron uptake. We report herein the isolation and structural characterization of a suite of amphiphilic siderophores called the ochrobactins-OH, which are produced by a Vibrio species isolated from the Gulf of Mexico after the 2010 Deepwater Horizon oil spill. The citrate-based ochrobactins-OH are derivatives of aerobactin, replacing the acetyl groups with fatty acid appendages ranging in size from C8 to C12, and are distinctly different from the ochrobactins in that the fatty acid appendages are hydroxylated rather than unsaturated. The discovery of the marine amphiphilic ochrobactin-OH suite of siderophores increases the geographic and phylogenetic diversity of siderophore-producing bacteria.
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Affiliation(s)
- Julia M Gauglitz
- Graduate Program in Marine Science, University of California, Santa Barbara, CA 93106, USA
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152
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Gao X, Wang LM, Bai YL, Jiang H, Li Y, Shi CH, Zhang H, Xue Y. Expression of Mycobacterium tuberculosis ferric uptake regulator A gene in Escherichia coli and generation of monoclonal antibodies to FurA. Hybridoma (Larchmt) 2011; 30:331-9. [PMID: 21851232 DOI: 10.1089/hyb.2011.0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Ferric uptake regulator A of Mycobacterium tuberculosis (MTB), which belongs to the Fur superfamily, is situated immediately upstream of katG encoding catalase-peroxidase, a major virulence factor that also activates the pro-drug isoniazid. The feature and role of FurA in oxidative stress contribute to research on the pathogenesis of mycobacteria. In this study, four novel mouse monoclonal antibodies were generated using the prokaryotically expressed FurA protein as immunogen. The furA gene of M. tuberculosis H37Rv was inserted into a bacterial expression vector of pRSET-A and effectively expressed in Escherichia coli BL21(DE3). The expressed fusion protein existed as soluble form in cell lysates and was purified via Ni-NTA purification system. Using the fusion protein to immunize BALB/c mice, four monoclonal antibodies (H9H6, H9E12, H10H6, and H10H8) were produced. As shown by Western blot analysis and cell fluorescence microscopy assay, the four antibodies could recognize the FurA protein, respectively. Then we assessed the effect of iron on the expression of FurA in MTB H37Rv and we concluded that iron does not affect FurA expression. These results suggest that the antibodies against FurA may provide a powerful tool for elucidating FurA biofunctions and regulation mechanism in the pathogenesis of tuberculosis.
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Affiliation(s)
- Xue Gao
- Department of Otorhinolaryngology, General Hospital of Second Artillery, Beijing, P.R. China
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153
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Ghosh S, Prasad KVS, Vishveshwara S, Chandra N. Rule-based modelling of iron homeostasis in tuberculosis. MOLECULAR BIOSYSTEMS 2011; 7:2750-68. [PMID: 21833436 DOI: 10.1039/c1mb05093a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
To establish itself within the host system, Mycobacterium tuberculosis (Mtb) has formulated various means of attacking the host system. One such crucial strategy is the exploitation of the iron resources of the host system. Obtaining and maintaining the required concentration of iron becomes a matter of contest between the host and the pathogen, both trying to achieve this through complex molecular networks. The extent of complexity makes it important to obtain a systems perspective of the interplay between the host and the pathogen with respect to iron homeostasis. We have reconstructed a systems model comprising 92 components and 85 protein-protein or protein-metabolite interactions, which have been captured as a set of 194 rules. Apart from the interactions, these rules also account for protein synthesis and decay, RBC circulation and bacterial production and death rates. We have used a rule-based modelling approach, Kappa, to simulate the system separately under infection and non-infection conditions. Various perturbations including knock-outs and dual perturbation were also carried out to monitor the behavioral change of important proteins and metabolites. From this, key components as well as the required controlling factors in the model that are critical for maintaining iron homeostasis were identified. The model is able to re-establish the importance of iron-dependent regulator (ideR) in Mtb and transferrin (Tf) in the host. Perturbations, where iron storage is increased, appear to enhance nutritional immunity and the analysis indicates how they can be harmful for the host. Instead, decreasing the rate of iron uptake by Tf may prove to be helpful. Simulation and perturbation studies help in identifying Tf as a possible drug target. Regulating the mycobactin (myB) concentration was also identified as a possible strategy to control bacterial growth. The simulations thus provide significant insight into iron homeostasis and also for identifying possible drug targets for tuberculosis.
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Affiliation(s)
- Soma Ghosh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
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154
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155
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Pourfallah F, Javadian S, Zamani Z, Saghiri R, Sadeghi S, Zarea B, Mirkhani F, Fatemi N, Kordi T. Evaluation of serum levels of essential trace elements in patients with pulmonary tuberculosis before and after treatment by age and gender. Pak J Biol Sci 2011; 14:590-594. [PMID: 22097095 DOI: 10.3923/pjbs.2011.590.594] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The purpose of this study was to evaluate the levels of Zinc, Copper, Iron and Copper/Zinc ratio in the serum of adult patients with pulmonary tuberculosis in Iran. Serum levels of Zinc and Copper were determined by flame atomic absorption spectrophotometer and scrum iron concentration was measured by using an Auto Analyzer. The study group consisted of 50 pulmonary tuberculosis patients before treatment and after 6 months of anti-tubercular therapy. Levels of scrum Zn (p < 0.001) and Fe (p < 0.001) in TB patients were significantly increased after 6 months of anti-tubercular therapy. However, serum Cu concentration (p < 0.01) and Cu/Zn ratio (p < 0.05) were decreased after 6 months of anti-tubercular therapy. Some studies indicated a strong association of Zn, Cu, Fe and the Cu/Zn ratio with TB. In this study, we found remarkable change in Cu/Zn ratio. Some researchers mentioned that serum Cu/Zn ratio could be used as an important laboratory marker for diagnosis and treatment of tuberculosis. They also mentioned that trace element levels must be closely monitored during the process of disease.
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Affiliation(s)
- F Pourfallah
- Department of Biochemistry, Pasteur Institute of Iran, Tehran, Iran
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156
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Cossu A, Rosu V, Paccagnini D, Cossu D, Pacifico A, Sechi LA. MAP3738c and MptD are specific tags of Mycobacterium avium subsp. paratuberculosis infection in type I diabetes mellitus. Clin Immunol 2011; 141:49-57. [PMID: 21664191 DOI: 10.1016/j.clim.2011.05.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 05/02/2011] [Accepted: 05/05/2011] [Indexed: 12/31/2022]
Abstract
Mycobacterium avium subsp. paratuberculosis (Map) is the causative agent of Johne's disease, a chronic inflammation of ruminants' intestine. Recent studies have linked Map to type I Diabetes mellitus (T1DM). We searched the presence of antibodies against two specific proteins of Map (MptD and MAP3738c) in sera of patients affected by T1DM and type II Diabetes mellitus (T2DM). MptD protein (MAP3733c) has been recognized as a Map virulent factor whereas MAP3738c has not yet been studied. Both proteins are encoded by genes belonging to a Map specific pathogenicity island. Forty three T1DM patients' sera, 56 T2DM patients' sera and 48 healthy subjects' sera were screened by ELISA to evaluate the immunoresponse against MptD or MAP3738c recombinant proteins. Results showed a positive response to both proteins in T1DM patients whereas no difference with controls was found for T2DM patients. Results suggest a potential relation between T1DM and the bacterial infection.
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MESH Headings
- Adult
- Aged
- Antibodies, Bacterial/blood
- Antigens, Bacterial/genetics
- Bacterial Proteins/genetics
- Bacterial Proteins/immunology
- Base Sequence
- Case-Control Studies
- DNA, Bacterial/genetics
- Diabetes Complications/immunology
- Diabetes Complications/microbiology
- Diabetes Mellitus, Type 1/complications
- Diabetes Mellitus, Type 1/immunology
- Diabetes Mellitus, Type 1/microbiology
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/immunology
- Diabetes Mellitus, Type 2/microbiology
- Enzyme-Linked Immunosorbent Assay
- Female
- Genes, Bacterial
- Humans
- Male
- Middle Aged
- Mycobacterium avium subsp. paratuberculosis/genetics
- Mycobacterium avium subsp. paratuberculosis/immunology
- Paratuberculosis/complications
- Paratuberculosis/immunology
- Paratuberculosis/microbiology
- Recombinant Proteins/genetics
- Recombinant Proteins/immunology
- Young Adult
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Affiliation(s)
- Andrea Cossu
- Department of Biomedical Sciences, Division of Experimental and Clinical Microbiology, University of Sassari, Sassari, Italy
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157
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Khare G, Gupta V, Nangpal P, Gupta RK, Sauter NK, Tyagi AK. Ferritin structure from Mycobacterium tuberculosis: comparative study with homologues identifies extended C-terminus involved in ferroxidase activity. PLoS One 2011; 6:e18570. [PMID: 21494619 PMCID: PMC3072985 DOI: 10.1371/journal.pone.0018570] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 03/04/2011] [Indexed: 11/19/2022] Open
Abstract
Ferritins are recognized as key players in the iron storage and detoxification processes. Iron acquisition in the case of pathogenic bacteria has long been established as an important virulence mechanism. Here, we report a 3.0 Å crystal structure of a ferritin, annotated as Bacterioferritin B (BfrB), from Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis that continues to be one of the world's deadliest diseases. Similar to the other members of ferritin family, the Mtb BfrB subunit exhibits the characteristic fold of a four-helical bundle that possesses the ferroxidase catalytic centre. We compare the structure of Mtb BfrB with representatives of the ferritin family belonging to the archaea, eubacteria and eukarya. Unlike most other ferritins, Mtb BfrB has an extended C-terminus. To dissect the role of this extended C-terminus, truncated Mtb BfrB was purified and biochemical studies implicate this region in ferroxidase activity and iron release in addition to providing stability to the protein. Functionally important regions in a protein of known 3D-structure can be determined by estimating the degree of conservation of the amino-acid sites with its close homologues. Based on the comparative studies, we identify the slowly evolving conserved sites as well as the rapidly evolving variable sites and analyze their role in relation to structure and function of Mtb BfrB. Further, electrostatic computations demonstrate that although the electrostatic environment of catalytic residues is preserved within the family, extensive variability is exhibited by residues defining the channels and pores, in all likelihood keeping up with the diverse functions executed by these ferritins in varied environments.
