The Role of Pseudomonas aeruginosa Lipopolysaccharide in Bacterial Pathogenesis and Physiology

The major constituent of the outer membrane of Gram-negative bacteria is lipopolysaccharide (LPS), which is comprised of lipid A, core oligosaccharide, and O antigen, which is a long polysaccharide chain extending into the extracellular environment. Due to the localization of LPS, it is a key molecule on the bacterial cell wall that is recognized by the host to deploy an immune defence in order to neutralize invading pathogens. However, LPS also promotes bacterial survival in a host environment by protecting the bacteria from these threats. This review explores the relationship between the different LPS glycoforms of the opportunistic pathogen Pseudomonas aeruginosa and the ability of this organism to cause persistent infections, especially in the genetic disease cystic fibrosis. We also discuss the role of LPS in facilitating biofilm formation, antibiotic resistance, and how LPS may be targeted by new antimicrobial therapies.

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The In Vitro Antibiofilm Activity of Water Leaf Extract of Papaya (Carica papaya L.) against Pseudomonas aeruginosa

Current Biochemistry ◽

10.29244/cb.2.3.150-163 ◽

2017 ◽

Vol 2 (3) ◽

pp. 150-163

Author(s):

Ekajayanti Kining ◽

Syamsul Falah ◽

Novik Nurhidayat

Keyword(s):

Pseudomonas Aeruginosa ◽

Contact Time ◽

Cell Attachment ◽

Water Extract ◽

Opportunistic Pathogen ◽

Bacterial Biofilm ◽

Antibiofilm Activity ◽

Bacterial Survival ◽

Optimum Conditions

Pseudomonas aeruginosa is one of opportunistic pathogen forming bacterial biofilm. The biofilm sustains the bacterial survival and infections. This study aimed to assess the activity of water extract of papaya leaves on inhibition of cells attachment, growth and degradation of the biofilm using crystal violet (CV) biofilm assay. Research results showed that water extract of papaya leaves contains alkaloids, tanins, flavonoids, and steroids/terpenoids and showed antibacterial activity and antibiofilm against P. aeruginosa. Addition of extract can inhibit the cell attachment and was able to degrade the biofilm of 40.92% and 48.058% respectively at optimum conditions: extract concentration of 25% (v/v), temperature 37.5 °C and contact time 45 minutes. With a concentration of 25% (v/v), temperature of 50 °C and the contact time of 3 days, extract of papaya leaves can inhibit the growth of biofilms of 39.837% v/v.

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Role of pili in adherence of Pseudomonas aeruginosa to mammalian buccal epithelial cells

Infection and Immunity ◽

10.1128/iai.29.3.1146-1151.1980 ◽

1980 ◽

Vol 29 (3) ◽

pp. 1146-1151 ◽

Cited By ~ 1

Author(s):

D E Woods ◽

D C Straus ◽

W G Johanson ◽

V K Berry ◽

J A Bass

Keyword(s):

Pseudomonas Aeruginosa ◽

Epithelial Cells ◽

Opportunistic Pathogen ◽

In Vitro System ◽

Heterologous Antiserum ◽

Buccal Epithelial Cells ◽

Serological Studies ◽

Seriously Ill Patients

Adherence of Pseudomonas aeruginosa organisms to the upper respiratory epithelium of seriously ill patients in vitro is correlated with subsequent colonization of the respiratory tract by this opportunistic pathogen. The role of pili in the attachment to epithelial cells of P. aeruginosa was studied in an in vitro system employing human buccal epithelial cells and P. aeruginosa pretreated by various means. Pretreatment of the bacteria with proteases, heat, or Formalin caused a significant decrease in adherence. A decrease when compared with controls was also noted in the adherence of P. aeruginosa organisms to buccal epithelial cells preincubated with purified pili prepared from the strain used for adherence testing; however, pili prepared from a heterologous strain failed to block adherence. Similar results were obtained in serological studies when antisera to purified pili prepared from the strain used for adherence testing decreased adherence, whereas heterologous antiserum to pili did not decrease adherence. From these results it appears that pili mediate the adherence of P. aeruginosa organisms to human buccal epithelial cells.

