scholarly journals Hierarchy of Iron Uptake Systems: Yfu and Yiu Are Functional in Yersinia pestis

2006 ◽  
Vol 74 (11) ◽  
pp. 6171-6178 ◽  
Author(s):  
Olga Kirillina ◽  
Alexander G. Bobrov ◽  
Jacqueline D. Fetherston ◽  
Robert D. Perry
Keyword(s):  
Yersinia Pestis ◽  
Iron Uptake ◽  
Disease Process ◽  
Transport Systems ◽  
Growth Defect ◽  
Uptake System ◽  
Outer Membrane Receptor ◽  
Abc Transport ◽  
Iron Deficient ◽  
Additional Iron

ABSTRACT In addition to the yersiniabactin (Ybt) siderophore-dependent system, two inorganic iron ABC transport systems of Yersinia pestis, Yfe and Yfu, have been characterized. Here we show that the Yfu system functions in Y. pestis: a Ybt− Yfe− Yfu− mutant exhibited a greater growth defect under iron-deficient conditions than its Ybt− Yfe− parental strain. We also demonstrate that another putative Y. pestis iron uptake system, Yiu, which potentially encodes an outer membrane receptor, YiuR, and an ABC iron transport cassette, YiuABC, is functional. The cloned yiuABC operon restored growth of an enterobactin-deficient mutant Escherichia coli strain, 1017, under iron-chelated conditions. Iron uptake by the Yiu system in Y. pestis was demonstrated only when the Ybt, Yfe, and Yfu systems were mutated. Using a yiuA::lacZ fusion, we show that the yiuABC promoter is repressed by iron through Fur. A mouse model of bubonic plague failed to show a significant role for the Yiu system in the disease process. These results demonstrate that two additional iron transporters are functional in Y. pestis and indicate that there is a hierarchy of iron transporters, with Ybt being most effective and Yiu being the least effective of those systems which have been characterized.

scholarly journals Znu Is the Predominant Zinc Importer in Yersinia pestis during In Vitro Growth but Is Not Essential for Virulence

2010 ◽  
Vol 78 (12) ◽  
pp. 5163-5177 ◽  
Author(s):  
Daniel C. Desrosiers ◽  
Scott W. Bearden ◽  
Ildefonso Mier ◽  
Jennifer Abney ◽  
James T. Paulley ◽  
...  
Keyword(s):  
Yersinia Pestis ◽  
Binding Protein ◽  
Bacterial Pathogens ◽  
Titration Calorimetry ◽  
Growth Defect ◽  
Uptake System ◽  
High Affinity ◽  
Zn Uptake ◽  
Low Concentrations

ABSTRACT Little is known about Zn homeostasis in Yersinia pestis, the plague bacillus. The Znu ABC transporter is essential for zinc (Zn) uptake and virulence in a number of bacterial pathogens. Bioinformatics analysis identified ZnuABC as the only apparent high-affinity Zn uptake system in Y. pestis. Mutation of znuACB caused a growth defect in Chelex-100-treated PMH2 growth medium, which was alleviated by supplementation with submicromolar concentrations of Zn. Use of transcriptional reporters confirmed that Zur mediated Zn-dependent repression and that it can repress gene expression in response to Zn even in the absence of Znu. Virulence testing in mouse models of bubonic and pneumonic plague found only a modest increase in survival in low-dose infections by the znuACB mutant. Previous studies of cluster 9 (C9) transporters suggested that Yfe, a well-characterized C9 importer for manganese (Mn) and iron in Y. pestis, might function as a second, high-affinity Zn uptake system. Isothermal titration calorimetry revealed that YfeA, the solute-binding protein component of Yfe, binds Mn and Zn with comparably high affinities (dissociation constants of 17.8 ± 4.4 nM and 6.6 ± 1.2 nM, respectively), although the complete Yfe transporter could not compensate for the loss of Znu in in vitro growth studies. Unexpectedly, overexpression of Yfe interfered with the znu mutant's ability to grow in low concentrations of Zn, while excess Zn interfered with the ability of Yfe to import iron at low concentrations; these results suggest that YfeA can bind Zn in the bacterial cell but that Yfe is incompetent for transport of the metal. In addition to Yfe, we have now eliminated MntH, FetMP, Efe, Feo, a substrate-binding protein, and a putative nickel transporter as the unidentified, secondary Zn transporter in Y. pestis. Unlike other bacterial pathogens, Y. pestis does not require Znu for high-level infectivity and virulence; instead, it appears to possess a novel class of transporter, which can satisfy the bacterium's Zn requirements under in vivo metal-limiting conditions. Our studies also underscore the need for bacterial cells to balance binding and transporter specificities within the periplasm in order to maintain transition metal homeostasis.

