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Abdeljelil N, Ben Miloud Yahia N, Landoulsi A, Chatti A, Wattiez R, Gillan D, Van Houdt R. Proteomic and morphological insights into the exposure of Cupriavidus metallidurans CH34 planktonic cells and biofilms to aluminium. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133403. [PMID: 38215523 DOI: 10.1016/j.jhazmat.2023.133403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/15/2023] [Accepted: 12/27/2023] [Indexed: 01/14/2024]
Abstract
Aluminium (Al) is one of the most popular materials for industrial and domestic use. Nevertheless, research has proven that this metal can be toxic to most organisms. This light metal has no known biological function and to date very few aluminium-specific biological pathways have been identified. In addition, information about the impact of this metal on microbial life is scarce. Here, we aimed to study the effect of aluminium on the metal-resistant soil bacterium Cupriavidus metallidurans CH34 in different growth modes, i.e. planktonic cells, adhered cells and mature biofilms. Our results indicated that despite a significant tolerance to aluminium (minimal inhibitory concentration of 6.25 mM Al₂(SO₄)₃.18H₂O), the exposure of C. metallidurans to a sub-inhibitory dose (0.78 mM) caused early oxidative stress and an increase in hydrolytic activity. Changes in the outer membrane surface of planktonic cells were observed, in addition to a rapid disruption of mature biofilms. On protein level, aluminium exposure increased the expression of proteins involved in metabolic activity such as pyruvate kinase, formate dehydrogenase and poly(3-hydroxybutyrate) polymerase, whereas proteins involved in chemotaxis, and the production and transport of iron scavenging siderophores were significantly downregulated.
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Affiliation(s)
- Nissem Abdeljelil
- Proteomics and Microbiology Lab, Research Institute for Biosciences, Mons University, Mons, Belgium; Microbiology Unit, Belgian Nuclear Research Centre, SCK CEN, Mol, Belgium; Laboratory of Biochemistry and Molecular Biology, Faculty of Sciences of Bizerte, University of Carthage, Jarzouna, Tunisia
| | | | - Ahmed Landoulsi
- Laboratory of Biochemistry and Molecular Biology, Faculty of Sciences of Bizerte, University of Carthage, Jarzouna, Tunisia
| | - Abdelwaheb Chatti
- Laboratory of Biochemistry and Molecular Biology, Faculty of Sciences of Bizerte, University of Carthage, Jarzouna, Tunisia
| | - Ruddy Wattiez
- Proteomics and Microbiology Lab, Research Institute for Biosciences, Mons University, Mons, Belgium
| | - David Gillan
- Proteomics and Microbiology Lab, Research Institute for Biosciences, Mons University, Mons, Belgium
| | - Rob Van Houdt
- Microbiology Unit, Belgian Nuclear Research Centre, SCK CEN, Mol, Belgium.
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Giddings LA, Lountos GT, Kim KW, Brockley M, Needle D, Cherry S, Tropea JE, Waugh DS. Characterization of a broadly specific cadaverine N-hydroxylase involved in desferrioxamine B biosynthesis in Streptomyces sviceus. PLoS One 2021; 16:e0248385. [PMID: 33784308 PMCID: PMC8009421 DOI: 10.1371/journal.pone.0248385] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/26/2021] [Indexed: 02/07/2023] Open
Abstract
N-hydroxylating flavin-dependent monooxygenases (FMOs) are involved in the biosynthesis of hydroxamate siderophores, playing a key role in microbial virulence. Herein, we report the first structural and kinetic characterization of a novel alkyl diamine N-hydroxylase DesB from Streptomyces sviceus (SsDesB). This enzyme catalyzes the first committed step in the biosynthesis of desferrioxamine B, a clinical drug used to treat iron overload disorders. X-ray crystal structures of the SsDesB holoenzyme with FAD and the ternary complex with bound NADP+ were solved at 2.86 Å and 2.37 Å resolution, respectively, providing a structural view of the active site environment. SsDesB crystallized as a tetramer and the structure of the individual protomers closely resembles the structures of homologous N-hydroxylating FMOs from Erwinia amylovora (DfoA), Pseudomonas aeruginosa (PvdA), and Aspergillus fumigatus (SidA). Using NADPH oxidation, oxygen consumption, and product formation assays, kinetic parameters were determined for various substrates with SsDesB. SsDesB exhibited typical saturation kinetics with substrate inhibition at high concentrations of NAD(P)H as well as cadaverine. The apparent kcat values for NADPH in steady-state NADPH oxidation and oxygen consumption assays were 0.28 ± 0.01 s-1 and 0.24 ± 0.01 s-1, respectively. However, in product formation assays used to measure the rate of N-hydroxylation, the apparent kcat for NADPH (0.034 ± 0.008 s-1) was almost 10-fold lower under saturating FAD and cadaverine concentrations, reflecting an uncoupled reaction, and the apparent NADPH KM was 33 ± 24 μM. Under saturating FAD and NADPH concentrations, the apparent kcat and KM for cadaverine in Csaky assays were 0.048 ± 0.004 s-1 and 19 ± 9 μM, respectively. SsDesB also N-hydroxylated putrescine, spermidine, and L-lysine substrates but not alkyl (di)amines that were branched or had fewer than four methylene units in an alkyl chain. These data demonstrate that SsDesB has wider substrate scope compared to other well-studied ornithine and lysine N-hydroxylases, making it an amenable biocatalyst for the production of desferrioxamine B, derivatives, and other N-substituted products.
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Affiliation(s)
- Lesley-Ann Giddings
- Department of Chemistry, Smith College, Northampton, MA, United States of America
- Department of Chemistry & Biochemistry, Middlebury College, Middlebury, VT, United States of America
| | - George T. Lountos
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD, United States of America
| | - Kang Woo Kim
- Department of Chemistry & Biochemistry, Middlebury College, Middlebury, VT, United States of America
| | - Matthew Brockley
- Department of Chemistry & Biochemistry, Middlebury College, Middlebury, VT, United States of America
| | - Danielle Needle
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States of America
| | - Scott Cherry
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States of America
| | - Joseph E. Tropea
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States of America
| | - David S. Waugh
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States of America
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Mügge C, Heine T, Baraibar AG, van Berkel WJH, Paul CE, Tischler D. Flavin-dependent N-hydroxylating enzymes: distribution and application. Appl Microbiol Biotechnol 2020; 104:6481-6499. [PMID: 32504128 PMCID: PMC7347517 DOI: 10.1007/s00253-020-10705-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/18/2020] [Accepted: 05/24/2020] [Indexed: 02/06/2023]
Abstract
Amino groups derived from naturally abundant amino acids or (di)amines can be used as "shuttles" in nature for oxygen transfer to provide intermediates or products comprising N-O functional groups such as N-hydroxy, oxazine, isoxazolidine, nitro, nitrone, oxime, C-, S-, or N-nitroso, and azoxy units. To this end, molecular oxygen is activated by flavin, heme, or metal cofactor-containing enzymes and transferred to initially obtain N-hydroxy compounds, which can be further functionalized. In this review, we focus on flavin-dependent N-hydroxylating enzymes, which play a major role in the production of secondary metabolites, such as siderophores or antimicrobial agents. Flavoprotein monooxygenases of higher organisms (among others, in humans) can interact with nitrogen-bearing secondary metabolites or are relevant with respect to detoxification metabolism and are thus of importance to understand potential medical applications. Many enzymes that catalyze N-hydroxylation reactions have specific substrate scopes and others are rather relaxed. The subsequent conversion towards various N-O or N-N comprising molecules is also described. Overall, flavin-dependent N-hydroxylating enzymes can accept amines, diamines, amino acids, amino sugars, and amino aromatic compounds and thus provide access to versatile families of compounds containing the N-O motif. Natural roles as well as synthetic applications are highlighted. Key points • N-O and N-N comprising natural and (semi)synthetic products are highlighted. • Flavin-based NMOs with respect to mechanism, structure, and phylogeny are reviewed. • Applications in natural product formation and synthetic approaches are provided. Graphical abstract .
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Affiliation(s)
- Carolin Mügge
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany
| | - Thomas Heine
- Environmental Microbiology, Faculty of Chemistry and Physics, TU Bergakademie Freiberg, Leipziger Str. 29, 09599, Freiberg, Germany
| | - Alvaro Gomez Baraibar
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany
- Rottendorf Pharma GmbH, Ostenfelder Str. 51-61, 59320, Ennigerloh, Germany
| | - Willem J H van Berkel
- Laboratory of Food Chemistry, Wageningen University & Research, Bornse Weilanden 9, 6708 WG, Wageningen, The Netherlands
| | - Caroline E Paul
- Biocatalysis, Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, HZ 2629, Delft, The Netherlands
| | - Dirk Tischler
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstr. 150, 44780, Bochum, Germany.
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Abstract
In vitro growth conditions for bacteria do not fully recapitulate the host environment. RNA sequencing transcriptome analysis allows for the characterization of the infection gene expression profiles of pathogens in complex environments. Isolation of the pathogen from infected tissues is critical because of the large amounts of host RNA present in crude lysates of infected organs. A filtration method was developed that enabled enrichment of the pathogen RNA for RNA-seq analysis. The resulting data describe the “infection transcriptome” of B. pertussis in the murine lung. This strategy can be utilized for pathogens in other hosts and, thus, expand our knowledge of what bacteria express during infection. Bordetella pertussis causes the disease whooping cough through coordinated control of virulence factors by the Bordetella virulence gene system. Microarrays and, more recently, RNA sequencing (RNA-seq) have been used to describe in vitro gene expression profiles of B. pertussis and other pathogens. In previous studies, we have analyzed the in vitro gene expression profiles of B. pertussis, and we hypothesize that the infection transcriptome profile in vivo is significantly different from that under laboratory growth conditions. To study the infection transcriptome of B. pertussis, we developed a simple filtration technique for isolation of bacteria from infected lungs. The work flow involves filtering the bacteria out of the lung homogenate using a 5-μm-pore-size syringe filter. The captured bacteria are then lysed to isolate RNA for Illumina library preparation and RNA-seq analysis. Upon comparing the in vitro and in vivo gene expression profiles, we identified 351 and 255 genes as activated and repressed, respectively, during murine lung infection. As expected, numerous genes associated with virulent-phase growth were activated in the murine host, including pertussis toxin (PT), the PT secretion apparatus, and the type III secretion system. A significant number of genes encoding iron acquisition and heme uptake proteins were highly expressed during infection, supporting iron acquisition as critical for B. pertussis survival in vivo. Numerous metabolic genes were repressed during infection. Overall, these data shed light on the gene expression profile of B. pertussis during infection, and this method will facilitate efforts to understand how this pathogen causes infection. IMPORTANCEIn vitro growth conditions for bacteria do not fully recapitulate the host environment. RNA sequencing transcriptome analysis allows for the characterization of the infection gene expression profiles of pathogens in complex environments. Isolation of the pathogen from infected tissues is critical because of the large amounts of host RNA present in crude lysates of infected organs. A filtration method was developed that enabled enrichment of the pathogen RNA for RNA-seq analysis. The resulting data describe the “infection transcriptome” of B. pertussis in the murine lung. This strategy can be utilized for pathogens in other hosts and, thus, expand our knowledge of what bacteria express during infection.
