scholarly journals Effects of Exogenous N-Acyl-Homoserine Lactone as Signal Molecule on Nitrosomonas Europaea under ZnO Nanoparticle Stress

2019 ◽  
Vol 16 (16) ◽  
pp. 3003
Author(s):  
Junkang Wu ◽  
Huan Gao ◽  
Jinyu Ye ◽  
Yan Chang ◽  
Ran Yu ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Membrane Integrity ◽  
Amoa Gene ◽  
Nitrosomonas Europaea ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Zno Nanoparticle ◽  
Nano Zno ◽  
Monooxygenase Activity ◽  
The Impact

Despite the adverse effects of emerging ZnO nanoparticles (nano-ZnO) on wastewater biological nitrogen removal (BNR) systems being widely documented, strategies for mitigating nanoparticle (NP) toxicity impacts on nitrogen removal have not been adequately addressed. Herein, N-acyl-homoserine lactone (AHL)-based quorum sensing (QS) was investigated for its effects against nano-ZnO toxicity to a model nitrifier, Nitrosomonas europaea. The results indicated that AHL-attenuated nano-ZnO toxicity, which was inversely correlated with the increasing dosage of AHL from 0.01 to 1 µM. At 0.01 µM, AHL notably enhanced the tolerance of N. europaea cells to nano-ZnO stress, and the inhibited cell proliferation, membrane integrity, ammonia oxidation rate, ammonia monooxygenase activity and amoA gene expression significantly increased by 18.2 ± 2.1, 2.4 ± 0.9, 58.7 ± 7.1, 32.3 ± 1.7, and 7.3 ± 5.9%, respectively, after 6 h of incubation. However, increasing the AHL dosage compromised the QS-mediated effects and even aggravated the NPs’ toxicity effects. Moreover, AHLs, at all tested concentrations, significantly increased superoxide dismutase activity, indicating the potential of QS regulations to enhance cellular anti-oxidative stress capacities when facing NP invasion. These results provide novel insights into the development of QS regulation strategies to reduce the impact of nanotoxicity on BNR systems.

scholarly journals Physiological State, Growth Mode, and Oxidative Stress Play a Role in Cd(II)-Mediated Inhibition of Nitrosomonas europaea 19718

2008 ◽  
Vol 74 (8) ◽  
pp. 2447-2453 ◽  
Author(s):  
Kartik Chandran ◽  
Nancy G. Love
Keyword(s):  
Oxidative Stress ◽  
16S Rrna ◽  
Physiological State ◽  
Membrane Integrity ◽  
Fold Increase ◽  
Nitrosomonas Europaea ◽  
Growth Mode ◽  
Batch Cultures ◽  
Growth Modes ◽  
The Impact

ABSTRACT The goal of this study was to determine the impact of physiological growth states (batch exponential and batch stationary growth) and growth modes (substrate-limited chemostat, substrate-sufficient exponential batch, and substrate-depleted stationary batch growth) on several measures of growth and responses to Cd(II)-mediated inhibition of Nitrosomonas europaea strain 19718. The specific oxygen uptake rate (sOUR) was the most sensitive indicator of inhibition among the different responses analyzed, including total cell abundance, membrane integrity, intracellular 16S rRNA/DNA ratio, and amoA expression. This observation remained true irrespective of the physiological state, the growth mode, or the mode of Cd(II) exposure. Based on the sOUR, a strong time-dependent exacerbation of inhibition (in terms of an inhibition coefficient [Ki ]) in exponential batch cultures was observed. Long-term inhibition levels (based on Ki estimates) in metabolically active chemostat and exponential batch cultures were also especially severe and comparable. In contrast, the inhibition level in stationary-phase cultures was 10-fold lower and invariable with exposure time. Different strategies for surviving substrate limitation (a 10-fold increase in amoA expression) and starvation (the retention of 16S rRNA levels) in N. europaea cultures were observed. amoA expression was most negatively impacted by Cd(II) exposure in the chemostat cultures, was less impacted in exponential batch cultures, and was least impacted in stationary batch cultures. Although the amoA response was consistent with that of the sOUR, the amoA response was not as strong. The intracellular 16S rRNA/DNA ratio, as determined by fluorescence in situ hybridization, also did not uniformly correlate with the sOUR under conditions of inhibition or no inhibition. Finally, Cd(II)-mediated inhibition of N. europaea was attributed partially to oxidative stress.