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Pseudomonas aeruginosa Oligoribonuclease Controls Susceptibility to Polymyxin B by Regulating Pel Exopolysaccharide Production

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02072-21 ◽

2022 ◽

Author(s):

Baopeng Yang ◽

Yujun Jiang ◽

Yongxin Jin ◽

Fang Bai ◽

Zhihui Cheng ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Bacterial Resistance ◽

Defense Mechanism ◽

Extracellular Polysaccharide ◽

Opportunistic Pathogen ◽

Polymyxin B ◽

Guanosine Monophosphate ◽

Extracellular Dna ◽

Bacterial Cells ◽

Bacterial Survival

Polymyxins are considered as the last resort antibiotics to treat infections caused by multidrug-resistant Gram negative pathogens. Pseudomonas aeruginosa is an opportunistic pathogen that causes various infections in humans. Proteins involved in lipopolysaccharide modification and maintaining inner and outer membrane integrities have been found to contribute to the bacterial resistance to polymyxins. Oligoribonuclease (Orn) is an exonuclease that regulates the homeostasis of intracellular (3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP), thereby regulating the production of extracellular polysaccharide in P. aeruginosa . Previously, we demonstrated that Orn affects the bacterial resistance to fluoroquinolone, β-lactam and aminoglycoside antibiotics. In this study, we found that mutation of orn increased the bacterial survival following polymyxin B treatment in a wild type P. aeruginosa strain PA14. Overexpression of c-di-GMP degradation enzymes in the orn mutant reduced the bacterial survival. By using a fluorescence labeled polymyxin B, we found that mutation of orn increased the bacterial surface bound polymyxin B. Deletion of the Pel synthesis genes or treatment with a Pel hydrolase reduced the surface bound polymyxin B and bacterial survival. We further demonstrated that Pel binds to extracellular DNA (eDNA), which traps polymyxin B and thus protects the bacterial cells. Collectively, our results revealed a novel defense mechanism against polymyxin in P. aeruginosa .

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Pseudomonas aeruginosa-Mediated Damage Requires Distinct Receptors at the Apical and Basolateral Surfaces of the Polarized Epithelium

Infection and Immunity ◽

10.1128/iai.01215-09 ◽

2009 ◽

Vol 78 (3) ◽

pp. 939-953 ◽

Cited By ~ 36

Author(s):

Iwona Bucior ◽

Keith Mostov ◽

Joanne N. Engel

Keyword(s):

Pseudomonas Aeruginosa ◽

Mdck Cells ◽

Three Dimensional ◽

Opportunistic Pathogen ◽

Necessary And Sufficient ◽

Plastic Surfaces ◽

Pharmacologic Inhibition ◽

Increased Susceptibility ◽

Polarized Epithelium

ABSTRACT Pseudomonas aeruginosa, an important opportunistic pathogen of humans, exploits epithelial damage to establish infection. We have rigorously explored the role of N-glycoproteins and heparan sulfate proteoglycans (HSPGs) in P. aeruginosa-mediated attachment and subsequent downstream events at the apical (AP) and basolateral (BL) surfaces of polarized epithelium. We demonstrate that the N-glycan chains at the AP surface are necessary and sufficient for binding, invasion, and cytotoxicity to kidney (MDCK) and airway (Calu-3) cells grown at various states of polarization on Transwell filters. Upregulation of N-glycosylation enhanced binding, whereas pharmacologic inhibition of N-glycosylation or infection of MDCK cells defective in N-glycosylation resulted in decreased binding. In contrast, at the BL surface, the HS moiety of HSPGs mediated P. aeruginosa binding, cytotoxicity, and invasion. In incompletely polarized epithelium, HSPG abundance was increased at the AP surface, explaining its increased susceptibility to P. aeruginosa colonization and damage. Using MDCK cells grown as three-dimensional cysts as a model for epithelial organs, we show that P. aeruginosa specifically colocalized with HS-rich areas at the BL membrane but with complex N-glycans at the AP surface. Finally, P. aeruginosa bound to HS chains and N-glycans coated on plastic surfaces, showing the highest binding affinity toward isolated HS chains. Together, these findings demonstrate that P. aeruginosa recognizes distinct receptors on the AP and BL surfaces of polarized epithelium. Changes in the composition of N-glycan chains and/or in the distribution of HSPGs may explain the enhanced susceptibility of damaged epithelium to P. aeruginosa.

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PmtA Regulates Pyocyanin Expression and Biofilm Formation in Pseudomonas aeruginosa

Frontiers in Microbiology ◽

10.3389/fmicb.2021.789765 ◽

2021 ◽

Vol 12 ◽

Author(s):

Amy V. Thees ◽

Kathryn M. Pietrosimone ◽

Clare K. Melchiorre ◽

Jeremiah N. Marden ◽

Joerg Graf ◽

...