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Analogues of desferrioxamine B (DFOB) with new properties and new functions generated using precursor-directed biosynthesis. Biometals 2019; 32:395-408. [PMID: 30701380 DOI: 10.1007/s10534-019-00175-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 01/21/2019] [Indexed: 10/27/2022]
Abstract
Desferrioxamine B (DFOB) is a siderophore native to Streptomyces pilosus biosynthesised by the DesABCD enzyme cluster as a high affinity Fe(III) chelator. Although DFOB has a long clinical history for the treatment of chronic iron overload, limitations encourage the development of new analogues. This review describes a recent body of work that has used precursor-directed biosynthesis (PDB) to access new DFOB analogues. PDB exploits the native biosynthetic machinery of a producing organism in culture medium augmented with non-native substrates that compete against native substrates during metabolite assembly. The method allows access to analogues of natural products using benign methods, compared to multistep organic synthesis. The disadvantages of PDB are the production of metabolites in low yield and the need to purify complex mixtures. Streptomyces pilosus medium was supplemented with different types of non-native diamine substrates to compete against native 1,5-diaminopentane to generate DFOB analogues containing alkene bonds, fluorine atoms, ether or thioether functional groups, or a disulfide bond. All analogues retained function as Fe(III) chelators and have properties that could broaden the utility of DFOB. These PDB studies have also added knowledge to the understanding of DFOB biosynthesis.
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Telfer TJ, Codd R. Fluorinated Analogues of Desferrioxamine B from Precursor-Directed Biosynthesis Provide New Insight into the Capacity of DesBCD. ACS Chem Biol 2018; 13:2456-2471. [PMID: 30081629 DOI: 10.1021/acschembio.8b00340] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The siderophore desferrioxamine B (DFOB, 1) native to Streptomyces pilosus is biosynthesized by the DesABCD enzyme cluster. DesA-mediated decarboxylation of l-lysine gives 1,5-diaminopentane (DP) for processing by DesBCD. S. pilosus culture medium was supplemented with rac-1,4-diamino-2-fluorobutane ( rac-FDB) to compete against DP to generate fluorinated analogues of DFOB, as agents of potential clinical interest. LC-MS/MS analysis identified fluorinated analogues of DFOB with one, two, or three DP units (binary notation: 0) exchanged for one (DFOA-F1[001] (2), DFOA-F1[010] (3), DFOA-F1[100] (4)), two (DFOA-F2[011] (5), DFOA-F2[110] (6), DFOA-F2[101] (7)), or three (DFOA-F3[111] (8)) rac-FDB units (binary notation: 1). The two sets of constitutional isomers 2-4 and 5-7 arose from the position of the substrates in the N-acetyl, internal, or amine-containing regions of the DFOB trimer. N-Acetylated fluorinated DFOB analogues were formed where the rac-FDB substrate was positioned in the amine region ( e.g., N-Ac-DFOA-F1[001] (2a)). Other analogues contained two hydroxamic acid groups and three amide bonds. Experiments using rac-FDB, R-FDB, or S-FDB showed a similar species profile between rac-FDB and R-FDB. These data are consistent with the following. (i) DesB can act on rac-FDB. (ii) DesC can act directly on rac-FDB. (iii) The products of DesBC or DesC catalysis of rac-FDB can undergo a second round of DesC catalysis at the free amine. (iv) DesD catalysis of these products gives N, N'-diacetylated compounds. (v) A minimum of two hydroxamic acid groups is required to form a viable DesD-substrate(s) precomplex. (vi) One or more DesBCD-catalyzed steps in DFOB biosynthesis is enantioselective. This work has provided a potential path to access fluorinated analogues of DFOB and new insight into its biosynthesis.
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Affiliation(s)
- Thomas J. Telfer
- School of Medical Sciences (Pharmacology), The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Rachel Codd
- School of Medical Sciences (Pharmacology), The University of Sydney, Sydney, New South Wales 2006, Australia
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Cloning of the Bisucaberin B Biosynthetic Gene Cluster from the Marine Bacterium Tenacibaculum mesophilum, and Heterologous Production of Bisucaberin B. Mar Drugs 2018; 16:md16090342. [PMID: 30235820 PMCID: PMC6164419 DOI: 10.3390/md16090342] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 09/12/2018] [Accepted: 09/15/2018] [Indexed: 11/17/2022] Open
Abstract
The biosynthetic gene cluster for bisucaberin B (1, bsb gene cluster), an N-hydroxy-N-succinyl diamine (HSD)-based siderophore, was cloned from the marine bacterium Tenacibaculum mesophilum, originated from a marine sponge. The bsb gene cluster consists of six open reading frames (ORFs), in contrast to the four ORFs typically seen in biosynthetic gene clusters of the related molecules. Heterologous expression of the key enzyme, BsbD2, which is responsible for the final biosynthetic step of 1 resulted in production of bisucaberin B (1), but not bisucaberin (2) a macrocyclic counterpart of 1. To date, numbers of related enzymes producing macrocyclic analogues have been reported, but this work represents the first example of the HSD-based siderophore biosynthetic enzyme which exclusively produces a linear molecule rather than macrocyclic counterparts.
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Codd R, Soe CZ, Pakchung AAH, Sresutharsan A, Brown CJM, Tieu W. The chemical biology and coordination chemistry of putrebactin, avaroferrin, bisucaberin, and alcaligin. J Biol Inorg Chem 2018; 23:969-982. [PMID: 29946977 DOI: 10.1007/s00775-018-1585-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 06/20/2018] [Indexed: 12/30/2022]
Abstract
Dihydroxamic acid macrocyclic siderophores comprise four members: putrebactin (putH2), avaroferrin (avaH2), bisucaberin (bisH2), and alcaligin (alcH2). This mini-review collates studies of the chemical biology and coordination chemistry of these macrocycles, with an emphasis on putH2. These Fe(III)-binding macrocycles are produced by selected bacteria to acquire insoluble Fe(III) from the local environment. The macrocycles are optimally pre-configured for Fe(III) binding, as established from the X-ray crystal structure of dinuclear [Fe2(alc)3] at neutral pH. The dimeric macrocycles are biosynthetic products of two endo-hydroxamic acid ligands flanked by one amine group and one carboxylic acid group, which are assembled from 1,4-diaminobutane and/or 1,5-diaminopentane as initial substrates. The biosynthesis of alcH2 includes an additional diamine C-hydroxylation step. Knowledge of putH2 biosynthesis supported the use of precursor-directed biosynthesis to generate unsaturated putH2 analogues by culturing Shewanella putrefaciens in medium supplemented with unsaturated diamine substrates. The X-ray crystal structures of putH2, avaH2 and alcH2 show differences in the relative orientations of the amide and hydroxamic acid functional groups that could prescribe differences in solvation and other biological properties. Functional differences have been borne out in biological studies. Although evolved for Fe(III) acquisition, solution coordination complexes have been characterised between putH2 and oxido-V(IV/V), Mo(VI), or Cr(V). Retrosynthetic analysis of 1:1 complexes of [Fe(put)]+, [Fe(ava)]+, and [Fe(bis)]+ that dominate at pH < 5 led to a forward metal-templated synthesis approach to generate the Fe(III)-loaded macrocycles, with apo-macrocycles furnished upon incubation with EDTA. This mini-review aims to capture the rich chemistry and chemical biology of these seemingly simple compounds.
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Affiliation(s)
- Rachel Codd
- School of Medical Sciences (Pharmacology) and Bosch Institute, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Cho Zin Soe
- School of Medical Sciences (Pharmacology) and Bosch Institute, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Amalie A H Pakchung
- School of Medical Sciences (Pharmacology) and Bosch Institute, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Athavan Sresutharsan
- School of Medical Sciences (Pharmacology) and Bosch Institute, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Christopher J M Brown
- School of Medical Sciences (Pharmacology) and Bosch Institute, The University of Sydney, Sydney, NSW, 2006, Australia
| | - William Tieu
- School of Medical Sciences (Pharmacology) and Bosch Institute, The University of Sydney, Sydney, NSW, 2006, Australia
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Carroll CS, Moore MM. Ironing out siderophore biosynthesis: a review of non-ribosomal peptide synthetase (NRPS)-independent siderophore synthetases. Crit Rev Biochem Mol Biol 2018; 53:356-381. [DOI: 10.1080/10409238.2018.1476449] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Affiliation(s)
| | - Margo M. Moore
- Department of Biological Sciences, Simon Fraser University, Burnaby, Canada
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Waldman AJ, Ng TL, Wang P, Balskus EP. Heteroatom-Heteroatom Bond Formation in Natural Product Biosynthesis. Chem Rev 2017; 117:5784-5863. [PMID: 28375000 PMCID: PMC5534343 DOI: 10.1021/acs.chemrev.6b00621] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Natural products that contain functional groups with heteroatom-heteroatom linkages (X-X, where X = N, O, S, and P) are a small yet intriguing group of metabolites. The reactivity and diversity of these structural motifs has captured the interest of synthetic and biological chemists alike. Functional groups containing X-X bonds are found in all major classes of natural products and often impart significant biological activity. This review presents our current understanding of the biosynthetic logic and enzymatic chemistry involved in the construction of X-X bond containing functional groups within natural products. Elucidating and characterizing biosynthetic pathways that generate X-X bonds could both provide tools for biocatalysis and synthetic biology, as well as guide efforts to uncover new natural products containing these structural features.
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Affiliation(s)
- Abraham J. Waldman
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Tai L. Ng
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Peng Wang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
| | - Emily P. Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, United States
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Rütschlin S, Gunesch S, Böttcher T. One Enzyme, Three Metabolites: Shewanella algae Controls Siderophore Production via the Cellular Substrate Pool. Cell Chem Biol 2017; 24:598-604.e10. [PMID: 28434877 DOI: 10.1016/j.chembiol.2017.03.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 01/25/2017] [Accepted: 03/24/2017] [Indexed: 11/16/2022]
Abstract
Shewanella algae B516 produces avaroferrin, an asymmetric hydroxamate siderophore, which has been shown to inhibit swarming motility of Vibrio alginolyticus. We aimed to elucidate the biosynthesis of this siderophore and to investigate how S. algae coordinates the production of avaroferrin and its two symmetric counterparts. We reconstituted the reaction in vitro with the main enzyme AvbD and the putative biosynthetic precursors, and demonstrate that multispecificity of this enzyme results in the production of all three cyclic hydroxamate siderophores that were previously isolated as natural products from S. algae. Surprisingly, purified AvbD exhibited a clear preference for the larger cadaverine-derived substrate. In live cells, however, siderophore ratios are maximized toward avaroferrin production, and we demonstrate that these siderophore ratios are the result of a regulation on substrate pool level, which may allow rapid evolutionary adaptation to environmental changes. Our results thereby give insights into a unique evolutionary strategy toward metabolite diversity.
