scholarly journals Insight into the resistome and quorum sensing system of a divergent Acinetobacter pittii isolate from an untouched site of the Lechuguilla Cave

2019 ◽  
Author(s):  
Han Ming Gan ◽  
Peter Wengert ◽  
Hazel A. Barton ◽  
André O. Hudson ◽  
Michael A. Savka
Keyword(s):  
Culture Medium ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Whole Genome Sequence ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Acinetobacter Pittii ◽  
Hospital Acquired ◽  
Type Strains ◽  
Insight Into

AbstractAcinetobacter are Gram-negative bacteria belonging to the sub-phyla Gammaproteobacteria, commonly associated with soils, animal feeds and water. Some members of the Acinetobacter have been implicated in hospital-acquired infections, with broad-spectrum antibiotic resistance. Here we report the whole genome sequence of LC510, an Acinetobacter species isolated from deep within a pristine location of the Lechuguilla Cave. Pairwise nucleotide comparison to three type strains within the genus Acinetobacter assigned LC510 as an Acinetobacter pittii isolate. Scanning of the LC510 genome identified two genes coding for β-lactamase resistance, despite the fact that LC510 was isolated from a portion of the cave not previously visited by humans and protected from anthropogenic input. The ability to produce acyl-homoserine lactone (AHL) signal in culture medium, an observation that is consistent with the identification of the luxI and luxR homologs in its genome, suggests that cell-to-cell communication remains important in an isolated cave ecosystem.

scholarly journals Volatiles from Subtropical Convolvulaceae That Interfere with Bacterial Cell-to-Cell Communication as Potential Antipathogenic Drugs

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
María C. Luciardi ◽  
María V. Pérez Hernández ◽  
Nora Muruaga ◽  
Alicia Bardón ◽  
Mario E. Arena ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Cell Communication ◽  
Homoserine Lactone ◽  
Key Factors ◽  
Elastase Activity ◽  
Persistent Infections ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Alternative Approaches

Increasing chronic bacterial infections create an urgent need for new antimicrobial agents or strategies for their control. Targeting virulence is one of the alternative approaches to find new medicines to treat persistent infections due to bacteria with biofilm-phenotype which are more resistant to antibiotics than their planktonic counterparts having an extreme capacity for evading the host defences. A bioguided study of sixteen extracts from flowers and leaves of four subtropical Convolvulaceae species provided evidence of the occurrence of antipathogenic natural products active against Gram positive and negative bacteria. Particularly, volatile metabolites fromMerremia dissectacreeper, a food and medicinal plant, were able to interfere with thePseudomonas aeruginosaquorum sensing system by a strong decrease ofN-acyl homoserine lactone (AHL) biosynthesis (63–75%), which attenuated the virulence factor expression like biofilm (55%) and elastase activity (up to 27%), key factors that enable the colonization and dissemination of the infection in the host. Control of theP. aeruginosabiofilm and the QS process by phytochemicals, such as (+) spathulenol, isolated from a bioactive extract ofM. dissectaleaves would be a good strategy for the development of new and effective antipathogenic drugs.

scholarly journals Inhibition of exoprotease production in Aeromonas hydrophila by rhizome extract of temu lawak (Curcuma xanthorrhiza (Roxb.)

2006 ◽  
Vol 4 (2) ◽  
pp. 45-54
Author(s):  
UMI LESTARI ◽  
ARTINI PANGASTUTI ◽  
ARI SUSILOWATI
Keyword(s):  
Quorum Sensing ◽  
Ethyl Acetate ◽  
Aeromonas Hydrophila ◽  
Ethanol Extract ◽  
Homoserine Lactone ◽  
Sensing System ◽  
Development Of Resistance ◽  
Quorum Sensing System ◽  
Assay Result ◽  
Curcuma Xanthorrhiza