Keyword(s):

Oxidative Stress ◽

Pseudomonas Aeruginosa ◽

Metal Binding ◽

Biofilm Formation ◽

Binding Capacity ◽

Opportunistic Pathogen ◽

Small Molecular Weight ◽

Heavy Metal Binding ◽

The Impact

The opportunistic pathogen Pseudomonas aeruginosa expresses a small molecular weight, cysteine-rich protein (PmtA), identified as a metallothionein (MT) protein family member. The MT family proteins have been well-characterized in eukaryotes as essential for zinc and copper homeostasis, protection against oxidative stress, and the ability to modify a variety of immune activities. Bacterial MTs share sequence homology, antioxidant chemistry, and heavy metal-binding capacity with eukaryotic MTs, however, the impact of bacterial MTs on virulence and infection have not been well-studied. In the present study, we investigated the role of PmtA in P. aeruginosa PAO1 using a PmtA-deficient strain (ΔpmtA). Here we demonstrated the virulence factor, pyocyanin, relies on the expression of PmtA. We showed that PmtA may be protective against oxidative stress, as an alternative antioxidant, glutathione, can rescue pyocyanin expression. Furthermore, the expression of phzM, which encodes a pyocyanin precursor enzyme, was decreased in the ΔpmtA mutant during early stationary phase. Upregulated pmtA expression was previously detected in confluent biofilms, which are essential for chronic infection, and we observed that the ΔpmtA mutant was disrupted for biofilm formation. As biofilms also modulate antibiotic susceptibility, we examined the ΔpmtA mutant susceptibility to antibiotics and found that the ΔpmtA mutant is more susceptible to cefepime and ciprofloxacin than the wild-type strain. Finally, we observed that the deletion of pmtA results in decreased virulence in a waxworm model. Taken together, our results support the conclusion that PmtA is necessary for the full virulence of P. aeruginosa and may represent a potential target for therapeutic intervention.

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Recent advances in understanding Pseudomonas aeruginosa as a pathogen

F1000Research ◽

10.12688/f1000research.10506.1 ◽

2017 ◽

Vol 6 ◽

pp. 1261 ◽

Cited By ~ 63

Author(s):

Jens Klockgether ◽

Burkhard Tümmler

Keyword(s):

Pseudomonas Aeruginosa ◽

Population Biology ◽

Recent Progress ◽

Human Subjects ◽

Opportunistic Pathogen ◽

Mammalian Host ◽

Secretion Systems ◽

Chronic Infections ◽

Type Vi Secretion

The versatile and ubiquitousPseudomonas aeruginosais an opportunistic pathogen causing acute and chronic infections in predisposed human subjects. Here we review recent progress in understandingP. aeruginosapopulation biology and virulence, its cyclic di-GMP-mediated switches of lifestyle, and its interaction with the mammalian host as well as the role of the type III and type VI secretion systems inP. aeruginosainfection.

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PmrB Mutations Promote Polymyxin Resistance of Pseudomonas aeruginosa Isolated from Colistin-Treated Cystic Fibrosis Patients

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.05829-11 ◽

2011 ◽

Vol 56 (2) ◽

pp. 1019-1030 ◽

Cited By ~ 106

Author(s):

Samuel M. Moskowitz ◽

Mark K. Brannon ◽

Nandini Dasgupta ◽

Miyuki Pier ◽

Nicole Sgambati ◽

...

Keyword(s):

Cystic Fibrosis ◽

Pseudomonas Aeruginosa ◽

Lipid A ◽

Clinical Isolates ◽

Gain Of Function ◽

Content Type ◽

Regulatory Systems ◽

Repeated Passage ◽

High Level

ABSTRACTPseudomonas aeruginosacan develop resistance to polymyxin and other cationic antimicrobial peptides. Previous work has shown that mutations in the PmrAB and PhoPQ regulatory systems can confer low to moderate levels of colistin (polymyxin E) resistance in laboratory strains and clinical isolates of this organism (MICs of 8 to 64 mg/liter). To explore the role of PmrAB in high-level clinical polymyxin resistance,P. aeruginosaisolates from chronically colistin-treated cystic fibrosis patients, most with colistin MICs of >512 mg/liter, were analyzed. These cystic fibrosis isolates contained probable gain-of-functionpmrBalleles that conferred polymyxin resistance to strains with a wild-type orpmrABdeletion background. Double mutantpmrBalleles that contained mutations in both the periplasmic and dimerization-phosphotransferase domains markedly augmented polymyxin resistance. Expression of mutantpmrBalleles induced transcription from the promoter of thearnBoperon and stimulated addition of 4-amino-l-arabinose to lipid A, consistent with the known role of this lipid A modification in polymyxin resistance. For some highly polymyxin-resistant clinical isolates, repeated passage without antibiotic selection pressure resulted in loss of resistance, suggesting that secondary suppressors occur at a relatively high frequency and account for the instability of this phenotype. These results indicate thatpmrBgain-of-function mutations can contribute to high-level polymyxin resistance in clinical strains ofP. aeruginosa.