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Affiliation(s)
- Garima Khare
- Department of Biochemistry, University of Delhi South Campus, New Delhi, India
| | - Vibha Gupta
- Department of Biochemistry, University of Delhi South Campus, New Delhi, India
| | - Prachi Nangpal
- Department of Biochemistry, University of Delhi South Campus, New Delhi, India
| | - Rakesh K. Gupta
- Department of Biochemistry, University of Delhi South Campus, New Delhi, India
- Ram Lal Anand College, University of Delhi, New Delhi, India
| | - Nicholas K. Sauter
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Anil K. Tyagi
- Department of Biochemistry, University of Delhi South Campus, New Delhi, India
- * E-mail:
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158
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Liu Y, Jacobs HK, Gopalan AS. A new approach to cyclic hydroxamic acids: Intramolecular cyclization of N-benzyloxy carbamates with carbon nucleophiles. Tetrahedron 2011; 67:2206-2214. [PMID: 21499514 DOI: 10.1016/j.tet.2011.01.073] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
N-Alkyl-N-benzyloxy carbamates, 2, undergo facile intramolecular cyclization with a variety of carbon nucleophiles to give functionalized 5- and 6-membered protected cyclic hydroxamic acids, 3, in good to excellent yields. This method can be extended to prepare seven-membered cyclic hydroxamic acids in moderate yields. The sulfone intermediates 3 from this study can be alkylated while the corresponding phosphonates have been shown to undergo HWE reaction. The α,β-unsaturated synthon, 8, prepared by thermal elimination of sulfoxide 3m, undergoes Michael addition with secondary amines. The usefulness of this approach to prepare polydentate chelators has been demonstrated by the synthesis of bis cyclic hydroxamic acids 12, 14, and 15.
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Affiliation(s)
- Yuan Liu
- Department of Chemistry and Biochemistry, MSC 3C, New Mexico State University, Las Cruces, NM 88003-8001
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159
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Miller MJ, Walz AJ, Zhu H, Wu C, Moraski G, Möllmann U, Tristani EM, Crumbliss AL, Ferdig MT, Checkley L, Edwards RL, Boshoff HI. Design, synthesis, and study of a mycobactin-artemisinin conjugate that has selective and potent activity against tuberculosis and malaria. J Am Chem Soc 2011; 133:2076-9. [PMID: 21275374 PMCID: PMC3045749 DOI: 10.1021/ja109665t] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Although the antimalarial agent artemisinin itself is not active against tuberculosis, conjugation to a mycobacterial-specific siderophore (microbial iron chelator) analogue induces significant and selective antituberculosis activity, including activity against multi- and extensively drug-resistant strains of Mycobacterium tuberculosis. The conjugate also retains potent antimalarial activity. Physicochemical and whole-cell studies indicated that ferric-to-ferrous reduction of the iron complex of the conjugate initiates the expected bactericidal Fenton-type radical chemistry on the artemisinin component. Thus, this "Trojan horse" approach demonstrates that new pathogen-selective therapeutic agents in which the iron component of the delivery vehicle also participates in triggering the antibiotic activity can be generated. The result is that one appropriate conjugate has potent and selective activity against two of the most deadly diseases in the world.
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Affiliation(s)
- Marvin J Miller
- Department of Chemistry and Biochemistry, University of Notre Dame, 251 Nieuwland Science Hall, Notre Dame, Indiana 46556, United States.
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160
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Harrington JM, Park H, Ying Y, Hong J, Crumbliss AL. Characterization of Fe(iii) sequestration by an analog of the cytotoxic siderophore brasilibactin A: Implications for the iron transport mechanism in mycobacteria. Metallomics 2011; 3:464-71. [DOI: 10.1039/c0mt00109k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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161
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Tarallo MB, Urquiola C, Monge A, Costa BP, Ribeiro RR, Costa-Filho AJ, Mercader RC, Pavan FR, Leite CQ, Torre MH, Gambino D. Design of novel iron compounds as potential therapeutic agents against tuberculosis. J Inorg Biochem 2010; 104:1164-70. [DOI: 10.1016/j.jinorgbio.2010.07.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 07/01/2010] [Accepted: 07/09/2010] [Indexed: 11/25/2022]
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162
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Abstract
Many bacteria rely on siderophores to extract iron from the environment. However, acquisition of iron-loaded siderophores is dependent on high-affinity uptake systems that are not produced under high-iron conditions. The fact that bacteria are able to maintain iron homeostasis in the absence of siderophores indicates that alternative iron acquisition systems exist. It has been speculated that such low-affinity uptake of iron in Gram-negative bacteria includes diffusion of iron ions or chelates across the outer membrane through porins. The outer membrane of the saprophytic Mycobacterium smegmatis contains the Msp family of porins, which enable the diffusion of small and hydrophilic solutes, such as monosaccharides, amino acids, and phosphate. However, it is unknown how cations cross the outer membrane of mycobacteria. Here, we show that the Msp porins of M. smegmatis are involved in the acquisition of soluble iron under high-iron conditions. Uptake of ferric ions by a triple porin mutant was reduced compared to wild-type (wt) M. smegmatis. An intracellular iron reporter indicated that derepression of iron-responsive genes occurs at higher iron concentrations in the porin mutant. This was consistent with the finding that the porin mutant produced more siderophores under low-iron conditions than wt M. smegmatis. In contrast, uptake of the exochelin MS, the main siderophore of M. smegmatis, was not affected by the lack of porins, indicating that a specific outer membrane siderophore receptor exists. These results provide, to our knowledge, the first experimental evidence that general porins are indeed the outer membrane conduit of low-affinity iron acquisition systems in bacteria.
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163
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Abstract
Iron and its homeostasis are intimately tied to the inflammatory response. The adaptation to iron deficiency, which confers resistance to infection and improves the inflammatory condition, underlies what is probably the most obvious link: the anemia of inflammation or chronic disease. A large number of stimulatory inputs must be integrated to tightly control iron homeostasis during the inflammatory response. In order to understand the pathways of iron trafficking and how they are regulated, this article presents a brief overview of iron homeostasis. A major focus is on the regulation of the peptide hormone hepcidin during the inflammatory response and how its function contributes to the process of iron withdrawal. The review also summarizes new and emerging information about other iron metabolic regulators and effectors that contribute to the inflammatory response. Potential benefits of treatment to ameliorate the hypoferremic condition promoted by inflammation are also considered.
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Affiliation(s)
- Marianne Wessling-Resnick
- Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts 02115, USA.
