scholarly journals Characterization of the Yersinia pestisYfu ABC Inorganic Iron Transport System

2001 ◽  
Vol 69 (5) ◽  
pp. 2829-2837 ◽  
Author(s):  
Shimei Gong ◽  
Scott W. Bearden ◽  
Valerie A. Geoffroy ◽  
Jacqueline D. Fetherston ◽  
Robert D. Perry
Keyword(s):  
Transport System ◽  
Iron Transport ◽  
Iron Acquisition ◽  
Lethal Dose ◽  
In Vitro Transcription ◽  
Defined Medium ◽  
Transport Systems ◽  
Regulation Of Transcription ◽  
Iron Deficient

ABSTRACT In Yersinia pestis, the causative agent of plague, two inorganic iron transport systems have been partially characterized. The yersiniabactin (Ybt) system is a siderophore-dependent transport system required for full virulence. Yfe is an ABC transport system that accumulates both iron and manganese. We have identified and cloned aY. pestis yfuABC operon. The YfuABC system is a member of the cluster of bacterial ABC iron transporters that include Sfu ofSerratia, Hit of Haemophilus, and Yfu ofYersinia enterocolitica. The Y. pestis KIM6+ system is most homologous to that in Y. enterocolitica, showing identities of 84% for YfuA (periplasmic binding protein), 87% for YfuB (inner membrane permease), and 75% for YfuC (ATP hydrolase). We constructed a yfuABC promoter-lacZ fusion to examine regulation of transcription. This promoter contains a potential Fur binding sequence and is iron and Fur regulated. Significant expression from the yfuABC promoter occurred during iron-deficient growth conditions. In vitro transcription and translation of a recombinant plasmid encoding yfuABCindicates that YfuABC proteins are expressed. Escherichia coli 1017 (an enterobactin-deficient mutant) carrying this plasmid was able to grow in an iron-restrictive complex medium. We constructed a deletion encompassing the yfuABC promoter and most of yfuA. This mutation was introduced into strains with mutations in Ybt, Yfe, or both systems to examine the role of Yfu in iron acquisition in Y. pestis. Growth of theyfu mutants in a deferrated, defined medium (PMH2) at 26 and 37°C failed to identify a growth or iron transport defect due to the yfu mutation. Fifty percent lethal dose studies in mice did not demonstrate a role for the Yfu system in mammalian virulence.

scholarly journals Characterization of Ferric and Ferrous Iron Transport Systems in Vibrio cholerae

2006 ◽  
Vol 188 (18) ◽  
pp. 6515-6523 ◽  
Author(s):  
Elizabeth E. Wyckoff ◽  
Alexandra R. Mey ◽  
Andreas Leimbach ◽  
Carolyn F. Fisher ◽  
Shelley M. Payne
Keyword(s):  
Vibrio Cholerae ◽  
Transport System ◽  
Iron Transport ◽  
Iron Acquisition ◽  
Shigella Flexneri ◽  
Transport Systems ◽  
Infant Mouse ◽  
Mouse Intestine ◽  
Dependent Transport

ABSTRACT Vibrio cholerae has multiple iron acquisition systems, including TonB-dependent transport of heme and of the catechol siderophore vibriobactin. Strains defective in both of these systems grow well in laboratory media and in the infant mouse intestine, indicating the presence of additional iron acquisition systems. Previously uncharacterized potential iron transport systems, including a homologue of the ferrous transporter Feo and a periplasmic binding protein-dependent ATP binding cassette (ABC) transport system, termed Fbp, were identified in the V. cholerae genome sequence. Clones encoding either the Feo or the Fbp system exhibited characteristics of iron transporters: both repressed the expression of lacZ cloned under the control of a Fur-regulated promoter in Escherichia coli and also conferred growth on a Shigella flexneri mutant that has a severe defect in iron transport. Two other ABC transporters were also evaluated but were negative by these assays. Transport of radioactive iron by the Feo system into the S. flexneri iron transport mutant was stimulated by the reducing agent ascorbate, consistent with Feo functioning as a ferrous transporter. Conversely, ascorbate inhibited transport by the Fbp system, suggesting that it transports ferric iron. The growth of V. cholerae strains carrying mutations in one or more of the potential iron transport genes indicated that both Feo and Fbp contribute to iron acquisition. However, a mutant defective in the vibriobactin, Fbp, and Feo systems was not attenuated in a suckling mouse model, suggesting that at least one other iron transport system can be used in vivo.

