Deletion of potD, encoding a putative spermidine-binding protein, results in a complex phenotype in Legionella pneumophila

Nasrallah, Gheyath K.; Abdelhady, Hany; Tompkins, Nicholas; Carson, Kaitlyn R.; Garduño, Rafael A.

doi:10.1016/j.ijmm.2014.05.004

Cited by 10 publications

(8 citation statements)

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“…7B) (33). In addition to having the genes necessary to synthesize putrescine, L. pneumophila appears to have the ability to import exogenous putrescine-utilizing proteins analogous to the PotABCD putrescine/spermidine transporter of Escherichia coli (34). Finally, we propose that LbtA helps catalyze the final step of legiobactin synthesis, namely, the joining of two citrates via a putrescine link (Fig.…”

Section: Discussionmentioning

confidence: 95%

The Legionella pneumophila Siderophore Legiobactin Is a Polycarboxylate That Is Identical in Structure to Rhizoferrin

Burnside

Shafaie

et al. 2015

Infect Immun

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bLegionella pneumophila, the agent of Legionnaires' disease, secretes a siderophore (legiobactin) that promotes bacterial infection of the lung. In past work, we determined that cytoplasmic LbtA (from Legiobactin gene A) promotes synthesis of legiobactin, inner membrane LbtB aids in export of the siderophore, and outer membrane LbtU and inner membrane LbtC help mediate ferrilegiobactin uptake and assimilation. However, the past studies examined legiobactin contained within bacterial culture supernatants. By utilizing high-pressure liquid chromatography that incorporates hydrophilic interaction-based chemistry, we have now purified legiobactin from supernatants of virulent strain 130b that is suitable for detailed chemical analysis. High-resolution mass spectrometry (MS) revealed that the molecular mass of (protonated) legiobactin is 437.140 Da. On the basis of the results obtained from both MS analysis and various forms of nuclear magnetic resonance, we found that legiobactin is composed of two citric acid residues linked by a putrescine bridge and thus is identical in structure to rhizoferrin, a polycarboxylate-type siderophore made by many fungi and several unrelated bacteria. Both purified legiobactin and rhizoferrin obtained from the fungus Cunninghamella elegans were able to promote Fe 3؉ uptake by wild-type L. pneumophila as well as enhance growth of iron-starved bacteria. These results did not occur with 130b mutants lacking lbtU or lbtC, indicating that both endogenously made legiobactin and exogenously derived rhizoferrin are assimilated by L. pneumophila in an LbtU-and LbtC-dependent manner.T he Gram-negative bacterium Legionella pneumophila is both an inhabitant of natural and man-made water systems and the primary etiologic agent of Legionnaires' disease, an increasingly common and serious form of pneumonia (1-3). In its aquatic habitats, L. pneumophila survives in biofilms and as an intracellular parasite of amoebae, and in the lung, it grows primarily in macrophages (4-7). Iron has long been recognized as a major aspect of L. pneumophila replication, intracellular infection, and virulence (8, 9). For ferrous iron assimilation, L. pneumophila utilizes a secreted pyomelanin that has ferric reductase activity and the inner membrane Fe 2ϩ transporter FeoB (10, 11). For ferric iron uptake, the bacterium uses the siderophore legiobactin (12, 13). Both of these iron acquisition pathways are required for infection of the lungs by L. pneumophila (10,14).The investigation of legiobactin has followed a rather circuitous path. Indeed, it was originally thought that L. pneumophila does not produce siderophores; this conclusion was based on negative data obtained from both the Arnow and Csáky assays, which detect catecholate and hydroxymate structures, respectively, and the Chrome Azurol S (CAS) assay, which detects iron chelators independently of their structure (15-17). However, in 2000, we demonstrated that L. pneumophila strains can secrete a siderophore activity that is detected by the CAS assay when the ba...