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164
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Letek M, González P, MacArthur I, Rodríguez H, Freeman TC, Valero-Rello A, Blanco M, Buckley T, Cherevach I, Fahey R, Hapeshi A, Holdstock J, Leadon D, Navas J, Ocampo A, Quail MA, Sanders M, Scortti MM, Prescott JF, Fogarty U, Meijer WG, Parkhill J, Bentley SD, Vázquez-Boland JA. The genome of a pathogenic rhodococcus: cooptive virulence underpinned by key gene acquisitions. PLoS Genet 2010; 6:e1001145. [PMID: 20941392 PMCID: PMC2947987 DOI: 10.1371/journal.pgen.1001145] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Accepted: 08/31/2010] [Indexed: 11/29/2022] Open
Abstract
We report the genome of the facultative intracellular parasite Rhodococcus equi, the only animal pathogen within the biotechnologically important actinobacterial genus Rhodococcus. The 5.0-Mb R. equi 103S genome is significantly smaller than those of environmental rhodococci. This is due to genome expansion in nonpathogenic species, via a linear gain of paralogous genes and an accelerated genetic flux, rather than reductive evolution in R. equi. The 103S genome lacks the extensive catabolic and secondary metabolic complement of environmental rhodococci, and it displays unique adaptations for host colonization and competition in the short-chain fatty acid–rich intestine and manure of herbivores—two main R. equi reservoirs. Except for a few horizontally acquired (HGT) pathogenicity loci, including a cytoadhesive pilus determinant (rpl) and the virulence plasmid vap pathogenicity island (PAI) required for intramacrophage survival, most of the potential virulence-associated genes identified in R. equi are conserved in environmental rhodococci or have homologs in nonpathogenic Actinobacteria. This suggests a mechanism of virulence evolution based on the cooption of existing core actinobacterial traits, triggered by key host niche–adaptive HGT events. We tested this hypothesis by investigating R. equi virulence plasmid-chromosome crosstalk, by global transcription profiling and expression network analysis. Two chromosomal genes conserved in environmental rhodococci, encoding putative chorismate mutase and anthranilate synthase enzymes involved in aromatic amino acid biosynthesis, were strongly coregulated with vap PAI virulence genes and required for optimal proliferation in macrophages. The regulatory integration of chromosomal metabolic genes under the control of the HGT–acquired plasmid PAI is thus an important element in the cooptive virulence of R. equi. Rhodococcus is a prototypic genus within the Actinobacteria, one of the largest microbial groups on Earth. Many of the ubiquitous rhodococcal species are biotechnologically useful due to their metabolic versatility and biodegradative properties. We have deciphered the genome of a facultatively parasitic Rhodococcus, the animal and human pathogen R. equi. Comparative genomic analyses of related species provide a unique opportunity to increase our understanding of niche-adaptive genome evolution and specialization. The environmental rhodococci have much larger genomes, richer in metabolic and degradative pathways, due to gene duplication and acquisition, not genome contraction in R. equi. This probably reflects that the host-associated R. equi habitat is more stable and favorable than the chemically diverse but nutrient-poor environmental niches of nonpathogenic rhodococci, necessitating metabolically more complex, expanded genomes. Our work also highlights that the recruitment or cooption of core microbial traits, following the horizontal acquistion of a few critical genes that provide access to the host niche, is an important mechanism in actinobacterial virulence evolution. Gene cooption is a key evolutionary mechanism allowing rapid adaptive change and novel trait acquisition. Recognizing the contribution of cooption to virulence provides a rational framework for understanding and interpreting the emergence and evolution of microbial pathogenicity.
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Affiliation(s)
- Michal Letek
- Microbial Pathogenesis Unit, Centres for Infectious Diseases and Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Patricia González
- Microbial Pathogenesis Unit, Centres for Infectious Diseases and Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Irish Equine Centre, Johnstown, Naas, Ireland
| | - Iain MacArthur
- Microbial Pathogenesis Unit, Centres for Infectious Diseases and Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Irish Equine Centre, Johnstown, Naas, Ireland
- Department of Pathobiology, University of Guelph, Guelph, Canada
| | - Héctor Rodríguez
- Microbial Pathogenesis Unit, Centres for Infectious Diseases and Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Irish Equine Centre, Johnstown, Naas, Ireland
| | - Tom C. Freeman
- Division of Genetics and Genomics, Roslin BioCentre, University of Edinburgh, Edinburgh, United Kingdom
| | - Ana Valero-Rello
- Microbial Pathogenesis Unit, Centres for Infectious Diseases and Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Irish Equine Centre, Johnstown, Naas, Ireland
| | - Mónica Blanco
- Microbial Pathogenesis Unit, Centres for Infectious Diseases and Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Irish Equine Centre, Johnstown, Naas, Ireland
| | - Tom Buckley
- Irish Equine Centre, Johnstown, Naas, Ireland
| | - Inna Cherevach
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Ruth Fahey
- School of Biomolecular and Biomedical Sciences, University College Dublin, Dublin, Ireland
| | - Alexia Hapeshi
- Microbial Pathogenesis Unit, Centres for Infectious Diseases and Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh, United Kingdom
| | - Jolyon Holdstock
- Oxford Gene Technology, Begbroke Science Park, Oxford, United Kingdom
| | | | - Jesús Navas
- Departamento de Biología Molecular, Universidad de Cantabria, Santander, Spain
| | | | - Michael A. Quail
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Mandy Sanders
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Mariela M. Scortti
- Microbial Pathogenesis Unit, Centres for Infectious Diseases and Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Departamento de Bioquímica y Biología Molecular IV, Universidad Complutense, Madrid, Spain
| | - John F. Prescott
- Department of Pathobiology, University of Guelph, Guelph, Canada
| | | | - Wim G. Meijer
- School of Biomolecular and Biomedical Sciences, University College Dublin, Dublin, Ireland
| | - Julian Parkhill
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Stephen D. Bentley
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - José A. Vázquez-Boland
- Microbial Pathogenesis Unit, Centres for Infectious Diseases and Immunity, Infection, and Evolution, University of Edinburgh, Edinburgh, United Kingdom
- Grupo de Patogenómica Bacteriana, Universidad de León, León, Spain
- * E-mail:
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165
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Nagachar N, Ratledge C. Knocking out salicylate biosynthesis genes in Mycobacterium smegmatis induces hypersensitivity to p-aminosalicylate (PAS). FEMS Microbiol Lett 2010; 311:193-9. [PMID: 20735479 DOI: 10.1111/j.1574-6968.2010.02091.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Because of the emergence of strains of Mycobacterium tuberculosis resistant to first-line antituberculosis agents, one of the second-line drugs, p-aminosalicylate (PAS), has regained importance in the treatment of tuberculosis. The mode of action of PAS, however, remains controversial as to whether it inhibits mycobactin or folate biosynthesis. To unravel this, we have studied the effect of PAS on wild-type Mycobacterium smegmatis and its mutants (gene knockouts of the salicylate pathway -trpE2, entC and entD). The wild type had no sensitivity to PAS (MIC>400 μg mL(-1) ), whereas the mutants were hypersensitive, with 1 μg mL(-1) inhibiting growth. The sulphonamides, trimethoprim and dapsone, had little effect on the growth of either the mutants or the wild type. In addition, PAS at 0.5 μg mL(-1) increased the accumulation of salicylate with the wild type and mutants. These results support our hypothesis that PAS targets the conversion of salicylate to mycobactin, thus preventing iron acquisition from the host.
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166
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Kazmi SA, Shorter AL, McArdle JV, Ashiq U, Jamal RA. Studies on the redox characteristics of ferrioxamine E. Chem Biodivers 2010; 7:656-65. [PMID: 20232334 DOI: 10.1002/cbdv.200900031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Thermodynamic parameters for the reduction of ferrioxamine E as calculated from redox potentials determined at four different temperatures were found to be DeltaH( not equal)=7.1+/-3.4 kJ mol(-1) and DeltaS( not equal)=-146 J mol(-1) K(-1). The negative entropy value is large, because the decrease in the charge at the metal center and an increase in its ionic radius force the structure of the complex to become less rigid and resemble the desferrisiderophore. The hydrophilic groups of the system are now (relatively more) available for solvent interaction. Thus, a large negative entropy change accompanies the reduction of the complex. Kinetics of reduction of ferrioxamine by V(II), Cr(II), Eu(II), and dithionite were measured at different temperatures and by dithionite at different pH values. The Cr(II) and Eu(II) reactions proceed by an inner-sphere mechanism and have second-order rate constants at 25 degrees of 1.37x10(4) and 1.23x10(5) M(-1) s(-1), respectively. For the V(II) reduction, the corresponding rate constant was 1.89x10(3) M(-1) s(-1). The activation parameters for the V(II) reduction were DeltaH( not equal) = 8.3 kJ mol(-1); DeltaS( not equal) =-154 J mol(-1) K(-1). These values are indicative of an outer-sphere mechanism for V(II) reduction. The reduction by dithionite is half order in dithionite concentration indicating that SO(2)(-*) is the sole reducing species. log of reduction rate constants of different trihydroxamates by this reductant were correlated with their respective redox potentials, and the variation was found to be in approximate correspondence with the expectations of Marcus relationship.
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Affiliation(s)
- S Arif Kazmi
- H.E.J. Research Institute of Chemistry, University of Karachi, Karachi-75270, Pakistan.