scholarly journals Anaerobic Regulation of Shigella flexneri Virulence: ArcA Regulates fur and Iron Acquisition Genes

2007 ◽  
Vol 189 (19) ◽  
pp. 6957-6967 ◽  
Author(s):  
Megan L. Boulette ◽  
Shelley M. Payne
Keyword(s):  
Transcription Factors ◽  
Transport System ◽  
Iron Transport ◽  
Iron Acquisition ◽  
Shigella Flexneri ◽  
Plaque Assay ◽  
Plaque Formation ◽  
Transport Systems ◽  
Dependent Manner ◽  
Anaerobic Conditions

ABSTRACT Invasion and plaque formation in epithelial monolayers are routinely used to assess the virulence of Shigella flexneri, a causative agent of dysentery. A modified plaque assay was developed to identify factors contributing to the virulence of S. flexneri under the anaerobic conditions present in the colon. This assay demonstrated the importance of the ferrous iron transport system Feo, as well as the global transcription factors Fur, ArcA, and Fnr, for Shigella plaque formation in anoxic environments. Transcriptional analyses of S. flexneri iron transport genes indicated that anaerobic conditions activated feoABC while repressing genes encoding two other iron transport systems, the ABC transporter Sit and the Iuc/Iut aerobactin siderophore synthesis and transport system. The anaerobic transcription factors ArcA and Fnr activated expression of feoABC, while ArcA repressed iucABCD iutA. Transcription of fur, encoding the iron-responsive transcriptional repressor of bacterial iron acquisition, was also repressed anaerobically in an ArcA-dependent manner.

scholarly journals DNA Sequence of a ColV Plasmid and Prevalence of Selected Plasmid-Encoded Virulence Genes among Avian Escherichia coli Strains

2006 ◽  
Vol 188 (2) ◽  
pp. 745-758 ◽  
Author(s):  
Timothy J. Johnson ◽  
Kylie E. Siek ◽  
Sara J. Johnson ◽  
Lisa K. Nolan
Keyword(s):  
Escherichia Coli ◽  
Dna Sequence ◽  
Transport System ◽  
Iron Transport ◽  
Virulence Genes ◽  
Iron Acquisition ◽  
Transport Systems ◽  
E Coli ◽  
Virulence Traits ◽  
Associated Sequences

ABSTRACT ColV plasmids have long been associated with the virulence of Escherichia coli, despite the fact that their namesake trait, ColV production, does not appear to contribute to virulence. Such plasmids or their associated sequences appear to be quite common among avian pathogenic E. coli (APEC) and are strongly linked to the virulence of these organisms. In the present study, a 180-kb ColV plasmid was sequenced and analyzed. This plasmid, pAPEC-O2-ColV, possesses a 93-kb region containing several putative virulence traits, including iss, tsh, and four putative iron acquisition and transport systems. The iron acquisition and transport systems include those encoding aerobactin and salmochelin, the sit ABC iron transport system, and a putative iron transport system novel to APEC, eit. In order to determine the prevalence of the virulence-associated genes within this region among avian E. coli strains, 595 APEC and 199 avian commensal E. coli isolates were examined for genes of this region using PCR. Results indicate that genes contained within a portion of this putative virulence region are highly conserved among APEC and that the genes of this region occur significantly more often in APEC than in avian commensal E. coli. The region of pAPEC-O2-ColV containing genes that are highly prevalent among APEC appears to be a distinguishing trait of APEC strains.