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Affiliation(s)
- Sina Rütschlin
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Sandra Gunesch
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Thomas Böttcher
- Department of Chemistry, Konstanz Research School Chemical Biology, University of Konstanz, 78457 Konstanz, Germany.
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Identification and characterization of a FAD-dependent putrescine N-hydroxylase (GorA) from Gordonia rubripertincta CWB2. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcatb.2016.08.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Li B, Lowe-Power T, Kurihara S, Gonzales S, Naidoo J, MacMillan JB, Allen C, Michael AJ. Functional Identification of Putrescine C- and N-Hydroxylases. ACS Chem Biol 2016; 11:2782-2789. [PMID: 27541336 DOI: 10.1021/acschembio.6b00629] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The small polyamine putrescine (1,4-diaminobutane) is ubiquitously and abundantly found in all three domains of life. It is a precursor, through N-aminopropylation or N-aminobutylation, for biosynthesis of the longer polyamines spermidine, sym-homospermidine, spermine, and thermospermine and longer and branched chain polyamines. Putrescine is also biochemically modified for purposes of metabolic regulation and catabolism, e.g. N-acetylation and N-glutamylation, and for incorporation into specialized metabolites, e.g. N-methylation, N-citrylation, N-palmitoylation, N-hydroxylation, and N-hydroxycinnamoylation. Only one example is known where putrescine is modified on a methylene carbon: the formation of 2-hydroxyputrescine by an unknown C-hydroxylase. Here, we report the functional identification of a previously undescribed putrescine 2-hydroxylase, a Rieske-type nonheme iron sulfur protein from the β-proteobacteria Bordetella bronchiseptica and Ralstonia solanacearum. Identification of the putrescine 2-hydroxylase will facilitate investigation of the physiological functions of 2-hydroxyputrescine. One known role of 2-hydroxyputrescine has direct biomedical relevance: its role in the biosynthesis of the cyclic hydroxamate siderophore alcaligin, a potential virulence factor of the causative agent of whooping cough, Bordetella pertussis. We also report the functional identification of a putrescine N-hydroxylase from the γ-proteobacterium Shewanella oneidensis, which is homologous to FAD- and NADPH-dependent ornithine and lysine N-monooxygenases involved in siderophore biosynthesis. Heterologous expression of the putrescine N-hydroxylase in E. coli produced free N-hydroxyputrescine, never detected previously in a biological system. Furthermore, the putrescine C- and N-hydroxylases identified here could contribute new functionality to polyamine structural scaffolds, including C-H bond functionalization in synthetic biology strategies.
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Affiliation(s)
| | - Tiffany Lowe-Power
- Deptartment of Plant Pathology, University of Wisconsin, Madison, Wisconsin, United States
| | | | | | | | | | - Caitilyn Allen
- Deptartment of Plant Pathology, University of Wisconsin, Madison, Wisconsin, United States
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Alvarez Hayes J, Lamberti Y, Surmann K, Schmidt F, Völker U, Rodriguez ME. Shotgun proteome analysis of Bordetella pertussis
reveals a distinct influence of iron availability on the bacterial metabolism, virulence, and defense response. Proteomics 2015; 15:2258-66. [DOI: 10.1002/pmic.201400512] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/09/2015] [Accepted: 03/03/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Jimena Alvarez Hayes
- CINDEFI (UNLP CONICET La Plata); Facultad de Ciencias Exactas; Universidad Nacional de La Plata; La Plata Argentina
| | - Yanina Lamberti
- CINDEFI (UNLP CONICET La Plata); Facultad de Ciencias Exactas; Universidad Nacional de La Plata; La Plata Argentina
| | - Kristin Surmann
- Interfaculty Institute for Genetics and Functional Genomics; University Medicine Greifswald; Greifswald Germany
| | - Frank Schmidt
- Interfaculty Institute for Genetics and Functional Genomics; University Medicine Greifswald; Greifswald Germany
- ZIK-FunGene Junior Research Group Applied Proteomics; University Medicine Greifswald; Greifswald Germany
| | - Uwe Völker
- Interfaculty Institute for Genetics and Functional Genomics; University Medicine Greifswald; Greifswald Germany
| | - Maria Eugenia Rodriguez
- CINDEFI (UNLP CONICET La Plata); Facultad de Ciencias Exactas; Universidad Nacional de La Plata; La Plata Argentina
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15
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Binda C, Robinson RM, Martin Del Campo JS, Keul ND, Rodriguez PJ, Robinson HH, Mattevi A, Sobrado P. An unprecedented NADPH domain conformation in lysine monooxygenase NbtG provides insights into uncoupling of oxygen consumption from substrate hydroxylation. J Biol Chem 2015; 290:12676-88. [PMID: 25802330 DOI: 10.1074/jbc.m114.629485] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 01/01/2023] Open
Abstract
N-Hydroxylating monooxygenases are involved in the biosynthesis of iron-chelating hydroxamate-containing siderophores that play a role in microbial virulence. These flavoenzymes catalyze the NADPH- and oxygen-dependent hydroxylation of amines such as those found on the side chains of lysine and ornithine. In this work we report the biochemical and structural characterization of Nocardia farcinica Lys monooxygenase (NbtG), which has similar biochemical properties to mycobacterial homologs. NbtG is also active on d-Lys, although it binds l-Lys with a higher affinity. Differently from the ornithine monooxygenases PvdA, SidA, and KtzI, NbtG can use both NADH and NADPH and is highly uncoupled, producing more superoxide and hydrogen peroxide than hydroxylated Lys. The crystal structure of NbtG solved at 2.4 Å resolution revealed an unexpected protein conformation with a 30° rotation of the NAD(P)H domain with respect to the flavin adenine dinucleotide (FAD) domain that precludes binding of the nicotinamide cofactor. This "occluded" structure may explain the biochemical properties of NbtG, specifically with regard to the substantial uncoupling and limited stabilization of the C4a-hydroperoxyflavin intermediate. Biological implications of these findings are discussed.
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Affiliation(s)
- Claudia Binda
- From the Department of Biology and Biotechnology, University of Pavia, Pavia 27100, Italy
| | - Reeder M Robinson
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, and
| | | | - Nicholas D Keul
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, and
| | - Pedro J Rodriguez
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, and
| | - Howard H Robinson
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973
| | - Andrea Mattevi
- From the Department of Biology and Biotechnology, University of Pavia, Pavia 27100, Italy,
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, and
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16
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Robinson RM, Rodriguez PJ, Sobrado P. Mechanistic studies on the flavin-dependent N⁶-lysine monooxygenase MbsG reveal an unusual control for catalysis. Arch Biochem Biophys 2014; 550-551:58-66. [PMID: 24769337 DOI: 10.1016/j.abb.2014.04.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/10/2014] [Accepted: 04/15/2014] [Indexed: 10/25/2022]
Abstract
The mechanism of Mycobacterium smegmatis G (MbsG), a flavin-dependent l-lysine monooxygenase, was investigated under steady-state and rapid reaction conditions using primary and solvent kinetic isotope effects, substrate analogs, pH and solvent viscosity effects as mechanistic probes. The results suggest that l-lysine binds before NAD(P)H, which leads to a decrease in the rate constant for flavin reduction. l-lysine binding has no effect on the rate of flavin oxidation, which occurs in a one-step process without the observation of a C4a-hydroperoxyflavin intermediate. Similar effects were determined with several substrate analogs. Flavin oxidation is pH independent while the kcat/Km and kred/KD pH profiles for NAD(P)H exhibit single pKa values of ∼6.0, with increasing activity as the pH decreases. At lower pH, the enzyme becomes more uncoupled, producing more hydrogen peroxide and superoxide. Hydride transfer is partially rate-limiting at neutral pH and becomes more rate-limiting at low pH. An inverse solvent viscosity effect on kcat/Km for NAD(P)H was observed at neutral pH whereas a normal solvent viscosity effect was observed at lower pH. Together, the results indicate a unique mechanism where a rate-limiting and pH-sensitive conformational change occurs in the reductive half-reaction, which affects the efficiency of lysine hydroxylation.
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Affiliation(s)
- Reeder M Robinson
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Pedro J Rodriguez
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA 24061, USA; Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, VA 24061, USA.
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17
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Olucha J, Lamb AL. Mechanistic and structural studies of the N-hydroxylating flavoprotein monooxygenases. Bioorg Chem 2011; 39:171-7. [PMID: 21871647 PMCID: PMC3188341 DOI: 10.1016/j.bioorg.2011.07.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 07/28/2011] [Accepted: 07/29/2011] [Indexed: 10/17/2022]
Abstract
The N-hydroxylating flavoprotein monooxygenases are siderophore biosynthetic enzymes that catalyze the hydroxylation of the sidechain amino-group of ornithine or lysine or the primary amino-group of putrescine. This hydroxylated product is subsequently formylated or acylated and incorporated into the siderophore. Importantly, the modified amino-group is a hydroxamate and serves as an iron chelating moiety in the siderophore. This review describes recent work to characterize the ornithine hydroxylases from Pseudomonas aeruginosa (PvdA) and Aspergillus fumigatus (SidA) and the lysine hydroxylase from Escherichia coli (IucD). This includes summaries of steady and transient state kinetic data for all three enzymes and the X-ray crystallographic structure of PvdA.
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Affiliation(s)
- Jose Olucha
- Molecular Biosciences, University of Kansas, 1200 Sunnyside Ave, Lawrence, Kansas
| | - Audrey L. Lamb
- Molecular Biosciences, University of Kansas, 1200 Sunnyside Ave, Lawrence, Kansas
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18
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Fujita MJ, Kimura N, Yokose H, Otsuka M. Heterologous production of bisucaberin using a biosynthetic gene cluster cloned from a deep sea metagenome. MOLECULAR BIOSYSTEMS 2011; 8:482-5. [PMID: 22051782 DOI: 10.1039/c1mb05431g] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A siderophore biosynthetic gene cluster was cloned from a metagenomic library generated from deep sea sediment. The gene cluster was successfully expressed in Escherichia coli to produce bisucaberin, a siderophore originally reported from the marine bacterium Alteromonas haloplanktis. The cloned bisucaberin biosynthetic gene cluster was moderately similar to that of the known bisucaberin producer Vibrio salmonicida. However, the cloned gene cluster consists of four genes rather than three genes found in the V. salmonicida cluster. The low overall homology of the amino acid and nucleotide sequences with those of other species suggests that the cloned genes were derived from one of the unsequenced bacteria including uncultured species.
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Affiliation(s)
- Masaki J Fujita
- Priority Organization for Innovation and Excellence, Kumamoto University, Kumamoto, Japan.