scholarly journals Identification and functional characterization of a novel Candida albicans gene CaMNN5 that suppresses the iron-dependent growth defect of Saccharomyces cerevisiae aft1Δ mutant

2005 ◽  
Vol 389 (1) ◽  
pp. 27-35 ◽  
Author(s):  
Chen BAI ◽  
Fong Yee CHAN ◽  
Yue WANG
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Iron Uptake ◽  
Iron Transport ◽  
Lucifer Yellow ◽  
Functional Characterization ◽  
Endocytic Pathway ◽  
Transport Systems ◽  
Growth Defect ◽  
Iron Starvation

In Saccharomyces cerevisiae, the transcription factor Aft1p plays a central role in regulating many genes involved in iron acquisition and utilization. An aft1Δ mutant exhibits severely retarded growth under iron starvation. To identify the functional counterpart of AFT1 in Candida albicans, we transformed a C. albicans genomic DNA library into aft1Δ to isolate genes that could allow the mutant to grow under iron-limiting conditions. In the present paper, we describe the unexpected discovery in this screen of CaMNN5. CaMnn5p is an α-1,2-mannosyltransferease, but its growth-promoting function in iron-limiting conditions does not require this enzymatic activity. Its function is also independent of the high-affinity iron transport systems that are mediated by Ftr1p and Fth1p. We obtained evidence suggesting that CaMnn5p may function along the endocytic pathway, because it cannot promote the growth of end4Δ and vps4Δ mutants, where the endocytic pathway is blocked at an early and late step respectively. Neither can it promote the growth of a fth1Δ smf3Δ mutant, where the vacuole–cytosol iron transport is blocked. Expression of CaMNN5 in S. cerevisiae specifically enhances an endocytosis-dependent mechanism of iron uptake without increasing the uptake of Lucifer Yellow, a marker for fluid-phase endocytosis. CaMnn5p contains three putative Lys-Glu-Xaa-Xaa-Glu iron-binding sites and co-immunoprecipitates with 55Fe. We propose that CaMnn5p promotes iron uptake and usage along the endocytosis pathway under iron-limiting conditions, a novel function that might have evolved in C. albicans.

scholarly journals Importance of the Ornibactin and Pyochelin Siderophore Transport Systems in Burkholderia cenocepacia Lung Infections

2004 ◽  
Vol 72 (5) ◽  
pp. 2850-2857 ◽  
Author(s):  
M. B. Visser ◽  
S. Majumdar ◽  
E. Hani ◽  
P. A. Sokol
Keyword(s):  
Salicylic Acid ◽  
Outer Membrane ◽  
Parent Strain ◽  
Membrane Receptor ◽  
Burkholderia Cenocepacia ◽  
Transport Systems ◽  
Uptake System ◽  
Outer Membrane Receptor ◽  
Gene Encoding ◽  
Lung Infections