scholarly journals Deletion of the c2515 and c2516 Genes Affects Iron Uptake and Virulence of APEC O1 Strain E516

2021 ◽  
Vol 8 ◽  
Author(s):  
Qingqing Gao ◽  
Xi Li ◽  
Senyan Su ◽  
Lei Yang ◽  
Song Gao
Keyword(s):  
Iron Uptake ◽  
Target Genes ◽  
Iron Acquisition ◽  
Bacterial Colonization ◽  
Lethal Dose ◽  
Growth Defect ◽  
Cell Infection ◽  
Intracellular Iron

Avian pathogenic Escherichia coli (APEC), widely spread among poultry, is well-known to cause colibacillosis in chickens, which results in significant losses in poultry industry. The ability to uptake iron in the extra-intestinal environment is prerequisite for APEC survival. For adaptation to the low-iron environments, the bacteria have evolved multiple iron acquisition systems to ensure optimal iron uptake. However, many components of these iron acquisition pathways are still not clearly known. An in silico analysis of the genome of a septicemic APEC O1 strain E516 identified two putative iron transport genes homologous to the c2515 and c2516 genes from uropathogenic E. coli CFT073. In this study, we constructed the single and double gene deletion mutants, and studied their biological characteristic and pathogenic traits through in vitro and in vivo assays. Reverse transcriptase PCR (RT-PCR) analyses demonstrated that the mutations destroying the reading frame of the target genes abolished their transcription. Deletion of the single or double genes of c2515 and c2516 in APEC E516 weakened its ability to produce siderophore. Consistently, the mutants exhibited growth defect under iron-depleted conditions and the intracellular iron levels in the mutants were decreased in comparison with that of the wild-type (WT). Cell infection assays showed that the iron uptake defective mutants were more easily eliminated by the macrophage. Inactivation of the c2515 and c2516 genes affected bacterial colonization of chicken tissues, as well as the 50% lethal dose levels compared with the WT strain. Moreover, the expression levels of several iron uptake-related genes were significantly decreased in the double-deletion mutant. In total, the c2515 and c2516 may involve in siderophore-mediated iron uptake and participate in the pathogenesis of APEC O1 strain E516.

scholarly journals Utilization of Oligopeptides by Listeria monocytogenes Scott A

1998 ◽  
Vol 64 (3) ◽  
pp. 1059-1065 ◽  
Author(s):  
Annette Verheul ◽  
Frank M. Rombouts ◽  
Tjakko Abee
Keyword(s):  
Listeria Monocytogenes ◽  
Transport System ◽  
Growth Stimulation ◽  
Sole Source ◽  
Fermented Milk ◽  
Defined Medium ◽  
Peptide Transport ◽  
Transport Systems ◽  
Oligopeptide Transport System ◽  
Oligopeptide Transport

ABSTRACT For effective utilization of peptides, Listeria monocytogenes possesses two different peptide transport systems. The first one is the previously described proton motive force (PMF)-driven di- and tripeptide transport system (A. Verheul, A. Hagting, M.-R. Amezaga, I. R. Booth, F. M. Rombouts, and T. Abee, Appl. Environ. Microbiol. 61:226–233, 1995). The present results reveal that L. monocytogenes possesses an oligopeptide transport system, presumably requiring ATP rather than the PMF as the driving force for translocation. Experiments to determine growth in a defined medium containing peptides of various lengths suggested that the oligopeptide permease transports peptides of up to 8 amino acid residues. Peptidase activities towards several oligopeptides were demonstrated in cell extract from L. monocytogenes, which indicates that upon internalization, the oligopeptides are hydrolyzed to serve as sources of amino acids for growth. The peptide transporters of the nonproteolytic L. monocytogenes might play an important role in foods that harbor indigenous proteinases and/or proteolytic microorganisms, since Pseudomonas fragi as well as Bacillus cereus was found to enhance the growth ofL. monocytogenes to a large extent in a medium in which the milk protein casein was the sole source of nitrogen. In addition, growth stimulation was elicited in this medium when casein was hydrolyzed by using purified protease from Bacillus licheniformis. The possible contribution of the oligopeptide transport system in the establishment of high numbers of L. monocytogenes cells in fermented milk products is discussed.