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19
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Morton DJ, Turman EJ, Hensley PD, VanWagoner TM, Seale TW, Whitby PW, Stull TL. Identification of a siderophore utilization locus in nontypeable Haemophilus influenzae. BMC Microbiol 2010; 10:113. [PMID: 20398325 PMCID: PMC2859871 DOI: 10.1186/1471-2180-10-113] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 04/15/2010] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Haemophilus influenzae has an absolute aerobic growth requirement for either heme, or iron in the presence of protoporphyrin IX. Both iron and heme in the mammalian host are strictly limited in their availability to invading microorganisms. Many bacterial species overcome iron limitation in their environment by the synthesis and secretion of small iron binding molecules termed siderophores, which bind iron and deliver it into the bacterial cell via specific siderophore receptor proteins on the bacterial cell surface. There are currently no reports of siderophore production or utilization by H. influenzae. RESULTS Comparative genomics revealed a putative four gene operon in the recently sequenced nontypeable H. influenzae strain R2846 that encodes predicted proteins exhibiting significant identity at the amino acid level to proteins involved in the utilization of the siderophore ferrichrome in other bacterial species. No siderophore biosynthesis genes were identified in the R2846 genome. Both comparative genomics and a PCR based analysis identified several additional H. influenzae strains possessing this operon. In growth curve assays strains containing the genes were able to utilize ferrichrome as an iron source. H. influenzae strains lacking the operon were unable to obtain iron from ferrichrome. An insertional mutation in one gene of the operon abrogated the ability of strains to utilize ferrichrome. In addition transcription of genes in the identified operon were repressible by high iron/heme levels in the growth media. CONCLUSIONS We have identified an iron/heme-repressible siderophore utilization locus present in several nontypeable H. influenzae strains. The same strains do not possess genes encoding proteins associated with siderophore synthesis. The siderophore utilization locus may enable the utilization of siderophores produced by other microorganisms in the polymicrobial environmental niche of the human nasopharynx colonized by H. influenzae. This is the first report of siderophore utilization by H. influenzae.
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Affiliation(s)
- Daniel J Morton
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Elizabeth J Turman
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Patrick D Hensley
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Timothy M VanWagoner
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- Department of Biology, Oklahoma Christian University, Oklahoma City, OK 73136, USA
| | - Thomas W Seale
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Paul W Whitby
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Terrence L Stull
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
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20
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Oves-Costales D, Kadi N, Challis GL. The long-overlooked enzymology of a nonribosomal peptide synthetase-independent pathway for virulence-conferring siderophore biosynthesis. Chem Commun (Camb) 2009:6530-41. [PMID: 19865642 DOI: 10.1039/b913092f] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Siderophores are high-affinity ferric iron chelators biosynthesised and excreted by most microorganisms that play an important role in iron acquisition. Siderophore-mediated scavenging of ferric iron from hosts contributes significantly to the virulence of pathogenic microbes. As a consequence siderophore biosynthesis is an attractive target for chemotherapeutic intervention. Two main pathways for siderophore biosynthesis exist in microbes. One pathway involves nonribosomal peptide synthetase (NRPS) multienzymes while the other is NRPS-independent. The enzymology of NRPS-mediated siderophore biosynthesis has been extensively studied for more than a decade. In contrast, the enzymology of NRPS-independent siderophore (NIS) biosynthesis was overlooked for almost thirty years since the first genetic characterisation of the NIS biosynthetic pathway to aerobactin. However, the past three years have witnessed an explosion of interest in the enzymology of NIS synthetases, the key enzymes in the assembly of siderophores via the NIS pathway. The biochemical characterisation of ten purified recombinant synthetases has been reported since 2007, along with the first structural characterisation of a synthetase by X-ray crystallography in 2009. In this feature article we summarise the recent progress that has been made in understanding the long-overlooked enzymology of NRPS-independent siderophore biosynthesis, highlight important remaining questions, and suggest likely directions for future research.
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21
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Brickman TJ, Armstrong SK. Temporal signaling and differential expression of Bordetella iron transport systems: the role of ferrimones and positive regulators. Biometals 2009; 22:33-41. [PMID: 19130264 DOI: 10.1007/s10534-008-9189-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 12/07/2008] [Indexed: 01/16/2023]
Abstract
The bacterial respiratory pathogens Bordetella pertussis and Bordetella bronchiseptica employ multiple alternative iron acquisition pathways to adapt to changes in the mammalian host environment during infection. The alcaligin, enterobactin, and heme utilization pathways are differentially expressed in response to the cognate iron source availability by a mechanism involving substrate-inducible positive regulators. As inducers, the iron sources function as chemical signals termed ferrimones. Ferrimone-sensing allows the pathogen to adapt and exploit early and late events in the infection process.
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Affiliation(s)
- Timothy J Brickman
- Department of Microbiology, University of Minnesota Medical School, MMC 196, Minneapolis, MN 55455-0312, USA
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22
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Chourey K, Wei W, Wan XF, Thompson DK. Transcriptome analysis reveals response regulator SO2426-mediated gene expression in Shewanella oneidensis MR-1 under chromate challenge. BMC Genomics 2008; 9:395. [PMID: 18718017 PMCID: PMC2535785 DOI: 10.1186/1471-2164-9-395] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 08/21/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Shewanella oneidensis MR-1 exhibits diverse metal ion-reducing capabilities and thus is of potential utility as a bioremediation agent. Knowledge of the molecular components and regulatory mechanisms dictating cellular responses to heavy metal stress, however, remains incomplete. In a previous work, the S. oneidensis so2426 gene, annotated as a DNA-binding response regulator, was demonstrated to be specifically responsive at both the transcript and protein levels to acute chromate [Cr(VI)] challenge. To delineate the cellular function of SO2426 and its contribution to metal stress response, we integrated genetic and physiological approaches with a genome-wide screen for target gene candidates comprising the SO2426 regulon. RESULTS Inactivation of so2426 by an in-frame deletion resulted in enhanced chromate sensitivity and a reduced capacity to remove extracellular Cr(VI) relative to the parental strain. Time-resolved microarray analysis was used to compare transcriptomic profiles of wild-type and SO2426-deficient mutant S. oneidensis under conditions of chromate exposure. In total, 841 genes (18% of the arrayed genome) were up- or downregulated at least twofold in the Deltaso2426 mutant for at least one of six time-point conditions. Hierarchical cluster analysis of temporal transcriptional profiles identified a distinct cluster (n = 46) comprised of co-ordinately regulated genes exhibiting significant downregulated expression (p < 0.05) over time. Thirteen of these genes encoded proteins associated with transport and binding functions, particularly those involved in Fe transport and homeostasis (e.g., siderophore biosynthetic enzymes, TonB-dependent receptors, and the iron-storage protein ferritin). A conserved hypothetical operon (so1188-so1189-so1190), previously identified as a potential target of Fur-mediated repression, as well as a putative bicyclomycin resistance gene (so2280) and cation efflux family protein gene (so2045) also were repressed in the so2426 deletion mutant. Furthermore, the temporal expression profiles of four regulatory genes including a cpxR homolog were perturbed in the chromate-challenged mutant. CONCLUSION Our findings suggest a previously unrecognized functional role for the response regulator SO2426 in the activation of genes required for siderophore-mediated Fe acquisition, Fe storage, and other cation transport mechanisms. SO2426 regulatory function is involved at a fundamental molecular level in the linkage between Fe homeostasis and the cellular response to chromate-induced stress in S. oneidensis.
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Affiliation(s)
- Karuna Chourey
- Department of Biological Sciences, Purdue University, 915 W, State Street, West Lafayette, IN 47907, USA.
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23
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Norepinephrine mediates acquisition of transferrin-iron in Bordetella bronchiseptica. J Bacteriol 2008; 190:3940-7. [PMID: 18390651 DOI: 10.1128/jb.00086-08] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous research demonstrated that the sympathoadrenal catecholamine norepinephrine could promote the growth of Bordetella bronchiseptica in iron-restricted medium containing serum. In this study, norepinephrine was demonstrated to stimulate growth of this organism in the presence of partially iron-saturated transferrin but not lactoferrin. Although norepinephrine is known to induce transcription of the Bordetella bfeA enterobactin catechol xenosiderophore receptor gene, neither a bfeA mutant nor a bfeR regulator mutant was defective in growth responsiveness to norepinephrine. However, growth of a tonB mutant strain was not enhanced by norepinephrine, indicating that the response to this catecholamine was the result of high-affinity outer membrane transport. The B. bronchiseptica genome encodes a total of 19 known and predicted iron transport receptor genes, none of which, when mutated individually, were found to confer a defect in norepinephrine-mediated growth stimulation in the presence of transferrin. Labeling experiments demonstrated a TonB-dependent increase in cell-associated iron levels when bacteria grown in the presence of (55)Fe-transferrin were exposed to norepinephrine. In addition, TonB was required for maximum levels of cell-associated norepinephrine. Together, these results demonstrate that norepinephrine facilitates B. bronchiseptica iron acquisition from the iron carrier protein transferrin and this process may represent a mechanism by which some bacterial pathogens obtain this essential nutrient in the host environment.
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The genome sequence of the tomato-pathogenic actinomycete Clavibacter michiganensis subsp. michiganensis NCPPB382 reveals a large island involved in pathogenicity. J Bacteriol 2008; 190:2138-49. [PMID: 18192381 DOI: 10.1128/jb.01595-07] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clavibacter michiganensis subsp. michiganensis is a plant-pathogenic actinomycete that causes bacterial wilt and canker of tomato. The nucleotide sequence of the genome of strain NCPPB382 was determined. The chromosome is circular, consists of 3.298 Mb, and has a high G+C content (72.6%). Annotation revealed 3,080 putative protein-encoding sequences; only 26 pseudogenes were detected. Two rrn operons, 45 tRNAs, and three small stable RNA genes were found. The two circular plasmids, pCM1 (27.4 kbp) and pCM2 (70.0 kbp), which carry pathogenicity genes and thus are essential for virulence, have lower G+C contents (66.5 and 67.6%, respectively). In contrast to the genome of the closely related organism Clavibacter michiganensis subsp. sepedonicus, the genome of C. michiganensis subsp. michiganensis lacks complete insertion elements and transposons. The 129-kb chp/tomA region with a low G+C content near the chromosomal origin of replication was shown to be necessary for pathogenicity. This region contains numerous genes encoding proteins involved in uptake and metabolism of sugars and several serine proteases. There is evidence that single genes located in this region, especially genes encoding serine proteases, are required for efficient colonization of the host. Although C. michiganensis subsp. michiganensis grows mainly in the xylem of tomato plants, no evidence for pronounced genome reduction was found. C. michiganensis subsp. michiganensis seems to have as many transporters and regulators as typical soil-inhabiting bacteria. However, the apparent lack of a sulfate reduction pathway, which makes C. michiganensis subsp. michiganensis dependent on reduced sulfur compounds for growth, is probably the reason for the poor survival of C. michiganensis subsp. michiganensis in soil.