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The LasB Elastase of Pseudomonas aeruginosa Acts in Concert with Alkaline Protease AprA To Prevent Flagellin-Mediated Immune Recognition

Infection and Immunity ◽

10.1128/iai.00939-15 ◽

2015 ◽

Vol 84 (1) ◽

pp. 162-171 ◽

Cited By ~ 35

Author(s):

Fiordiligie Casilag ◽

Anne Lorenz ◽

Jonas Krueger ◽

Frank Klawonn ◽

Siegfried Weiss ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Alkaline Protease ◽

Opportunistic Pathogen ◽

Airway Epithelial Cells ◽

Immune Recognition ◽

Airway Epithelial ◽

Content Type ◽

Persistent Infections ◽

Modulating Functions ◽

Immune Detection

The opportunistic pathogenPseudomonas aeruginosais capable of establishing severe and persistent infections in various eukaryotic hosts. It encodes a wide array of virulence factors and employs several strategies to evade immune detection. In the present study, we screened the Harvard Medical School transposon mutant library ofP. aeruginosaPA14 for bacterial factors that modulate interleukin-8 responses in A549 human airway epithelial cells. We found that in addition to the previously identified alkaline protease AprA, the elastase LasB is capable of degrading exogenous flagellin under calcium-replete conditions and prevents flagellin-mediated immune recognition. Our results indicate that the production of two proteases with anti-flagellin activity provides a failsafe mechanism forP. aeruginosato ensure the maintenance of protease-dependent immune-modulating functions.

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Biosynthesis of lipopolysaccharides with different length of the O-specific region as a virulence factor of Gram-negative bacteria

Postępy Higieny i Medycyny Doświadczalnej ◽

10.5604/01.3001.0012.1735 ◽

2018 ◽

Vol 72 ◽

pp. 573-586

Author(s):

Eva Krzyżewska ◽

Jacek Rybka

Keyword(s):

Outer Membrane ◽

Lipid A ◽

Specific Antigen ◽

Gram Negative Bacteria ◽

Bacterial Survival ◽

Core Oligosaccharide ◽

Gram Negative ◽

O Antigen ◽

Length Regulation ◽

External Part

The outer membrane of Gram-negative bacteria is a biological structure with a unique composition that significantly contributes to the survival of bacteria in the unfavorable conditions of the host organism. The lipopolysaccharide constitutes about 70% of the external part of the outer membrane. The LPS molecule is composed of three different parts: lipid A, core oligosaccharide and O antigen. Despite the O-specific antigen being one of the most intensely studied surface structures of bacterial polysaccharides, a number of questions regarding the mechanism of the O antigen biosynthesis and its transport to the cell surface are still unanswered. The paper describes the biosynthesis of the lipopolysaccharide molecule, with particular emphasis on the O-specific chain biosynthesis, the mechanism of lipopolysaccharide length regulation and the influence of the type of synthesized O-specific chains on bacterial survival in adverse host organisms.

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Discovery of an inhibitor of the production of the Pseudomonas aeruginosa virulence factor pyocyanin in wild-type cells

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.12.137 ◽

2016 ◽

Vol 12 ◽

pp. 1428-1433 ◽

Cited By ~ 8

Author(s):

Bernardas Morkunas ◽

Balint Gal ◽

Warren R J D Galloway ◽

James T Hodgkinson ◽

Brett M Ibbeson ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Quorum Sensing ◽

Cell Signalling ◽

Opportunistic Pathogen ◽

Wild Type ◽

Wide Range ◽

Potential Applications ◽

Therapeutic Context ◽

Pyocyanin Production

Pyocyanin is a small molecule produced by Pseudomonas aeruginosa that plays a crucial role in the pathogenesis of infections by this notorious opportunistic pathogen. The inhibition of pyocyanin production has been identified as an attractive antivirulence strategy for the treatment of P. aeruginosa infections. Herein, we report the discovery of an inhibitor of pyocyanin production in cultures of wild-type P. aeruginosa which is based around a 4-alkylquinolin-2(1H)-one scaffold. To the best of our knowledge, this is the first reported example of pyocyanin inhibition by a compound based around this molecular framework. The compound may therefore be representative of a new structural sub-class of pyocyanin inhibitors, which could potentially be exploited in in a therapeutic context for the development of critically needed new antipseudomonal agents. In this context, the use of wild-type cells in this study is notable, since the data obtained are of direct relevance to native situations. The compound could also be of value in better elucidating the role of pyocyanin in P. aeruginosa infections. Evidence suggests that the active compound reduces the level of pyocyanin production by inhibiting the cell–cell signalling mechanism known as quorum sensing. This could have interesting implications; quorum sensing regulates a range of additional elements associated with the pathogenicity of P. aeruginosa and there is a wide range of other potential applications where the inhibition of quorum sensing is desirable.

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