Structure–function relationships in the bifunctional ferrisiderophore FpvA receptor from Pseudomonas aeruginosa

Schalk, Isabelle J.; Lamont, Iain L.; Cobessi, David

doi:10.1007/s10534-008-9203-2

Cited by 32 publications

(21 citation statements)

References 40 publications

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“…The topology of the signaling domain of HasR is similar to that of other known signaling domains of TonB dependent transporters especially those of FpvA [33]–[35] and PupA [36], which are its closest structural neighbors found by Dali program [37]. However a slight difference can be observed in the long loop of 13 residues (40–52) connecting the β2 strand to the β3 strand.…”

Section: Resultssupporting

confidence: 56%

Interaction of a Partially Disordered Antisigma Factor with Its Partner, the Signaling Domain of the TonB-Dependent Transporter HasR

et al. 2014

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Bacteria use diverse signaling pathways to control gene expression in response to external stimuli. In Gram-negative bacteria, the binding of a nutrient is sensed by an outer membrane transporter. This signal is then transmitted to an antisigma factor and subsequently to the cytoplasm where an ECF sigma factor induces expression of genes related to the acquisition of this nutrient. The molecular interactions involved in this transmembrane signaling are poorly understood and structural data on this family of antisigma factor are rare. Here, we present the first structural study of the periplasmic domain of an antisigma factor and its interaction with the transporter. The study concerns the signaling in the heme acquisition system (Has) of Serratia marcescens. Our data support unprecedented partially disordered periplasmic domain of an anti-sigma factor HasS in contact with a membrane-mimicking environment. We solved the 3D structure of the signaling domain of HasR transporter and identified the residues at the HasS−HasR interface. Their conservation in several bacteria suggests wider significance of the proposed model for the understanding of bacterial transmembrane signaling.

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Section: Resultssupporting

confidence: 56%

Interaction of a Partially Disordered Antisigma Factor with Its Partner, the Signaling Domain of the TonB-Dependent Transporter HasR

et al. 2014

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“…Newly synthesized Pvd is stored in the bacterial periplasm (21) before secretion into the extracellular medium by the efflux system PvdRT-OpmQ (23). After iron chelation in the extracellular medium, ferri-Pvd is imported across the outer membrane by the ferri-Pvd outer membrane transporter FpvA (24) and iron is released from the siderophore in the periplasm (25). Free Pvd is then recycled into the extracellular medium by the efflux pump PvdRT-OpmQ (26,27).…”

Section: Resultsmentioning

confidence: 99%

Cell–cell contacts confine public goods diffusion inside Pseudomonas aeruginosa clonal microcolonies

Julou

Mora

Guillon

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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134

160

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The maintenance of cooperation in populations where public goods are equally accessible to all but inflict a fitness cost on individual producers is a long-standing puzzle of evolutionary biology. An example of such a scenario is the secretion of siderophores by bacteria into their environment to fetch soluble iron. In a planktonic culture, these molecules diffuse rapidly, such that the same concentration is experienced by all bacteria. However, on solid substrates, bacteria form dense and packed colonies that may alter the diffusion dynamics through cell-cell contact interactions. In Pseudomonas aeruginosa microcolonies growing on solid substrate, we found that the concentration of pyoverdine, a secreted iron chelator, is heterogeneous, with a maximum at the center of the colony. We quantitatively explain the formation of this gradient by local exchange between contacting cells rather than by global diffusion of pyoverdine. In addition, we show that this local trafficking modulates the growth rate of individual cells. Taken together, these data provide a physical basis that explains the stability of public goods production in packed colonies.biofilm | evolution | noise | variability | ecology I ron is required for many enzymatic processes, and is therefore an essential nutrient. To overcome the low abundance of free iron in aerobic environments, bacteria, as well as other microorganisms, synthesize and secrete iron-chelating molecules called siderophores (1). Once released in the extracellular environment, siderophores diffuse and complex with iron. Because other bacteria can import them, siderophores can be regarded as public goods (2) and siderophore secretion is often cited as a model system for studying the stability of cooperation (3, 4). In this context, nonproducing mutants, which can enjoy the benefit of siderophores without bearing the cost of their production, have a selective advantage over the WT-producing strain and could, in principle, displace them on evolutionary time scales.This argument usually assumes that public good molecules are readily available to all, as is the case in planktonic cultures, where molecules diffuse freely and rapidly between cells. In liquid conditions, mutants that do not produce siderophores have, in fact, been shown to outcompete WT strains (5-8). However, the limited spatial dispersal of public goods can challenge this picture and has been proposed as a general mechanism for explaining the maintenance of cooperation (8-12). When dispersal is limited, public good molecules tend to stay in the vicinity of the producing subpopulations, allowing them to benefit preferentially from their own production, and thus to balance the advantage of opportunistic nonproducing strains. In many ecological situations, bacteria form complex, tightly packed, and spatially structured colonies, such as biofilms, where public good dispersal may be severely reduced compared with planktonic cultures. This raises the questions of how public good molecules circulate between cells in these natur...

