The sensor kinase CbrA is a global regulator that modulates metabolism, virulence, and antibiotic resistance in Pseudomonas aeruginosa.
Yeung Amy T Y,Bains Manjeet,Hancock Robert E W
Journal of bacteriology
Pseudomonas aeruginosa is an opportunistic pathogen that possesses a large arsenal of virulence factors enabling the pathogen to cause serious infections in immunocompromised patients, burn victims, and cystic fibrosis patients. CbrA is a sensor kinase that has previously been implied to play a role with its cognate response regulator CbrB in the metabolic regulation of carbon and nitrogen utilization in P. aeruginosa. Here it is demonstrated that CbrA and CbrB play an important role in various virulence and virulence-related processes of the bacteria, including swarming, biofilm formation, cytotoxicity, and antibiotic resistance. The cbrA deletion mutant was completely unable to swarm while exhibiting an increase in biofilm formation, supporting the inverse regulation of swarming and biofilm formation in P. aeruginosa. The cbrA mutant also exhibited increased cytotoxicity to human lung epithelial cells as early as 4 and 6 h postinfection. Furthermore, the cbrA mutant demonstrated increased resistance toward a variety of clinically important antibiotics, including polymyxin B, ciprofloxacin, and tobramycin. Microarray analysis revealed that under swarming conditions, CbrA regulated the expression of many genes, including phoPQ, pmrAB, arnBCADTEF, dnaK, and pvdQ, consistent with the antibiotic resistance and swarming impairment phenotypes of the cbrA mutant. Phenotypic and real-time quantitative PCR (RT-qPCR) analyses of a PA14 cbrB mutant suggested that CbrA may be modulating swarming, biofilm formation, and cytotoxicity via CbrB and that the CrcZ small RNA is likely downstream of this two-component regulator. However, as CbrB did not have a resistance phenotype, CbrA likely modulates antibiotic resistance in a manner independent of CbrB.
10.1128/JB.00911-10
PA0305 of Pseudomonas aeruginosa is a quorum quenching acylhomoserine lactone acylase belonging to the Ntn hydrolase superfamily.
Wahjudi Mariana,Papaioannou Evelina,Hendrawati Oktavia,van Assen Aart H G,van Merkerk Ronald,Cool Robbert H,Poelarends Gerrit J,Quax Wim J
Microbiology (Reading, England)
The Pseudomonas aeruginosa PAO1 genome has at least two genes, pvdQ and quiP, encoding acylhomoserine lactone (AHL) acylases. Two additional genes, pa1893 and pa0305, have been predicted to encode penicillin acylase proteins, but have not been characterized. Initial studies on a pa0305 transposon insertion mutant suggested that the gene is not related to the AHL growth phenotype of P. aeruginosa. The close similarity (67 %) of pa0305 to HacB, an AHL acylase of Pseudomonas syringae, prompted us to investigate whether the PA0305 protein might also function as an AHL acylase. The pa0305 gene has been cloned and the protein (PA0305) has been overproduced, purified and subjected to functional characterization. Analysis of the purified protein showed that, like β-lactam acylases, PA0305 undergoes post-translational processing resulting in α- and β-subunits, with the catalytic serine as the first amino acid of the β-subunit, strongly suggesting that PA0305 is a member of the N-terminal nucleophile hydrolase superfamily. Using a biosensor assay, PA0305his was shown to degrade AHLs with acyl side chains ranging in length from 6 to 14 carbons. Kinetics studies using N-octanoyl-L-homoserine lactone (C(8)-HSL) and N-(3-oxo-dodecanoyl)-L-homoserine lactone (3-oxo-C(12)-HSL) as substrates showed that the enzyme has a robust activity towards these two AHLs, with apparent K(cat)/K(m) values of 0.14 × 10(4) M(-1) s(-1) towards C(8)-HSL and 7.8 × 10(4) M(-1 )s(-1) towards 3-oxo-C(12)-HSL. Overexpression of the pa0305 gene in P. aeruginosa showed significant reductions in both accumulation of 3-oxo-C(12)-HSL and expression of virulence factors. A mutant P. aeruginosa strain with a deleted pa0305 gene showed a slightly increased capacity to kill Caenorhabditis elegans compared with the P. aeruginosa PAO1 wild-type strain and the PAO1 strain carrying a plasmid overexpressing pa0305. The harmful effects of the Δpa0305 strain on the animals were most visible at 5 days post-exposure and the mortality rate of the animals fed on the Δpa0305 strain was faster than for the animals fed on either the wild-type strain or the strain overexpressing pa0305. In conclusion, the pa0305 gene encodes an efficient acylase with activity towards long-chain homoserine lactones, including 3-oxo-C(12)-HSL, the natural quorum sensing signal molecule in P. aeruginosa, and we propose to name this acylase HacB.
