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Pi H, Jones SA, Mercer LE, Meador JP, Caughron JE, Jordan L, Newton SM, Conway T, Klebba PE. Role of catecholate siderophores in gram-negative bacterial colonization of the mouse gut. PLoS One 2012; 7:e50020. [PMID: 23209633 PMCID: PMC3510177 DOI: 10.1371/journal.pone.0050020] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/16/2012] [Indexed: 11/20/2022] Open
Abstract
We investigated the importance of the production of catecholate siderophores, and the utilization of their iron (III) complexes, to colonization of the mouse intestinal tract by Escherichia coli. First, a ΔtonB strain was completely unable to colonize mice. Next, we compared wild type E. coli MG1655 to its derivatives carrying site-directed mutations of genes for enterobactin synthesis (ΔentA::Cm; strain CAT0), ferric catecholate transport (Δfiu, ΔfepA, Δcir, ΔfecA::Cm; CAT4), or both (Δfiu, ΔfepA, ΔfecA, Δcir, ΔentA::Cm; CAT40) during colonization of the mouse gut. Competitions between wild type and mutant strains over a 2-week period in vivo showed impairment of all the genetically engineered bacteria relative to MG1655. CAT0, CAT4 and CAT40 colonized mice 101-, 105-, and 102-fold less efficiently, respectively, than MG1655. Unexpectedly, the additional inability of CAT40 to synthesize enterobactin resulted in a 1000-fold better colonization efficiency relative to CAT4. Analyses of gut mucus showed that CAT4 hyperexcreted enterobactin in vivo, effectively rendering the catecholate transport-deficient strain iron-starved. The results demonstrate that, contrary to prior reports, iron acquisition via catecholate siderophores plays a fundamental role in bacterial colonization of the murine intestinal tract.
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Affiliation(s)
- Hualiang Pi
- Department of Chemistry and Biochemistry, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Shari A. Jones
- Department of Microbiology and Plant Biology, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Lynn E. Mercer
- Department of Chemistry and Biochemistry, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Jessica P. Meador
- Department of Microbiology and Plant Biology, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Joyce E. Caughron
- Department of Microbiology and Plant Biology, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Lorne Jordan
- Department of Chemistry and Biochemistry, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
| | - Salete M. Newton
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
| | - Tyrrell Conway
- Department of Microbiology and Plant Biology, University of Oklahoma, Stevenson Life Sciences Research Center, Norman, Oklahoma, United States of America
| | - Phillip E. Klebba
- Department of Biochemistry, Kansas State University, Manhattan, Kansas, United States of America
- * E-mail:
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Klebba PE, Charbit A, Xiao Q, Jiang X, Newton SM. Mechanisms of iron and haem transport byListeria monocytogenes. Mol Membr Biol 2012; 29:69-86. [DOI: 10.3109/09687688.2012.694485] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Anderson DS, Adhikari P, Weaver KD, Crumbliss AL, Mietzner TA. The Haemophilus influenzae hFbpABC Fe3+ transporter: analysis of the membrane permease and development of a gallium-based screen for mutants. J Bacteriol 2007; 189:5130-41. [PMID: 17496104 PMCID: PMC1951847 DOI: 10.1128/jb.00145-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The obligate human pathogen Haemophilus influenzae utilizes a siderophore-independent (free) Fe(3+) transport system to obtain this essential element from the host iron-binding protein transferrin. The hFbpABC transporter is a binding protein-dependent ABC transporter that functions to shuttle (free) Fe(3+) through the periplasm and across the inner membrane of H. influenzae. This investigation focuses on the structure and function of the hFbpB membrane permease component of the transporter, a protein that has eluded prior characterization. Based on multiple-sequence alignments between permease orthologs, a series of site-directed mutations targeted at residues within the two conserved permease motifs were generated. The hFbpABC transporter was expressed in a siderophore-deficient Escherichia coli background, and effects of mutations were analyzed using growth rescue and radiolabeled (55)Fe(3+) transport assays. Results demonstrate that mutation of the invariant glycine (G418A) within motif 2 led to attenuated transport activity, while mutation of the invariant glycine (G155A/V/E) within motif 1 had no discernible effect on activity. Individual mutations of well-conserved leucines (L154D and L417D) led to attenuated and null transport activities, respectively. As a complement to site-directed methods, a mutant screen based on resistance to the toxic iron analog gallium, an hFbpABC inhibitor, was devised. The screen led to the identification of several significant hFbpB mutations; V497I, I174F, and S475I led to null transport activities, while S146Y resulted in attenuated activity. Significant residues were mapped to a topological model of the hFbpB permease, and the implications of mutations are discussed in light of structural and functional data from related ABC transporters.