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“…However, the slight differences between the three mutants at the highest CFU concentrations in panel C were not observed in all replicate experiments. minal 22-stranded ␤-barrel that forms a gated porin across the membrane and a long (ϳ150-residue) N-terminal periplasmic domain that acts as a "plug" that opens, with the assistance of TonB-ExbBD, when the receptor is engaged and the siderophore is to be imported (14,28,48,88,92,100,103,117,136). For comparison to LbtU, the secondary structures of two wellknown receptors appear in Fig.…”

Section: Discussionmentioning

confidence: 99%

Legionella pneumophila LbtU Acts as a Novel, TonB-Independent Receptor for the Legiobactin Siderophore

et al. 2011

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Gram-negative Legionella pneumophila produces a siderophore (legiobactin) that promotes lung infection. We previously determined that lbtA and lbtB are required for the synthesis and secretion of legiobactin. DNA sequence and reverse transcription-PCR (RT-PCR) analyses now reveal the presence of an iron-repressed gene (lbtU) directly upstream of the lbtAB-containing operon. In silico analysis predicted that LbtU is an outer membrane protein consisting of a 16-stranded transmembrane ␤-barrel, multiple extracellular domains, and short periplasmic tails. Immunoblot analysis of cell fractions confirmed an outer membrane location for LbtU. Although replicating normally in standard media, lbtU mutants, like lbtA mutants, were impaired for growth on iron-depleted agar media. While producing typical levels of legiobactin, lbtU mutants were unable to use supplied legiobactin to stimulate growth on iron-depleted media and displayed an inability to take up iron. Complemented lbtU mutants behaved as the wild type did. The lbtU mutants were also impaired for infection in a legiobactin-dependent manner. Together, these data indicate that LbtU is involved in the uptake of legiobactin and, based upon its location, is most likely the Legionella siderophore receptor. The sequence and predicted two-dimensional (2D) and 3D structures of LbtU were distinct from those of all known siderophore receptors, which generally contain a 22-stranded ␤-barrel and an extended N terminus that binds TonB in order to transduce energy from the inner membrane. This observation coupled with the fact that L. pneumophila does not encode TonB suggests that LbtU is a new type of receptor that participates in a form of iron uptake that is mechanistically distinct from the existing paradigm.

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Structure–function relationships in the bifunctional ferrisiderophore FpvA receptor from Pseudomonas aeruginosa

Cited by 32 publications

References 40 publications

Interaction of a Partially Disordered Antisigma Factor with Its Partner, the Signaling Domain of the TonB-Dependent Transporter HasR

Interaction of a Partially Disordered Antisigma Factor with Its Partner, the Signaling Domain of the TonB-Dependent Transporter HasR

Cell–cell contacts confine public goods diffusion inside Pseudomonas aeruginosa clonal microcolonies

Legionella pneumophila LbtU Acts as a Novel, TonB-Independent Receptor for the Legiobactin Siderophore

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