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167
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Nunes A, Podinovskaia M, Leite A, Gameiro P, Zhou T, Ma Y, Kong X, Schaible UE, Hider RC, Rangel M. Fluorescent 3-hydroxy-4-pyridinone hexadentate iron chelators: intracellular distribution and the relevance to antimycobacterial properties. J Biol Inorg Chem 2010; 15:861-77. [PMID: 20364296 DOI: 10.1007/s00775-010-0650-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Accepted: 03/19/2010] [Indexed: 11/29/2022]
Abstract
We report the synthesis and characterization of a fluorescent iron chelator (4), shown to be effective in inhibiting the growth of Mycobacterium avium in macrophages, together with the synthesis and characterization of two unsuccessful analogues selected to facilitate identification of the molecular properties responsible for the antimicrobial activity. Partition of the chelators in liposomes was investigated and the compounds were assessed with respect to uptake by macrophages, responsiveness to iron overload/iron deprivation and intracellular distribution by flow cytometry and confocal microscopy. The synthesis of the hexadentate chelators is based on a tetrahedral structure to which three bidentate 3-hydroxy-4-pyridinone chelating units are linked via amide bonds. The structure is synthetically versatile, allowing further addition of functional groups such as fluorophores. Here, we analyse the non-functionalized hexadentate unit (3) and the corresponding rhodamine B (4) and fluorescein (5) labelled chelators. The iron(III) stability constant was determined for 3 and the values log beta = 34.4 and pFe(3+) = 29.8 indicate an affinity for iron of the same order of magnitude as that of mycobacteria siderophores. Fluorescence properties in the presence of liposomes show that 4 strongly interacts with the lipid phase, whereas 5 does not. Such different behaviour may explain their distinct intracellular localization as revealed by confocal microscopy. The flow cytometry and confocal microscopy studies indicate that 4 is readily engulfed by macrophages and targeted to cytosol and vesicles of the endolysosomal continuum, whereas 5 is differentially distributed and only partially colocalizes with 4 after prolonged incubation. Differential distribution of the compounds is likely to account for their different efficacy against mycobacteria.
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Affiliation(s)
- Ana Nunes
- REQUIMTE, Departamento de Química, Faculdade de Ciências, Universidade do Porto, 4069-007, Porto, Portugal
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168
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del Castillo-Rueda A, Khosravi-Shahi P. Papel del hierro en la interacción entre el huésped y el patógeno. Med Clin (Barc) 2010; 134:452-6. [DOI: 10.1016/j.medcli.2009.11.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 11/04/2009] [Accepted: 11/05/2009] [Indexed: 11/27/2022]
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169
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Fernandes SS, Nunes A, Gomes AR, de Castro B, Hider RC, Rangel M, Appelberg R, Gomes MS. Identification of a new hexadentate iron chelator capable of restricting the intramacrophagic growth of Mycobacterium avium. Microbes Infect 2010; 12:287-94. [DOI: 10.1016/j.micinf.2010.01.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Revised: 01/06/2010] [Accepted: 01/12/2010] [Indexed: 11/28/2022]
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170
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Halaas O, Steigedal M, Haug M, Awuh JA, Ryan L, Brech A, Sato S, Husebye H, Cangelosi GA, Akira S, Strong RK, Espevik T, Flo TH. Intracellular Mycobacterium avium intersect transferrin in the Rab11(+) recycling endocytic pathway and avoid lipocalin 2 trafficking to the lysosomal pathway. J Infect Dis 2010; 201:783-92. [PMID: 20121435 DOI: 10.1086/650493] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Iron is an essential nutrient for microbes, and many pathogenic bacteria depend on siderophores to obtain iron. The mammalian innate immunity protein lipocalin 2 (Lcn2; also known as neutrophil gelatinase-associated lipocalin, 24p3, or siderocalin) binds the siderophore carboxymycobactin, an essential component of the iron acquisition apparatus of mycobacteria. Here we show that Lcn2 suppressed growth of Mycobacterium avium in culture, and M. avium induced Lcn2 production from mouse macrophages. Lcn2 also had elevated levels and initially limited the growth of M. avium in the blood of infected mice but did not impede growth in tissues and during long-term infections. M. avium is an intracellular pathogen. Subcellular imaging of infected macrophages revealed that Lcn2 trafficked to lysosomes separate from M. avium, whereas transferrin was efficiently transported to the mycobacteria. Thus, mycobacteria seem to reside in the Rab11(+) endocytic recycling pathway, thereby retaining access to nutrition and avoiding endocytosed immunoproteins like Lcn2.
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Affiliation(s)
- Oyvind Halaas
- Department of Cancer Research and Molecular Medicine, Norges Teknisk-Naturvitenskapelige Universitet, and St. Olavs Hospital, Trondheim, Norway
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171
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Koyama N, Kojima S, Fukuda T, Nagamitsu T, Yasuhara T, O̅mura S, Tomoda H. Structure and Total Synthesis of Fungal Calpinactam, A New Antimycobacterial Agent. Org Lett 2009; 12:432-5. [DOI: 10.1021/ol902553z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nobuhiro Koyama
- Graduate School of Pharmaceutical Sciences and Kitasato Institute for Life Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Shigenobu Kojima
- Graduate School of Pharmaceutical Sciences and Kitasato Institute for Life Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Takeo Fukuda
- Graduate School of Pharmaceutical Sciences and Kitasato Institute for Life Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Tohru Nagamitsu
- Graduate School of Pharmaceutical Sciences and Kitasato Institute for Life Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Tadashi Yasuhara
- Graduate School of Pharmaceutical Sciences and Kitasato Institute for Life Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Satoshi O̅mura
- Graduate School of Pharmaceutical Sciences and Kitasato Institute for Life Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
| | - Hiroshi Tomoda
- Graduate School of Pharmaceutical Sciences and Kitasato Institute for Life Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan
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172
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Chim N, Iniguez A, Nguyen TQ, Goulding CW. Unusual diheme conformation of the heme-degrading protein from Mycobacterium tuberculosis. J Mol Biol 2009; 395:595-608. [PMID: 19917297 DOI: 10.1016/j.jmb.2009.11.025] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 11/06/2009] [Accepted: 11/10/2009] [Indexed: 10/20/2022]
Abstract
Heme degradation plays a pivotal role in the availability of the essential nutrient, iron, in pathogenic bacteria. A previously unannotated protein from Mycobacterium tuberculosis, Rv3592, which shares homology to heme-degrading enzymes, has been identified. Biochemical analyses confirm that Rv3592, which we have termed MhuD (mycobacterial heme utilization, degrader), is able to bind and degrade heme. Interestingly, contrary to previously reported stoichiometry for the Staphylococcus aureus heme degraders, iron-regulated surface determinant (Isd)G and IsdI, MhuD has the ability to bind heme in a 1:2 protein-to-heme ratio, although the MhuD-diheme complex is inactive. Furthermore, the 1.75-A crystal structure of the MhuD-diheme complex reveals two stacked hemes forming extensive contacts with residues in the active site. In particular, the solvent-exposed heme is axially liganded by His75 and is stacked planar upon the solvent-protected heme. The solvent-protected heme is coordinated by a chloride ion, which is, in turn, stabilized by Asn7. Structural comparison between MhuD-diheme and inactive IsdG and IsdI bound to only one highly distorted metalloporphyrin ring reveals that several residues located in alpha-helix 2 and the subsequent loop appear to be responsible for heme stoichiometric differences and suggest open and closed conformations for substrate entry and product exit.
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Affiliation(s)
- Nicholas Chim
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
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173
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Affiliation(s)
- Moriah Sandy
- Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106-9510, USA
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174
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Mukai A, Komaki H, Takagi M, Shin-ya K. Novel siderophore, JBIR-16, isolated from Nocardia tenerifensis NBRC 101015. J Antibiot (Tokyo) 2009; 62:601-3. [DOI: 10.1038/ja.2009.84] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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175
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Young DC, Kasmar A, Moraski G, Cheng TY, Walz AJ, Hu J, Xu Y, Endres GW, Uzieblo A, Zajonc D, Costello CE, Miller MJ, Moody DB. Synthesis of dideoxymycobactin antigens presented by CD1a reveals T cell fine specificity for natural lipopeptide structures. J Biol Chem 2009; 284:25087-96. [PMID: 19605355 DOI: 10.1074/jbc.m109.000802] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mycobacterium tuberculosis survival in cells requires mycobactin siderophores. Recently, the search for lipid antigens presented by the CD1a antigen-presenting protein led to the discovery of a mycobactin-like compound, dideoxymycobactin (DDM). Here we synthesize DDMs using solution phase and solid phase peptide synthesis chemistry. Comparison of synthetic standards to natural mycobacterial mycobactins by nuclear magnetic resonance and mass spectrometry allowed identification of an unexpected alpha-methyl serine unit in natural DDM. This finding further distinguishes these pre-siderophores as foreign compounds distinct from conventional peptides, and we provide evidence that this chemical variation influences the T cell response. One synthetic DDM recapitulated natural structures and potently stimulated T cells, making it suitable for patient studies of CD1a in infectious disease. DDM analogs differing in the stereochemistry of their butyrate or oxazoline moieties were not recognized by human T cells. Therefore, we conclude that T cells show precise specificity for both arms of the peptide, which are predicted to lie at the CD1a-T cell receptor interface.