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Brickman TJ, Armstrong SK. Impact of alcaligin siderophore utilization on in vivo growth of Bordetella pertussis. Infect Immun 2007; 75:5305-12. [PMID: 17724074 PMCID: PMC2168284 DOI: 10.1128/iai.00849-07] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Revised: 07/31/2007] [Accepted: 08/13/2007] [Indexed: 11/20/2022] Open
Abstract
Bordetella pertussis, the causative agent of human whooping cough, or pertussis, is an obligate human pathogen with diverse high-affinity transport systems for the assimilation of iron, a biometal that is essential for growth. Under iron starvation stress conditions, B. pertussis produces the siderophore alcaligin. The alcaligin siderophore gene cluster, consisting of the alcABCDERS and fauA genes, encodes activities required for alcaligin biosynthesis, the export of the siderophore from the cell, the uptake of the ferric alcaligin complex across the outer membrane, and the transcriptional activation of alcaligin system genes by an autogenous mechanism involving alcaligin sensing. The fauA gene encodes a 79-kDa TonB-dependent outer membrane receptor protein required for the uptake and utilization of ferric alcaligin as an iron source. In this study, using mixed-infection competition experiments in a mouse respiratory model, inactivation of the B. pertussis ferric alcaligin receptor protein was found to have a profound impact on in vivo growth and survival of a fauA mutant compared with a coinfecting wild-type strain. The attenuating effect of fauA inactivation was evident early in the course of the infection, suggesting that the contribution of ferric alcaligin transport to the ecological fitness of B. pertussis may be important for adaptation to iron-restricted host conditions that exist at the initial stages of infection. Alcaligin-mediated iron acquisition by B. pertussis may be critical for successful host colonization and establishment of infection.
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Affiliation(s)
- Timothy J Brickman
- Department of Microbiology, University of Minnesota, MMC 196, 420 Delaware Street SE, Minneapolis, MN 55455-0312, USA.
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26
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Kadi N, Oves-Costales D, Barona-Gomez F, Challis GL. A new family of ATP-dependent oligomerization-macrocyclization biocatalysts. Nat Chem Biol 2007; 3:652-6. [PMID: 17704771 DOI: 10.1038/nchembio.2007.23] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Accepted: 07/06/2007] [Indexed: 11/09/2022]
Abstract
Oligomerization and macrocyclization reactions are key steps in the biosynthesis of many bioactive natural products. Important macrocycles include the antibiotic daptomycin (1; ref. 1), the immunosuppressant FK-506 (2; ref. 2), the anthelmintic avermectin B1a (3; ref. 3) and the insecticide spinosyn A (4; ref. 4); important oligomeric macrocycles include the siderophores enterobactin (5; ref. 5) and desferrioxamine E (6; ref. 6). Biosynthetic oligomerization and macrocyclization reactions typically involve covalently tethered intermediates and are catalyzed by thioesterase domains of polyketide synthase and nonribosomal peptide synthetase multienzymes. Here we report that the purified recombinant desferrioxamine siderophore synthetase DesD from Streptomyces coelicolor M145 catalyzes ATP-dependent trimerization-macrocyclization of a chemically synthesized 10-aminocarboxylic acid substrate via noncovalently bound intermediates. DesD is dissimilar to other known synthetase families but is similar to other enzymes known or proposed to be required for the biosynthesis of omega-aminocarboxylic acid-derived cyclodimeric siderophores. This suggests that DesD is the first biochemically characterized member of a new family of oligomerizing and macrocyclizing synthetases.
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Affiliation(s)
- Nadia Kadi
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
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27
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Brickman TJ, Anderson MT, Armstrong SK. Bordetella iron transport and virulence. Biometals 2007; 20:303-22. [PMID: 17295050 DOI: 10.1007/s10534-006-9031-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2006] [Accepted: 07/20/2006] [Indexed: 11/26/2022]
Abstract
Bordetella pertussis, Bordetella parapertussis, and Bordetella bronchiseptica are pathogens with a complex iron starvation stress response important for adaptation to nutrient limitation and flux in the mammalian host environment. The iron starvation stress response is globally regulated by the Fur repressor using ferrous iron as the co-repressor. Expression of iron transport system genes of Bordetella is coordinated by priority regulation mechanisms that involve iron source sensing. Iron source sensing is mediated by distinct transcriptional activators that are responsive to the cognate iron source acting as the inducer.
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Affiliation(s)
- Timothy J Brickman
- Department of Microbiology, University of Minnesota Medical School, MMC 196, 420 Delaware Street S.E., Minneapolis, MN 55455-0312, USA
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28
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Diavatopoulos DA, Cummings CA, van der Heide HGJ, van Gent M, Liew S, Relman DA, Mooi FR. Characterization of a highly conserved island in the otherwise divergent Bordetella holmesii and Bordetella pertussis genomes. J Bacteriol 2006; 188:8385-94. [PMID: 17041054 PMCID: PMC1698220 DOI: 10.1128/jb.01081-06] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The recently discovered pathogen Bordetella holmesii has been isolated from the airways and blood of diseased humans. Genetic events contributing to the emergence of B. holmesii are not understood, and its phylogenetic position among the bordetellae remains unclear. To address these questions, B. holmesii strains were analyzed by comparative genomic hybridization (CGH) to a Bordetella pertussis microarray and by multilocus sequence typing. Both methods indicated substantial sequence divergence between B. pertussis and B. holmesii. However, CGH identified a putative pathogenicity island of 66 kb that is highly conserved between these species and contains several IS481 elements that may have been laterally transferred from B. pertussis to B. holmesii. This island contains, among other genes, a functional, iron-regulated locus encoding the biosynthesis, export, and uptake of the siderophore alcaligin. The acquisition of this genomic island by B. holmesii may have significantly contributed to its emergence as a human pathogen. Horizontal gene transfer between B. pertussis and B. holmesii may also explain the unusually high sequence identity of their 16S rRNA genes.
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Affiliation(s)
- D A Diavatopoulos
- Laboratory for Vaccine Preventable Diseases, National Institute of Public Health and the Environment, Antonie van Leeuwenhoeklaan 9, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
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29
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Register KB, DeJong KD. Analytical verification of a multiplex PCR for identification of Bordetella bronchiseptica and Pasteurella multocida from swine. Vet Microbiol 2006; 117:201-10. [PMID: 16782287 DOI: 10.1016/j.vetmic.2006.05.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Revised: 05/04/2006] [Accepted: 05/05/2006] [Indexed: 11/27/2022]
Abstract
Bordetella bronchiseptica and Pasteurella multocida are etiologic agents of progressive atrophic rhinitis (PAR) and bronchopneumonia in swine. Only dermonecrotic toxin-producing strains of P. multocida play a role in atrophic rhinitis while both toxigenic and nontoxigenic strains have been associated with pneumonia. Monitoring and investigation of outbreaks involving these bacteria require sensitive and accurate identification and reliable determination of the toxigenic status of P. multocida isolates. In the present study, we report the development, optimization, and performance characteristics of a multiplex PCR assay for simultaneous amplification of up to three different targets, one common to all P. multocida strains, one found only in toxigenic P. multocida strains, and one common to B. bronchiseptica strains. Based on analysis of 94 P. multocida isolates (31 toxigenic) and 126 B. bronchiseptica isolates assay sensitivity is 100% for all amplicons. Evaluation of 22 isolates of other bacterial genera and species commonly found in the swine respiratory tract demonstrated a specificity of 100% for all gene targets. The limit of detection for simultaneous amplification of all targets is 1-10pg of DNA per target, corresponding to a few hundred genomes or less. Amplicon mobility in agarose gels and sequence analysis indicate the amplicons are highly stable. The data presented establish this multiplex PCR as a reliable method for identification of B. bronchiseptica and both toxigenic and nontoxigenic P. multocida that may greatly simplify investigations of swine PAR and bronchopneumonia.
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Affiliation(s)
- Karen B Register
- Respiratory Diseases of Livestock Research Unit, USDA/Agricultural Research Service/National Animal Disease Center, Ames, IA 50010, USA.
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Topanurak S, Sinchaikul S, Sookkheo B, Phutrakul S, Chen ST. Functional proteomics and correlated signaling pathway of the thermophilic bacterium Bacillus stearothermophilus TLS33 under cold-shock stress. Proteomics 2005; 5:4456-71. [PMID: 16222717 DOI: 10.1002/pmic.200401250] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The thermophilic bacterium Bacillus stearothermophilus TLS33 was examined under cold-shock stress by a proteomic approach to gain a better understanding of the protein synthesis and complex regulatory pathways of bacterial adaptation. After downshift in the temperature from 65 degrees C, the optimal growth temperature for this bacterium, to 37 degrees C and 25 degrees C for 2 h, we used the high-throughput techniques of proteomic analysis combining 2-DE and MS to identify 53 individual proteins including differentially expressed proteins. The bioinformatics database was used to search the biological functions of proteins and correlate these with gene homology and metabolic pathways in cell protection and adaptation. Eight cold-shock-induced proteins were shown to have markedly different protein expression: glucosyltransferase, anti-sigma B (sigma(B)) factor, Mrp protein homolog, dihydroorthase, hypothetical transcriptional regulator in FeuA-SigW intergenic region, RibT protein, phosphoadenosine phosphosulfate reductase and prespore-specific transcriptional activator RsfA. Interestingly, six of these cold-shock-induced proteins are correlated with the signal transduction pathway of bacterial sporulation. This study aims to provide a better understanding of the functional adaptation of this bacterium to environmental cold-shock stress.
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Affiliation(s)
- Supachai Topanurak
- Institute of Biological Chemistry and Genomics Research Center, Academia Sinica, Taipei, Taiwan
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Brickman TJ, Armstrong SK. Bordetella AlcS transporter functions in alcaligin siderophore export and is central to inducer sensing in positive regulation of alcaligin system gene expression. J Bacteriol 2005; 187:3650-61. [PMID: 15901687 PMCID: PMC1112062 DOI: 10.1128/jb.187.11.3650-3661.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bordetella pertussis and Bordetella bronchiseptica, which are respiratory mucosal pathogens of mammals, produce and utilize the siderophore alcaligin to acquire iron in response to iron starvation. A predicted permease of the major facilitator superfamily class of membrane efflux pumps, AlcS (synonyms, OrfX and Bcr), was reported to be encoded within the alcaligin gene cluster. In this study, alcS null mutants were found to be defective in growth under iron starvation conditions, in iron source utilization, and in alcaligin export. trans complementation using cloned alcS genes of B. pertussis or B. bronchiseptica restored the wild-type phenotype to the alcS mutants. Although the levels of extracellular alcaligin measured in alcS strain culture fluids were severely reduced compared with the wild-type levels, alcS mutants had elevated levels of cell-associated alcaligin, implicating AlcS in alcaligin export. Interestingly, a deltaalcA mutation that eliminated alcaligin production suppressed the growth defects of alcS mutants. This suppression and the alcaligin production defect were reversed by trans complementation of the deltaalcA mutation in the double-mutant strain, confirming that the growth-defective phenotype of alcS mutants is associated with alcaligin production. In an alcA::mini-Tn5 lacZ1 operon fusion strain background, an alcS null mutation resulted in enhanced AlcR-dependent transcriptional responsiveness to alcaligin inducer; conversely, AlcS overproduction blunted the transcriptional response to alcaligin. These transcription studies indicate that the alcaligin exporter activity of AlcS is required to maintain appropriate intracellular alcaligin levels for normal inducer sensing and responsiveness necessary for positive regulation of alcaligin system gene expression.
