New insights into <i>Legionella pneumophila</i> biofilm regulation by c-di-GMP signaling

Pécastaings, Sophie; Allombert, Julie; Lajoie, Barbora; Doublet, Patricia; Roques, Christine; Vianney, Anne

doi:10.1080/08927014.2016.1212988

Cited by 29 publications

(50 citation statements)

References 62 publications

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“…Although a role for NO/NosP has yet to be established in organisms other than P. aeruginosa , we speculate a possible role for NO/NosP in biofilm regulation in S. oneidensis , 26 where the histidine kinase cocistronic with NosP is directly involved in regulating S. oneidensis biofilm. Furthermore, NosP is clearly involved in biofilm regulation in V. cholerae and in L. pneumophila : in V. cholerae , a NosP-fused cyclic-di-GMP phosphodiesterase protein has been shown to be involved in V. cholerae biofilm formation by regulating cyclic-di-GMP concentrations, 34 and a NosP- co -cistronic bifunctional diguanylate cyclase/cyclic-di-GMP phosphodiesterase enzyme has been shown to be involved in L. pneumophila (35) biofilm formation. We are currently working to evaluate the role for NO/NosP is these and other bacterial systems.…”

Section: Resultsmentioning

confidence: 99%

Discovery of a Novel Nitric Oxide Binding Protein and Nitric-Oxide-Responsive Signaling Pathway in Pseudomonas aeruginosa

2017

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Nitric oxide (NO) is a radical diatomic gas molecule that, at low concentrations, plays important signaling roles in both eukaryotes and bacteria. In recent years, it has become evident that bacteria respond to low levels of NO in order to modulate their group behavior. Many bacteria respond via NO ligation to a well-established NO sensor called H-NOX (heme-nitric oxide/oxygen binding domain). Many others, such as Pseudomonas aeruginosa, lack an annotated hnoX gene in their genome yet are able to respond to low levels of NO to disperse their biofilms. This suggests the existence of a previously uncharacterized NO sensor. In this study, we describe the discovery of a novel nitric oxide binding protein (NosP; NO-sensing protein), which is much more widely conserved in bacteria than H-NOX, as well as a novel NO-responsive pathway in P. aeruginosa. We demonstrate that biofilms of a P. aeruginosa mutant lacking components of the NosP pathway lose the ability to disperse in response to NO. Upon cloning, expressing, and purifying NosP, we find it binds heme and ligates to NO with a dissociation rate constant that is comparable to that of other well-established NO-sensing proteins. Moreover, we show that NO-bound NosP is able to regulate the phosphorelay activity of a hybrid histidine kinase that is involved in biofilm regulation in P. aeruginosa. Thus, here, we present evidence of a novel NO-responsive pathway that regulates biofilm in P. aeruginosa.

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Section: Resultsmentioning

confidence: 99%

Discovery of a Novel Nitric Oxide Binding Protein and Nitric-Oxide-Responsive Signaling Pathway in Pseudomonas aeruginosa

2017

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“…Expression and DNA binding studies indicated that LvbR regulates the metabolism of c-di-GMP, a second messenger, which plays a role in L. pneumophila biofilm formation (Carlson et al, 2010;Pécastaings et al, 2016). Therefore, we hypothesized that LvbR might also be involved in biofilm formation.…”

Section: Regulation Of L Pneumophila Biofilm Formation and Architectmentioning

confidence: 98%

“…Only a few determinants of L. pneumophila implicated in biofilm formation have been described: the Tat transporter (De Buck et al, 2005), type IV pili (Lucas et al, 2006) and the collagen-like adhesin (Lcl) (Mallegol et al, 2012). Furthermore, L. pneumophila biofilm formation is regulated by the alternative sigma factor FliA (Mampel et al, 2006) and by cyclic di-guanosine monophosphate (c-di-GMP) (Carlson et al, 2010;Pécastaings et al, 2016). The universal second messenger c-di-GMP is a key regulator of a variety of bacterial processes, such as motility, cell division, differentiation, virulence, as well as biofilm formation (Tamayo et al, 2007;Hengge, 2009;Schirmer and Jenal, 2009;Römling et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The pleiotropic Legionella transcription factor LvbR links the Lqs and c‐di‐GMP regulatory networks to control biofilm architecture and virulence