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Affiliation(s)
- David C Young
- Division of Rheumatology, Immunology and Allergy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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176
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Nguyen L, Pieters J. Mycobacterial subversion of chemotherapeutic reagents and host defense tactics: challenges in tuberculosis drug development. Annu Rev Pharmacol Toxicol 2009; 49:427-53. [PMID: 19281311 DOI: 10.1146/annurev-pharmtox-061008-103123] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent worldwide emergence of multidrug-resistant and extensively drug-resistant tuberculosis is threatening to destabilize tuberculosis control programs and urging global attention to the development of alternative tuberculosis therapies. Major roadblocks limiting the development and effectiveness of new drugs to combat tuberculosis are the profound innate resistance of Mycobacterium tuberculosis to host defense mechanisms as well as its intrinsic tolerance to chemotherapeutic reagents. The triangle of interactions among the pathogen, the host responses, and the drugs used to cure the disease are critical for the outcome of tuberculosis. We must better understand this three-way interaction in order to develop drugs that are able to kill the bacillus in the most effective way and minimize the emergence of drug resistance. Here we review our recent understanding of the molecular basis underlying intrinsic antibiotic resistance and survival tactics of M. tuberculosis. This knowledge may help to reveal current targets for the development of novel antituberculosis drugs.
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Affiliation(s)
- Liem Nguyen
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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177
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Miller MJ, Zhu H, Xu Y, Wu C, Walz AJ, Vergne A, Roosenberg JM, Moraski G, Minnick AA, McKee-Dolence J, Hu J, Fennell K, Kurt Dolence E, Dong L, Franzblau S, Malouin F, Möllmann U. Utilization of microbial iron assimilation processes for the development of new antibiotics and inspiration for the design of new anticancer agents. Biometals 2009; 22:61-75. [PMID: 19130268 PMCID: PMC4066965 DOI: 10.1007/s10534-008-9185-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Accepted: 12/07/2008] [Indexed: 11/28/2022]
Abstract
Pathogenic microbes rapidly develop resistance to antibiotics. To keep ahead in the "microbial war", extensive interdisciplinary research is needed. A primary cause of drug resistance is the overuse of antibiotics that can result in alteration of microbial permeability, alteration of drug target binding sites, induction of enzymes that destroy antibiotics (ie., beta-lactamase) and even induction of efflux mechanisms. A combination of chemical syntheses, microbiological and biochemical studies demonstrate that the known critical dependence of iron assimilation by microbes for growth and virulence can be exploited for the development of new approaches to antibiotic therapy. Iron recognition and active transport relies on the biosyntheses and use of microbe-selective iron-chelating compounds called siderophores. Our studies, and those of others, demonstrate that siderophores and analogs can be used for iron transport-mediated drug delivery ("Trojan Horse" antibiotics) and induction of iron limitation/starvation (Development of new agents to block iron assimilation). Recent extensions of the use of siderophores for the development of novel potent and selective anticancer agents are also described.
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Affiliation(s)
- Marvin J Miller
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA.
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178
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Chopra T, Gokhale RS. Chapter 12 Polyketide Versatility in the Biosynthesis of Complex Mycobacterial Cell Wall Lipids. Methods Enzymol 2009; 459:259-94. [DOI: 10.1016/s0076-6879(09)04612-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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179
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DAVIES PDO. The mycobacterioses. IMAGING 2008. [DOI: 10.1259/imaging/25758678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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180
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Almeida RS, Brunke S, Albrecht A, Thewes S, Laue M, Edwards JE, Filler SG, Hube B. the hyphal-associated adhesin and invasin Als3 of Candida albicans mediates iron acquisition from host ferritin. PLoS Pathog 2008; 4:e1000217. [PMID: 19023418 PMCID: PMC2581891 DOI: 10.1371/journal.ppat.1000217] [Citation(s) in RCA: 227] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Accepted: 10/23/2008] [Indexed: 12/28/2022] Open
Abstract
Iron sequestration by host iron-binding proteins is an important mechanism of resistance to microbial infections. Inside oral epithelial cells, iron is stored within ferritin, and is therefore not usually accessible to pathogenic microbes. We observed that the ferritin concentration within oral epithelial cells was directly related to their susceptibility to damage by the human pathogenic fungus, Candida albicans. Thus, we hypothesized that host ferritin is used as an iron source by this organism. We found that C. albicans was able to grow on agar at physiological pH with ferritin as the sole source of iron, while the baker's yeast Saccharomyces cerevisiae could not. A screen of C. albicans mutants lacking components of each of the three known iron acquisition systems revealed that only the reductive pathway is involved in iron utilization from ferritin by this fungus. Additionally, C. albicans hyphae, but not yeast cells, bound ferritin, and this binding was crucial for iron acquisition from ferritin. Transcriptional profiling of wild-type and hyphal-defective C. albicans strains suggested that the C. albicans invasin-like protein Als3 is required for ferritin binding. Hyphae of an Δals3 null mutant had a strongly reduced ability to bind ferritin and these mutant cells grew poorly on agar plates with ferritin as the sole source of iron. Heterologous expression of Als3, but not Als1 or Als5, two closely related members of the Als protein family, allowed S. cerevisiae to bind ferritin. Immunocytochemical localization of ferritin in epithelial cells infected with C. albicans showed ferritin surrounding invading hyphae of the wild-type, but not the Δals3 mutant strain. This mutant was also unable to damage epithelial cells in vitro. Therefore, C. albicans can exploit iron from ferritin via morphology dependent binding through Als3, suggesting that this single protein has multiple virulence attributes. Iron is an essential nutrient for all microbes. Many human pathogenic microbes have developed sophisticated strategies to acquire iron from the host as most compartments in the body contain little free iron. For example, in oral epithelial cells intracellular iron is bound to ferritin, a protein that is highly resistant to microbial attack. In fact, no microorganism has so far been shown to directly exploit ferritin as an iron source during interaction with host cells. This study demonstrates that the pathogenic fungus Candida albicans can use ferritin as the sole source of iron. Most intriguingly, C. albicans binds ferritin via a receptor that is only exposed on invasive hyphae. This receptor is Als3, which is a member of the Als-protein family. Als3 was previously demonstrated to be an adhesin with invasin-like properties. Mutants lacking Als3 failed to bind ferritin, grew poorly with ferritin as an iron source and were unable to damage epithelial cells. Strains of the baker's yeast expressing C. albicans Als3, but not two closely related proteins, Als1 or Als5, were able to bind ferritin. Therefore, C. albicans uses an additional morphology specific and unique iron uptake strategy based on ferritin while invading into host cells where ferritin is located.
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Affiliation(s)
- Ricardo S. Almeida
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
- Friedrich Schiller University Jena, Jena, Germany
| | - Sascha Brunke
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
| | - Antje Albrecht
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
| | - Sascha Thewes
- Department of Biology, Chemistry and Pharmacy, Institute for Biology – Microbiology, Free University Berlin, Berlin, Germany
| | - Michael Laue
- Centre for Biological Safety 4 (ZBS4), Robert Koch Institute, Berlin, Germany
| | - John E. Edwards
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Medicine, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Scott G. Filler
- David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States of America
- Department of Medicine, Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Bernhard Hube
- Department of Microbial Pathogenicity Mechanisms, Leibniz Institute for Natural Product Research and Infection Biology – Hans Knoell Institute, Jena, Germany
- Friedrich Schiller University Jena, Jena, Germany
- * E-mail:
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181
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Ranjan S, Yellaboina S, Ranjan A. IdeR in Mycobacteria: From Target Recognition to Physiological Function. Crit Rev Microbiol 2008; 32:69-75. [PMID: 16809230 DOI: 10.1080/10408410600709768] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
In mycobacteria, iron dependent transcription regulator (IdeR) regulates transcription of genes in response to iron levels. The IdeR regulated genes have been investigated mostly in M. tuberculosis, M. smegmatis, and in few of the other related species. Recent advances in crystal structure solution and computational as well as experimental identification of IdeR targets has provided insight into IdeR structure and function. Here in this review we take stock of current state of knowledge on IdeR and its targets to understand the underlying design of the IdeR regulon and its role in mycobacterial physiology.
