Proteomic analysis of iron acquisition, metabolic and regulatory responses of Yersinia pestis to iron starvation

Iron is essential for the growth and virulence of most intravacuolar pathogens. The mechanisms by which microbes bypass host iron restriction to gain access to this metal across the host vacuolar membrane are poorly characterized. In this work, we identify a unique intracellular iron acquisition strategy used byLegionella pneumophila.The bacterial Icm/Dot (intracellular multiplication/defect in organelle trafficking) type IV secretion system targets the bacterial-derived MavN (more regions allowing vacuolar colocalization N) protein to the surface of theLegionella-containing vacuole where this putative transmembrane protein facilitates intravacuolar iron acquisition. TheΔmavNmutant exhibits a transcriptional iron-starvation signature before its growth is arrested during the very early stages of macrophage infection. This intracellular growth defect is rescued only by the addition of excess exogenous iron to the culture medium and not a variety of other metals. Consistent with MavN being a translocated substrate that plays an exclusive role during intracellular growth, the mutant shows no defect for growth in broth culture, even under severe iron-limiting conditions. Putative iron-binding residues within the MavN protein were identified, and point mutations in these residues resulted in defects specific for intracellular growth that are indistinguishable from the ΔmavNmutant. This model of a bacterial protein inserting into host membranes to mediate iron transport provides a paradigm for how intravacuolar pathogens can use virulence-associated secretion systems to manipulate and acquire host iron.

Download Full-text

Genes Essential to Iron Transport in the Cyanobacterium Synechocystis sp. Strain PCC 6803

Journal of Bacteriology ◽

10.1128/jb.183.9.2779-2784.2001 ◽

2001 ◽

Vol 183 (9) ◽

pp. 2779-2784 ◽

Cited By ~ 135

Author(s):

Hirokazu Katoh ◽

Natsu Hagino ◽

Arthur R. Grossman ◽

Teruo Ogawa

Keyword(s):

Iron Uptake ◽

Iron Transport ◽

Ferric Iron ◽

Iron Acquisition ◽

Complete Medium ◽

Iron Starvation ◽

Transporter Family ◽

Genes Encoding ◽

In Cells ◽

Pcc 6803

ABSTRACT Genes encoding polypeptides of an ATP binding cassette (ABC)-type ferric iron transporter that plays a major role in iron acquisition inSynechocystis sp. strain PCC 6803 were identified. These genes are slr1295, slr0513, slr0327, and recently reportedsll1878 (Katoh et al., J. Bacteriol. 182:6523–6524, 2000) and were designated futA1, futA2, futB, andfutC, respectively, for their involvement in ferric iron uptake. Inactivation of these genes individually or futA1and futA2 together greatly reduced the activity of ferric iron uptake in cells grown in complete medium or iron-deprived medium. All the fut genes are expressed in cells grown in complete medium, and expression was enhanced by iron starvation. ThefutA1 and futA2 genes appear to encode periplasmic proteins that play a redundant role in iron binding. The deduced products of futB and futC genes contain nucleotide-binding motifs and belong to the ABC transporter family of inner-membrane-bound and membrane-associated proteins, respectively. These results and sequence similarities among the four genes suggest that the Fut system is related to the Sfu/Fbp family of iron transporters. Inactivation of slr1392, a homologue offeoB in Escherichia coli, greatly reduced the activity of ferrous iron transport. This system is induced by intracellular low iron concentrations that are achieved in cells exposed to iron-free medium or in the fut-less mutants grown in complete medium.

Download Full-text

Iron acquisition in plague: modular logic in enzymatic biogenesis of yersiniabactin by Yersinia pestis

Chemistry & Biology ◽

10.1016/s1074-5521(98)90115-6 ◽

1998 ◽

Vol 5 (10) ◽

pp. 573-586 ◽

Cited By ~ 161

Author(s):

Amy M. Gehring ◽

Edward DeMoll ◽

Jacqueline D. Fetherston ◽

Ichiro Mori ◽

George F. Mayhew ◽

...

