Cell envelope proteases and peptidases of Pseudomonas aeruginosa: multiple roles, multiple mechanisms

2020 ◽  
Vol 44 (6) ◽  
pp. 857-873
Author(s):  
Astra Heywood ◽  
Iain L Lamont
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Protein Quality ◽  
Environmental Changes ◽  
Cell Envelope ◽  
Opportunistic Pathogen ◽  
Multiple Roles ◽  
Current State ◽  
Wide Range ◽  
Membrane Cell

ABSTRACT Pseudomonas aeruginosa is a Gram-negative bacterium that is commonly isolated from damp environments. It is also a major opportunistic pathogen, causing a wide range of problematic infections. The cell envelope of P. aeruginosa, comprising the cytoplasmic membrane, periplasmic space, peptidoglycan layer and outer membrane, is critical to the bacteria's ability to adapt and thrive in a wide range of environments. Over 40 proteases and peptidases are located in the P. aeruginosa cell envelope. These enzymes play many crucial roles. They are required for protein secretion out of the cytoplasm to the periplasm, outer membrane, cell surface or the environment; for protein quality control and removal of misfolded proteins; for controlling gene expression, allowing adaptation to environmental changes; for modification and remodelling of peptidoglycan; and for metabolism of small molecules. The key roles of cell envelope proteases in ensuring normal cell functioning have prompted the development of inhibitors targeting some of these enzymes as potential new anti-Pseudomonas therapies. In this review, we summarise the current state of knowledge across the breadth of P. aeruginosa cell envelope proteases and peptidases, with an emphasis on recent findings, and highlight likely future directions in their study.

scholarly journals Stress-Responsive Periplasmic Chaperones in Bacteria

2021 ◽  
Vol 8 ◽  
Author(s):  
Hyunhee Kim ◽  
Kevin Wu ◽  
Changhan Lee
Keyword(s):  
Outer Membrane ◽  
Protein Unfolding ◽  
Protein Quality ◽  
Environmental Changes ◽  
Outer Membrane Proteins ◽  
Acid Stress ◽  
Bacterial Survival ◽  
Wide Range ◽  
Periplasmic Proteins ◽  
Periplasmic Chaperones

Periplasmic proteins are involved in a wide range of bacterial functions, including motility, biofilm formation, sensing environmental cues, and small-molecule transport. In addition, a wide range of outer membrane proteins and proteins that are secreted into the media must travel through the periplasm to reach their final destinations. Since the porous outer membrane allows for the free diffusion of small molecules, periplasmic proteins and those that travel through this compartment are more vulnerable to external environmental changes, including those that result in protein unfolding, than cytoplasmic proteins are. To enable bacterial survival under various stress conditions, a robust protein quality control system is required in the periplasm. In this review, we focus on several periplasmic chaperones that are stress responsive, including Spy, which responds to envelope-stress, DegP, which responds to temperature to modulate chaperone/protease activity, HdeA and HdeB, which respond to acid stress, and UgpB, which functions as a bile-responsive chaperone.

scholarly journals Transcriptomic Analysis of the Sulfate Starvation Response of Pseudomonas aeruginosa

2007 ◽  
Vol 189 (19) ◽  
pp. 6743-6750 ◽  
Author(s):  
Tewes Tralau ◽  
Stéphane Vuilleumier ◽  
Christelle Thibault ◽  
Barry J. Campbell ◽  
C. Anthony Hart ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Stress Proteins ◽  
Large Family ◽  
Opportunistic Pathogen ◽  
Transport Systems ◽  
Sulfur Source ◽  
Secretion Systems ◽  
Starvation Response ◽  
Wide Range

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that causes a number of infections in humans, but is best known for its association with cystic fibrosis. It is able to use a wide range of sulfur compounds as sources of sulfur for growth. Gene expression in response to changes in sulfur supply was studied in P. aeruginosa E601, a cystic fibrosis isolate that displays mucin sulfatase activity, and in P. aeruginosa PAO1. A large family of genes was found to be upregulated by sulfate limitation in both isolates, encoding sulfatases and sulfonatases, transport systems, oxidative stress proteins, and a sulfate-regulated TonB/ExbBD complex. These genes were localized in five distinct islands on the genome and encoded proteins with a significantly reduced content of cysteine and methionine. Growth of P. aeruginosa E601 with mucin as the sulfur source led not only to a sulfate starvation response but also to induction of genes involved with type III secretion systems.