Conventional treatment of infectious diseases is based on compounds that kill or inhibit the growth of bacteria. A major concern with this approach is the frequent development of resistance to antimicrobial compounds. The discovery of communication (quorum sensing system) regulating bacterial virulence opens up ways to control certain bacterial infectious without interfering the growth. The fish pathogen Aeromonas hydrophila produces quorum sensing signal, NButanoyl-L-Homoserine Lactone (C4-HSL). C4-HSL regulates exoprotease synthesis, a virulence factor of A. hydrophila. Expression of exoprotease can be blocked by using quorum sensing inhibitor. The purpose of this study was to investigate the inhibiting effect of Curcuma xanthorrhiza (Roxb.) extract to exoprotease production of A. hydrophila. Extraction was conducted by using n-hexane, ethyl acetate and ethanol. The qualitative exoprotease assay result showed that n-hexane extract of C. xanthorrhiza had not effect on growth and exoprotease production of A. hydrophila. Meanwhile, 4% of ethyl acetate and ethanol extract of C. xanthorrhiza can inhibit exoprotease production without affecting A. hydrophilla growth. The quantitative exoprotease assay result showed that 4% of ethyl acetate and ethanol extract can inhibit the exoprotease production by 93,9% and 95,6%. The growth of A. hydrophila was not affected by this extract.

scholarly journals PqsE Functions Independently of PqsR-Pseudomonas Quinolone Signal and Enhances the rhl Quorum-Sensing System

2008 ◽  
Vol 190 (21) ◽  
pp. 7043-7051 ◽  
Author(s):  
John M. Farrow ◽  
Zoe M. Sund ◽  
Matthew L. Ellison ◽  
Dana S. Wade ◽  
James P. Coleman ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Virulence Factors ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Chronic Infections ◽  
Signaling Systems ◽  
Sensing System ◽  
Pseudomonas Quinolone Signal ◽  
Quorum Sensing System ◽  
Hostile Environments

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that causes both acute and chronic infections in immunocompromised individuals. This gram-negative bacterium produces a battery of virulence factors that allow it to infect and survive in many different hostile environments. The control of many of these virulence factors falls under the influence of one of three P. aeruginosa cell-to-cell signaling systems. The focus of this study, the quinolone signaling system, functions through the Pseudomonas quinolone signal (PQS), previously identified as 2-heptyl-3-hydroxy-4-quinolone. This signal binds to and activates the LysR-type transcriptional regulator PqsR (also known as MvfR), which in turn induces the expression of the pqsABCDE operon. The first four genes of this operon are required for PQS synthesis, but the fifth gene, pqsE, is not. The function of the pqsE gene is not known, but it is required for the production of multiple PQS-controlled virulence factors and for virulence in multiple models of infection. In this report, we show that PqsE can activate PQS-controlled genes in the absence of PqsR and PQS. Our data also suggest that the regulatory activity of PqsE requires RhlR and indicate that a pqsE mutant can be complemented for pyocyanin production by a large excess of exogenous N-butyryl homoserine lactone (C4-HSL). Finally, we show that PqsE enhances the ability of Escherichia coli expressing RhlR to respond to C4-HSL. Overall, our data lead us to conclude that PqsE functions as a regulator that is independent of PqsR and PQS but dependent on the rhl quorum-sensing system.

scholarly journals Bacterial Growth Stimulation with Exogenous Siderophore and Synthetic N-Acyl Homoserine Lactone Autoinducers under Iron-Limited and Low-Nutrient Conditions

2000 ◽  
Vol 66 (7) ◽  
pp. 2797-2803 ◽  
Author(s):  
Le Luo Guan ◽  
Hiroyuki Onuki ◽  
Kei Kamino
Keyword(s):  
Bacterial Growth ◽  
Culture Medium ◽  
Cell Communication ◽  
Direct Interaction ◽  
Growth Stimulation ◽  
Homoserine Lactone ◽  
Marine Sponges ◽  
Siderophore Production ◽  
Iron Binding ◽  
Chemical Signal

ABSTRACT The growth of marine bacteria under iron-limited conditions was investigated. Neither siderophore production nor bacterial growth was detected for Pelagiobacter sp. strain V0110 when Fe(III) was present in the culture medium at a concentration of <1.0 μM. However, the growth of V0110 was strongly stimulated by the presence of trace amounts of exogenous siderophore from an alpha proteobacterium, V0902, and 1 nM N-acyl-octanoylhomoserine lactone (C8-HSL), which is known as a quorum-sensing chemical signal. Even though the iron-binding functionality of a hydroxamate siderophore was undetected in the supernatant of V0902, a hydroxamate siderophore was detected in the supernatant of V0110 under the above conditions. These results indicated that hydroxamate siderophore biosynthesis by V0110 began in response to the exogenous siderophore from V0902 when in the presence of C8-HSL; however, C8-HSL production by V0110 and V0902 was not detected. Direct interaction between V0902 and V0110 through siderophore from V0902 was observed in the dialyzing culture. Similar stimulated growth by exogenous siderophore and HSL was also observed in other non-siderophore-producing bacteria isolated from marine sponges and seawater. The requirement of an exogenous siderophore and an HSL for heterologous siderophore production indicated the possibility that cell-cell communication between different species was occurring.