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Affiliation(s)
- Sarita Ranjan
- Sun Centre of Excellence in Medical Bioinformatics, Centre for DNA Fingerprinting and Diagnostics, EMBnet India Node, Hyderabad 500076, India
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182
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A Replication-Limited Recombinant Mycobacterium bovis BCG vaccine against tuberculosis designed for human immunodeficiency virus-positive persons is safer and more efficacious than BCG. Infect Immun 2008; 76:5200-14. [PMID: 18725418 DOI: 10.1128/iai.00434-08] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Tuberculosis is the leading cause of death in AIDS patients, yet the current tuberculosis vaccine, Mycobacterium bovis bacillus Calmette-Guérin (BCG), is contraindicated for immunocompromised individuals, including human immunodeficiency virus-positive persons, because it can cause disseminated disease; moreover, its efficacy is suboptimal. To address these problems, we have engineered BCG mutants that grow normally in vitro in the presence of a supplement, are preloadable with supplement to allow limited growth in vivo, and express the highly immunoprotective Mycobacterium tuberculosis 30-kDa major secretory protein. The limited replication in vivo renders these vaccines safer than BCG in SCID mice yet is sufficient to induce potent cell-mediated and protective immunity in the outbred guinea pig model of pulmonary tuberculosis. In the case of one vaccine, rBCG(mbtB)30, protection was superior to that with BCG (0.3-log fewer CFU of M. tuberculosis in the lung [P < 0.04] and 0.6-log fewer CFU in the spleen [P = 0.001] in aerosol-challenged animals [means for three experiments]); hence, rBCG(mbtB)30 is the first live mycobacterial vaccine that is both more attenuated than BCG in the SCID mouse and more potent than BCG in the guinea pig. Our study demonstrates the feasibility of developing safer and more potent vaccines against tuberculosis. The novel approach of engineering a replication-limited vaccine expressing a recombinant immunoprotective antigen and preloading it with a required nutrient, such as iron, that is capable of being stored should be generally applicable to other live vaccine vectors targeting intracellular pathogens.
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183
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Rao PK, Rodriguez GM, Smith I, Li Q. Protein dynamics in iron-starved Mycobacterium tuberculosis revealed by turnover and abundance measurement using hybrid-linear ion trap-Fourier transform mass spectrometry. Anal Chem 2008; 80:6860-9. [PMID: 18690695 DOI: 10.1021/ac800288t] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
To study the proteome response of Mycobacterium tuberculosis H37Rv to a change in iron level, iron-starved late-log-phase cells were diluted in fresh low- and high-iron media containing [ (15)N]-labeled asparagine as the sole nitrogen source for labeling the proteins synthesized upon dilution. We determined the relative protein abundance and protein turnover in M. tuberculosis H37Rv under these two conditions. For measurements, we used a high-resolution hybrid-linear ion trap-Fourier transform mass spectrometer coupled with nanoliquid chromatography separation. While relative protein abundance analysis shows that only 5 proteins were upregulated by high iron, 24 proteins had elevated protein turnover for the cells in the high-iron medium. This suggests that protein turnover is a sensitive parameter to assess the proteome dynamics. Cluster analysis was used to explore the interconnection of protein abundance and turnover, revealing coordination of the cellular processes of protein synthesis, degradation, and secretion that determine the abundance and allocation of a protein in the cytosol and the extracellular matrix of the cells. Further potential utility of the approach is discussed.
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Affiliation(s)
- Prahlad K Rao
- Center for Pharmaceutical Biotechnology, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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184
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Syhre M, Chambers ST. The scent of Mycobacterium tuberculosis. Tuberculosis (Edinb) 2008; 88:317-23. [DOI: 10.1016/j.tube.2008.01.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2007] [Revised: 11/26/2007] [Accepted: 01/07/2008] [Indexed: 10/22/2022]
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185
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Van Zandt KE, Sow FB, Florence WC, Zwilling BS, Satoskar AR, Schlesinger LS, Lafuse WP. The iron export protein ferroportin 1 is differentially expressed in mouse macrophage populations and is present in the mycobacterial-containing phagosome. J Leukoc Biol 2008; 84:689-700. [PMID: 18586980 DOI: 10.1189/jlb.1107781] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Intracellular pathogens, including Mycobacterium tuberculosis, obtain iron from the host for their survival. Ferroportin 1 (FPN1; SLC40A1) is the sole iron exporter from mammalian cells and is expressed in the duodenum and macrophages. In the present study, we show that FPN1 mRNA levels in the mouse macrophage cell line RAW264.7 are synergistically induced by treatment with live or gamma-irradiated M. tuberculosis and IFN-gamma. FPN1 mRNA levels were also induced by Mycobacterium avium and IFN-gamma in RAW264.7 cells and the mouse alveolar macrophage cell line AMJ2-C8. Treatment of mouse resident peritoneal macrophages with M. tuberculosis and IFN-gamma resulted in a sixfold increase in FPN1 mRNA expression. In contrast, M. tuberculosis and IFN-gamma inhibited FPN1 mRNA expression in bone marrow-derived macrophages and lung macrophages, which have high basal levels of FPN1 mRNA expression. Using confocal microscopy, FPN1 protein localized rapidly to M. tuberculosis phagosomes after infection in RAW264.7 macrophages. In RAW264.7 cells expressing wild-type natural resistance-associated macrophage protein 1 (Nramp1(Gly169)), FPN1 and Nramp1 partially colocalized in late endosomes/lysosomes prior to infection. After 2 h of infection, Nramp1 and FPN1 were present in M. tuberculosis phagosomes. Our studies provide evidence for transcriptional regulation of FPN1 by pathogenic mycobacteria and IFN-gamma, which is dependent on the macrophage type. The trafficking of FPN1 to the M. tuberculosis phagosome suggests that it is involved in regulating iron availability to the mycobacteria in this locale.
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Affiliation(s)
- Kristopher E Van Zandt
- Department of Microbiology, The Ohio State University, 333 W. 10th Ave., Columbus, OH 43210, USA
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186
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Mechanistic analysis of Mycobacterium tuberculosis Rv1347c, a lysine Nepsilon-acyltransferase involved in mycobactin biosynthesis. Arch Biochem Biophys 2008; 477:259-66. [PMID: 18539130 DOI: 10.1016/j.abb.2008.05.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Revised: 05/05/2008] [Accepted: 05/18/2008] [Indexed: 11/20/2022]
Abstract
Mycobactin acylation plays a crucial role in the ability of Mycobacterium tuberculosis to acquire intracellular iron during infection. M. tuberculosis Rv1347c, the lysine N(epsilon)-acyltransferase responsible for mycobactin acylation, represents a valid target for the development of novel anti-tubercular agents. Here we investigate the substrate specificity of Rv1347c, evaluate its kinetic mechanism and probe the contributions of active-site residues to catalysis. Our results confirm that Rv1347c demonstrates a preference for longer acyl-chains and suggest that mycobactin acylation occurs subsequent to mycobactin core assembly. Steady-state bisubstrate kinetics and dead-end inhibitor studies support a random sequential kinetic mechanism. Analysis of the pH dependence of k(cat)/K(m) revealed the presence of two groups that must be deprotonated for efficient catalysis. Mutagenesis of His(130) and Asp(168) indicated that both residues are critical for acyltransferase activity and suggests that His(130) is responsible for general base activation of the epsilon-amino group of lysine.
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187
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Mechanistic insights into a novel exporter-importer system of Mycobacterium tuberculosis unravel its role in trafficking of iron. PLoS One 2008; 3:e2087. [PMID: 18461140 PMCID: PMC2330087 DOI: 10.1371/journal.pone.0002087] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Accepted: 03/23/2008] [Indexed: 12/04/2022] Open
Abstract
Background Elucidation of the basic mechanistic and biochemical principles underlying siderophore mediated iron uptake in mycobacteria is crucial for targeting this principal survival strategy vis-à-vis virulence determinants of the pathogen. Although, an understanding of siderophore biosynthesis is known, the mechanism of their secretion and uptake still remains elusive. Methodology/Principal Findings Here, we demonstrate an interplay among three iron regulated Mycobacterium tuberculosis (M.tb) proteins, namely, Rv1348 (IrtA), Rv1349 (IrtB) and Rv2895c in export and import of M.tb siderophores across the membrane and the consequent iron uptake. IrtA, interestingly, has a fused N-terminal substrate binding domain (SBD), representing an atypical subset of ABC transporters, unlike IrtB that harbors only the permease and ATPase domain. SBD selectively binds to non-ferrated siderophores whereas Rv2895c exhibits relatively higher affinity towards ferrated siderophores. An interaction between the permease domain of IrtB and Rv2895c is evident from GST pull-down assay. In vitro liposome reconstitution experiments further demonstrate that IrtA is indeed a siderophore exporter and the two-component IrtB-Rv2895c system is an importer of ferrated siderophores. Knockout of msmeg_6554, the irtA homologue in Mycobacterium smegmatis, resulted in an impaired M.tb siderophore export that is restored upon complementation with M.tb irtA. Conclusion Our data suggest the interplay of three proteins, namely IrtA, IrtB and Rv2895c in synergizing the balance of siderophores and thus iron inside the mycobacterial cell.