scholarly journals Mutational Analysis of RetS, an Unusual Sensor Kinase-Response Regulator Hybrid Required for Pseudomonas aeruginosa Virulence

2006 ◽  
Vol 74 (8) ◽  
pp. 4462-4473 ◽  
Author(s):  
Michelle A. Laskowski ◽  
Barbara I. Kazmierczak
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Mutational Analysis ◽  
Response Regulator ◽  
Acute Infection ◽  
Opportunistic Pathogen ◽  
Sensor Kinase ◽  
Chronic Infections ◽  
Reciprocal Regulation ◽  
Wide Range

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen capable of causing both acute and chronic infections in a wide range of hosts. Expression of the type III secretion system (T3SS) proteins is correlated with virulence in models of acute infection, while downregulation of the T3SS and upregulation of genes important for biofilm formation are observed during chronic infections. RetS, a hybrid sensor kinase-response regulator protein of P. aeruginosa, plays a key role in the reciprocal regulation of virulence factors required for acute versus chronic infection and is postulated to act in concert with two other sensor kinase-response regulator hybrids, GacS and LadS. This work examines the roles of the putative sensing and signal transduction domains of RetS in induction of the T3SS in vitro and in a murine model of acute pneumonia. We identify distinct signaling roles for the tandem receiver domains of RetS and present evidence suggesting that RetS may serve as a substrate for another sensor kinase. Phenotypes associated with RetS alleles lacking periplasmic and/or transmembrane domains further indicate that the periplasmic domain of RetS may transmit a signal that inhibits RetS activity during acute infections.

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

2016 ◽  
Vol 12 ◽  
pp. 1428-1433 ◽  
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.

Pseudomonas aeruginosa lectin LecB is located in the outer membrane and is involved in biofilm formation

Microbiology ◽  
2005 ◽  
Vol 151 (5) ◽  
pp. 1313-1323 ◽  
Author(s):  
Denis Tielker ◽  
Stephanie Hacker ◽  
Remy Loris ◽  
Martin Strathmann ◽  
Jost Wingender ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Biofilm Formation ◽  
Membrane Fraction ◽  
Opportunistic Pathogen ◽  
Cell Fractionation ◽  
Intrinsic Resistance ◽  
Outer Membrane Fraction ◽  
Airway Mucosa ◽  
Tract Infections

Pseudomonas aeruginosa is an opportunistic pathogen which causes a variety of diseases, including respiratory tract infections in patients suffering from cystic fibrosis. Therapeutic treatment of P. aeruginosa infections is still very difficult because the bacteria exhibit high intrinsic resistance against a variety of different antibiotics and, in addition, form stable biofilms, e.g. in the human lung. Several virulence factors are produced by P. aeruginosa, among them the two lectins LecA and LecB, which exert different cytotoxic effects on respiratory epithelial cells and presumably facilitate bacterial adhesion to the airway mucosa. Here, the physiology has been studied of the lectin LecB, which binds specifically to l-fucose. A LecB-deficient P. aeruginosa mutant was shown to be impaired in biofilm formation when compared with the wild-type strain, suggesting an important role for LecB in this process. This result prompted an investigation of the subcellular localization of LecB by cell fractionation and subsequent immunoblotting. The results show that LecB is abundantly present in the bacterial outer-membrane fraction. It is further demonstrated that LecB could be released specifically by treatment of the outer-membrane fraction with p-nitrophenyl α-l-fucose, whereas treatment with d-galactose had no effect. In contrast, a LecB protein carrying the mutation D104A, which results in a defective sugar-binding site, was no longer detectable in the membrane fraction, suggesting that LecB binds to specific carbohydrate ligands located at the bacterial cell surface. Staining of biofilm cells using fluorescently labelled LecB confirmed the presence of these ligands.

scholarly journals Insights into the Assembly of the Alginate Biosynthesis Machinery in Pseudomonas aeruginosa

2013 ◽  
Vol 79 (10) ◽  
pp. 3264-3272 ◽  
Author(s):  
Zahid U. Rehman ◽  
Yajie Wang ◽  
M. Fata Moradali ◽  
Iain D. Hay ◽  
Bernd H. A. Rehm
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stability Analysis ◽  
Experimental Evidence ◽  
Outer Membrane ◽  
Opportunistic Pathogen ◽  
Multiprotein Complex ◽  
Inner Membrane ◽  
Content Type ◽  
Alginate Production ◽  
The Impact