10.1099/mic.0.043935-0
Identification of extracellular N-acylhomoserine lactone acylase from a Streptomyces sp. and its application to quorum quenching.
Park Sun-Yang,Kang Hye-Ok,Jang Hak-Sun,Lee Jung-Kee,Koo Bon-Tag,Yum Do-Young
Applied and environmental microbiology
N-acylhomoserine lactones (AHLs) play an important role in regulating virulence factors in pathogenic bacteria. Recently, the enzymatic inactivation of AHLs, which can be used as antibacterial targets, has been identified in several soil bacteria. In this study, strain M664, identified as a Streptomyces sp., was found to secrete an AHL-degrading enzyme into a culture medium. The ahlM gene for AHL degradation from Streptomyces sp. strain M664 was cloned, expressed heterologously in Streptomyces lividans, and purified. The enzyme was found to be a heterodimeric protein with subunits of approximately 60 kDa and 23 kDa. A comparison of AhlM with known AHL-acylases, Ralstonia strain XJ12B AiiD and Pseudomonas aeruginosa PAO1 PvdQ, revealed 35% and 32% identities in the deduced amino acid sequences, respectively. However, AhlM was most similar to the cyclic lipopeptide acylase from Streptomyces sp. strain FERM BP-5809, exhibiting 93% identity. A mass spectrometry analysis demonstrated that AhlM hydrolyzed the amide bond of AHL, releasing homoserine lactone. AhlM exhibited a higher deacylation activity toward AHLs with long acyl chains rather than short acyl chains. Interestingly, AhlM was also found to be capable of degrading penicillin G by deacylation, showing that AhlM has a broad substrate specificity. The addition of AhlM to the growth medium reduced the accumulation of AHLs and decreased the production of virulence factors, including elastase, total protease, and LasA, in P. aeruginosa. Accordingly, these results suggest that AHL-acylase, AhlM could be effectively applied to the control of AHL-mediated pathogenicity.
10.1128/AEM.71.5.2632-2641.2005
Swarming of Pseudomonas aeruginosa is a complex adaptation leading to increased production of virulence factors and antibiotic resistance.
Overhage Joerg,Bains Manjeet,Brazas Michelle D,Hancock Robert E W
Journal of bacteriology
In addition to exhibiting swimming and twitching motility, Pseudomonas aeruginosa is able to swarm on semisolid (viscous) surfaces. Recent studies have indicated that swarming is a more complex type of motility influenced by a large number of different genes. To investigate the adaptation process involved in swarming motility, gene expression profiles were analyzed by performing microarrays on bacteria from the leading edge of a swarm zone compared to bacteria growing in identical medium under swimming conditions. Major shifts in gene expression patterns were observed under swarming conditions, including, among others, the overexpression of a large number of virulence-related genes such as those encoding the type III secretion system and its effectors, those encoding extracellular proteases, and those associated with iron transport. In addition, swarming cells exhibited adaptive antibiotic resistance against polymyxin B, gentamicin, and ciprofloxacin compared to what was seen for their planktonic (swimming) counterparts. By analyzing a large subset of up-regulated genes, we were able to show that two virulence genes, lasB and pvdQ, were required for swarming motility. These results clearly favored the conclusion that swarming of P. aeruginosa is a complex adaptation process in response to a viscous environment resulting in a substantial change in virulence gene expression and antibiotic resistance.
10.1128/JB.01659-07
Targeting Acyl Homoserine Lactones (AHLs) by the quorum quenching bacterial strains to control biofilm formation in .