scholarly journals Induction of iron regulated proteins during normal growth of Neisseria meningitidis in a chemically defined medium

1994 ◽  
Vol 36 (4) ◽  
pp. 301-310 ◽  
Author(s):  
Maria Cristina de Cunto Brandileone ◽  
Rosemeire Cobo Zanella ◽  
Vera Simonsen Dias Vieira ◽  
Claudio Tavares Sacciii ◽  
Lucimar Gonçalves Milagres ◽  
...  
Keyword(s):  
Bacterial Growth ◽  
Culture Supernatant ◽  
Culture Media ◽  
Membrane Vesicles ◽  
Normal Growth ◽  
Growth Conditions ◽  
Defined Medium ◽  
Outer Membrane Vesicles ◽  
Iron Deficient

The expression of iron regulated proteins (IRPs) in vitro has been obtained in the past by adding iron chelators to the culture after bacterial growth, in the presence of an organic iron source. We have investigated aspects concerning full expression of the meningococcal IRPs during normal growth, in defined conditions using Catlin medium, Mueller Hinton and Tryptic Soy Broth (TSB). The expression of IRPs varied between different strains with respect to Ethylenediamine Di-ortho-Hidroxy-phenyl-acetic acid (EDDA) concentrations, and according to culture medium, and also between different lots of TSB. For each strain, a specific set of IRPs were expressed and higher EDDA concentrations, or addition of glucose, or use of different culture media did not resulted in a differential expression of IRPs. We were not able to grow N. meningitidis under normal growth conditions using Desferal. We looked for a good yield of outer membrane vesicles (OMVs) expressing IRPs in iron-deficient Catlin medium containing EDDA and Hemin. Culture for 32 h at 30ºC after growing for 16 h at 37ºC supported good bacterial growth. Bacterial lysis was noted after additional 24 h at 30ºC. Approximately 4 times more OMVs was recoverable from a culture supernatant after 24 h at 30ºC than from the cells after 16 h at 37ºC. The IRP were as well expressed in OMVs from culture supernatant obtained after 24 h at 30ºC as from the cells after 16 h at 37ºC.

scholarly journals Expression of Virulence Factors by Staphylococcus aureus Grown in Serum

2011 ◽  
Vol 77 (22) ◽  
pp. 8097-8105 ◽  
Author(s):  
Yuichi Oogai ◽  
Miki Matsuo ◽  
Masahito Hashimoto ◽  
Fuminori Kato ◽  
Motoyuki Sugai ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Iron Acquisition ◽  
Calf Serum ◽  
Growth Conditions ◽  
Defined Medium ◽  
Chemically Defined Medium ◽  
Regulatory Factor ◽  
Content Type

ABSTRACTStaphylococcus aureusproduces many virulence factors, including toxins, immune-modulatory factors, and exoenzymes. Previous studies involving the analysis of virulence expression were mainly performed byin vitroexperiments using bacterial medium. However, whenS. aureusinfects a host, the bacterial growth conditions are quite different from those in a medium, which may be related to the different expression of virulence factors in the host. In this study, we investigated the expression of virulence factors inS. aureusgrown in calf serum. The expression of many virulence factors, including hemolysins, enterotoxins, proteases, and iron acquisition factors, was significantly increased compared with that in bacterial medium. In addition, the expression of RNA III, a global regulon for virulence expression, was significantly increased. This effect was partially restored by the addition of 300 μM FeCl3into serum, suggesting that iron depletion is associated with the increased expression of virulence factors in serum. In chemically defined medium without iron, a similar effect was observed. In a mutant withagrinactivated grown in serum, the expression of RNA III,psm, andsec4was not increased, while other factors were still induced in the mutant, suggesting that another regulatory factor(s) is involved. In addition, we found that serum albumin is a major factor for the capture of free iron to prevent the supply of iron to bacteria grown in serum. These results indicate thatS. aureusexpresses virulence factors in adaptation to the host environment.