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Affiliation(s)
- Damon S Anderson
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, E1240 Biomedical Science Tower, Lothrop Street, Pittsburgh, PA 15261, USA
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Massé E, Arguin M. Ironing out the problem: new mechanisms of iron homeostasis. Trends Biochem Sci 2005; 30:462-8. [PMID: 15996868 DOI: 10.1016/j.tibs.2005.06.005] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Revised: 05/10/2005] [Accepted: 06/22/2005] [Indexed: 10/25/2022]
Abstract
For most organisms, iron is an essential nutrient that is both difficult to acquire from the environment and toxic at high concentration. Therefore, to avoid deprivation or over-abundance of iron, bacteria and eukaryotes have developed a tight regulatory system to keep the metal within a narrow concentration range. Recent work in the bacteria Escherichia coli and in Pseudomonas aeruginosa has demonstrated that small regulatory RNAs function post-transcriptionally to repress iron-using proteins, thereby ensuring that limited iron resources are allocated to crucial cellular functions during iron starvation. Following this discovery, a parallel mechanism that uses a protein and not a small RNA was described in the budding yeast Saccharomyces cerevisiae under iron restriction. The common characteristics of these three different organisms suggest a novel mechanism of iron homeostasis.
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Affiliation(s)
- Eric Massé
- Université de Sherbrooke, Département de Biochimie, Québec, Canada.
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Cox AJ, Hunt ML, Boyce JD, Adler B. Functional characterization of HgbB, a new hemoglobin binding protein of Pasteurella multocida. Microb Pathog 2003; 34:287-96. [PMID: 12782481 DOI: 10.1016/s0882-4010(03)00062-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The biological function and role in pathogenesis of a Pasteurella multocida A:1 strain hemoglobin binding protein was investigated. The hgbB gene from the P. multocida A:1 strain, VP161, was cloned and characterized. hgbB was 2991 bp in length and encoded a mature length protein of 111 kDa. HgbB was predicted to be an outer membrane protein and shared 68 and 69% similarity to the hemoglobin/hemoglobin-haptoglobin binding protein, HI0712 from Haemophilus influenzae Rd and HgpC, from H. influenzae b, respectively. HgbB exhibited features typical of TonB dependent receptors, including seven conserved regions typical of these proteins, and conserved invariant residues. Escherichia coli expressing recombinant HgbB was found to bind hemoglobin in a solid phase dot blot binding assay. However, when a truncated form of the protein was expressed in E. coli, cells could no longer bind hemoglobin. Insertional inactivation of hgbB did not affect the ability of P. multocida to bind hemoglobin, nor its ability to produce disease in a mouse model. In addition, recombinant HgbB did not confer any protection against homologous or heterologous challenge.
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Affiliation(s)
- Angela J Cox
- Bacterial Pathogenesis Research Group, Department of Microbiology, Monash University, Clayton, Vic. 3800, Australia
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Luke NR, Campagnari AA. Construction and characterization of Moraxella catarrhalis mutants defective in expression of transferrin receptors. Infect Immun 1999; 67:5815-9. [PMID: 10531234 PMCID: PMC96960 DOI: 10.1128/iai.67.11.5815-5819.1999] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have previously reported the construction of an isogenic mutant defective in expression of OmpB1, the TbpB homologue, in Moraxella catarrhalis 7169. In this report, we have extended these studies by constructing and characterizing two new isogenic mutants in this clinical isolate. One mutant is defective in expression of TbpA, and the other mutant is defective in expression of both TbpA and TbpB. These isogenic mutants were confirmed by using PCR analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and sequencing. In vitro growth studies, comparing all three mutants, demonstrated that the tbpA mutant and the tbpAB mutant were severely limited in their ability to grow with human holotransferrin as the sole source of iron. In contrast, the ompB1 (tbpB) mutant was capable of utilizing iron from human transferrin, although not to the extent of the parental strain. While affinity chromatography with human holotransferrin showed that each Tbp was capable of binding independently to transferrin, solid-phase transferrin binding studies using whole cells demonstrated that the tbpA mutant exhibited binding characteristics similar to those seen with the wild-type bacteria. However, the ompB1 (tbpB) mutant exhibited a diminished capacity for binding transferrin, and no binding was detected with the double mutant. These data suggest that the M. catarrhalis TbpA is necessary for the acquisition of iron from transferrin. In contrast, TbpB is not essential but may serve as a facilitory protein that functions to optimize this process. Together these mutants are essential to provide a more thorough understanding of iron acquisition mechanisms utilized by M. catarrhalis.
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Affiliation(s)
- N R Luke
- Department of Microbiology, Center for Microbial Pathogenesis, State University of New York at Buffalo, Buffalo, New York 14214, USA
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