A new mechanism for membrane iron transport in Pseudomonas aeruginosa

2002 ◽  
Vol 30 (4) ◽  
pp. 702-705 ◽  
Author(s):  
I.J. Schalk ◽  
M. A. Abdallah ◽  
F. Pattus
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Iron Uptake ◽  
Iron Transport ◽  
Membrane Receptor ◽  
Gram Negative Bacteria ◽  
Outer Membrane Receptor ◽  
Uptake Mechanism ◽  
Atp Binding Cassette Transporter ◽  
Biophysical Studies

Various biochemical and biophysical studies have demonstrated the existence of a novel iron-uptake mechanism in Pseudomonas aeruginosa, different from that generally described for ferrichrome and ferric-enterobactin in Escherichia coli. This new iron-uptake mechanism involves all the proteins generally reported to be involved in the uptake of ferric-siderophore complexes in Gram-negative bacteria (i.e. the outer membrane receptor, periplasmic binding protein and ATP-binding-cassette transporter), but differs in the behaviour of the siderophore. One of the key features of this process is the binding of iron-free pyoverdin to the outer membrane receptor FpvA in conditions of iron deficiency.

scholarly journals Iron-free pyoverdin binds to its outer membrane receptor FpvA in Pseudomonas aeruginosa: a new mechanism for membrane iron transport

2001 ◽  
Vol 39 (2) ◽  
pp. 351-361 ◽  
Author(s):  
Isabelle J. Schalk ◽  
Christophe Hennard ◽  
Christophe Dugave ◽  
Keith Poole ◽  
Mohamed A. Abdallah ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Iron Transport ◽  
Membrane Receptor ◽  
Outer Membrane Receptor

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.

scholarly journals Identification and characterization of an iron-regulated gene, chtA, required for the utilization of the xenosiderophores aerobactin, rhizobactin 1021 and schizokinen by Pseudomonas aeruginosa

Microbiology ◽  
2006 ◽  
Vol 152 (4) ◽  
pp. 945-954 ◽  
Author(s):  
Páraic Ó Cuív ◽  
Paul Clarke ◽  
Michael O'Connell
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Membrane Receptor ◽  
Outer Membrane Receptor ◽  
Significant Similarity ◽  
Hydroxamate Siderophores ◽  
Insertional Inactivation ◽  
Titration Assay

Pseudomonas aeruginosa utilizes several xenosiderophores under conditions of iron limitation, including the citrate hydroxamate siderophore aerobactin. Analysis of the P. aeruginosa genome sequence revealed the presence of two genes, chtA (PA4675) and PA1365, encoding proteins displaying significant similarity to the aerobactin outer-membrane receptor, IutA, of Escherichia coli. The chtA and PA1365 genes were mutated by insertional inactivation and it was demonstrated that ChtA is the outer-membrane receptor for aerobactin. ChtA also mediated the utilization of rhizobactin 1021 and schizokinen, which are structurally similar to aerobactin. In contrast to the utilization of other xenosiderophores by P. aeruginosa, there was no apparent redundancy in the utilization of aerobactin, rhizobactin 1021 and schizokinen. The utilization of citrate hydroxamate siderophores by P. aeruginosa was demonstrated to be TonB1 dependent. A Fur box was identified in the region directly upstream of chtA and it was demonstrated by the in vivo Fur titration assay that this region is capable of binding Fur and accordingly that expression of chtA is iron regulated. The PA1365 mutant was unaffected in the utilization of citrate hydroxamate siderophores.

scholarly journals Identification of rhtX and fptX, Novel Genes Encoding Proteins That Show Homology and Function in the Utilization of the Siderophores Rhizobactin 1021 by Sinorhizobium meliloti and Pyochelin by Pseudomonas aeruginosa, Respectively

2004 ◽  
Vol 186 (10) ◽  
pp. 2996-3005 ◽  
Author(s):  
Páraic Ó Cuív ◽  
Paul Clarke ◽  
Damien Lynch ◽  
Michael O'Connell
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Membrane Transport ◽  
Sinorhizobium Meliloti ◽  
Iron Acquisition ◽  
Membrane Receptor ◽  
Receptor Protein ◽  
Outer Membrane Receptor ◽  
E Coli ◽  
Genes Encoding