scholarly journals Comparison of the Effects of Deferiprone versus Deferoxamine on Growth and Virulence of Yersinia enterocolitica

2002 ◽  
Vol 46 (6) ◽  
pp. 1741-1745 ◽  
Author(s):  
Biliana Lesic ◽  
Jeannine Foulon ◽  
Elisabeth Carniel
Keyword(s):  
Chelation Therapy ◽  
Lethal Dose ◽  
Iron Chelation ◽  
Defined Medium ◽  
Dependent Manner ◽  
Chemically Defined Medium ◽  
Mouse Model Of Infection ◽  
Orally Active ◽  
Dose Dependent

ABSTRACT Deferoxamine, a drug used to treat patients with iron overload, has the capacity to promote systemic Y. enterocolitica infections in humans. The aim of this study was to determine whether deferiprone, the only orally active alternative treatment, has the same potential. When Y. enterocolitica IP864 was grown in an iron-poor chemically defined medium, addition of deferoxamine promoted its growth, while various concentrations of deferiprone did not display this activity. Similarly, on iron-poor agar plates, various Y. enterocolitica strains were able to grow around paper disks impregnated with deferoxamine in a dose-dependent manner, while no growth was observed around the deferiprone disks. In a mouse experimental model of infection, the 50% lethal dose (LD50) of strain IP864 was decreased by more than 5 log units in mice pretreated with deferoxamine, while a deferiprone pretreatment did not affect it. Therefore, in contrast to deferoxamine, deferiprone does not enhance growth of pathogenic Y. enterocolitica in vitro and does not have the potential to promote Y. enterocolitica septicemia in a mouse model of infection. Deferiprone may thus represent a useful alternative iron-chelation therapy during invasive Y. enterocolitica infections.

scholarly journals Study on RNA Regulating Iron Transport in Outer Membrane Vesicles of Hypervirulent Klebsiella Pneumoniae

2020 ◽  
Author(s):  
Mao Zhou ◽  
Siyi Wang ◽  
You Lan ◽  
Xin Li ◽  
Xuan Liu ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Iron Transport ◽  
High Throughput Sequencing ◽  
Iron Acquisition ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Transporter Family ◽  
Iron Deficient ◽  
Deficient Medium

Abstract Background: The iron acquisition ability of hypervirulent Klebsiella pneumoniae (hvKP) is an important part of its super virulence mechanism, increasing studies have proved that outer membrane vesicles (OMVs) are involved in the iron acquisition process of bacteria. Thus, we compared the difference in RNA expression in OMVs of hvKP in iron-rich and iron-deficient medium, and explore the possible mechanism of RNA in OMVs involved in hvKP iron acquisition. Results: The results of high-throughput sequencing showed that in iron-deficient medium, there were 239 up-regulated and 89 down-regulated mRNAs in OMVs of hvKP, of which 20 mRNAs related to iron transport was up-regulated, mainly including siderophore synthesis and receptor genes, ATP binding cassette transporter family and iron sulfur cluster. Only two of the differential ncRNAs that regulate these mRNAs are up-regulated, which are lncRNAs.Conclusion: We demonstrated that mRNA and lncRNA in OMVs were directly or indirectly involved in the iron acquisition mechanism of hvKP under iron deficiency environment, which enhanced the adaptive survival ability of hvKP. It provided a basis for further exploring the iron acquisition mechanism of OMVs involved in hvKP.

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