Hochstrasser

Kessler

Sahr

et al. 2019

Environmental Microbiology

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Summary The causative agent of Legionnaires' disease, Legionella pneumophila, colonizes amoebae and biofilms in the environment. The opportunistic pathogen employs the Lqs (Legionella quorum sensing) system and the signalling molecule LAI‐1 (Legionella autoinducer‐1) to regulate virulence, motility, natural competence and expression of a 133 kb genomic “fitness island”, including a putative novel regulator. Here, we show that the regulator termed LvbR is an LqsS‐regulated transcription factor that binds to the promoter of lpg1056/hnox1 (encoding an inhibitor of the diguanylate cyclase Lpg1057), and thus, regulates proteins involved in c‐di‐GMP metabolism. LvbR determines biofilm architecture, since L. pneumophila lacking lvbR accumulates less sessile biomass and forms homogeneous mat‐like structures, while the parental strain develops more compact bacterial aggregates. Comparative transcriptomics of sessile and planktonic ΔlvbR or ΔlqsR mutant strains revealed concerted (virulence, fitness island, metabolism) and reciprocally (motility) regulated genes in biofilm and broth respectively. Moreover, ΔlvbR is hyper‐competent for DNA uptake, defective for phagocyte infection, outcompeted by the parental strain in amoebae co‐infections and impaired for cell migration inhibition. Taken together, our results indicate that L. pneumophila LvbR is a novel pleiotropic transcription factor, which links the Lqs and c‐di‐GMP regulatory networks to control biofilm architecture and pathogen–host cell interactions.

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“…11 NO-bound Vc NosP has been demonstrated to regulate the autophosphorylation activity 18 of the quorum sensing kinase VpsS, 19–21 and Lpg NosP modulates a co-cistronic kinase (Fischer, et al unpublished data) whose cognate response regulator has been shown to result in a hyper-biofilm phenotype when deleted. 21, 22 …”

Section: Introductionmentioning

confidence: 99%

Spectral Characterization of a Novel NO Sensing Protein in Bacteria: NosP

et al. 2018

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A novel family of bacterial hemoproteins named NosP has been discovered recently; its members are proposed to function as nitric oxide (NO) responsive proteins involved in bacterial group behaviors such as quorum sensing and biofilm growth and dispersal. Currently, little is known about molecular activation mechanisms in NosP. Here, functional studies were performed utilizing the distinct spectroscopic characteristics associated with the NosP heme cofactor. NosPs from Pseudomonas aeruginosa (Pa), Vibrio cholerae (Vc) and Legionella pneumophila (Lpg) were studied in their ferrous-unligated forms as well as their ferrous-CO, ferrous-NO, and ferric-CN adducts. The resonance Raman (rR) data collected on the ferric forms strongly support the existence of a distorted heme-cofactor, which is a common feature in NO sensors. The ferrous spectra exhibit a 213 cm−1 feature, which is assigned to the Fe-Nhis stretching mode. The Fe-C and C-O frequencies in the spectra of ferrous-CO NosP complexes are inversely correlated with relatively similar frequencies, consistent with a proximal histidine ligand and a relatively hydrophobic environment. The rR spectra obtained for isotopically labeled ferrous-NO adducts provide evidence of formation of a 5-coordinate NO complex, resulting from proximal Fe-Nhis cleavage, which is believed to play a role in biological heme-NO signal transduction. Additionally, we found that of the three NosPs studied, Lpg NosP contains the most electropositive ligand binding pocket, while Pa NosP has the most electronegative ligand binding pocket. This pattern is also observed in the measured heme reduction potentials for these three proteins, which may indicate distinct functions for each.

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New insights into Legionella pneumophila biofilm regulation by c-di-GMP signaling

Cited by 29 publications

References 62 publications

Discovery of a Novel Nitric Oxide Binding Protein and Nitric-Oxide-Responsive Signaling Pathway in Pseudomonas aeruginosa

Discovery of a Novel Nitric Oxide Binding Protein and Nitric-Oxide-Responsive Signaling Pathway in Pseudomonas aeruginosa

The pleiotropic Legionella transcription factor LvbR links the Lqs and c‐di‐GMP regulatory networks to control biofilm architecture and virulence

Spectral Characterization of a Novel NO Sensing Protein in Bacteria: NosP

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