scholarly journals The LuxM Homologue VanM from Vibrio anguillarumDirects the Synthesis of N-(3-Hydroxyhexanoyl)homoserine Lactone and N-Hexanoylhomoserine Lactone

2001 ◽  
Vol 183 (12) ◽  
pp. 3537-3547 ◽  
Author(s):  
Debra L. Milton ◽  
Victoria J. Chalker ◽  
David Kirke ◽  
Andrea Hardman ◽  
Miguel Cámara ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Vibrio Anguillarum ◽  
Homoserine Lactone ◽  
Regulatory Elements ◽  
Sequencing Error ◽  
Infection Model ◽  
Reading Frame ◽  
Acylhomoserine Lactone ◽  
Sensing System ◽  
Quorum Sensing System

ABSTRACT Vibrio anguillarum, which causes terminal hemorrhagic septicemia in fish, was previously shown to possess a LuxRI-type quorum-sensing system (vanRI) and to produceN-(3-oxodecanoyl)homoserine lactone (3-oxo-C10-HSL). However, a vanI null mutant still activatedN-acylhomoserine lactone (AHL) biosensors, indicating the presence of an additional quorum-sensing circuit in V. anguillarum. In this study, we have characterized this second system. Using high-pressure liquid chromatography in conjunction with mass spectrometry and chemical analysis, we identified two additional AHLs as N-hexanoylhomoserine lactone (C6-HSL) andN-(3-hydroxyhexanoyl)homoserine lactone (3-hydroxy-C6-HSL). Quantification of each AHL present in stationary-phase V. anguillarum spent culture supernatants indicated that 3-oxo-C10-HSL, 3-hydroxy-C6-HSL, and C6-HSL are present at approximately 8.5, 9.5, and 0.3 nM, respectively. Furthermore,vanM, the gene responsible for the synthesis of these AHLs, was characterized and shown to be homologous to the luxLand luxM genes, which are required for the production ofN-(3-hydroxybutanoyl)homoserine lactone in Vibrio harveyi. However, resequencing of the V. harveyi luxL/luxM junction revealed a sequencing error present in the published sequence, which when corrected resulted in a single open reading frame (termed luxM). Downstream ofvanM, we identified a homologue of luxN(vanN) that encodes a hybrid sensor kinase which forms part of a phosphorelay cascade involved in the regulation of bioluminescence in V. harveyi. A mutation in vanM abolished the production of C6-HSL and 3-hydroxy-C6-HSL. In addition, production of 3-oxo-C10-HSL was abolished in the vanM mutant, suggesting that 3-hydroxy-C6-HSL and C6-HSL regulate the production of 3-oxo-C10-HSL via vanRI. However, a vanN mutant displayed a wild-type AHL profile. Neither mutation affected either the production of proteases or virulence in a fish infection model. These data indicate that V. anguillarum possesses a hierarchical quorum sensing system consisting of regulatory elements homologous to those found in both V. fischeri (the LuxRI homologues VanRI) and V. harveyi (the LuxMN homologues, VanMN).

scholarly journals The Plant Pathogen Pantoea ananatis Produces N-Acylhomoserine Lactone and Causes Center Rot Disease of Onion by Quorum Sensing

2007 ◽  
Vol 189 (22) ◽  
pp. 8333-8338 ◽  
Author(s):  
Tomohiro Morohoshi ◽  
Yuta Nakamura ◽  
Go Yamazaki ◽  
Akio Ishida ◽  
Norihiro Kato ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Receptor Gene ◽  
Homoserine Lactone ◽  
Pantoea Ananatis ◽  
Signal Molecule ◽  
Acylhomoserine Lactone ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Rot Disease

