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Liu M, Liu J, Ren J, Liu L, Chen R, Li Y. Bacterial community in commercial airliner cabins in China. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2020; 30:284-295. [PMID: 30897937 DOI: 10.1080/09603123.2019.1593329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Accepted: 03/06/2019] [Indexed: 06/09/2023]
Abstract
Considering the amount of time that crew members and passengers spend on airliners and the potential health impact of pathogenic bacteria, it is important to understand the population of bacteria inside airliners and the factors affecting the bacterial concentration. This study recorded the species of airborne and cabin surface culturable bacteria inside various airliner. Seven flights ranging from 3 to 5 hours in duration on different types of airliner were chosen. Multiple species of bacteria in the air of the airliners, such as Brachybacterium paraconglomeratum, were identified by means of the 16S ribosomal RNA gene sequencing method, and most of the bacteria were Gram-positive. This study found that the bacterial concentration in the airliners decreases as the relative humidity increases. The decrease in the number of airborne bacteria may be the reason for the reduced occurrence of unwanted symptoms exhibited by passengers.
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Affiliation(s)
- Mingxin Liu
- Tianjin Key Lab of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Junjie Liu
- Tianjin Key Lab of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Jianlin Ren
- Tianjin Key Lab of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Lumeng Liu
- Tianjin Key Lab of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Ruiqing Chen
- Tianjin Key Lab of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Yanju Li
- School of Energy and Safety Engineering, Tianjin Chengjian University, Tianjin, China
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2
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Sahar T, Nigam A, Anjum S, Waziri F, Biswas S, Jain SK, Wajid S. Interactome Analysis of the Differentially Expressed Proteins in Uterine Leiomyoma. Anticancer Agents Med Chem 2020; 19:1293-1312. [PMID: 30727917 DOI: 10.2174/1871520619666190206143523] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 01/22/2019] [Accepted: 01/26/2019] [Indexed: 12/18/2022]
Abstract
BACKGROUND Recent advances in proteomics present enormous opportunities to discover proteome related disparities and thus understanding the molecular mechanisms related to a disease. Uterine leiomyoma is a benign monoclonal tumor, located in the pelvic region, and affecting 40% of reproductive aged female. OBJECTIVE Identification and characterization of the differentially expressed proteins associated with leiomyogenesis by comparing uterine leiomyoma and normal myometrium. METHODS Paired samples of uterine leiomyoma and adjacent myometrium retrieved from twenty-five females suffering from uterine leiomyoma (n=50) were submitted to two-dimensional electrophoresis (2-DE), matrixassisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and to reverse transcription polymerase chain reaction (RT-PCR). RESULTS Comparison of protein patterns revealed seven proteins with concordantly increased spot intensities in leiomyoma samples. E3 ubiquitin-protein ligase MIB2 (MIB2), Mediator of RNA polymerase II transcription subunit 10 (MED10), HIRA-interacting protein (HIRP3) and Fatty acid binding protein brain (FABP7) were found to be upregulated. While, Biogenesis of lysosome-related organelles complex 1 subunit 2 (BL1S2), Shadow of prion protein (SPRN) and RNA binding motif protein X linked like 2 (RMXL2) were found to be exclusively present in leiomyoma sample. The expression modulations of the corresponding genes were further validated which corroborated with the 2-DE result showing significant upregulation in leiomyoma. We have generated a master network showing the interactions of the experimentally identified proteins with their close neighbors and further scrutinized the network to prioritize the routes leading to cell proliferation and tumorigenesis. CONCLUSION This study highlights the importance of identified proteins as potential targets for therapeutic purpose. This work provides an insight into the mechanism underlying the overexpression of the proteins but warrants further investigations.
