Self-cleavage of the Pseudomonas aeruginosa Cell-surface Signaling Anti-sigma Factor FoxR Occurs through an N-O Acyl Rearrangement

Bastiaansen, Karlijn C.; Ulsen, Peter van; Bitter, Wilbert; Llamas, María A.

doi:10.1074/jbc.m115.643098

Cited by 26 publications

(39 citation statements)

References 53 publications

(87 reference statements)

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“…D). In fact, small amounts of the HxuR and HasS N‐tail subfragments, usually indicative of CSS activation (Bastiaansen et al ., , ), could still be detected in the Δprc mutant (Fig. B).…”

Section: Resultsmentioning

confidence: 99%

“…A). Presence of GT residues in the cleavage site of HasS and HxuR suggests that this step occurs by a protease‐independent mechanism known as N–O acyl rearrangement, as we demonstrated for the P. aeruginosa FoxR anti‐σ factor (Bastiaansen et al ., , ). This spontaneous cleavage produces a HasS and HxuR N‐domain that by analogy with FoxR (Bastiaansen et al ., ) likely interacts with its corresponding C‐domain in the periplasm (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…We have recently determined that most Pseudomonas CSS anti-σ factors undergo self-cleavage immediately upon production (Bastiaansen et al, 2015a(Bastiaansen et al, , 2015b. This spontaneous cleavage occurs in a conserved Gly-Thr (GT) cleavage site located in the periplasmic domain of CSS anti-σ factors by a protease-independent chemical reaction known as N-O/S acyl rearrangement (Bastiaansen et al, 2015b). This cleavage produces two functional N-and Canti-σ factor domains ( Fig.…”

Section: P Aeruginosa Responds To the Presence Of Haem In The Extracmentioning

confidence: 99%

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Pseudomonas aeruginosa possesses three distinct systems for sensing and using the host molecule haem

Otero-Asman

García‐García

Civantos

et al. 2019

Environmental Microbiology

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Summary Pathogens have developed several strategies to obtain iron during infection, including the use of iron‐containing molecules from the host. Haem accounts for the vast majority of the iron pool in vertebrates and thus represents an important source of iron for pathogens. Using a proteomic approach, we have identified in this work a previously uncharacterized system, which we name Hxu, that together with the known Has and Phu systems, is used by the human pathogen Pseudomonas aeruginosa to respond to haem. We show that the Has and Hxu systems are functional signal transduction pathways of the cell‐surface signalling class and report the mechanism triggering the activation of these signalling systems. Both signalling cascades involve an outer membrane receptor (HasR and HxuA respectively) that upon sensing haem in the extracellular medium produces the activation of an σECF factor in the cytosol. HxuA has a major role in signalling and a minor role in haem acquisition in conditions in which the HasR and PhuR receptors or other sources of iron are present. Remarkably, P. aeruginosa compensates the lack of the HasR receptor by increasing the production of HxuA, which underscores the importance of haem signalling for this pathogen.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: P Aeruginosa Responds To the Presence Of Haem In The Extracmentioning

confidence: 99%

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Pseudomonas aeruginosa possesses three distinct systems for sensing and using the host molecule haem

Otero-Asman

García‐García

Civantos

et al. 2019

Environmental Microbiology

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“…FpvA transports pyoverdine, while other receptors interact with siderophores produced by other microorganisms (e.g., aerobactin, ferrioxamine, ferrichrome; Cornelis and Matthijs, 2002;Schalk, 2008;Llamas et al, 2014). For example, IutA (PP_2193) is an aerobactin receptor (Bastiaansen et al, 2014) while FoxA (PP_0160) interacts with ferrioxamine (Llamas et al, 2006;Bastiaansen et al, 2015). Proteomic assays also showed FoxA to be upregulated in the Hfq/ Crc-null strain (Supporting Information Table S6).…”

Section: Fig 2 Effect Of Hfq On the Expression Of Genes Involved Inmentioning

confidence: 99%

Influence of the Hfq and Crc global regulators on the control of iron homeostasis in Pseudomonas putida