ABSTRACTPseudomonas aeruginosais an opportunistic pathogen of particular significance to cystic fibrosis patients. This bacterium produces the exopolysaccharide alginate, which is an indicator of poor prognosis for these patients. The proteins required for alginate polymerization and secretion are encoded by genes organized in a single operon; however, the existence of internal promoters has been reported. It has been proposed that these proteins form a multiprotein complex which extends from the inner to outer membrane. Here, experimental evidence supporting such a multiprotein complex was obtained via mutual stability analysis, pulldown assays, and coimmunoprecipitation. The impact of the absence of single proteins or subunits on this multiprotein complex, i.e., on the stability of potentially interacting proteins, as well as on alginate production was investigated. Deletion ofalgKin an alginate-overproducing strain, PDO300, interfered with the polymerization of alginate, suggesting that in the absence of AlgK, the polymerase and copolymerase subunits, Alg8 and Alg44, are destabilized. Based on mutual stability analysis, interactions between AlgE (outer membrane), AlgK (periplasm), AlgX (periplasm), Alg44 (inner membrane), Alg8 (inner membrane), and AlgG (periplasm) were proposed. Coimmunoprecipitation using a FLAG-tagged variant of AlgE further demonstrated its interaction with AlgK. Pulldown assays using histidine-tagged AlgK showed that AlgK interacts with AlgX, which in turn was also copurified with histidine-tagged Alg44. Detection of AlgG and AlgE in PAO1 supported the existence of internal promoters controlling expression of the respective genes. Overall experimental evidence was provided for the existence of a multiprotein complex required for alginate polymerization and secretion.

scholarly journals A Large-Scale Whole-Genome Comparison Shows that Experimental Evolution in Response to Antibiotics Predicts Changes in Naturally Evolved Clinical Pseudomonas aeruginosa

2019 ◽  
Vol 63 (12) ◽  
Author(s):  
Samuel J. T. Wardell ◽  
Attika Rehman ◽  
Lois W. Martin ◽  
Craig Winstanley ◽  
Wayne M. Patrick ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Experimental Evolution ◽  
Large Scale ◽  
Opportunistic Pathogen ◽  
Clinical Isolates ◽  
Genome Comparison ◽  
Chronic Infections ◽  
Content Type ◽  
Large Deletions ◽  
Wide Range

ABSTRACT Pseudomonas aeruginosa is an opportunistic pathogen that causes a wide range of acute and chronic infections. An increasing number of isolates have mutations that make them antibiotic resistant, making treatment difficult. To identify resistance-associated mutations, we experimentally evolved the antibiotic-sensitive strain P. aeruginosa PAO1 to become resistant to three widely used antipseudomonal antibiotics, namely, ciprofloxacin, meropenem, and tobramycin. Mutants could tolerate up to 2,048-fold higher concentrations of antibiotics than strain PAO1. Genome sequences were determined for 13 mutants for each antibiotic. Each mutant had between 2 and 8 mutations. For each antibiotic, at least 8 genes were mutated in multiple mutants, demonstrating the genetic complexity of resistance. For all three antibiotics, mutations arose in genes known to be associated with resistance but also in genes not previously associated with resistance. To determine the clinical relevance of mutations uncovered in this study, we analyzed the corresponding genes in 558 isolates of P. aeruginosa from patients with chronic lung disease and in 172 isolates from the general environment. Many genes identified through experimental evolution had predicted function-altering changes in clinical isolates but not in environmental isolates, showing that mutated genes in experimentally evolved bacteria can predict those that undergo mutation during infection. Additionally, large deletions of up to 479 kb arose in experimentally evolved meropenem-resistant mutants, and large deletions were present in 87 of the clinical isolates. These findings significantly advance understanding of antibiotic resistance in P. aeruginosa and demonstrate the validity of experimental evolution in identifying clinically relevant resistance-associated mutations.

scholarly journals Role of Pseudomonas aeruginosa Peptidoglycan-Associated Outer Membrane Proteins in Vesicle Formation

2012 ◽  
Vol 195 (2) ◽  
pp. 213-219 ◽  
Author(s):  
Aimee K. Wessel ◽  
Jean Liew ◽  
Taejoon Kwon ◽  
Edward M. Marcotte ◽  
Marvin Whiteley
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Membrane Proteins ◽  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Opportunistic Pathogen ◽  
Outer Membrane Vesicles ◽  
Gram Negative Bacteria ◽  
Content Type