ABSTRACT Rhizobactin 1021 is a hydroxymate siderophore produced by the soil bacterium Sinorhizobium meliloti 2011. A regulon comprising rhtA, encoding the outer membrane receptor protein for the ferrisiderophore; the biosynthesis operon rhbABCDEF; and rhrA, the Ara-C-like regulator of the receptor and biosynthesis genes has been previously described. We report the discovery of a gene, located upstream of rhbA and named rhtX (for “rhizobactin transport”), which is required, in addition to rhtA, to confer the ability to utilize rhizobactin 1021 on a strain of S. meliloti that does not naturally utilize the siderophore. Rhizobactin 1021 is structurally similar to aerobactin, which is transported in Escherichia coli via the IutA outer membrane receptor and the FhuCDB inner membrane transport system. E. coli expressing iutA and fhuCDB was found to also transport rhizobactin 1021. We demonstrated that RhtX alone could substitute for FhuCDB to transport rhizobactin 1021 in E. coli. RhtX shows similarity to a number of uncharacterized proteins which are encoded proximal to genes that are either known to be or predicted to be involved in iron acquisition. Among these is PA4218 of Pseudomonas aeruginosa, which is located close to the gene cluster that functions in pyochelin biosynthesis and outer membrane transport. PA4218 was mutated by allelic replacement, and the mutant was found to have a pyochelin utilization-defective phenotype. It is proposed that PA4218 be named fptX (for “ferripyochelin transport”). RhtX and FptX appear to be members of a novel family of permeases that function as single-subunit transporters of siderophores.

scholarly journals Contributions of the heme coordinating ligands of the Pseudomonas aeruginosa outer membrane receptor HasR to extracellular heme sensing and transport

2020 ◽  
Vol 295 (30) ◽  
pp. 10456-10467 ◽  
Author(s):  
Alecia T. Dent ◽  
Angela Wilks
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Membrane Receptor ◽  
Site Directed Mutagenesis ◽  
Uptake System ◽  
Outer Membrane Receptor ◽  
Heme Uptake ◽  
Functional Link ◽  
Heme Transport ◽  
Σ Factor

Pseudomonas aeruginosa exhibits a high requirement for iron, which it can acquire via several mechanisms, including the acquisition and utilization of heme. The P. aeruginosa genome encodes two heme uptake systems, the heme assimilation system (Has) and the Pseudomonas heme utilization (Phu) system. Extracellular heme is sensed via the Has system, which encodes an extracytoplasmic function (ECF) σ factor system. Previous studies have shown that the transfer of heme from the extracellular hemophore HasAp to the outer membrane receptor HasR is required for activation of the σ factor HasI and upregulation of has operon expression. Here, employing site-directed mutagenesis, allelic exchange, quantitative PCR analyses, immunoblotting, and 13C-heme uptake experiments, we delineated the differential contributions of the extracellular FRAP/PNPNL loop residue His-624 in HasR and of His-221 in its N-terminal plug domain required for heme capture to heme transport and signaling, respectively. Specifically, we show that substitution of the N-terminal plug His-221 disrupts both signaling and transport, leading to dysregulation of both the Has and Phu uptake systems. Our results are consistent with a model wherein heme release from HasAp to the N-terminal plug of HasR is required to initiate signaling, whereas His-624 is required for simultaneously closing off the heme transport channel from the extracellular medium and triggering heme transport. Our results provide critical insight into heme release, signaling, and transport in P. aeruginosa and suggest a functional link between the ECF σ factor and Phu heme uptake system.

scholarly journals The Hem and Has haem uptake systems in Serratia marcescens

Microbiology ◽  
2010 ◽  
Vol 156 (6) ◽  
pp. 1749-1757 ◽  
Author(s):  
Najla Benevides-Matos ◽  
Francis Biville
Keyword(s):  
Serratia Marcescens ◽  
Outer Membrane ◽  
Membrane Receptor ◽  
Gram Negative Bacteria ◽  
Uptake System ◽  
Outer Membrane Receptor ◽  
Iron Depletion ◽  
Two Systems ◽  
Uptake Activity ◽  
Different Sources