scholarly journals Probing the Impact of Ligand Binding on the Acyl-Homoserine Lactone-Hindered Transcription Factor EsaR of Pantoea stewartii subsp. stewartii

2011 ◽  
Vol 193 (22) ◽  
pp. 6315-6322 ◽  
Author(s):  
Daniel J. Schu ◽  
Revathy Ramachandran ◽  
Jared S. Geissinger ◽  
Ann M. Stevens
Keyword(s):  
Conformational Changes ◽  
Homoserine Lactone ◽  
Biologically Active ◽  
Acyl Homoserine Lactone ◽  
Content Type ◽  
Pantoea Stewartii ◽  
Cell Densities ◽  
The Impact

The quorum-sensing regulator EsaR fromPantoea stewartiisubsp.stewartiiis a LuxR homologue that is inactivated by acyl-homoserine lactone (AHL). In the corn pathogenP. stewartii, production of exopolysaccharide (EPS) is repressed by EsaR at low cell densities. However, at high cell densities when high concentrations of its cognate AHL signal are present, EsaR is inactivated and derepression of EPS production occurs. Thus, EsaR responds to AHL in a manner opposite to that of most LuxR family members. Depending on the position of its binding site within target promoters, EsaR serves as either a repressor or activator in the absence rather than in the presence of its AHL ligand. The effect of AHL on LuxR homologues has been difficult to studyin vitrobecause AHL is required for purification and stability. EsaR, however, can be purified without AHL enabling anin vitroanalysis of the response of the protein to ligand. Western immunoblots and pulse-chase experiments demonstrated that EsaR is stablein vivoin the absence or presence of AHL. Limitedin vitroproteolytic digestions of a biologically active His-MBP tagged version of EsaR highlighted intradomain and interdomain conformational changes that occur in the protein in response to AHL. Gel filtration chromatography of the full-length fusion protein and cross-linking of the N-terminal domain both suggest that this conformational change does not impact the multimeric state of the protein. These findings provide greater insight into the diverse mechanisms for AHL responsiveness found within the LuxR family.

scholarly journals Biofilm activity, ammonia removal and cell growth of the heterotrophic nitrifier,Acinetobactersp., facilitated by exogenousN-acyl-homoserine lactones

RSC Advances ◽  
2018 ◽  
Vol 8 (54) ◽  
pp. 30783-30793 ◽  
Author(s):  
Xiujie Wang ◽  
Weiqi Wang ◽  
Yun Li ◽  
Jing Zhang ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Cell Growth ◽  
Nitrogen Removal ◽  
Homoserine Lactone ◽  
Ammonia Removal ◽  
Heterotrophic Nitrification ◽  
Aerobic Denitrification ◽  
Acyl Homoserine Lactone ◽  
Homoserine Lactones ◽  
Removal Process ◽  
Acyl Homoserine Lactones

In the present study, the heterotrophic nitrification–aerobic denitrification strain,Acinetobactersp. JQ1004, was treated with three typicalN-acyl-homoserine lactone (AHL) molecules (C6-HSL, C8-HSL, and 3-oxo-C10-HSL) during the nitrogen removal process.

scholarly journals Identification of Acyl-Homoserine Lactone Signal Molecules Produced by Nitrosomonas europaea Strain Schmidt

2005 ◽  
Vol 71 (8) ◽  
pp. 4906-4909 ◽  
Author(s):  
E. O. Burton ◽  
H. W. Read ◽  
M. C. Pellitteri ◽  
W. J. Hickey
Keyword(s):  
Chemostat Culture ◽  
Present Report ◽  
Nitrosomonas Europaea ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Responsive Systems ◽  
Alternate Pathway