Khalid Syeda Javariya,Ain Quratul,Khan Sher Jamal,Jalil Amna,Siddiqui Muhammad Faisal,Ahmad Tahir,Badshah Malik,Adnan Fazal
Saudi journal of biological sciences
Navigating novel biological strategies to mitigate bacterial biofilms have great worth to combat bacterial infections. Bacterial infections caused by the biofilm forming bacteria are 1000 times more resistant to antibiotics than the planktonic bacteria. Among the known bacterial infections, more than 70% involve biofilms which severely complicates treatment options. Biofilm formation is mainly regulated by the Quorum sensing (QS) mechanism. Interference with the QS system by the quorum quenching (QQ) enzyme is a potent strategy to mitigate biofilm. In this study, bacterial strains with QQ activity were identified and their anti-biofilm potential was investigated against the Multidrug Resistant (MDR) . A CV026 and A136-based bioassays were used to confirm the degradation of different Acyl Homoserine Lactones (AHLs) by QQ isolates. The gene sequencing of the isolated strains identified them as strain QSP03, strain QSP10, strain QQ3 and strain QSP01. Biofilm mitigation potential of QQ isolates was tested against MDR and the results suggested that 50% biofilm reduction was observed by QQ3 and QSP01 strains, and around 60% reduction by QSP10 and QSP03 bacterial isolates. The presence of AHL degrading enzymes, lactonases and acylases, was confirmed by PCR based screening and sequencing of the already annotated genes , and Altogether, these results exhibit that QQ bacterial strains or their products could be useful to control biofilm formation in
10.1016/j.sjbs.2021.10.064
Biosynthesis of the pyoverdine siderophore of Pseudomonas aeruginosa involves precursors with a myristic or a myristoleic acid chain.
Hannauer Mélissa,Schäfer Mathias,Hoegy Françoise,Gizzi Patrick,Wehrung Patrick,Mislin Gaëtan L A,Budzikiewicz Herbert,Schalk Isabelle J
FEBS letters
Pyoverdine I (PVDI) is the major siderophore produced by Pseudomonas aeruginosa to import iron. Biosynthesis of this chelator involves non-ribosomal peptide synthetases and other enzymes. PvdQ is a periplasmic enzyme from the NTN hydrolase family and is involved in the final steps of PVDI biosynthesis. A pvdQ mutant produces two non-fluorescent PVDI precursors with a higher molecular mass than PVDI. In the present study, we describe the use of mass spectrometry to determine the structure of these PVDI precursors and show that they both contain a unformed chromophore like ferribactin, and either a myristic or myristoleic chain that must be removed before PVDI is secreted into the extracellular medium.
10.1016/j.febslet.2011.12.004
Synthesis of the siderophore pyoverdine in Pseudomonas aeruginosa involves a periplasmic maturation.
Yeterian Emilie,Martin Lois W,Guillon Laurent,Journet Laure,Lamont Iain L,Schalk Isabelle J
Amino acids
Pyoverdines, the main siderophores produced by fluorescent Pseudomonads, comprise a fluorescent dihydroxyquinoline chromophore attached to a strain-specific peptide. These molecules are thought to be synthesized as non-fluorescent precursor peptides that are then modified to give functional pyoverdines. Using the fluorescent properties of PVDI, the pyoverdine produced by Pseudomonas aeruginosa PAO1, we were able to show that PVDI was not present in the cytoplasm of the bacteria, but large amounts of a fluorescent PVDI precursor PVDIp were stored in the periplasm. Like PVDI, PVDIp is able to transport iron into P. aeruginosa cells. Mutation of genes encoding the periplasmic PvdN, PvdO and PvdP proteins prevented accumulation of PVDIp in the periplasm and secretion of PVDI into the growth medium, indicating that these three enzymes are involved in PVDI synthesis. Mutation of the gene encoding PvdQ resulted in the presence of fluorescent PVDI precursor in the periplasm and secretion of a functional fluorescent siderophore that had different isoelectric properties to PVDI, suggesting a role for PvdQ in the periplasmic maturation of PVDI. Mutation of the gene encoding the export ABC transporter PvdE prevented PVDI production and accumulation of PVDIp in the periplasm. These data are consistent with a model in which a PVDI precursor peptide is synthesized in the cytoplasm and exported to the periplasm by PvdE where siderophore maturation, including formation of the chromophore moiety, occurs in a process involving the PvdN, PvdO, PvdP and PvdQ proteins.