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Affiliation(s)
- Tahreem Sahar
- Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi 110062, India
| | - Aruna Nigam
- Department of Obstetrics and Gynecology, HIMSR and HAH Centenary Hospital, Jamia Hamdard, New Delhi 110062, India
| | - Shadab Anjum
- Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi 110062, India
| | - Farheen Waziri
- Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi 110062, India
| | - Shipie Biswas
- Molecular Diagnostics, Genetix Biotech Asia Pvt. Ltd., New Delhi 110015, India
| | - Swatantra K Jain
- Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi 110062, India.,Department of Biochemistry, Hamdard Institute of Medical Sciences and Research, Jamia Hamdard, New Delhi 110062, India
| | - Saima Wajid
- Department of Biotechnology, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi 110062, India
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Hind SR, Hoki JS, Baccile JA, Boyle PC, Schroeder FC, Martin GB. Detecting the interaction of peptide ligands with plant membrane receptors. ACTA ACUST UNITED AC 2017; 2:240-269. [PMID: 29098191 DOI: 10.1002/cppb.20053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The field of plant receptor biology has rapidly expanded in recent years, however the demonstration of direct interaction between receptor-ligand pairs remains a challenge. Click chemistry has revolutionized small molecule research but lacks popularity in plant research. Here we describe a method that tests for the direct physical interaction of a candidate receptor protein and a peptide ligand. This protocol describes the generation of the ligand probe, transient expression of a receptor protein, enrichment of membrane-bound receptors, photo-crosslinking and click chemistry-mediated reporter addition, and detection of the receptor-ligand complex. Copper-based click chemistry confers several advantages, including the versatility to use almost any azide-containing reporter molecule for detection or visualization of the complex and addition of the reporter molecule after receptor-ligand binding which reduces the need for bulky ligand modifications that could interfere with the interaction.
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Affiliation(s)
| | - Jason S Hoki
- Boyce Thompson Institute, Ithaca, New York.,Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York
| | - Joshua A Baccile
- Boyce Thompson Institute, Ithaca, New York.,Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York
| | | | - Frank C Schroeder
- Boyce Thompson Institute, Ithaca, New York.,Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York
| | - Gregory B Martin
- Boyce Thompson Institute, Ithaca, New York.,School of Integrative Plant Science, Cornell University, Ithaca, New York
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4
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Heda GD, Omotola OB, Heda RP, Avery J. Effects of Reusing Gel Electrophoresis and Electrotransfer Buffers on Western Blotting. J Biomol Tech 2016; 27:113-8. [PMID: 27582639 DOI: 10.7171/jbt.16-2703-004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
SDS-PAGE and Western blotting are 2 of the most commonly used biochemical methods for protein analysis. Proteins are electrophoretically separated based on their MWs by SDS-PAGE and then electrotransferred to a solid membrane surface for subsequent protein-specific analysis by immunoblotting, a procedure commonly known as Western blotting. Both of these procedures use a salt-based buffer, with the latter procedure consisting of methanol as an additive known for its toxicity. Previous reports present a contradictory view in favor or against reusing electrotransfer buffer, also known as Towbin's transfer buffer (TTB), with an aim to reduce the toxic waste. In this report, we present a detailed analysis of not only reusing TTB but also gel electrophoresis buffer (EB) on proteins of low to high MW range. Our results suggest that EB can be reused for at least 5 times without compromising the electrophoretic separation of mixture of proteins in an MW standard, BSA, and crude cell lysates. Additionally, reuse of EB did not affect the quality of subsequent Western blots. Successive reuse of TTB, on the other hand, diminished the signal of proteins of different MWs in a protein standard and a high MW membrane protein cystic fibrosis transmembrane-conductance regulator (CFTR) in Western blotting.