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JIANG HONG, GAO XUE, LI YUAN, XU ZHIKAI, WANG LIMEI, BAI XUEFAN, XUE YING. Prokaryotic expression and monoclonal antibody preparation ofMycobacterium tuberculosisferric uptake regulator B. APMIS 2008; 116:372-81. [DOI: 10.1111/j.1600-0463.2008.00975.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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189
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Fennell KA, Möllmann U, Miller MJ. Syntheses and biological activity of amamistatin B and analogs. J Org Chem 2008; 73:1018-24. [PMID: 18173285 DOI: 10.1021/jo7020532] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Amamistatins A and B, natural products isolated from a strain of Nocardia, showed growth inhibition against three human tumor cell lines (IC(50) 0.24-0.56 microM). Structurally related mycobactins affect the growth of both mycobacterial and human cells through interference with iron chelation. To further probe the biological activity of this class of compounds, the total syntheses of amamistatin B and two analogs were completed, and the synthetic samples were screened for tumor cell growth inhibition, HDAC inhibition, and Mycobacterium tuberculosis growth inhibition. Amamistatin B (15) and diastereomer 18 were both active against MCF-7 cells (IC(50) 0.12-0.20 microM), and less so against PC-3 cells (IC(50) 8-13 microM). Amamistatin B only moderately inhibited the growth of M. tuberculosis (MIC 47 microM) but showed growth promotion of Mycobacterium smegmatis and other bacteria.
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Affiliation(s)
- Kelley A Fennell
- Department of Chemistry and Biochemistry and Walther Cancer Center, University of Notre Dame, Notre Dame, Indiana 46556, USA
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190
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Marquis JF, Gros P. Genetic analysis of resistance to infections in mice: A/J meets C57BL/6J. Curr Top Microbiol Immunol 2008; 321:27-57. [PMID: 18727486 DOI: 10.1007/978-3-540-75203-5_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Susceptibility to infectious diseases has long been known to have a genetic component in human populations. This genetic effect is often complex and difficult to study as it is further modified by environmental factors including the disease-causing pathogen itself. The laboratory mouse has proved a useful alternative to implement a genetic approach to study host defenses against infections. Our laboratory has used genetic analysis and positional cloning to characterize single and multi-gene effects regulating inter-strain differences in the susceptibility of A/J and C57BL/6J mice to infection with several bacterial and parasitic pathogens. This has led to the identification of several proteins including Nrampl (Slc11a1), Birc1e, Icsbp, C5a, and others that play critical roles in the antimicrobial defenses of macrophages against intracellular pathogens. The use of AcB/BcA recombinant congenic strains has further facilitated the characterization of single gene effects in complex traits such as susceptibility to malaria. The genetic identification of erythrocyte pyruvate kinase (Pklr) and myeloid pantetheinase enzymes (Vnn1/3) as key regulators of blood-stage parasitemia has suggested that cellular redox potential may be a key biochemical determinant of Plasmodium parasite replication. Expanding these types of studies to additional inbred strains and to emerging stocks of mutagenized mice will undoubtedly continue to unravel the molecular basis of host defense against infections.
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Affiliation(s)
- J-F Marquis
- Department of Biochemistry, McGill University, McIntyre Medical Building, Montreal, QC H3G 1Y6, Canada
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191
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The intracellular pathogen Rhodococcus equi produces a catecholate siderophore required for saprophytic growth. J Bacteriol 2007; 190:1631-7. [PMID: 18156254 DOI: 10.1128/jb.01570-07] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Little is known about the iron acquisition systems of the soilborne facultative intracellular pathogen Rhodococcus equi. We previously reported that expression of iupABC, encoding a putative siderophore ABC transporter system, is iron regulated and required for growth at low iron concentrations. Here we show that disruption of iupA leads to the concomitant accumulation of catecholates and a chromophore with absorption maxima at 341 and 528 nm during growth under iron-replete conditions. In contrast, the wild-type strain produces these compounds only in iron-depleted medium. Disruption of iupU and iupS, encoding nonribosomal peptide synthetases, prevented growth of the corresponding R. equi SID1 and SID3 mutants at low iron concentrations. However, only R. equi SID3 did not produce the chromophore produced by the wild-type strain during growth at low iron concentrations. The phenotype of R. equi SID3, but not that of R. equi SID1, could be rescued by coculture with the wild type, allowing growth at low iron concentrations. This strongly suggests that the product of the iupS gene is responsible for the synthesis of a diffusible compound required for growth at low iron concentrations. Transcription of iupU was constitutive, but that of iupS was iron regulated, with an induction of 3 orders of magnitude during growth in iron-depleted compared to iron-replete medium. Neither mutant was attenuated in vivo in a mouse infection model, indicating that the iupU- and iupS-encoded iron acquisition systems are primarily involved in iron uptake during saprophytic life.
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192
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Bacon J, Dover LG, Hatch KA, Zhang Y, Gomes JM, Kendall S, Wernisch L, Stoker NG, Butcher PD, Besra GS, Marsh PD. Lipid composition and transcriptional response of Mycobacterium tuberculosis grown under iron-limitation in continuous culture: identification of a novel wax ester. MICROBIOLOGY-SGM 2007; 153:1435-1444. [PMID: 17464057 PMCID: PMC3123377 DOI: 10.1099/mic.0.2006/004317-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The low level of available iron in vivo is a major obstacle for microbial pathogens and is a stimulus for the expression of virulence genes. In this study, Mycobacterium tuberculosis H37Rv was grown aerobically in the presence of limited iron availability in chemostat culture to determine the physiological response of the organism to iron-limitation. A previously unidentified wax ester accumulated under iron-limited growth, and changes in the abundance of triacylglycerol and menaquinone were also observed between iron-replete and iron-limited chemostat cultures. DNA microarray analysis revealed differential expression of genes involved in glycerolipid metabolism and isoprenoid quinone biosynthesis, providing some insight into the underlying genetic changes that correlate with cell-wall lipid profiles of M. tuberculosis growing in an iron-limited environment.
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Affiliation(s)
- Joanna Bacon
- TB Research group, Health Protection Agency, Centre for Emergency Preparedness and Response, Porton Down, Salisbury, Wiltshire SP4 0JG, UK
| | - Lynn G. Dover
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Kim A. Hatch
- TB Research group, Health Protection Agency, Centre for Emergency Preparedness and Response, Porton Down, Salisbury, Wiltshire SP4 0JG, UK
| | - Yi Zhang
- School of Crystallography, Birkbeck College, University of London, Malet Street, London, WC1E 7HX, UK
| | - Jessica M. Gomes
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Sharon Kendall
- Department of Pathology and Infectious Diseases, Royal Veterinary College, Royal College Street, London NW1 0TU, UK
| | - Lorenz Wernisch
- School of Crystallography, Birkbeck College, University of London, Malet Street, London, WC1E 7HX, UK
| | - Neil G. Stoker
- Department of Pathology and Infectious Diseases, Royal Veterinary College, Royal College Street, London NW1 0TU, UK
| | - Philip D. Butcher
- Bacterial Microarray Group, Department of Cellular and Molecular Medicine, St George’s Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK
| | - Gurdyal S. Besra
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Philip D. Marsh
- TB Research group, Health Protection Agency, Centre for Emergency Preparedness and Response, Porton Down, Salisbury, Wiltshire SP4 0JG, UK
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193
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Basaraba RJ, Bielefeldt-Ohmann H, Eschelbach EK, Reisenhauer C, Tolnay AE, Taraba LC, Shanley CA, Smith EA, Bedwell CL, Chlipala EA, Orme IM. Increased expression of host iron-binding proteins precedes iron accumulation and calcification of primary lung lesions in experimental tuberculosis in the guinea pig. Tuberculosis (Edinb) 2007; 88:69-79. [PMID: 17942369 DOI: 10.1016/j.tube.2007.09.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 08/26/2007] [Accepted: 09/09/2007] [Indexed: 11/25/2022]
Abstract
The growth and virulence of Mycobacterium tuberculosis depends on its ability to scavenge host iron, an essential and limited micronutrient in vivo. In this study, we show that ferric iron accumulates both intra- and extra-cellularly in the primary lung lesions of guinea pigs aerosol-infected with the H37Rv strain of M. tuberculosis. Iron accumulated within macrophages at the periphery of the primary granulomatous lesions while extra-cellular ferric iron was concentrated in areas of lesion necrosis. Accumulation of iron within primary lesions was preceded by an increase in expression of heavy chain (H) ferritin, lactoferrin and receptors for transferrin, primarily by macrophages and granulocytes. The increased expression of intra-cellular H ferritin and extra-cellular lactoferrin, more so than transferrin receptor, paralleled the development of necrosis within primary lesions. The deposition of extra-cellular ferric iron within necrotic foci coincided with the accumulation of calcium and phosphorus and other cations in the form of dystrophic calcification. Primary lung lesions from guinea pigs vaccinated with Mycobactrium bovis BCG prior to experimental infection, had reduced iron accumulation as well as H ferritin, lactoferrin and transferrin receptor expression. The amelioration of primary lesion necrosis and dystrophic calcification by BCG vaccination was coincident with the lack of extra-cellular ferric iron and lactoferrin accumulation. These data demonstrate that BCG vaccination ameliorates primary lesion necrosis, dystrophic mineralization and iron accumulation, in part by down-regulating the expression of macrophage H ferritin, lactoferrin and transferrin receptors, in vivo.
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Affiliation(s)
- Randall J Basaraba
- Department of Microbiology, Immunology and Pathology, 1619 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1619, USA.