ABSTRACT A number of gram-negative bacteria have a quorum-sensing system and produce N-acyl-l-homoserine lactone (AHL) that they use them as a quorum-sensing signal molecule. Pantoea ananatis is reported as a common colonist of wheat heads at ripening and causes center rot of onion. In this study, we demonstrated that P. ananatis SK-1 produced two AHLs, N-hexanoyl-l-homoserine lactone (C6-HSL) and N-(3-oxohexanoyl)-l-homoserine lactone (3-oxo-C6-HSL). We cloned the AHL-synthase gene (eanI) and AHL-receptor gene (eanR) and revealed that the deduced amino acid sequence of EanI/EanR showed high identity to those of EsaI/EsaR from P. stewartii. EanR repressed the ean box sequence and the addition of AHLs resulted in derepression of ean box. Inactivation of the chromosomal eanI gene in SK-1 caused disruption of exopolysaccharide (EPS) biosynthesis, biofilm formation, and infection of onion leaves, which were recovered by adding exogenous 3-oxo-C6-HSL. These results demonstrated that the quorum-sensing system involved the biosynthesis of EPS, biofilm formation, and infection of onion leaves in P. ananatis SK-1.

scholarly journals N-Acyl-l-Homoserine Lactone-Mediated Regulation of the Lip Secretion System inSerratia liquefaciens MG1

2001 ◽  
Vol 183 (5) ◽  
pp. 1805-1809 ◽  
Author(s):  
Kathrin Riedel ◽  
Thomas Ohnesorg ◽  
Karen A. Krogfelt ◽  
Thomas S. Hansen ◽  
Kenji Omori ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Homoserine Lactone ◽  
Secretion System ◽  
Type I ◽  
Extracellular Lipase ◽  
Sensing System ◽  
Serratia Liquefaciens ◽  
Quorum Sensing System ◽  
Insertion Mutants

ABSTRACT The analysis of Serratia liquefaciens MG1 ′luxAB insertion mutants that are responsive toN-butanoyl-l-homoserine lactone revealed that expression of lipB is controlled by the swrquorum-sensing system. LipB is part of the Lip exporter, a type I secretion system, which is responsible for the secretion of extracellular lipase, metalloprotease, and S-layer protein.

scholarly journals Global Regulatory Networks Control the Hrp Regulon of the Gall-Forming Bacterium Pantoea agglomerans pv. gypsophilae

2013 ◽  
Vol 26 (9) ◽  
pp. 1031-1043 ◽  
Author(s):  
Mary Panijel ◽  
Laura Chalupowicz ◽  
Guido Sessa ◽  
Shulamit Manulis-Sasson ◽  
Isaac Barash
Keyword(s):  
Type Iii Secretion ◽  
Regulatory Networks ◽  
Homoserine Lactone ◽  
Hypersensitive Reaction ◽  
Pantoea Agglomerans ◽  
Dependent Manner ◽  
Gall Formation ◽  
Sensing System ◽  
Regulatory Cascade ◽  
Quorum Sensing System

Gall formation by Pantoea agglomerans pv. gypsophilae is dependent on the hypersensitive response and pathogenicity (hrp) system. Previous studies demonstrated that PagR and PagI, regulators of the quorum-sensing system, induce expression of the hrp regulatory cascade (i.e., hrpXY, hrpS, and hrpL) that activates the HrpL regulon. Here, we isolated the genes of the Gac/Rsm global regulatory pathway (i.e., gacS, gacA, rsmB, and csrD) and of the post-transcriptional regulator rsmA. Our results demonstrate that PagR and PagI also upregulate expression of the Gac/Rsm pathway. PagR acts as a transcriptional activator of each of the hrp regulatory genes and gacA in a N-butanoyl-L-homoserine lactone-dependent manner as shown by gel shift experiments. Mutants of the Gac/Rsm genes or overexpression of rsmA significantly reduced Pantoea agglomerans virulence and colonization of gypsophila. Overexpression of rsmB sRNA abolished gall formation, colonization, and hypersensitive reaction on nonhost plants and prevented transcription of the hrp regulatory cascade, indicating a lack of functional type III secretion system. Expression of rsmB sRNA in the background of the csrD null mutant suggests that CsrD may act as a safeguard for preventing excessive production of rsmB sRNA. Results presented indicate that the hrp regulatory cascade is controlled directly by PagR and indirectly by RsmA, whereas deficiency in RsmA activity is epistatic to PagR induction.

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