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Affiliation(s)
- Timothy J Brickman
- Department of Microbiology, University of Minnesota, MMC 196, 420 Delaware Street S.E., Minneapolis, Minnesota 55455-0312, USA
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Challis GL. A Widely Distributed Bacterial Pathway for Siderophore Biosynthesis Independent of Nonribosomal Peptide Synthetases. Chembiochem 2005; 6:601-11. [PMID: 15719346 DOI: 10.1002/cbic.200400283] [Citation(s) in RCA: 235] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Anderson MT, Armstrong SK. The BfeR regulator mediates enterobactin-inducible expression of Bordetella enterobactin utilization genes. J Bacteriol 2004; 186:7302-11. [PMID: 15489442 PMCID: PMC523226 DOI: 10.1128/jb.186.21.7302-7311.2004] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2004] [Accepted: 08/10/2004] [Indexed: 11/20/2022] Open
Abstract
Utilization of the enterobactin siderophore by the respiratory pathogens Bordetella pertussis and Bordetella bronchiseptica is dependent on the BfeA outer membrane receptor. This study determined that production of BfeA was increased significantly in iron-starved bacteria upon supplementation of cultures with enterobactin. A 1.01-kb open reading frame, designated bfeR, encoding a predicted positive transcriptional regulator of the AraC family was identified upstream and divergently oriented from bfeA. In iron-depleted cultures containing enterobactin, a Bordetella bfeR mutant exhibited markedly decreased BfeA receptor production compared to that of the wild-type strain. Additionally, B. pertussis and B. bronchiseptica bfeR mutants exhibited impaired growth with ferric enterobactin as the sole source of iron, demonstrating that effective enterobactin utilization is bfeR dependent. Transcriptional analysis using bfeA-lacZ reporter fusions in wild-type strains demonstrated that bfeA transcription was stimulated in iron-depleted conditions in the presence of enterobactin, compared to modest expression levels in cultures lacking enterobactin. In contrast, bfeA transcription in B. pertussis and B. bronchiseptica bfeR mutants was completely unresponsive to the enterobactin inducer. bfeA transcriptional analyses of a bfeA mutant demonstrated that induction by enterobactin did not require BfeA receptor-mediated uptake of the siderophore. These studies establish that bfeR encodes an enterobactin-dependent positive regulator of bfeA transcription in these Bordetella species.
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Affiliation(s)
- Mark T Anderson
- Department of Microbiology, University of Minnesota, MMC 196, 420 Delaware Street S.E., Minneapolis, MN 55455-0312, USA
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Vanderpool CK, Armstrong SK. Integration of environmental signals controls expression of Bordetella heme utilization genes. J Bacteriol 2004; 186:938-48. [PMID: 14761988 PMCID: PMC344224 DOI: 10.1128/jb.186.4.938-948.2004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Bordetella pertussis heme utilization gene cluster hurIR bhuRSTUV encodes regulatory and transport functions required for assimilation of iron from heme and hemoproteins. Expression of the bhu genes is iron regulated and heme inducible. The putative extracytoplasmic function (ECF) sigma factor, HurI, is required for heme-responsive bhu gene expression. In this study, transcriptional activation of B. pertussis bhu genes in response to heme compounds was shown to be dose dependent and specific for heme; protoporphyrin IX and other heme structural analogs did not activate bhu gene expression. Two promoters controlling expression of the heme utilization genes were mapped by primer extension analysis. The hurI promoter showed similarity to sigma(70)-like promoters, and its transcriptional activity was iron regulated and heme independent. A second promoter identified upstream of bhuR exhibited little similarity to previously characterized ECF sigma factor-dependent promoters. Expression of bhuR was iron regulated, heme responsive, and hurI dependent in B. pertussis, as shown in a previous study with Bordetella bronchiseptica. Further analyses showed that transcription originating at a distal upstream site and reading through the hurR-bhuR intergenic region contributes to bhuR expression under iron starvation conditions in the absence of heme inducer. The pattern of regulation of the readthrough transcript was consistent with transcription from the hurI promoter. The positions and regulation of the two promoters within the hur-bhu gene cluster influence the production of heme transport machinery so that maximal expression of the bhu genes occurs under iron starvation conditions only in the presence of heme iron sources.
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Affiliation(s)
- Carin K Vanderpool
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455-0312, USA
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35
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Abstract
Bordetella pertussis and Bordetella bronchiseptica, gram-negative respiratory pathogens of mammals, possess a heme iron utilization system encoded by the bhuRSTUV genes. Preliminary evidence suggested that expression of the BhuR heme receptor was stimulated by the presence of heme under iron-limiting conditions. The hurIR (heme uptake regulator) genes were previously identified upstream of the bhuRSTUV gene cluster and are predicted to encode homologs of members of the iron starvation subfamily of extracytoplasmic function (ECF) regulators. In this study, B. pertussis and B. bronchiseptica DeltahurI mutants, predicted to lack an ECF sigma factor, were constructed and found to be deficient in the utilization of hemin and hemoglobin. Genetic complementation of DeltahurI strains with plasmid-borne hurI restored wild-type levels of heme utilization. B. bronchiseptica DeltahurI mutant BRM23 was defective in heme-responsive production of the BhuR heme receptor; hurI in trans restored heme-inducible BhuR expression to the mutant and resulted in BhuR overproduction. Transcriptional analyses with bhuR-lacZ fusion plasmids confirmed that bhuR transcription was activated in iron-starved cells in response to heme compounds. Heme-responsive bhuR transcription was not observed in mutant BRM23, indicating that hurI is required for positive regulation of bhu gene expression. Furthermore, bhuR was required for heme-inducible bhu gene activation, supporting the hypothesis that positive regulation of bhuRSTUV occurs by a surface signaling mechanism involving the heme-iron receptor BhuR.
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Affiliation(s)
- Carin K Vanderpool
- Department of Microbiology, University of Minnesota Medical School, 420 Delaware Street S.E., Minneapolis, MN 55455-0312, USA
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Brickman TJ, Armstrong SK. Alcaligin siderophore production by Bordetella bronchiseptica strain RB50 is not repressed by the BvgAS virulence control system. J Bacteriol 2002; 184:7055-7. [PMID: 12446655 PMCID: PMC135483 DOI: 10.1128/jb.184.24.7055-7057.2002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A previous study found that alcaligin siderophore production by Bordetella bronchiseptica strain RB50 is Bvg repressed. In contrast, we report that alcaligin production by RB50 does not require Bvg phenotypic phase modulation and that isogenic Bvg(Con) and Bvg(-) phase-locked mutants both produce alcaligin in response to iron starvation.
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Affiliation(s)
- Timothy J Brickman
- Department of Microbiology, University of Minnesota Medical School, Minneapolis 55455-0312, USA.
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Bobrov AG, Geoffroy VA, Perry RD. Yersiniabactin production requires the thioesterase domain of HMWP2 and YbtD, a putative phosphopantetheinylate transferase. Infect Immun 2002; 70:4204-14. [PMID: 12117929 PMCID: PMC128149 DOI: 10.1128/iai.70.8.4204-4214.2002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2002] [Revised: 03/15/2002] [Accepted: 05/02/2002] [Indexed: 12/30/2022] Open
Abstract
One requirement for the pathogenesis of Yersinia pestis, the causative agent of bubonic plague, is the yersiniabactin (Ybt) siderophore-dependent iron transport system that is encoded within a high-pathogenicity island (HPI) within the pgm locus of the Y. pestis chromosome. Nine gene products within the HPI have demonstrated functions in the nonribosomal peptide synthesis (NRPS)/polyketide (PK) synthesis or transport of Ybt. NRPS/PK synthetase or synthase enzymes are generally activated by phosphopantetheinylation. However, no products with similarities to known phosphopantetheinyl (P-pant) transferases were found within the pgm locus. We have identified a gene, ybtD, encoded outside the HPI and pgm locus, that is necessary for function of the Ybt system and has similarities to other P-pant transferases such as EntD of Escherichia coli. A deletion within ybtD yielded a strain (KIM6-2085+) defective in siderophore production. This strain was unable to grow on iron-deficient media at 37 degrees C but could be cross-fed by culture supernatants from Ybt-producing strains of Y. pestis. The promoter region of ybtD was fused to lacZ; beta-galactosidase expression from this reporter was not regulated by the iron status of the bacterial cells or by YbtA, a positive regulator of other genes of the ybt system. The ybtD mutant failed to express indicator Ybt proteins (high-molecular-weight protein 1 [HMWP1], HMWP2, and Psn), a pattern similar to those seen with several other ybt biosynthetic mutants. In contrast, cells containing a single amino acid substitution (S2908A) in the terminal thioesterase domain of HMWP2 failed to exhibit any ybt regulatory defects but did not elaborate extracellular Ybt under iron-deficient conditions.
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Affiliation(s)
- Alexander G Bobrov
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington 40536-0084, USA
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Brickman TJ, Armstrong SK. Bordetella interspecies allelic variation in AlcR inducer requirements: identification of a critical determinant of AlcR inducer responsiveness and construction of an alcR(Con) mutant allele. J Bacteriol 2002; 184:1530-9. [PMID: 11872703 PMCID: PMC134898 DOI: 10.1128/jb.184.6.1530-1539.2002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous studies established the critical roles of AlcR and alcaligin inducer in positive regulation of alcaligin siderophore biosynthesis and transport genes in Bordetella pertussis and Bordetella bronchiseptica. Transcriptional analyses using plasmid-borne alcR genes of B. pertussis UT25 and B. bronchiseptica B013N to complement the alcR defect of B. bronchiseptica strain BRM13 (Delta alcR1 alcA::mini-Tn5 lacZ1) revealed interspecies differences in AlcR inducer requirements for activation of alcABCDER operon transcription. Whereas the B. pertussis UT25 AlcR protein retained strong inducer dependence when produced from multicopy plasmids, B. bronchiseptica B013N alcR partially suppressed the alcaligin requirement for transcriptional activation. Functional analysis of AlcR chimeras produced by interspecies domain swapping and interspecies reciprocal site-specific mutagenesis determined that the phenotypic difference in AlcR inducer dependence was due to a single amino acid difference within the proposed inducer-binding and multimerization domain of AlcR. Structural predictions guided the design of a mutant AlcR protein with a single amino acid substitution at this critical position, AlcR(S103T), that was fully constitutive not only when produced from multicopy plasmids but also at a single-copy gene dosage. These results indicate that AlcR residue 103 affects a critical determinant of alcaligin inducer dependence of AlcR-mediated transcriptional activation. The alcR(S103T) mutant allele is the first alcR(Con) mutant allele identified.