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Affiliation(s)
- Ghanshyam D Heda
- Department of Sciences and Mathematics, Mississippi University for Women, Columbus, Mississippi 39701, USA;; College of Medicine, The University of Tennessee Health Sciences Center, Memphis, Tennessee 38163, USA; and
| | - Oluwabukola B Omotola
- Department of Sciences and Mathematics, Mississippi University for Women, Columbus, Mississippi 39701, USA;; Department of Biology, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Rajiv P Heda
- Department of Sciences and Mathematics, Mississippi University for Women, Columbus, Mississippi 39701, USA;; College of Medicine, The University of Tennessee Health Sciences Center, Memphis, Tennessee 38163, USA; and
| | - Jamie Avery
- Department of Sciences and Mathematics, Mississippi University for Women, Columbus, Mississippi 39701, USA
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5
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van der Meijden B, Robinson JA. Synthesis of a polymyxin derivative for photolabeling studies in the gram-negative bacteriumEscherichia coli. J Pept Sci 2015; 21:231-5. [DOI: 10.1002/psc.2736] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 12/10/2014] [Indexed: 11/12/2022]
Affiliation(s)
| | - John A. Robinson
- Department of Chemistry; University of Zurich; Winterthurerstrasse 190 8057 Zurich Switzerland
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Islam ST, Lam JS. Synthesis of bacterial polysaccharides via the Wzx/Wzy-dependent pathway. Can J Microbiol 2014; 60:697-716. [DOI: 10.1139/cjm-2014-0595] [Citation(s) in RCA: 162] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The surfaces of bacteria mediate a multitude of functions in the environment and in an infected host, including adhesion to both biotic and abiotic substrata, motility, immune system interaction and (or) activation, biofilm formation, and cell–cell communication, with many of these features directly influenced by cell-surface glycans. In both Gram-negative and Gram-positive bacteria, the majority of cell-surface polysaccharides are produced via the Wzx/Wzy-dependent assembly pathway; these glycans include heteropolymeric O-antigen, enterobacterial common antigen, exopolysaccharide, spore coat, and capsule in diverse bacteria. The key components of this assembly pathway are the integral inner membrane Wzx flippase, Wzy polymerase, and Wzz chain-length regulator proteins, which until recently have resisted detailed structural and functional characterization. In this review, we have provided a comprehensive synthesis of the latest structural and mechanistic data for each protein, as well as an examination of substrate specificity for each assembly step and complex formation between the constituent proteins. To complement the unprecedented explosion of genomic-sequencing data for bacteria, we have also highlighted both classical and state-of-the-art methods by which encoded Wzx, Wzy, and Wzz proteins can be reliably identified and annotated, using the model Gram-negative bacterium Pseudomonas aeruginosa as an example data set. Lastly, we outline future avenues of research, with the aim of stimulating researchers to take the next steps in investigating the function of, and interplay between, the constituents of this widespread assembly scheme.
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Affiliation(s)
- Salim T. Islam
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Joseph S. Lam
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
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7
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Conserved-residue mutations in Wzy affect O-antigen polymerization and Wzz-mediated chain-length regulation in Pseudomonas aeruginosa PAO1. Sci Rep 2013; 3:3441. [PMID: 24309320 PMCID: PMC3854497 DOI: 10.1038/srep03441] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 11/20/2013] [Indexed: 12/15/2022] Open
Abstract
O antigen (O-Ag) in many bacteria is synthesized via the Wzx/Wzy-dependent pathway in which Wzy polymerizes lipid-linked O-Ag subunits to modal lengths regulated by Wzz. Characterization of 83 site-directed mutants of Wzy from Pseudomonas aeruginosa PAO1 (WzyPa) in topologically-mapped periplasmic (PL) and cytoplasmic loops (CL) verified the functional importance of PL3 and PL5, with the former shown to require overall cationic properties. Essential Arg residues in the RX10G motifs of PL3 and PL5 were found to be conserved in putative homologues of WzyPa, as was the overall sequence homology between these two periplasmic loops in each protein. Amino acid substitutions in CL6 were found to alter Wzz-mediated O-antigen modality, with evidence suggesting that these changes may perturb the C-terminal WzyPa tertiary structure. Together, these data suggest that the catch-and-release mechanism of O-Ag polymerization is widespread among bacteria and that regulation of polymer length is affected by interaction of Wzz with Wzy.
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8
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Islam ST, Lam JS. Topological mapping methods for α-helical bacterial membrane proteins--an update and a guide. Microbiologyopen 2013; 2:350-64. [PMID: 23408725 PMCID: PMC3633358 DOI: 10.1002/mbo3.72] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 01/04/2013] [Accepted: 01/10/2013] [Indexed: 12/19/2022] Open
Abstract
Integral membrane proteins with α-helical transmembrane segments (TMS) are known to play important and diverse roles in prokaryotic cell physiology. The net hydrophobicity of TMS directly corresponds to the observed difficulties in expressing and purifying these proteins, let alone producing sufficient yields for structural studies using two-/three-dimensional (2D/3D) crystallographic or nuclear magnetic resonance methods. To gain insight into the function of these integral membrane proteins, topological mapping has become an important tool to identify exposed and membrane-embedded protein domains. This approach has led to the discovery of protein tracts of functional importance and to the proposition of novel mechanistic hypotheses. In this review, we synthesize the various methods available for topological mapping of α-helical integral membrane proteins to provide investigators with a comprehensive reference for choosing techniques suited to their particular topological queries and available resources.