ABSTRACT Nitrosomonas europaea strain Schmidt produces at least three acyl homoserine lactone (AHL) signal molecules: C6-homoserine lactone (HSL), C8-HSL, and C10-HSL. These compounds were identified in extracts of chemostat culture effluent by three independent methods. The concentrations of AHL in effluent were low (0.4 to 2.2 nM) but within the range known to induce AHL-responsive systems. The absence of LuxI and LuxM homologs from the genome of N. europaea strain Schmidt suggested that AHL synthesis occurs by an alternate pathway, possibly mediated by an HdtS homolog. To the best of our knowledge, the present report is the first to document the types and levels of AHLs produced by N. europaea.

scholarly journals ATP13A2 Regulates Cellular α-Synuclein Multimerization, Membrane Association, and Externalization

2021 ◽  
Vol 22 (5) ◽  
pp. 2689
Author(s):  
Jianmin Si ◽  
Chris Van den Haute ◽  
Evy Lobbestael ◽  
Shaun Martin ◽  
Sarah van Veen ◽  
...  
Keyword(s):  
Membrane Integrity ◽  
Ubiquitin Proteasome System ◽  
Regulatory Function ◽  
Membrane Association ◽  
Loss Of Function ◽  
Atypical Form ◽  
Polyamine Transport ◽  
Independent Functions ◽  
Ubiquitin Proteasome ◽  
The Impact

ATP13A2, a late endo-/lysosomal polyamine transporter, is implicated in a variety of neurodegenerative diseases, including Parkinson’s disease and Kufor–Rakeb syndrome, an early-onset atypical form of parkinsonism. Loss-of-function mutations in ATP13A2 result in lysosomal deficiency as a consequence of impaired lysosomal export of the polyamines spermine/spermidine. Furthermore, accumulating evidence suggests the involvement of ATP13A2 in regulating the fate of α-synuclein, such as cytoplasmic accumulation and external release. However, no consensus has yet been reached on the mechanisms underlying these effects. Here, we aimed to gain more insight into how ATP13A2 is linked to α-synuclein biology in cell models with modified ATP13A2 activity. We found that loss of ATP13A2 impairs lysosomal membrane integrity and induces α-synuclein multimerization at the membrane, which is enhanced in conditions of oxidative stress or exposure to spermine. In contrast, overexpression of ATP13A2 wildtype (WT) had a protective effect on α-synuclein multimerization, which corresponded with reduced αsyn membrane association and stimulation of the ubiquitin-proteasome system. We also found that ATP13A2 promoted the secretion of α-synuclein through nanovesicles. Interestingly, the catalytically inactive ATP13A2 D508N mutant also affected polyubiquitination and externalization of α-synuclein multimers, suggesting a regulatory function independent of the ATPase and transport activity. In conclusion, our study demonstrates the impact of ATP13A2 on α-synuclein multimerization via polyamine transport dependent and independent functions.

scholarly journals A single point mutation converts a glutaryl-7-aminocephalosporanic acid acylase into an N-acyl-homoserine lactone acylase

2021 ◽  
Author(s):  
Shereen A. Murugayah ◽  
Gary B. Evans ◽  
Joel D. A. Tyndall ◽  
Monica L. Gerth
Keyword(s):  
Single Point ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Site Directed Mutagenesis ◽  
Saturation Mutagenesis ◽  
Single Amino Acid ◽  
Single Point Mutation ◽  
Acyl Homoserine Lactone ◽  
Signalling Molecules ◽  
Single Amino Acid Residue

Abstract Objective To change the specificity of a glutaryl-7-aminocephalosporanic acid acylase (GCA) towards N-acyl homoserine lactones (AHLs; quorum sensing signalling molecules) by site-directed mutagenesis. Results Seven residues were identified by analysis of existing crystal structures as potential determinants of substrate specificity. Site-saturation mutagenesis libraries were created for each of the seven selected positions. High-throughput activity screening of each library identified two variants—Arg255Ala, Arg255Gly—with new activities towards N-acyl homoserine lactone substrates. Structural modelling of the Arg255Gly mutation suggests that the smaller side-chain of glycine (as compared to arginine in the wild-type enzyme) avoids a key clash with the acyl group of the N-acyl homoserine lactone substrate. Conclusions Mutation of a single amino acid residue successfully converted a GCA (with no detectable activity against AHLs) into an AHL acylase. This approach may be useful for further engineering of ‘quorum quenching’ enzymes.

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