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Affiliation(s)
- Timothy J Brickman
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455-0312, USA.
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Thompson DK, Beliaev AS, Giometti CS, Tollaksen SL, Khare T, Lies DP, Nealson KH, Lim H, Yates J, Brandt CC, Tiedje JM, Zhou J. Transcriptional and proteomic analysis of a ferric uptake regulator (fur) mutant of Shewanella oneidensis: possible involvement of fur in energy metabolism, transcriptional regulation, and oxidative stress. Appl Environ Microbiol 2002; 68:881-92. [PMID: 11823232 PMCID: PMC126683 DOI: 10.1128/aem.68.2.881-892.2002] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The iron-directed, coordinate regulation of genes depends on the fur (ferric uptake regulator) gene product, which acts as an iron-responsive, transcriptional repressor protein. To investigate the biological function of a fur homolog in the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1, a fur knockout strain (FUR1) was generated by suicide plasmid integration into this gene and characterized using phenotype assays, DNA microarrays containing 691 arrayed genes, and two-dimensional polyacrylamide gel electrophoresis. Physiological studies indicated that FUR1 was similar to the wild-type strain when they were compared for anaerobic growth and reduction of various electron acceptors. Transcription profiling, however, revealed that genes with predicted functions in electron transport, energy metabolism, transcriptional regulation, and oxidative stress protection were either repressed (ccoNQ, etrA, cytochrome b and c maturation-encoding genes, qor, yiaY, sodB, rpoH, phoB, and chvI) or induced (yggW, pdhC, prpC, aceE, fdhD, and ppc) in the fur mutant. Disruption of fur also resulted in derepression of genes (hxuC, alcC, fhuA, hemR, irgA, and ompW) putatively involved in iron uptake. This agreed with the finding that the fur mutant produced threefold-higher levels of siderophore than the wild-type strain under conditions of sufficient iron. Analysis of a subset of the FUR1 proteome (i.e., primarily soluble cytoplasmic and periplasmic proteins) indicated that 11 major protein species reproducibly showed significant (P < 0.05) differences in abundance relative to the wild type. Protein identification using mass spectrometry indicated that the expression of two of these proteins (SodB and AlcC) correlated with the microarray data. These results suggest a possible regulatory role of S. oneidensis MR-1 Fur in energy metabolism that extends the traditional model of Fur as a negative regulator of iron acquisition systems.
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Affiliation(s)
- Dorothea K Thompson
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Abstract
Bordetella pertussis and Bordetella bronchiseptica are capable of obtaining iron from hemin and hemoglobin. Genes encoding a putative bacterial heme iron acquisition system (bhu, for Bordetella heme utilization) were identified in a B. pertussis genomic sequence database, and the corresponding DNA was isolated from a virulent strain of B. pertussis. A B. pertussis bhuR mutant, predicted to lack the heme outer membrane receptor, was generated by allelic exchange. In contrast to the wild-type strain, bhuR mutant PM5 was incapable of acquiring iron from hemin and hemoglobin; genetic complementation of PM5 with the cloned bhuRSTUV genes restored heme utilization to wild-type levels. In parallel studies, B. bronchiseptica bhu sequences were also identified and a B. bronchiseptica bhuR mutant was constructed and confirmed to be defective in heme iron acquisition. The wild-type B. bronchiseptica parent strain grown under low-iron conditions produced the presumptive BhuR protein, which was absent in the bhuR mutant. Furthermore, production of BhuR by iron-starved B. bronchiseptica was markedly enhanced by culture in hemin-supplemented medium, suggesting that these organisms sense and respond to heme in the environment. Analysis of the genetic region upstream of the bhu cluster identified open reading frames predicted to encode homologs of the Escherichia coli ferric citrate uptake regulators FecI and FecR. These putative Bordetella regulators may mediate heme-responsive positive transcriptional control of the bhu genes.
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Affiliation(s)
- C K Vanderpool
- Department of Microbiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455-0312, USA
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Pradel E, Locht C. Expression of the putative siderophore receptor gene bfrZ is controlled by the extracytoplasmic-function sigma factor BupI in Bordetella bronchiseptica. J Bacteriol 2001; 183:2910-7. [PMID: 11292812 PMCID: PMC99509 DOI: 10.1128/jb.183.9.2910-2917.2001] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2000] [Accepted: 01/30/2001] [Indexed: 11/20/2022] Open
Abstract
A new gene from Bordetella bronchiseptica, bfrZ encoding a putative siderophore receptor, was identified in a Fur-repressor titration assay. A bfrZ null mutant was constructed by allelic exchange. The protein profile of this mutant is similar to that of the wild-type parent strain. The BfrZ(-)-BfrZ(+) isogenic pair was tested for utilization of 132 different siderophores as iron sources. None of these iron sources acted as a ligand for BfrZ. Translational bfrZ::phoA and transcriptional bfrZ::lacZ fusions were introduced into the B. bronchiseptica bfrZ locus. No alkaline phosphatase or beta-galactosidase activity was detected. Sequence analysis of the bfrZ upstream region revealed the presence of two tightly linked genes, bupI and bupR. Both of these genes are located downstream from a Fur-binding sequence. BupI is homologous to Escherichia coli FecI and Pseudomonas putida PupI and belongs to the family of extracytoplasmic-function sigma factors involved in transcription of genes with extracytoplasmic functions. BupR is homologous to the FecR and PupR antisigma factors and is predicted to be localized in the inner membrane. Similar to the surface signaling receptors FecA and PupB, BfrZ bears an N-terminal extension. We found that bfrZ is not transcribed when bupI and bupR are expressed at the same level. However, overexpression of bupI from a multicopy plasmid triggers bfrZ transcription, and under these conditions BfrZ was detected in membrane fractions. By analogy with the FecI-FecR-FecA and PupI-PupR-PupB systems, our data suggest that bfrZ expression is inducible by binding of the cognate ligand to BfrZ and transduction of a signal through the envelope.
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Affiliation(s)
- E Pradel
- INSERM U447, Institut Pasteur de Lille, 59019 Lille Cedex, France
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42
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Register KB, Ducey TF, Brockmeier SL, Dyer DW. Reduced virulence of a Bordetella bronchiseptica siderophore mutant in neonatal swine. Infect Immun 2001; 69:2137-43. [PMID: 11254568 PMCID: PMC98140 DOI: 10.1128/iai.69.4.2137-2143.2001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2000] [Accepted: 01/04/2001] [Indexed: 11/20/2022] Open
Abstract
One means by which Bordetella bronchiseptica scavenges iron is through production of the siderophore alcaligin. A nonrevertible alcaligin mutant derived from the virulent strain 4609, designated DBB25, was constructed by insertion of a kanamycin resistance gene into alcA, one of the genes essential for alcaligin biosynthesis. The virulence of the alcA mutant in colostrum-deprived, caesarean-delivered piglets was compared with that of the parent strain in two experiments. At 1 week of age, piglets were inoculated with phosphate-buffered saline, 4609, or DBB25. Two piglets in each group were euthanatized on day 10 postinfection. The remainder were euthanatized at 21 days postinfection. Clinical signs, including fever, coughing, and sneezing, were present in both groups. Nasal washes performed 7, 14, and 21 days postinoculation demonstrated that strain DBB25 colonized the nasal cavity but did so at levels that were significantly less than those achieved by strain 4609. Analysis of colonization based on the number of CFU per gram of tissue recovered from the turbinate, trachea, and lung also demonstrated significant differences between DBB25 and 4609, at both day 10 and day 21 postinfection. Mild to moderate turbinate atrophy was apparent in pigs inoculated with strain 4609, while turbinates of those infected with strain DBB25 developed no or mild atrophy. We conclude from these results that siderophore production by B. bronchiseptica is not essential for colonization of swine but is required for maximal virulence. B. bronchiseptica mutants with nonrevertible defects in genes required for alcaligin synthesis may be candidates for evaluation as attenuated, live vaccine strains in conventionally reared pigs.
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Affiliation(s)
- K B Register
- Respiratory Diseases of Livestock Research Unit, USDA Agricultural Research Service National Animal Disease Center, Ames, Iowa 50010, USA.
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Brickman TJ, Kang HY, Armstrong SK. Transcriptional activation of Bordetella alcaligin siderophore genes requires the AlcR regulator with alcaligin as inducer. J Bacteriol 2001; 183:483-9. [PMID: 11133941 PMCID: PMC94903 DOI: 10.1128/jb.183.2.483-489.2001] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genetic and biochemical studies have established that Fur and iron mediate repression of Bordetella alcaligin siderophore system (alc) genes under iron-replete nutritional growth conditions. In this study, transcriptional analyses using Bordetella chromosomal alc-lacZ operon fusions determined that maximal alc gene transcriptional activity under iron starvation stress conditions is dependent on the presence of alcaligin siderophore. Mutational analysis and genetic complementation confirmed that alcaligin-responsive transcriptional activation of Bordetella alcaligin system genes is dependent on AlcR, a Fur-regulated AraC-like positive transcriptional regulator encoded within the alcaligin gene cluster. AlcR-mediated transcriptional activation is remarkably sensitive to inducer, occurring at extremely low alcaligin concentrations. This positive autogenous control circuit involving alcaligin siderophore as the inducer for AlcR-mediated transcriptional activation of alcaligin siderophore biosynthesis and transport genes coordinates environmental and intracellular signals for maximal expression of these genes under conditions in which the presence of alcaligin in the environment is perceived.
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Affiliation(s)
- T J Brickman
- Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, North Carolina 27858-4354, USA
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Liles MR, Scheel TA, Cianciotto NP. Discovery of a nonclassical siderophore, legiobactin, produced by strains of Legionella pneumophila. J Bacteriol 2000; 182:749-57. [PMID: 10633110 PMCID: PMC94339 DOI: 10.1128/jb.182.3.749-757.2000] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanisms by which Legionella pneumophila, a facultative intracellular parasite and the agent of Legionnaires' disease, acquires iron are largely unexplained. Several earlier studies indicated that L. pneumophila does not elaborate siderophores. However, we now present evidence that supernatants from L. pneumophila cultures can contain a nonproteinaceous, high-affinity iron chelator. More specifically, when aerobically grown in a low-iron, chemically defined medium (CDM), L. pneumophila secretes a substance that is reactive in the chrome azurol S (CAS) assay. Importantly, the siderophore-like activity was only observed when the CDM cultures were inoculated to relatively high density with bacteria that had been grown overnight to log or early stationary phase in CDM or buffered yeast extract. Inocula derived from late-stationary-phase cultures, despite ultimately growing, consistently failed to result in the elaboration of siderophore-like activity. The Legionella CAS reactivity was detected in the culture supernatants of the serogroup 1 strains 130b and Philadelphia-1, as well as those from representatives of other serogroups and other Legionella species. The CAS-reactive substance was resistant to boiling and protease treatment and was associated with the <1-kDa supernatant fraction. As would also be expected for a siderophore, the addition of 0.5 or 2.0 microM iron to the cultures repressed the expression of the CAS-reactive substance. Interestingly, the supernatants were negative in the Arnow, Csáky, and Rioux assays, indicating that the Legionella siderophore was not a classic catecholate or hydroxamate and, hence, might have a novel structure. We have designated the L. pneumophila siderophore legiobactin.