Keyword(s):

Yersinia Pestis ◽

Iron Acquisition ◽

Modular Logic

Download Full-text

Ferricrocin, a Siderophore Involved in Intra- and Transcellular Iron Distribution in Aspergillus fumigatus

Applied and Environmental Microbiology ◽

10.1128/aem.00479-09 ◽

2009 ◽

Vol 75 (12) ◽

pp. 4194-4196 ◽

Cited By ~ 73

Author(s):

Anja Wallner ◽

Michael Blatzer ◽

Markus Schrettl ◽

Bettina Sarg ◽

Herbert Lindner ◽

...

Keyword(s):

Aspergillus Fumigatus ◽

Iron Acquisition ◽

Iron Starvation ◽

Intracellular Iron ◽

Iron Storage ◽

Essential Metal ◽

Iron Distribution ◽

Iron Transporter

ABSTRACT Iron is an essential metal for virtually all organisms. Iron acquisition is well characterized for various organisms, whereas intracellular iron distribution is poorly understood. In contrast to bacteria, plants, and animals, most fungi lack ferritin-mediated iron storage but possess an intracellular siderophore shown to be involved in iron storage. Here we demonstrate that deficiency in the intracellular siderophore ferricrocin causes iron starvation in conidia of Aspergillus fumigatus, demonstrating that ferricrocin is also involved in intra- and transcellular iron distribution. Thus, ferricrocin represents the first intracellular iron transporter identified in any organism.

Download Full-text

The Transcriptomic and Bioinformatic Characterizations of Iron Acquisition and Heme Utilization in Avibacterium paragallinarum in Response to Iron-Starvation

Frontiers in Microbiology ◽

10.3389/fmicb.2021.610196 ◽

2021 ◽

Vol 12 ◽

Author(s):

Caiyun Huo ◽

Ximin Zeng ◽

Fuzhou Xu ◽

Fangbing Li ◽

Donghai Li ◽

...

Keyword(s):

Iron Homeostasis ◽

Iron Acquisition ◽

Control Group ◽

Rna Seq ◽

Iron Starvation ◽

Transcriptomic Response ◽

Iron Restriction ◽

Infectious Coryza ◽

Avibacterium Paragallinarum ◽

Restriction Group

Avibacterium paragallinarum is the pathogen of infectious coryza, which is a highly contagious respiratory disease of chickens that brings a potentially serious threat to poultry husbandry. Iron is an important nutrient for bacteria and can be obtained from surroundings such as siderophores and hemophores. To date, the mechanisms of iron acquisition and heme utilization as well as detailed regulation in A. paragallinarum have been poorly understood. In this study, we investigated the transcriptomic profiles in detail and the changes of transcriptomes induced by iron restriction in A. paragallinarum using RNA-seq. Compared with the iron-sufficiency control group, many more differentially expressed genes (DEGs) and cellular functions as well as signaling pathways were verified in the iron-restriction group. Among these DEGs, the majority of genes showed decreased expression and some were found to be uniquely present in the iron-restriction group. With an in-depth study of bioinformatic analyses, we demonstrated the crucial roles of the Hut protein and DUF domain-containing proteins, which were preferentially activated in bacteria following iron restriction and contributed to the iron acquisition and heme utilization. Consequently, RT-qPCR results further verified the iron-related DEGs and were consistent with the RNA-seq data. In addition, several novel sRNAs were present in A. paragallinarum and had potential regulatory roles in iron homeostasis, especially in the regulation of Fic protein to ensure stable expression. This is the first report of the molecular mechanism of iron acquisition and heme utilization in A. paragallinarum from the perspective of transcriptomic profiles. The study will contribute to a better understanding of the transcriptomic response of A. paragallinarum to iron starvation and also provide novel insight into the development of new antigens for potential vaccines against infectious coryza by focusing on these iron-related genes.