10.1007/s00726-009-0358-0
Pyoverdine biosynthesis and secretion in Pseudomonas aeruginosa: implications for metal homeostasis.
Schalk Isabelle J,Guillon Laurent
Environmental microbiology
Pyoverdines are siderophores produced by fluorescent Pseudomonads to acquire iron. At least 60 different pyoverdines produced by diverse strains have been chemically characterized. They all consist of a dihydroquinoline-type chromophore linked to a peptide. These peptides are of various lengths and the sequences are strain specific. Pyoverdine biosynthesis in Pseudomonas aeruginosa and fluorescent Pseudomonads is a complex process involving at least 12 different proteins, starting in the cytoplasm and ending in the periplasm. The cellular localization of pyoverdine precursors was recently shown to be consistent with their biosynthetic enzymes. In the cytoplasm, pyoverdine appears to be assembled at the inner membrane and particularly at the old cell pole of the bacterium. Mature pyoverdine is uniformly distributed throughout the periplasm, like the periplasmic enzyme PvdQ. Secretion of pyoverdine involves a recently identified ATP-dependent efflux pump, PvdRT-OpmQ. This efflux system does not only secrete newly synthesized pyoverdine but also pyoverdine that already transported iron into the bacterial periplasm and any pyoverdine-metal complex other than ferri-pyoverdine present in the periplasm. This review considers how these new insights into pyoverdine biosynthesis and secretion contribute to our understanding of the role of pyoverdine in iron and metal homeostasis in fluorescent Pseudomonads.
10.1111/1462-2920.12013
Identification of inhibitors of PvdQ, an enzyme involved in the synthesis of the siderophore pyoverdine.
Wurst Jacqueline M,Drake Eric J,Theriault Jimmy R,Jewett Ivan T,VerPlank Lynn,Perez Jose R,Dandapani Sivaraman,Palmer Michelle,Moskowitz Samuel M,Schreiber Stuart L,Munoz Benito,Gulick Andrew M
ACS chemical biology
Pseudomonas aeruginosa produces the peptide siderophore pyoverdine, which is used to acquire essential Fe(3+) ions from the environment. PvdQ, an Ntn hydrolase, is required for the biosynthesis of pyoverdine. PvdQ knockout strains are not infectious in model systems, suggesting that disruption of siderophore production via PvdQ inhibition could be exploited as a target for novel antibacterial agents, by preventing cells from acquiring iron in the low iron environments of most biological settings. We have previously described a high-throughput screen to identify inhibitors of PvdQ that identified inhibitors with IC50 values of ∼100 μM. Here, we describe the discovery of ML318, a biaryl nitrile inhibitor of PvdQ acylase. ML318 inhibits PvdQ in vitro (IC50 = 20 nM) by binding in the acyl-binding site, as confirmed by the X-ray crystal structure of PvdQ bound to ML318. Additionally, the PvdQ inhibitor is active in a whole cell assay, preventing pyoverdine production and limiting the growth of P. aeruginosa under iron-limiting conditions.
10.1021/cb5001586
Influence of Pseudomonas aeruginosa pvdQ gene on altering antibiotic susceptibility under swarming conditions.