Serratia marcescens, like several other Gram-negative bacteria, possesses two functional haem uptake systems. The first, referred to as the Hem system, can transport haem present at a concentration equal to or above 10−6 M. It requires an active outer-membrane receptor which uses proton-motive force energy transmitted by the inner-membrane TonB protein. The other system, Has, takes up haem at lower concentrations and utilizes a small secreted haem-binding protein (haemophore) and its cognate TonB-dependent outer-membrane receptor HasR. Various combinations of mutations were used to examine haem uptake activity by the two systems in S. marcescens. The Hem uptake system enables S. marcescens to take up haem at a concentration of 10−6 M in the presence of various levels of iron depletion. The Has system, which enables such uptake even in the presence of lower haem concentrations, requires higher iron depletion conditions for function. Has haem uptake requires the presence of HasB, a TonB paralogue encoded by the has operon. These two systems enable S. marcescens to take up haem under various conditions from different sources, reflecting its capacity to confront conditions encountered in natural biotopes.

In vivo incorporation of selenomethionine in proteins using Pseudomonas aeruginosa as expression host: case study—the outer membrane receptor FpvA

2004 ◽  
Vol 38 (1) ◽  
pp. 79-83 ◽  
Author(s):  
Nicolas Folschweiller ◽  
Karine Pacaud ◽  
Hervé Celia ◽  
Noëlle Potier ◽  
David Cobessi ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Membrane Receptor ◽  
Outer Membrane Receptor ◽  
Expression Host

scholarly journals Contributions of the Heme Coordinating Ligands of the Pseudomonas aeruginosa Outer Membrane Receptor HasR to Extracellular Heme Sensing and Transport

2020 ◽  
Author(s):  
Alecia T. Dent ◽  
Angela Wilks
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Membrane Receptor ◽  
Site Directed Mutagenesis ◽  
Outer Membrane Receptor ◽  
Heme Uptake ◽  
Functional Link ◽  
Heme Transport ◽  
Σ Factor ◽  
Factor System

ABSTRACTPseudomonas aeruginosa exhibits a high requirement for iron which it can acquire via several mechanisms including the acquisition and utilization of heme. P. aeruginosa encodes two heme uptake systems, the heme assimilation system (Has) and the Pseudomonasheme utilization (Phu) system. Extracellular heme is sensed via the Has system that encodes an extra cytoplasmic function (ECF) σ factor system. Previous studies have shown release of heme from the extracellular hemophore HasAp to the outer membrane receptor HasR is required for activation of the σ factor HasI. Herein, employing site-directed mutagenesis, allelic exchange, quantitative PCR analyses, immunoblotting and 13C-heme uptake studies, we characterize the differential contributions of the outer membrane receptor HasR extracellular FRAP/PNPNL loop residue His-624 and the N-terminal plug residue His-221 to heme transport and signaling, respectively. Specifically, we show mutation of the N-terminal plug His-221 disrupts both signaling and transport. The data is consistent with a model where heme release from HasAp to the N-terminal plug of HasR is required to initiate signaling, whereas His624 is required for simultaneously closing off the heme transport channel from the extracellular medium and triggering heme transport. Furthermore, mutation of His-221 leads to dysregulation of both the Has and Phu uptake systems suggesting a possible functional link that is coordinated through the ECF σ factor system.

Characterization of the stability functions and inverted repeat structure X3 of the IncFI plasmid ColV2-K94

1986 ◽  
Vol 32 (10) ◽  
pp. 806-813
Author(s):  
Peter C. Weber ◽  
Sunil Palchaudhuri
Keyword(s):  
Outer Membrane ◽  
Inverted Repeat ◽  
Iron Uptake ◽  
Membrane Receptor ◽  
Outer Membrane Receptor ◽  
Plasmid Maintenance ◽  
Stability Functions ◽  
Repeat Structure ◽  
The Stability

A region of the IncFI plasmid ColV2-K94 which showed homology to the sop partitioning genes of F was cloned and characterized in an attempt to study the stability functions of this element. The sop region contained the incD incompatibility determinant common to many IncFI plasmids, but could not confer on ColV2-K94 miniplasmids the same stable inheritance found in the intact ColV2-K94; thus, other functions appear to be required for efficient plasmid maintenance. Adjacent to the area of sop homology was the X3 region, which was found to contain three inverted IS1-like sequences. The X3 region of ColV2-K94 was similar in organization to the aerobactin iron uptake region of ColV3-K30, but ColV2-K94 lacked the ability to synthesize either the aerobactin siderophore or its outer membrane receptor.

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