Download Full-text

Chlamydia trachomatis YtgA is an iron-binding periplasmic protein induced by iron restriction

Microbiology ◽

10.1099/mic.0.030247-0 ◽

2009 ◽

Vol 155 (9) ◽

pp. 2884-2894 ◽

Cited By ~ 20

Author(s):

J. D. Miller ◽

M. S. Sal ◽

M. Schell ◽

J. D. Whittimore ◽

J. E. Raulston

Keyword(s):

Chlamydia Trachomatis ◽

Iron Acquisition ◽

Periplasmic Protein ◽

Iron Starvation ◽

Sexually Transmitted ◽

Iron Restriction ◽

Abc Transport ◽

Transmission Electron ◽

Biochemical Assays

Chlamydia trachomatis is a Gram-negative obligate intracellular bacterium that is the causative agent of common sexually transmitted diseases and the leading cause of preventable blindness worldwide. It has been observed that YtgA (CT067) is very immunogenic in patients with chlamydial genital infections. Homology analyses suggested that YtgA is a soluble periplasmic protein and a component of an ATP-binding cassette (ABC) transport system for metals such as iron. Since little is known about iron transport in C. trachomatis, biochemical assays were used to determine the potential role of YtgA in iron acquisition. 59Fe binding and competition studies revealed that YtgA preferentially binds iron over nickel, zinc or manganese. Western blot and densitometry techniques showed that YtgA concentrations specifically increased 3–5-fold in C. trachomatis, when cultured under iron-starvation conditions rather than under general stress conditions, such as exposure to penicillin. Finally, immuno-transmission electron microscopy provided evidence that YtgA is more concentrated in C. trachomatis during iron restriction, supporting a possible role for YtgA as a component of an ABC transporter.

Download Full-text

Yersiniabactin contributes to overcoming zinc restriction during Yersinia pestis infection of mammalian and insect hosts

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2104073118 ◽

2021 ◽

Vol 118 (44) ◽

pp. e2104073118

Author(s):

Sarah L. Price ◽

Viveka Vadyvaloo ◽

Jennifer K. DeMarco ◽

Amanda Brady ◽

Phoenix A. Gray ◽

...

Keyword(s):

Yersinia Pestis ◽

Iron Acquisition ◽

Mammalian Host ◽

Independent Manner ◽

Transmission Cycle ◽

Nutritional Immunity ◽

Lethal Infection ◽

Bacterial Mutants ◽

Bona Fide ◽

Key Barrier

Yersinia pestis causes human plague and colonizes both a mammalian host and a flea vector during its transmission cycle. A key barrier to bacterial infection is the host’s ability to actively sequester key biometals (e.g., iron, zinc, and manganese) required for bacterial growth. This is referred to as nutritional immunity. Mechanisms to overcome nutritional immunity are essential virulence factors for bacterial pathogens. Y. pestis produces an iron-scavenging siderophore called yersiniabactin (Ybt) that is required to overcome iron-mediated nutritional immunity and cause lethal infection. Recently, Ybt has been shown to bind to zinc, and in the absence of the zinc transporter ZnuABC, Ybt improves Y. pestis growth in zinc-limited medium. These data suggest that, in addition to iron acquisition, Ybt may also contribute to overcoming zinc-mediated nutritional immunity. To test this hypothesis, we used a mouse model defective in iron-mediated nutritional immunity to demonstrate that Ybt contributes to virulence in an iron-independent manner. Furthermore, using a combination of bacterial mutants and mice defective in zinc-mediated nutritional immunity, we identified calprotectin as the primary barrier for Y. pestis to acquire zinc during infection and that Y. pestis uses Ybt to compete with calprotectin for zinc. Finally, we discovered that Y. pestis encounters zinc limitation within the flea midgut, and Ybt contributes to overcoming this limitation. Together, these results demonstrate that Ybt is a bona fide zinc acquisition mechanism used by Y. pestis to surmount zinc limitation during the infection of both the mammalian and insect hosts.

Download Full-text

Loss of RND-type multidrug efflux pumps triggers iron starvation and lipid A modifications in Pseudomonas aeruginosa

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00592-21 ◽

2021 ◽

Author(s):