Wang Lili,Zhang Chunling,Gong Fengyun,Li Hongtao,Xie Xuhua,Xia Chao,Chen Jia,Song Ying,Shen Aixia,Song Jianxin
Current microbiology
In Pseudomonas aeruginosa PAO1, the pvdQ gene has been shown to have at least two functions. It encodes the acylase enzyme and hydrolyzes 3-oxo-C12-HSL, the key signaling molecule of quorum sensing system. In addition, pvdQ is involved in swarming motility. It is required for up-regulated during swarming motility, which is triggered by high cell densities. As high-density bacterial populations also display elevated antibiotic resistance, studies have demonstrated that swarm-cell differentiation in P. aeruginosa promotes increased resistance to various antibiotics. PvdQ acts as a signal during swarm-cell differentiation, and thus may play a role in P. aeruginosa antibiotic resistance. The aim of this study is to examine whether pvdQ was involved in modifying antibiotic susceptibility during swarming conditions, and to investigate the mechanism by which this occurred. We constructed the PAO1pMEpvdQ strain, which overproduced PvdQ. PAO1pMEpvdQ promotes swarming motility, while PAO1ΔpvdQ abolishes swarming motility. In addition, both PAO1 and PAO1pMEpvdQ acquired resistance to ceftazidime, ciprofloxacin, meropenem, polymyxin B, and gentamicin, though PAO1pMEpvdQ exhibited a two to eightfold increase in antibiotic resistance compared to PAO1. These results indicate that pvdQ plays an important role in elevating antibiotic resistance via swarm-cell differentiation and possibly other mechanisms as well. We analyzed outer membrane permeability. Our data also suggest that pvdQ decreases P. aeruginosa outer membrane permeability, thereby elevating antibiotic resistance under swarming conditions. Our results suggest new approaches for reducing P. aeruginosa resistance.
10.1007/s00284-011-9979-0
Substrate Trapping in the Siderophore Tailoring Enzyme PvdQ.
Clevenger Kenneth D,Mascarenhas Romila,Catlin Daniel,Wu Rui,Kelleher Neil L,Drake Eric J,Gulick Andrew M,Liu Dali,Fast Walter
ACS chemical biology
Siderophore biosynthesis by Pseudomonas aeruginosa enhances virulence and represents an attractive drug target. PvdQ functions in the type-1 pyoverdine biosynthetic pathway by removing a myristoyl anchor from a pyoverdine precursor, allowing eventual release from the periplasm. A circularly permuted version of PvdQ bypasses the self-processing step of this Ntn-hydrolase and retains the activity, selectivity, and structure of wild-type PvdQ, as revealed by a 1.8 Å resolution X-ray crystal structure. A 2.55 Å resolution structure of the inactive S1A/N269D-cpPvdQ mutant in complex with the pyoverdine precursor PVDIq reveals a specific binding pocket for the d-Tyr of this modified peptide substrate. To our knowledge, this structure is the first of a pyoverdine precursor peptide bound to a biosynthetic enzyme. Details of the observed binding interactions have implications for control of pyoverdine biosynthesis and inform future drug design efforts.
10.1021/acschembio.7b00031
Role of PvdQ in Pseudomonas aeruginosa virulence under iron-limiting conditions.
Jimenez Pol Nadal,Koch Gudrun,Papaioannou Evelina,Wahjudi Mariana,Krzeslak Joanna,Coenye Tom,Cool Robbert H,Quax Wim J
Microbiology (Reading, England)
PvdQ, an acylase from Pseudomonas aeruginosa PAO1, has been shown to have at least two functions. It can act as a quorum quencher due to its ability to degrade long-chain N-acylhomoserine lactones (AHLs), e.g. 3-oxo-C12-HSL, leading to a decrease in virulence factors. In addition, PvdQ is involved in iron homeostasis by playing a role in the biosynthesis of pyoverdine, the major siderophore of P. aeruginosa. In accordance with earlier studies on RNA level, we could show at the protein level that PvdQ is only expressed when iron is present at very low concentrations. We therefore set out to investigate the two functions of PvdQ under iron-limiting conditions. Gene deletion of pvdQ does not affect growth of P. aeruginosa but abrogates pyoverdine production, and results in an accumulation of 3-oxo-C12-HSL. Phenotypic analyses of our DeltapvdQ mutant at low iron concentrations revealed that this mutant is impaired in swarming motility and biofilm formation. Additionally, a plant and a Caenorhabditis elegans infection model demonstrated that the deletion of pvdQ resulted in reduced virulence. None of the phenotypes in the present study could be linked to the presence or absence of AHLs. These results clearly indicate that under iron-limiting conditions PvdQ plays a major role in swarming motility, in biofilm development and in infection that is more likely to be linked to the pyoverdine pathway rather than the LasI/LasR/3-oxo-C12-HSL quorum-sensing circuit.