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194
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Martineau AR, Newton SM, Wilkinson KA, Kampmann B, Hall BM, Nawroly N, Packe GE, Davidson RN, Griffiths CJ, Wilkinson RJ. Neutrophil-mediated innate immune resistance to mycobacteria. J Clin Invest 2007; 117:1988-94. [PMID: 17607367 PMCID: PMC1904316 DOI: 10.1172/jci31097] [Citation(s) in RCA: 279] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Accepted: 04/02/2007] [Indexed: 12/31/2022] Open
Abstract
Neutrophils contain antimicrobial peptides with antituberculous activity, but their contribution to immune resistance to tuberculosis (TB) infection has not been previously investigated to our knowledge. We determined differential white cell counts in peripheral blood of 189 adults who had come into contact with patients diagnosed with active TB in London, United Kingdom, and evaluated them for evidence of TB infection and capacity to restrict mycobacterial growth in whole-blood assays. Risk of TB infection was inversely and independently associated with peripheral blood neutrophil count in contacts of patients diagnosed with pulmonary TB. The ability of whole blood to restrict growth of Mycobacterium bovis bacille Calmette Guérin and Mycobacterium tuberculosis was impaired 7.3- and 3.1-fold, respectively, by neutrophil depletion. In microbiological media, human neutrophil peptides (HNPs) 1-3 killed M. tuberculosis. The neutrophil peptides cathelicidin LL-37 and lipocalin 2 restricted growth of the organism, the latter in an iron-dependent manner. Black African participants had lower neutrophil counts and lower circulating concentrations of HNP1-3 and lipocalin 2 than south Asian and white participants. Neutrophils contribute substantially to innate resistance to TB infection, an activity associated with their antimicrobial peptides. Elucidation of the regulation of neutrophil antimicrobial peptides could facilitate prevention and treatment of TB.
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Affiliation(s)
- Adrian R. Martineau
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
| | - Sandra M. Newton
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
| | - Katalin A. Wilkinson
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
| | - Beate Kampmann
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
| | - Bridget M. Hall
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
| | - Niga Nawroly
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
| | - Geoffrey E. Packe
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
| | - Robert N. Davidson
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
| | - Christopher J. Griffiths
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
| | - Robert J. Wilkinson
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College, London, United Kingdom.
Center for Health Sciences, Queen Mary’s School of Medicine and Dentistry, Barts and The London NHS Trust, London, United Kingdom.
Institute of Infectious Diseases and Molecular Medicine and Department of Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
Department of Respiratory Medicine, National Heart and Lung Institute, Imperial College, London, United Kingdom.
Newham Chest Clinic, Newham University Hospital NHS Trust, London, United Kingdom.
Tuberculosis Clinic, Northwick Park Hospital, Harrow, United Kingdom
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195
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196
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Martineau AR, Wilkinson KA, Newton SM, Floto RA, Norman AW, Skolimowska K, Davidson RN, Sørensen OE, Kampmann B, Griffiths CJ, Wilkinson RJ. IFN-γ- and TNF-Independent Vitamin D-Inducible Human Suppression of Mycobacteria: The Role of Cathelicidin LL-37. THE JOURNAL OF IMMUNOLOGY 2007; 178:7190-8. [PMID: 17513768 DOI: 10.4049/jimmunol.178.11.7190] [Citation(s) in RCA: 289] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Vitamin D deficiency is associated with susceptibility to tuberculosis, and its biologically active metabolite, 1alpha,25 dihydroxyvitamin D(3) (1alpha,25(OH)(2)D(3)), has pleiotropic immune effects. The mechanisms by which 1alpha,25(OH)(2)D(3) protects against tuberculosis are incompletely understood. 1alpha,25(OH)(2)D(3) reduced the growth of mycobacteria in infected human PBMC cultures in a dose-dependent fashion. Coculture with agonists or antagonists of the membrane or nuclear vitamin D receptors indicated that these effects were primarily mediated by the nuclear vitamin D receptors. 1alpha,25(OH)(2)D(3) reduced transcription and secretion of protective IFN-gamma, IL-12p40, and TNF in infected PBMC and macrophages, indicating that 1alpha,25(OH)(2)D(3) does not mediate protection via these cytokines. Although NOS2A was up-regulated by 1alpha,25(OH)(2)D(3), inhibition of NO formation marginally affected the suppressive effect of 1alpha,25(OH)(2)D(3) on bacillus Calmette Guérin in infected cells. By contrast, 1alpha,25(OH)(2)D(3) strongly up-regulated the cathelicidin hCAP-18 gene, and some hCAP-18 polypeptide colocalized with CD14 in 1alpha,25(OH)(2)D(3) stimulated PBMC, although no detectable LL-37 peptide was found in supernatants from similar 1alpha,25(OH)(2)D(3)-stimulated PBMC cultures. A total of 200 mug/ml of the active peptide LL-37, in turn, reduced the growth of Mycobacterium tuberculosis in culture by 75.7%. These findings suggest that vitamin D contributes to protection against TB by "nonclassical" mechanisms that include the induction of antimicrobial peptides.
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Affiliation(s)
- Adrian R Martineau
- Wellcome Trust Center for Research in Clinical Tropical Medicine, Division of Medicine, Wright Fleming Institute, Imperial College London, United Kingdom
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197
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Abstract
Iron is essential for both host and pathogen, and complex systems of acquisition and utilization have evolved in competition. Our increasing knowledge of the basic mechanisms of homeostasis and their adaptation during deficiency, overload, and infection indicate that iron is a key regulator of host pathogen interactions. This review concentrated on the clinical and public health aspects of the interaction between the iron acquisition mechanisms of select pathogens of public health importance with host iron homeostasis. Knowledge of these interactions is essential in assessing likely morbidity responses to supplementation.
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198
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Walz AJ, Möllmann U, Miller MJ. Synthesis and studies of catechol-containing mycobactin S and T analogs. Org Biomol Chem 2007; 5:1621-8. [PMID: 17571193 DOI: 10.1039/b703116e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The syntheses of catechol-containing mycobactin S and T analogs are described. These analogs incorporate a catechol-glycine moiety in place of the phenol-oxazoline of the naturally occurring mycobactins S and T. Studies indicated that the new siderophore analogs bind iron, and promote the growth of a number of microbes, especially strains of mycobacteria, as expected.
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Affiliation(s)
- Andrew J Walz
- Department of Chemistry & Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA
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199
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Gebhardt P, Crumbliss AL, Miller MJ, Möllmann U. Synthesis and biological activity of saccharide based lipophilic siderophore mimetics as potential growth promoters for mycobacteria. Biometals 2007; 21:41-51. [PMID: 17390213 DOI: 10.1007/s10534-007-9091-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Accepted: 02/19/2007] [Indexed: 10/23/2022]
Abstract
Siderophores based on sugar backbones substituted at the 2,3,4- or 2,3,6 positions with hydroxamic or retro-hydroxamic acid chelating units were synthesized and characterized. The alkyl terminus of the iron-coordinating side chain units facilitate lipophilic interactions. Iron coordination properties and complex stability were investigated by ESI-MS and the CAS-Test. The results were correlated to structure activity relationships determined by microbial growth promotion studies under iron limited conditions using wild type strains and iron transport mutants of Mycobacterium smegmatis.
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Affiliation(s)
- Peter Gebhardt
- Biomolecular Chemistry, Leibniz Institute for Natural Products Research and Infection Biology - Hans-Knoell-Institute, Beutenbergstrasse 11a, 07745 Jena, Germany
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200
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Janin YL. Antituberculosis drugs: ten years of research. Bioorg Med Chem 2007; 15:2479-513. [PMID: 17291770 DOI: 10.1016/j.bmc.2007.01.030] [Citation(s) in RCA: 360] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 12/26/2006] [Accepted: 01/17/2007] [Indexed: 02/03/2023]
Abstract
Tuberculosis is today amongst the worldwide health threats. As resistant strains of Mycobacterium tuberculosis have slowly emerged, treatment failure is too often a fact, especially in countries lacking the necessary health care organisation to provide the long and costly treatment adapted to patients. Because of lack of treatment or lack of adapted treatment, at least two million people will die of tuberculosis this year. Due to this concern, this infectious disease was the focus of renewed scientific interest in the last decade. Regimens were optimized and much was learnt on the mechanisms of action of the antituberculosis drugs used. Moreover, the quest for original drugs overcoming some of the problems of current regimens also became the focus of research programmes and many new series of M. tuberculosis growth inhibitors were reported. This review presents the drugs currently used in antituberculosis treatments and the most advanced compounds undergoing clinical trials. We then provide a description of their mechanism of action along with other series of inhibitors known to act on related biochemical targets. This is followed by other inhibitors of M. tuberculosis growth, including recently reported compounds devoid of a reported mechanism of action.
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Affiliation(s)
- Yves L Janin
- URA 2128 CNRS-Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France.
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