ABSTRACT Previously, orbA, the gene encoding the outer membrane receptor for ferric-ornibactin, was identified in Burkholderia cenocepacia K56-2, a strain which produces ornibactin, salicylic acid, and negligible amounts of pyochelin. A K56-2 orbA mutant was less virulent than the parent strain in a rat agar bead infection model. In this study, an orbA mutant of B. cenocepacia Pc715j which produces pyochelin in addition to ornibactin and salicylic acid was constructed. The gene encoding the outer membrane receptor for ferric-pyochelin (fptA) was also identified. An fptA mutant was constructed in Pc715j and shown to be deficient in [59Fe]pyochelin uptake. A 75-kDa iron-regulated protein was identified in outer membrane preparations of Pc715j that was absent in outer membrane preparations of Pc715jfptA::tp. Pc715jfptA::tp and Pc715jorbA::tp produced smaller amounts of their corresponding siderophores. Both Pc715jorbA::tp and Pc715jfptA::tp were able to grow in iron starvation conditions in vitro. In the agar bead model, the Pc715jorbA::tp mutant was cleared from the lung, indicating that the pyochelin uptake system does not compensate for the absence of a functional ornibactin system. Pc715jfptA::tp persisted in rat lung infections in numbers similar to those of the parent strain, indicating that the ferric-ornibactin uptake system could compensate for the defect in ferric-pyochelin uptake in vivo. These studies suggest that the ornibactin uptake system is the most important siderophore-mediated iron transport system in B. cenocepacia lung infections.

scholarly journals The Yfe and Feo Transporters Are Involved in Microaerobic Growth and Virulence of Yersinia pestis in Bubonic Plague

2012 ◽  
Vol 80 (11) ◽  
pp. 3880-3891 ◽  
Author(s):  
Jacqueline D. Fetherston ◽  
Ildefonso Mier ◽  
Helena Truszczynska ◽  
Robert D. Perry
Keyword(s):  
Yersinia Pestis ◽  
Double Mutant ◽  
Lethal Dose ◽  
Growth Conditions ◽  
Transport Systems ◽  
Growth Defect ◽  
Dependent Manner ◽  
Bubonic Plague ◽  
Pneumonic Plague ◽  
Content Type

ABSTRACTThe Yfe/Sit and Feo transport systems are important for the growth of a variety of bacteria. InYersinia pestis, single mutations in eitheryfeorfeoresult in reduced growth under static (limited aeration), iron-chelated conditions, while ayfe feodouble mutant has a more severe growth defect. These growth defects were not observed when bacteria were grown under aerobic conditions or in strains capable of producing the siderophore yersiniabactin (Ybt) and the putative ferrous transporter FetMP. BothfetPand a downstream locus (flpforfetlinkedphenotype) were required for growth of ayfe feo ybtmutant under static, iron-limiting conditions. AnfeoBmutation alone had no effect on the virulence ofY. pestisin either bubonic or pneumonic plague models. Anfeo yfedouble mutant was still fully virulent in a pneumonic plague model but had an ∼90-fold increase in the 50% lethal dose (LD50) relative to the Yfe+Feo+parent strain in a bubonic plague model. Thus, Yfe and Feo, in addition to Ybt, play an important role in the progression of bubonic plague. Finally, we examined the factors affecting the expression of thefeooperon inY. pestis. Under static growth conditions, theY. pestis feo::lacZfusion was repressed by iron in a Fur-dependent manner but not in cells grown aerobically. Mutations infeoC,fnr,arcA,oxyR, orrstABhad no significant effect on transcription of theY. pestis feopromoter. Thus, the factor(s) that prevents repression by Fur under aerobic growth conditions remains to be identified.

scholarly journals Characterization of the Binding Protein-Dependent Cellobiose and Cellotriose Transport System of the Cellulose Degrader Streptomyces reticuli

1999 ◽  
Vol 65 (6) ◽  
pp. 2636-2643 ◽  
Author(s):  
Andreas Schlösser ◽  
Jens Jantos ◽  
Karl Hackmann ◽  
Hildgund Schrempf
Keyword(s):  
Abc Transporter ◽  
Binding Protein ◽  
Regulatory Protein ◽  
Transport Systems ◽  
Uptake System ◽  
Gene Products ◽  
Abc Transport ◽  
Insertional Inactivation ◽  
Atp Binding Protein