10.1099/mic.0.030973-0
Influence of Pseudomonas aeruginosa pvdQ gene on altering antibiotic susceptibility under swarming conditions.
Wang Lili,Zhang Chunling,Gong Fengyun,Li Hongtao,Xie Xuhua,Xia Chao,Chen Jia,Song Ying,Shen Aixia,Song Jianxin
Current microbiology
In Pseudomonas aeruginosa PAO1, the pvdQ gene has been shown to have at least two functions. It encodes the acylase enzyme and hydrolyzes 3-oxo-C12-HSL, the key signaling molecule of quorum sensing system. In addition, pvdQ is involved in swarming motility. It is required and up-regulated during swarming motility, which is triggered by high cell densities. As high density bacterial populations also display elevated antibiotics resistance, studies have demonstrated swarm-cell differentiation in P. aeruginosa promotes increased resistance to various antibiotics. PvdQ acts as a signal during swarm-cell differentiation, and thus may play a role in P. aeruginosa antibiotic resistance. The aim of this study was to examine whether pvdQ was involved in modifying antibiotic susceptibility during swarming conditions and to investigate the mechanism by which this occurred. We constructed the PAO1pMEpvdQ strain, which overproduces PvdQ. PAO1pMEpvdQ promotes swarming motility, while PAO1ΔpvdQ abolishes swarming motility. In addition, both PAO1 and PAO1pMEpvdQ acquired resistance to ceftazidime, ciprofloxacin, meropenem, polymyxin B, and gentamicin, though PAO1pMEpvdQ exhibited a twofold to eightfold increase in antibiotic resistance compared to PAO1. These results indicate that pvdQ plays an important role in elevating antibiotic resistance via swarm-cell differentiation and possibly other mechanisms as well. We analyzed outer membrane permeability. Our data also suggest that pvdQ decreases P. aeruginosa outer membrane permeability, thereby elevating antibiotic resistance under swarming conditions. Our results suggest new approaches for reducing P. aeruginosa resistance.
10.1007/s00284-012-0217-1
Immobilized Acylase PvdQ Reduces Biofilm Formation on PDMS Silicone.
Vogel Jan,Wakker-Havinga Marijke,Setroikromo Rita,Quax Wim J
Frontiers in chemistry
The bacterial biofilm plays a key role in nosocomial infections, especially those related to medical devices in sustained contact with patients. The active dispersion of bacterial cells out of biofilms acts as a reservoir for infectious diseases. The formation of such biofilms is a highly complex process, which is coordinated by many regulatory mechanisms of the pathogen including quorum sensing (QS). Many bacteria coordinate the expression of key virulence factors dependent on their population density through QS. The inhibition of this system is called quorum quenching (QQ). Thus, preventing the development of biofilms is considered a promising approach to prevent the development of hard to treat infections. Enzymatic QQ is the concept of interfering with the QS system of bacteria outside the cell. PvdQ is an acylase with an N-terminal nucleophile (Ntn-hydrolase) that is a part of the pyoverdine gene cluster (). It is able to cleave irreversibly the amide bond of long chain N-acyl homoserine lactones (AHL) rendering them inactive. Long chain AHLs are the main signaling molecule in the QS system of the gram-negative pathogen PA01, which is known for surface-associated biofilms on indwelling catheters and is also the cause of catheter-associated urinary tract infections. Furthermore, PA01 is a well characterized pathogen with respect to QS as well as QQ. In this study, we immobilized the acylase PvdQ on polydimethylsiloxane silicone (PDMS), creating a surface with quorum quenching properties. The goal is to control infections by minimizing the colonization of indwelling medical devices such as urinary catheters or intravascular catheters. The enzyme activity was confirmed by testing the degradation of the main auto-inducer that mediates QS in . In this article we report for the first time a successful immobilization of the quorum quenching acylase PvdQ on PDMS silicone. We could show that immobilized PvdQ retained its activity after the coating procedure and showed a 6-fold reduction of the auto-inducer 3-oxo-C12 in a biosensor setup. Further we report significant reduction of a PA01 biofilm on a coated PDMS surface compared to the same untreated material.