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Affiliation(s)
- Salim T Islam
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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9
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Frank CG, Reguerio V, Rother M, Moranta D, Maeurer AP, Garmendia J, Meyer TF, Bengoechea JA. Klebsiella pneumoniae targets an EGF receptor-dependent pathway to subvert inflammation. Cell Microbiol 2013; 15:1212-33. [PMID: 23347154 DOI: 10.1111/cmi.12110] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 12/21/2012] [Accepted: 01/12/2013] [Indexed: 12/24/2022]
Abstract
The NF-κB transcriptional factor plays a key role governing the activation of immune responses. Klebsiella pneumoniae is an important cause of community-acquired and nosocomial pneumonia. Evidence indicates that K. pneumoniae infections are characterized by lacking an early inflammatory response. Recently, we have demonstrated that Klebsiella antagonizes the activation of NF-κB via the deubiquitinase CYLD. In this work, by applying a high-throughput siRNA gain-of-function screen interrogating the human kinome, we identified 17 kinases that when targeted by siRNA restored IL-1β-dependent NF-κB translocation in infected cells. Further characterization revealed that K. pneumoniae activates an EGF receptor (EGFR)-phosphatidylinositol 3-OH kinase (PI3K)-AKT-PAK4-ERK-GSK3β signalling pathway to attenuate the cytokine-dependent nuclear translocation of NF-κB. Our data also revealed that CYLD is a downstream effector of K. pneumoniae-induced EGFR-PI3K-AKT-PAK4-ERK-GSK3β signalling pathway. Our efforts to identify the bacterial factor(s)responsible for EGFR activation demonstrate that a capsule (CPS) mutant did not activate EGFR hence suggesting that CPS could mediate the activation of EGFR. Supporting this notion, purified CPS did activate EGFR as well as the EGFR-dependent PI3K-AKT-PAK4-ERK-GSK3β signalling pathway. CPS-mediated EGFR activation was dependent on a TLR4-MyD88-c-SRC-dependent pathway. Several promising drugs have been developed to antagonize this cascade. We propose that agents targeting this signalling pathway might provide selective alternatives for the management of K. pneumoniae pneumonias.
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Affiliation(s)
- Christian G Frank
- Laboratory Microbial Pathogenesis, Fundació d'Investigació Sanitària de les Illes Balears (FISIB), Recinto Hospital Joan March, 07110, Bunyola, Spain
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10
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Aistleitner K, Heinz C, Hörmann A, Heinz E, Montanaro J, Schulz F, Maier E, Pichler P, Benz R, Horn M. Identification and characterization of a novel porin family highlights a major difference in the outer membrane of chlamydial symbionts and pathogens. PLoS One 2013; 8:e55010. [PMID: 23383036 PMCID: PMC3561449 DOI: 10.1371/journal.pone.0055010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 12/18/2012] [Indexed: 11/24/2022] Open
Abstract
The Chlamydiae constitute an evolutionary well separated group of intracellular bacteria comprising important pathogens of humans as well as symbionts of protozoa. The amoeba symbiont Protochlamydia amoebophila lacks a homologue of the most abundant outer membrane protein of the Chlamydiaceae, the major outer membrane protein MOMP, highlighting a major difference between environmental chlamydiae and their pathogenic counterparts. We recently identified a novel family of putative porins encoded in the genome of P. amoebophila by in silico analysis. Two of these Protochlamydiaouter membrane proteins, PomS (pc1489) and PomT (pc1077), are highly abundant in outer membrane preparations of this organism. Here we show that all four members of this putative porin family are toxic when expressed in the heterologous host Escherichia coli. Immunofluorescence analysis using antibodies against heterologously expressed PomT and PomS purified directly from elementary bodies, respectively, demonstrated the location of both proteins in the outer membrane of P. amoebophila. The location of the most abundant protein PomS was further confirmed by immuno-transmission electron microscopy. We could show that pomS is transcribed, and the corresponding protein is present in the outer membrane throughout the complete developmental cycle, suggesting an essential role for P. amoebophila. Lipid bilayer measurements demonstrated that PomS functions as a porin with anion-selectivity and a pore size similar to the Chlamydiaceae MOMP. Taken together, our results suggest that PomS, possibly in concert with PomT and other members of this porin family, is the functional equivalent of MOMP in P. amoebophila. This work contributes to our understanding of the adaptations of symbiotic and pathogenic chlamydiae to their different eukaryotic hosts.