Sánchez-Hevia

Yuste

Moreno

et al. 2018

Environmental Microbiology

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Metabolically versatile bacteria use catabolite repression control to select their preferred carbon sources, thus optimizing carbon metabolism. In pseudomonads, this occurs through the combined action of the proteins Hfq and Crc, which form stable tripartite complexes at target mRNAs, inhibiting their translation. The activity of Hfq/Crc is antagonised by small RNAs of the CrcZ family, the amounts of which vary according to carbon availability. The present work examines the role of Pseudomonas putida Hfq protein under conditions of low-level catabolite repression, in which Crc protein would have a minor role since it is sequestered by CrcZ/CrcY. The results suggest that, under these conditions, Hfq remains operative and plays an important role in iron homeostasis. In this scenario, Crc appears to participate indirectly by helping CrcZ/CrcY to control the amount of free Hfq in the cell. Iron homeostasis in pseudomonads relies on regulatory elements such as the Fur protein, the PrrF1-F2 sRNAs, and several extracytoplasmic sigma factors. Our results show that the absence of Hfq is paralleled by a reduction in PrrF1-F2 small RNAs. Hfq thus provides a regulatory link between iron and carbon metabolism, coordinating the iron supply to meet the needs of the enzymes operational under particular nutritional regimes.

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“…The exact mechanism of signal transduction by the sigma regulators has not been determined, although available data suggests that controlled inner membrane proteolysis of the sigma regulator cytoplasmic domain may release the cytoplasmic sigma regulator domain and associated sigma factor (5, 27). In certain anti-sigma factors, such as FecR, FpvR, and FoxR, cytoplasmic or periplasmic proteolysis appears to be preceded by a conserved autoproteolytic event induced via an enzyme-independent N-O acyl rearrangement (13, 28, 29). However, the residues responsible for this event are not conserved in PupR.…”

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confidence: 99%

Mechanistic Implications of the Unique Structural Features and Dimerization of the Cytoplasmic Domain of the Pseudomonas Sigma Regulator, PupR

et al. 2015

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Gram-negative bacteria tightly regulate intracellular levels of iron, an essential nutrient. To ensure this tight regulation, some outer membrane TonB-dependent transporters (TBDTs) that are responsible for iron import stimulate their own transcription in response to extracellular binding by an iron-laden siderophore. This process is mediated by an inner membrane sigma regulator protein (an anti-sigma factor) that transduces an unknown periplasmic signal from the TBDT to release an intracellular sigma factor from the inner membrane, which ultimately upregulates TBDT transcription. Here we use the Pseudomonas putida ferric-pseudobactin BN7/BN8 sigma regulator, PupR, as a model system to understand the molecular mechanism of this conserved class of sigma regulators. We have determined the X-ray crystal structure of the cytoplasmic anti-sigma domain (ASD) of PupR to 2.0 Å. Size exclusion chromatography, small angle X-ray scattering, and sedimentation velocity analytical ultracentrifugation, all indicate that in contrast to other ASDs, the PupR-ASD exists as a dimer in solution. Mutagenesis of residues at the dimer interface identified from the crystal structure disrupts dimerization and protein stability, as determined by sedimentation velocity analytical ultracentrifugation and thermal denaturation circular dichroism spectroscopy. These combined results suggest that this type of inner membrane sigma regulator may utilize an unusual mechanism to sequester their cognate sigma factors and prevent transcription activation.

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Self-cleavage of the Pseudomonas aeruginosa Cell-surface Signaling Anti-sigma Factor FoxR Occurs through an N-O Acyl Rearrangement

Cited by 26 publications

References 53 publications

Pseudomonas aeruginosa possesses three distinct systems for sensing and using the host molecule haem

Pseudomonas aeruginosa possesses three distinct systems for sensing and using the host molecule haem

Influence of the Hfq and Crc global regulators on the control of iron homeostasis in Pseudomonas putida

Mechanistic Implications of the Unique Structural Features and Dimerization of the Cytoplasmic Domain of the Pseudomonas Sigma Regulator, PupR

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