ABSTRACT Streptomyces reticuli has an inducible ATP-dependent uptake system specific for cellobiose and cellotriose. By reversed genetics a gene cluster encoding components of a binding protein-dependent cellobiose and cellotriose ABC transporter was cloned and sequenced. The deduced gene products comprise a regulatory protein (CebR), a cellobiose binding lipoprotein (CebE), two integral membrane proteins (CebF and CebG), and the NH2-terminal part of an intracellular β-glucosidase (BglC). The gene for the ATP binding protein MsiK is not linked to the ceb operon. We have shown earlier that MsiK is part of two different ABC transport systems, one for maltose and one for cellobiose and cellotriose, in S. reticuli and Streptomyces lividans. Transcription of polycistronic cebEFG and bglC mRNAs is induced by cellobiose, whereas the cebR gene is transcribed independently. Immunological experiments showed that CebE is synthesized during growth with cellobiose and that MsiK is produced in the presence of several sugars at high or moderate levels. The described ABC transporter is the first one of its kind and is the only specific cellobiose/cellotriose uptake system of S. reticuli, since insertional inactivation of the cebEgene prevents high-affinity uptake of cellobiose.

scholarly journals Pyoverdine-Mediated Iron Uptake in Pseudomonas aeruginosa: the Tat System Is Required for PvdN but Not for FpvA Transport

2006 ◽  
Vol 188 (9) ◽  
pp. 3317-3323 ◽  
Author(s):  
Romé Voulhoux ◽  
Alain Filloux ◽  
Isabelle J. Schalk
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Iron Uptake ◽  
Cytoplasmic Membrane ◽  
Signal Sequence ◽  
Iron Release ◽  
Outer Membrane Receptor ◽  
Uptake Pathway ◽  
Uptake Process ◽  
Tat System

ABSTRACT Under iron-limiting conditions, Pseudomonas aeruginosa PAO1 secretes a fluorescent siderophore called pyoverdine (Pvd). After chelating iron, this ferric siderophore is transported back into the cells via the outer membrane receptor FpvA. The Pvd-dependent iron uptake pathway requires several essential genes involved in both the synthesis of Pvd and the uptake of ferric Pvd inside the cell. A previous study describing the global phenotype of a tat-deficient P. aeruginosa strain showed that the defect in Pvd-mediated iron uptake was due to the Tat-dependent export of proteins involved in Pvd biogenesis and ferric Pvd uptake (U. Ochsner, A. Snyder, A. I. Vasil, and M. L. Vasil, Proc. Natl. Acad. Sci. USA 99:8312-8317, 2002). Using biochemical and biophysical tools, we showed that despite its predicted Tat signal sequence, FpvA is correctly located in the outer membrane of a tat mutant and is fully functional for all steps of the iron uptake process (ferric Pvd uptake and recycling of Pvd on FpvA after iron release). However, in the tat mutant, no Pvd was produced. This suggested that a key element in the Pvd biogenesis pathway must be exported to the periplasm by the Tat pathway. We located PvdN, a still unknown but essential component in Pvd biogenesis, at the periplasmic side of the cytoplasmic membrane and showed that its export is Tat dependent. Our results further support the idea that a critical step of the Pvd biogenesis pathway involving PvdN occurs at the periplasmic side of the cytoplasmic membrane.

The mechanism of iron uptake in Bacillus subtilis

1970 ◽  
Vol 16 (12) ◽  
pp. 1285-1291 ◽  
Author(s):  
W. J. Peters ◽  
R. A. J. Warren
Keyword(s):  
Bacillus Subtilis ◽  
Phenolic Compounds ◽  
Phenolic Acids ◽  
Phenolic Acid ◽  
Iron Uptake ◽  
Hydroxamic Acids ◽  
Acid Complex ◽  
Iron Deficient ◽  
Active Transport System ◽  
Energy Dependent