10.3389/fchem.2020.00054
Quorum-quenching potential of recombinant PvdQ-engineered bacteria for biofilm formation.
International microbiology : the official journal of the Spanish Society for Microbiology
Quorum sensing (QS) is a core mechanism for bacteria to regulate biofilm formation, and therefore, QS inhibition or quorum quenching (QQ) is used as an effective and economically feasible strategy against biofilms. In this study, the PvdQ gene encoding AHL acylase was introduced into Escherichia coli (DE3), and a PvdQ-engineered bacterium with highly efficient QQ activity was obtained and used to inhibit biofilm formation. Gene sequencing and western blot analysis showed that the recombinant pET-PvdQ strain was successfully constructed. The color reaction of Agrobacterium tumefaciens A136 indicated that PvdQ engineering bacteria had shown strong AHL signal molecule quenching activity and significantly inhibited the adhesion (motility) of Pseudomonas aeruginosa and biofilm formation of activated sludge bacteria in Membrane Bio-Reactor (MBR; inhibition rate 51-85%, p < 0.05). In addition, qRT-PCR testing revealed that recombinant PvdQ acylase significantly reduced the transcription level of QS biofilm formation-related genes (cdrA, pqsA, and lasR; p < 0.05). In this study, QQ genetically engineered bacteria enhanced by genetic engineering could effectively inhibit the QS signal transduction mechanism and have the potential to control biofilm formation of pathogenic bacteria in the aquaculture environment, providing an environmentally friendly and alternative antibiotic strategy to suppress biofilm contamination.
10.1007/s10123-023-00329-1
Discovery of chromene compounds as inhibitors of PvdQ acylase of Pseudomonas aeruginosa.
Microbes and infection
The acquisition of iron is a crucial mechanism for the survival of pathogenic bacteria such as Pseudomonas aeruginosa in eukaryotic hosts. The key iron chelator in this organism is the siderophore pyoverdine, which was shown to be crucial for iron homeostasis. Pyoverdine is a non-ribosomal peptide with several maturation steps in the cytoplasm and others in the periplasmatic space. A key enzyme for its maturation is the acylase PvdQ. The inhibition of PvdQ stops the maturation of pyoverdine causing a significant imbalance in the iron homeostasis and hence can negatively influence the survival of P. aeruginosa. In this work, we successfully synthesized chromene-derived inhibitory molecules targeting PvdQ in a low micromolar range. In silico modeling as well as kinetic evaluations of the inhibitors suggest a competitive inhibition of the PvdQ function. Further, we evaluated the inhibitor in vivo on P. aeruginosa cells and report a dose-dependent reduction of pyoverdine formation. The compound also showed a protecting effect in a Galleria mellonella infection model.
10.1016/j.micinf.2022.105017
Fighting Acinetobacter baumannii infections with the acylase PvdQ.
Microbes and infection
Acinetobacter baumannii is an opportunistic Gram-negative bacterial pathogen that poses a threat for frail patients worldwide. The high ability to withstand environmental stresses as well as its resistance towards a broad range of antibiotics make A. baumannii an effective hard-to-eradicate pathogen. One of the key mechanisms mediating tolerance against antibiotic treatment is the formation of biofilms, a process that is controlled by a multitude of different regulatory mechanisms. A key factor with major impact on biofilm formation is cell-to-cell communication by quorum-sensing, which in A. baumannii is mediated by acyl homoserine lactone signaling molecules. Here we show that the Ntn-Hydrolase PvdQ from Pseudomonas aeruginosa can reduce biofilm formation by the A. baumannii ATCC 17978 type strain and several clinical isolates on abiotic surfaces. Further, our study shows that a combination treatment of PvdQ-mediated quorum-quenching with the antibiotic gentamicin has a synergistic effect on the clearance of A. baumannii biofilms and possible biofilm dispersal. Moreover, we demonstrate in a Galleria mellonella larval infection model that PvdQ administration significantly prolongs survival of the larvae. Altogether, we conclude that the acylase-mediated irreversible cleavage of quorum-sensing signaling molecules as exemplified with PvdQ can set a profound limit to the progression of A. baumannii infections.
10.1016/j.micinf.2022.104951