Justyna W. Adamiak ◽

Varsha Jhawar ◽

Vincent Bonifay ◽

Courtney E. Chandler ◽

Inga V. Leus ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Lipid A ◽

Cell Envelope ◽

Iron Acquisition ◽

Bacterial Species ◽

Transport Systems ◽

Permeability Barrier ◽

Iron Starvation ◽

Analytical Approaches

Transporters belonging to the Resistance-Nodulation-Division (RND) superfamily of proteins are invariably present in the genomes of Gram-negative bacteria and are largely responsible for the intrinsic antibiotic resistance of these organisms. The number of genes encoding RND transporters per genome vary from one to sixteen and correlates with environmental versatilities of bacterial species. Pseudomonas aeruginosa PAO1 strain, a ubiquitous nosocomial pathogen, possesses twelve RND pumps, which are implicated in development of clinical multidrug resistance and known to contribute to virulence, quorum sensing and many other physiological functions. In this study, we analyzed how P. aeruginosa physiology adapts to the lack of RND-mediated efflux activities. A combination of transcriptomics, metabolomics, genetic and analytical approaches showed that the P. aeruginosa PΔ6 strain lacking six best characterized RND pumps activates a specific adaptation response that involves significant changes in abundance and activities of several transport systems, quorum sensing, iron acquisition and lipid A modifications. Our results demonstrate that these cells accumulate large quantities of pseudomonas quorum signal (PQS), which triggers iron starvation and activation of siderophore biosynthesis and acquisition pathways. The accumulation of iron in turn activates lipid A modification and membrane protection pathways. A transcriptionally regulated RND pump MuxABC-OpmB contributes to these transformations by controlling concentrations of coumarins. Our results suggest that these changes reduce the permeability barrier of the outer membrane and are needed to protect the cell envelope of efflux-deficient P. aeruginosa .

Download Full-text

Hemin-dependent siderophore utilization promotes iron-restricted growth of the Staphylococcus aureus hemB small colony variant

Journal of Bacteriology ◽

10.1128/jb.00458-21 ◽

2021 ◽

Author(s):

Izabela Z. Batko ◽

Ronald S. Flannagan ◽

Veronica Guariglia-Oropeza ◽

Jessica R. Sheldon ◽

David E. Heinrichs

Keyword(s):

Iron Acquisition ◽

Recurrent Infection ◽

Nutritional Requirement ◽

Iron Starvation ◽

Small Colony Variants ◽

Atp Production ◽

Small Colony ◽

Sense And Respond

Respiration deficient S. aureus small colony variants (SCVs) frequently cause persistent infections, which necessitates they acquire iron, yet how SCVs obtain iron remains unknown. To address this, we created a stable hemB mutant in S. aureus USA300 strain LAC. The hemB SCV utilized exogenously supplied hemin but was attenuated for growth under conditions of iron starvation. RNA-seq showed that both WT S. aureus and the hemB mutant sense and respond to iron starvation, however, growth assays show that the hemB mutant is defective for siderophore-mediated iron acquisition. Indeed, the hemB SCV demonstrated limited utilization of endogenous staphyloferrin B or exogenously provided staphyloferrin A, Desferal, and epinephrine. Direct measurement of intracellular ATP in hemB and WT S. aureus revealed that both strains can generate comparable levels of ATP during exponential growth suggesting defects in ATP production cannot account for the inability to efficiently utilize siderophores. Defective siderophore utilization by hemB bacteria was also evident in vivo , as administration of Desferal failed to promote hemB bacterial growth in every organ analyzed except for the kidneys. In support of the hypothesis that S. aureus accesses heme in kidney abscesses, in vitro analyses revealed that increased hemin availability enables hemB bacteria to utilize siderophores for growth when iron availability is restricted. Taken together, our data support the conclusion that hemin is not only used as an iron source itself, but as a nutrient that promotes utilization of siderophore-iron complexes. Importance S. aureus small colony variants (SCVs) are associated with chronic recurrent infection and worsened clinical outcome. SCVs persist within the host despite administration of antibiotics. This study yields insight into how S. aureus SCVs acquire iron which, during infection of a host, is a difficult-to-acquire metal nutrient. Under hemin-limited conditions, hemB S. aureus is impaired for siderophore-dependent growth and, in agreement, murine infection indicates that hemin-deficient SCVs meet their nutritional requirement for iron through utilization of hemin. Importantly, we demonstrate that hemB SCVs rely upon hemin as a nutrient to promote siderophore utilization. Therefore, perturbation of heme biosynthesis and/or utilization represents a viable to strategy to mitigate the ability of SCV bacteria to acquire siderophore-bound iron during infection.

Download Full-text