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Section: Discussionmentioning

confidence: 95%

The Legionella pneumophila Siderophore Legiobactin Is a Polycarboxylate That Is Identical in Structure to Rhizoferrin

Burnside

Shafaie

et al. 2015

Infect Immun

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“…Stress resistance assays were performed as the previously described methods (Wong et al, 2007 ; Allen and Schmitt, 2009 ; Liu et al, 2013 ; Xie et al, 2013 , 2016 ; Nasrallah et al, 2014 ; Huang et al, 2016 ). Fifty microliters of overnight cultures of MY1902, Δ qseC , and C-Δ qseC were subcultured at a dilution of 1:100 into 5 mL fresh TSB with 5% inactivated bovine serum and 0.01% NAD and the cells were grown at 37°C with 220 rpm.…”

Section: Methodsmentioning

confidence: 99%

QseC Mediates Osmotic Stress Resistance and Biofilm Formation in Haemophilus parasuis

Dai

Wen

et al. 2018

Front. Microbiol.

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Haemophilus parasuis is known as a commensal organism discovered in the upper respiratory tract of swine where the pathogenic bacteria survive in various adverse environmental stress. QseC, a histidine protein kinase of the two-component regulatory systems CheY/QseC, is involved in the environmental adaptation in bacteria. To investigate the role of QseC in coping with the adverse environment stresses and survive in the host, we constructed a qseC mutant of H. parasuis serovar 13 strain (ΔqseC), MY1902. In this study, we found that QseC was involved in stress tolerance of H. parasuis, by the ΔqseC exhibited a decreased resistance to osmotic pressure, oxidative stress, and heat shock. Moreover, the ΔqseC weakened the ability to take up iron and biofilm formation. We also found that the QseC participate in sensing the epinephrine in environment to regulate the density of H. parasuis.

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“…Other gene products implicated in the production of FFs are the HtpB chaperonin and the putative spermidine transporter PotD. Overexpression of HtpB leads to filamentation in Lp and E. coli (Garduño and Chong, 2013 ), and deletion of potD completely inhibits filamentation in stationary phase, while the pot operon promoter is highly activated in FFs (Nasrallah et al, 2014 ). Nonetheless, as for CsrA, no mechanism on how HtpB and PotD induce filamentation has been elucidated.…”

Section: Dissecting Lp's Developmental Networkmentioning

confidence: 99%

The many forms of a pleomorphic bacterial pathogenâ€”the developmental network of Legionella pneumophila

2014

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Legionella pneumophila is a natural intracellular bacterial parasite of free-living freshwater protozoa and an accidental human pathogen that causes Legionnaires' disease. L. pneumophila differentiates, and does it in style. Recent experimental data on L. pneumophila's differentiation point at the existence of a complex network that involves many developmental forms. We intend readers to: (i) understand the biological relevance of L. pneumophila's forms found in freshwater and their potential to transmit Legionnaires' disease, and (ii) learn that the common depiction of L. pneumophila's differentiation as a biphasic developmental cycle that alternates between a replicative and a transmissive form is but an oversimplification of the actual process. Our specific objectives are to provide updates on the molecular factors that regulate L. pneumophila's differentiation (Section The Differentiation Process and Its Regulation), and describe the developmental network of L. pneumophila (Section Dissecting Lp's Developmental Network), which for clarity's sake we have dissected into five separate developmental cycles. Finally, since each developmental form seems to contribute differently to the human pathogenic process and the transmission of Legionnaires' disease, readers are presented with a challenge to develop novel methods to detect the various L. pneumophila forms present in water (Section Practical Implications), as a means to improve our assessment of risk and more effectively prevent legionellosis outbreaks.

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Deletion of potD, encoding a putative spermidine-binding protein, results in a complex phenotype in Legionella pneumophila

Cited by 10 publications

References 70 publications

The Legionella pneumophila Siderophore Legiobactin Is a Polycarboxylate That Is Identical in Structure to Rhizoferrin

The Legionella pneumophila Siderophore Legiobactin Is a Polycarboxylate That Is Identical in Structure to Rhizoferrin

QseC Mediates Osmotic Stress Resistance and Biofilm Formation in Haemophilus parasuis

The many forms of a pleomorphic bacterial pathogenâ€”the developmental network of Legionella pneumophila

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