ABSTRACTGram-negative bacteria produce outer membrane vesicles (OMVs) that package and deliver proteins, small molecules, and DNA to prokaryotic and eukaryotic cells. The molecular details of OMV biogenesis have not been fully elucidated, but peptidoglycan-associated outer membrane proteins that tether the outer membrane to the underlying peptidoglycan have been shown to be critical for OMV formation in multipleEnterobacteriaceae. In this study, we demonstrate that the peptidoglycan-associated outer membrane proteins OprF and OprI, but not OprL, impact production of OMVs by the opportunistic pathogenPseudomonas aeruginosa. Interestingly, OprF does not appear to be important for tethering the outer membrane to peptidoglycan but instead impacts OMV formation through modulation of the levels of thePseudomonasquinolone signal (PQS), a quorum signal previously shown by our laboratory to be critical for OMV formation. Thus, the mechanism by which OprF impacts OMV formation is distinct from that for other peptidoglycan-associated outer membrane proteins, including OprI.

scholarly journals Effect of Two Unique Nanoparticle Formulations on the Efficacy of a Broadly Protective Vaccine Against Pseudomonas Aeruginosa

2021 ◽  
Vol 12 ◽  
Author(s):  
Debaki R. Howlader ◽  
Sayan Das ◽  
Ti Lu ◽  
Gang Hu ◽  
David J. Varisco ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Lipid A ◽  
Protective Efficacy ◽  
Initial Step ◽  
Opportunistic Pathogen ◽  
Multi Drug Resistance ◽  
Successful Vaccine ◽  
Wide Range ◽  
Tlr4 Agonist ◽  
Opsonophagocytic Killing

Pseudomonas aeruginosa is an opportunistic pathogen responsible for a wide range of infections in humans. In addition to its innate antibiotic resistance, P. aeruginosa is very effective in acquiring resistance resulting in the emergence of multi-drug resistance strains and a licensed vaccine is not yet available. We have previously demonstrated the protective efficacy of a novel antigen PaF (Pa Fusion), a fusion of the type III secretion system (T3SS) needle tip protein, PcrV, and the first of two translocator proteins, PopB. PaF was modified to provide a self-adjuvanting activity by fusing the A1 subunit of the heat-labile enterotoxin from Enterotoxigenic E. coli to its N-terminus to give L-PaF. In addition to providing protection against 04 and 06 serotypes of P. aeruginosa, L-PaF elicited opsonophagocytic killing and stimulated IL-17A secretion, which have been predicted to be required for a successful vaccine. While monomeric recombinant subunit vaccines can be protective in mice, this protection often does not transfer to humans where multimeric formulations perform better. Here, we use two unique formulations, an oil-in-water (o/w) emulsion and a chitosan particle, as well as the addition of a unique TLR4 agonist, BECC438 (a detoxified lipid A analogue designated Bacterial Enzymatic Combinatorial Chemistry 438), as an initial step in optimizing L-PaF for use in humans. The o/w emulsion together with BECC438 provided the best protective efficacy, which correlated with high levels of opsonophagocytic killing and IL-17A secretion, thereby reducing the lung burden among all the vaccinated groups tested.

scholarly journals Roles of Two-Component Systems in Pseudomonas aeruginosa Virulence

2021 ◽  
Vol 22 (22) ◽  
pp. 12152
Author(s):  
Maria Sultan ◽  
Rekha Arya ◽  
Kyeong Kyu Kim
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Opportunistic Pathogen ◽  
Secretion Systems ◽  
Chronic Infections ◽  
Potential Threat ◽  
Wide Range ◽  
Component Systems ◽  
Two Component ◽  
Two Component Systems

Pseudomonas aeruginosa is an opportunistic pathogen that synthesizes and secretes a wide range of virulence factors. P. aeruginosa poses a potential threat to human health worldwide due to its omnipresent nature, robust host accumulation, high virulence, and significant resistance to multiple antibiotics. The pathogenicity of P. aeruginosa, which is associated with acute and chronic infections, is linked with multiple virulence factors and associated secretion systems, such as the ability to form and utilize a biofilm, pili, flagella, alginate, pyocyanin, proteases, and toxins. Two-component systems (TCSs) of P. aeruginosa perform an essential role in controlling virulence factors in response to internal and external stimuli. Therefore, understanding the mechanism of TCSs to perceive and respond to signals from the environment and control the production of virulence factors during infection is essential to understanding the diseases caused by P. aeruginosa infection and further develop new antibiotics to treat this pathogen. This review discusses the important virulence factors of P. aeruginosa and the understanding of their regulation through TCSs by focusing on biofilm, motility, pyocyanin, and cytotoxins.

Sign in / Sign up

Export Citation Format

Share Document