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Affiliation(s)
- M R Liles
- Department of Microbiology and Immunology, Northwestern University Medical School, Chicago, Illinois 60611, USA
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Brickman TJ, Armstrong SK. Essential role of the iron-regulated outer membrane receptor FauA in alcaligin siderophore-mediated iron uptake in Bordetella species. J Bacteriol 1999; 181:5958-66. [PMID: 10498707 PMCID: PMC103622 DOI: 10.1128/jb.181.19.5958-5966.1999] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phenotypic analysis using heterologous host systems localized putative Bordetella pertussis ferric alcaligin transport genes and Fur-binding sequences to a 3.8-kb genetic region downstream from the alcR regulator gene. Nucleotide sequencing identified a TonB-dependent receptor family homolog gene, fauA, predicted to encode a polypeptide with high amino acid sequence similarity with known bacterial ferric siderophore receptors. In Escherichia coli, the fauA genes of both B. pertussis and Bordetella bronchiseptica directed the production of a 79-kDa polypeptide, approximating the predicted size of the mature FauA protein. B. bronchiseptica fauA insertion mutant BRM17 was unable to utilize ferric alcaligin, and in complementation analyses ferric alcaligin utilization was restored to this mutant by supplying the wild-type fauA gene in trans. Mutant BRM18, carrying a nonpolar in-frame fauA deletion mutation, was defective in ferric alcaligin utilization and (55)Fe-ferric alcaligin uptake and no longer produced a 79-kDa iron-regulated outer membrane protein. In complementation analyses, BRM18 merodiploids bearing the wild-type fauA gene in trans regained ferric alcaligin siderophore transport and utilization functions and produced the 79-kDa protein. Analysis of a plasmid-borne fauA-lacZ operon fusion confirmed that fauA is subject to iron regulation at the transcriptional level and that cis-acting transcriptional control elements mediating fauA iron repressibility reside within the 3.8-kb PstI fauA DNA region. Moreover, expression of the fauA-lacZ fusion gene under iron starvation conditions was shown to be alcR dependent. FauA is a 79-kDa iron-regulated outer membrane receptor protein required for transport and utilization of ferric alcaligin siderophore complexes by Bordetella species.
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Affiliation(s)
- T J Brickman
- Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, North Carolina 27858-4354, USA
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Murphy ER, Dickenson A, Militello KT, Connell TD. Genetic characterization of wild-type and mutant fur genes of Bordetella avium. Infect Immun 1999; 67:3160-5. [PMID: 10338537 PMCID: PMC96638 DOI: 10.1128/iai.67.6.3160-3165.1999] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For most, if not all, organisms, iron (Fe) is an essential element. In response to the nutritional requirement for Fe, bacteria evolved complex systems to acquire the element from the environment. The genes encoding these systems are often coordinately regulated in response to the Fe concentration. Recent investigations revealed that Bordetella avium, a respiratory pathogen of birds, expressed a number of Fe-regulated genes (T. D. Connell, A. Dickenson, A. J. Martone, K. T. Militello, M. J. Filiatraut, M. L. Hayman, and J. Pitula, Infect. Immun. 66:3597-3605, 1998). By using manganese selection on an engineered strain of B. avium that carried an Fe-regulated alkaline phosphatase reporter gene, a mutant was obtained that was affected in expression of Fe-regulated genes. To determine if Fe-dependent regulation in B. avium was mediated by a fur-like gene, a fragment of the B. avium chromosome, corresponding to the fur locus of B. pertussis, was cloned by PCR. Sequencing revealed that the fragment from B. avium encoded a polypeptide with 92% identity to the Fur protein of B. pertussis. In vivo experiments showed that the cloned gene complemented H1780, a fur mutant of Escherichia coli. Southern hybridizations and PCRs demonstrated that the manganese mutant had a deletion of 2 to 3 kbp of nucleotide sequence in the region located immediately 5' of the fur open reading frame. A spontaneous PCR-derived mutant of the B. avium fur gene was isolated that encoded a Fur protein in which a histidine was substituted for an arginine at amino acid position 18 (R18H). Genetic analysis showed that the R18H mutant gene when cloned into a low-copy-number vector did not complement the fur mutation in H1780. However, the R18H mutant gene was able to complement the fur mutation when cloned into a high-copy-number vector. The cloned wild-type fur gene will be useful as a genetic tool to identify Fur-regulated genes in the B. avium chromosome.
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Affiliation(s)
- E R Murphy
- Center for Microbial Pathogenesis and Department of Microbiology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA
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Connell TD, Dickenson A, Martone AJ, Militello KT, Filiatraut MJ, Hayman ML, Pitula J. Iron starvation of Bordetella avium stimulates expression of five outer membrane proteins and regulates a gene involved in acquiring iron from serum. Infect Immun 1998; 66:3597-605. [PMID: 9673238 PMCID: PMC108391 DOI: 10.1128/iai.66.8.3597-3605.1998] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Iron starvation of Bordetella avium induced expression of five outer membrane proteins with apparent molecular masses of 95, 92, 91.5, 84, and 51 kDa. Iron-responsive outer membrane proteins (FeRPs) of similar sizes were detected in six of six strains of B. avium, suggesting that the five FeRPs are common constituents of the outer membrane of most, if not all, strains of B. avium. Iron-regulated genes of B. avium were targeted for mutagenesis with the transposon TnphoA. Two mutants with iron-responsive alkaline phosphatase activities were isolated from the transposon library. The transposon insertion did not alter the iron-regulated expression of the five FeRPs in mutant Pho-6. The mutant Pho-20 exhibited a loss in expression of the 95-kDa FeRP and the 84-kDa FeRP. Both Pho-6 and Pho-20 were able to use free iron as a nutrient source. However, Pho-20 was severely compromised in its ability to use iron present in turkey serum. The data indicated that the mutation in Pho-20 affected expression of one or more components of an uptake machinery that is involved in acquisition of iron from organic ferricomplexes.
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Affiliation(s)
- T D Connell
- Center for Microbial Pathogenesis and the Department of Microbiology, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA.
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Dellagi A, Brisset MN, Paulin JP, Expert D. Dual role of desferrioxamine in Erwinia amylovora pathogenicity. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 1998; 11:734-42. [PMID: 9675889 DOI: 10.1094/mpmi.1998.11.8.734] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
To investigate the role of iron in Erwinia amylovora pathogenicity, virulence properties of two mutants of strain CFBP 1430 isolated by insertional mutagenesis and affected in the iron transport pathway mediated by desferrioxamine (DFO) were analyzed. One mutation (dfoA::MudIIpR13) disrupts DFO biosynthesis. The present analysis shows that this mutation affects an open reading frame that belongs to a biosynthetic gene cluster and shares identity with the alcA gene required for synthesis of the siderophore alcaligin in Bordetella spp. A second mutation (foxR::MudIIpR13) affects the synthesis of the ferrioxamine receptor FoxR, encoded by the foxR gene, and was shown to be transcribed into a monocistronic message. Accordingly, the foxR mutant accumulates DFO in the external medium. The growth of the mutants when supplied with various iron sources was examined; it indicates that the production of DFO and the specific transport of the DFO ferric complex are required only when iron is strongly liganded. Pathogenicity was scored after inoculation of apple seedlings and after infection of apple flowers. On seedlings, the DFO biosynthetic mutant behaved like the wild-type strain while the frequency of necrotic plants caused by the receptor mutant decreased by a factor of two to five, depending on the initial inoculum. On flowers, both mutants were strongly affected in their ability to initiate a necrotic symptom and their growth was reduced by two orders of magnitude relative to the wild-type strain. However, the virulence of the dfoA mutant varied with the inoculum concentration. Unlike the foxR mutant, the dfoA mutant only weakly induced plant cell electrolyte leakage in tobacco leaf disks. The supply with exogenous DFO, only when iron free, restored the ability to induce electrolyte leakage to the dfoA mutant and increased the leakage induced by other strains. DFO alone was not an inducer. Iron-free DFO was able to protect E. amylovora cells against lethal doses of hydrogen peroxide. The main conclusion was that production of DFO in E. amylovora during pathogenesis is not only a critical function for iron acquisition, but can play a role in the oxidative burst elicited by the bacteria.
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Affiliation(s)
- A Dellagi
- Laboratoire de Pathologie Végétale, INRA/INA P-G, Paris, France
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Stehr M, Diekmann H, Smau L, Seth O, Ghisla S, Singh M, Macheroux P. A hydrophobic sequence motif common to N-hydroxylating enzymes. Trends Biochem Sci 1998; 23:56-7. [PMID: 9538688 DOI: 10.1016/s0968-0004(97)01166-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- M Stehr
- Institut für Mikrobiologie, Universität Hannover, Germany
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Kang HY, Armstrong SK. Transcriptional analysis of the Bordetella alcaligin siderophore biosynthesis operon. J Bacteriol 1998; 180:855-61. [PMID: 9473039 PMCID: PMC106964 DOI: 10.1128/jb.180.4.855-861.1998] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/1997] [Accepted: 12/06/1997] [Indexed: 02/06/2023] Open
Abstract
The alc gene cluster of Bordetella pertussis includes three genes, alcA, alcB, and alcC, which are involved in alcaligin siderophore biosynthesis in response to iron starvation. The production of AlcA, AlcB, and AlcC in Bordetella cells and the transcriptional organization of alcA, alcB, and alcC were investigated by using a set of three alc'-'lacZ gene fusion constructs that were contiguous with the known promoter upstream of alcA and extended to fusion junctions within each alc cistron. All three alc'-'lacZ fusions exhibited iron-repressible reporter gene expression which was abolished by deletion of the 105-bp alcA promoter-operator region. In an immunoblot analysis using a monoclonal antibody specific for beta-galactosidase, the AlcA-LacZ, AlcB-LacZ, and AlcC-LacZ hybrid proteins were detected in Bordetella cells grown under iron-depleted conditions. A B. pertussis mutant in which the 105-bp alcA promoter-operator region was deleted by allelic exchange was unable to produce detectable levels of siderophore. Hybridization analysis using gene-specific probes showed that alc-specific transcript levels in the mutant were negligible compared with those of the wild-type parent. These results confirm that alcA, alcB, and alcC are cotranscribed from an iron-regulated control region immediately upstream of alcA. Transcript analysis using hybridization probes representing regions downstream of alcC demonstrated that alc transcription extends approximately 3.6 kb further downstream from the alcC coding region, suggesting the cotranscription of additional, uncharacterized alcaligin system genes.
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Affiliation(s)
- H Y Kang
- Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, North Carolina 27858-4354, USA
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