A variety of phenolic compounds and hydroxamic acids reduced or prevented phenolic acid and coproporphyrin accumulation by iron-deficient cultures of Bacillus subtilis, but only if they were added to cultures with levels of iron which alone did not prevent accumulation. The compounds also increased iron uptake by iron-deficient cultures and norma) cultures. When radioactive catechol or 2,3-dihydroxybenzoic acid was used to increase iron uptake by iron-deficient cells, only very low levels of radioactivity remained associated with the cells. It is suggested that B. subtilis produces phenolic acids to solubilize iron; that other phenolic compounds or hydroxamic acids may substitute for the phenolic acids produced by B. subtilis; that the iron: phenolic acid complex does not enter the cell; and that the iron is removed from the complex at the cell surface and taken into the cell by an energy-dependent active transport system.

Evidence for a copper-dependent iron transport system in the marine, magnetotactic bacterium strain MV-1

Microbiology ◽  
2004 ◽  
Vol 150 (9) ◽  
pp. 2931-2945 ◽  
Author(s):  
Bradley L. Dubbels ◽  
Alan A. DiSpirito ◽  
John D. Morton ◽  
Jeremy D. Semrau ◽  
J. N. E. Neto ◽  
...  
Keyword(s):  
Iron Content ◽  
Iron Uptake ◽  
Iron Transport ◽  
Dna Analysis ◽  
Iron Concentration ◽  
Protein A ◽  
Uptake System ◽  
Iron Uptake System ◽  
Cellular Iron ◽  
Solid Media

Cells of the magnetotactic marine vibrio, strain MV-1, produce magnetite-containing magnetosomes when grown anaerobically or microaerobically. Stable, spontaneous, non-magnetotactic mutants were regularly observed when cells of MV-1 were cultured on solid media incubated under anaerobic or microaerobic conditions. Randomly amplified polymorphic DNA analysis showed that these mutants are not all genetically identical. Cellular iron content of one non-magnetotactic mutant strain, designated MV-1nm1, grown anaerobically, was ∼20- to 80-fold less than the iron content of wild-type (wt) MV-1 for the same iron concentrations, indicating that MV-1nm1 is deficient in some form of iron uptake. Comparative protein profiles of the two strains showed that MV-1nm1 did not produce several proteins produced by wt MV-1. To understand the potential roles of these proteins in iron transport better, one of these proteins was purified and characterized. This protein, a homodimer with an apparent subunit mass of about 19 kDa, was an iron-regulated, periplasmic protein (p19). Two potential ‘copper-handling’ motifs (MXM/MX2M) are present in the amino acid sequence of p19, and the native protein binds copper in a 1 : 1 ratio. The structural gene for p19, chpA (copper handling protein) and two other putative genes upstream of chpA were cloned and sequenced. These putative genes encode a protein similar to the iron permease, Ftr1, from the yeast Saccharomyces cerevisiae, and a ferredoxin-like protein of unknown function. A periplasmic, copper-containing, iron(II) oxidase was also purified from wt MV-1 and MV-1nm1. This enzyme, like p19, was regulated by media iron concentration and contained four copper atoms per molecule of enzyme. It is hypothesized that ChpA, the iron permease and the iron(II) oxidase might have analogous functions for the three components of the S. cerevisiae copper-dependent high-affinity iron uptake system (Ctr1, Ftr1 and Fet3, respectively), and that strain MV-1 may have a similar iron uptake system. However, iron(II) oxidase purified from both wt MV-1 and MV-1nm1 displayed comparable iron oxidase activities using O2 as the electron acceptor, indicating that ChpA does not supply the multi-copper iron(II) oxidase with copper.

scholarly journals A Molecular Basis for Tungstate Selectivity in Prokaryotic ABC Transport Systems

2011 ◽  
Vol 193 (18) ◽  
pp. 4999-5001 ◽  
Author(s):  
L. E. Bevers ◽  
G. Schwarz ◽  
W. R. Hagen
Keyword(s):  
Molecular Basis ◽  
Transport Systems ◽  
Abc Transport
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