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Affiliation(s)
- Karin Aistleitner
- Department of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Christian Heinz
- Department of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Alexandra Hörmann
- Department of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Eva Heinz
- Department of Microbial Ecology, University of Vienna, Vienna, Austria
| | | | - Frederik Schulz
- Department of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Elke Maier
- Rudolf-Virchow-Center, Deutsche Forschungsgemeinschaft - Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
| | - Peter Pichler
- Christian Doppler Laboratory for Mass Spectrometry, Vienna, Austria
| | - Roland Benz
- Rudolf-Virchow-Center, Deutsche Forschungsgemeinschaft - Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
- School of Engineering and Science, Jacobs University Bremen, Bremen, Germany
| | - Matthias Horn
- Department of Microbial Ecology, University of Vienna, Vienna, Austria
- * E-mail:
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11
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Reinés M, Llobet E, Dahlström KM, Pérez-Gutiérrez C, Llompart CM, Torrecabota N, Salminen TA, Bengoechea JA. Deciphering the acylation pattern of Yersinia enterocolitica lipid A. PLoS Pathog 2012; 8:e1002978. [PMID: 23133372 PMCID: PMC3486919 DOI: 10.1371/journal.ppat.1002978] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 09/05/2012] [Indexed: 12/20/2022] Open
Abstract
Pathogenic bacteria may modify their surface to evade the host innate immune response. Yersinia enterocolitica modulates its lipopolysaccharide (LPS) lipid A structure, and the key regulatory signal is temperature. At 21°C, lipid A is hexa-acylated and may be modified with aminoarabinose or palmitate. At 37°C, Y. enterocolitica expresses a tetra-acylated lipid A consistent with the 3′-O-deacylation of the molecule. In this work, by combining genetic and mass spectrometric analysis, we establish that Y. enterocolitica encodes a lipid A deacylase, LpxR, responsible for the lipid A structure observed at 37°C. Western blot analyses indicate that LpxR exhibits latency at 21°C, deacylation of lipid A is not observed despite the expression of LpxR in the membrane. Aminoarabinose-modified lipid A is involved in the latency. 3-D modelling, docking and site-directed mutagenesis experiments showed that LpxR D31 reduces the active site cavity volume so that aminoarabinose containing Kdo2-lipid A cannot be accommodated and, therefore, not deacylated. Our data revealed that the expression of lpxR is negatively controlled by RovA and PhoPQ which are necessary for the lipid A modification with aminoarabinose. Next, we investigated the role of lipid A structural plasticity conferred by LpxR on the expression/function of Y. enterocolitica virulence factors. We present evidence that motility and invasion of eukaryotic cells were reduced in the lpxR mutant grown at 21°C. Mechanistically, our data revealed that the expressions of flhDC and rovA, regulators controlling the flagellar regulon and invasin respectively, were down-regulated in the mutant. In contrast, the levels of the virulence plasmid (pYV)-encoded virulence factors Yops and YadA were not affected in the lpxR mutant. Finally, we establish that the low inflammatory response associated to Y. enterocolitica infections is the sum of the anti-inflammatory action exerted by pYV-encoded YopP and the reduced activation of the LPS receptor by a LpxR-dependent deacylated LPS. Lipopolysaccharide (LPS) is one of the major surface components of Gram-negative bacteria. The LPS contains a molecular pattern recognized by the innate immune system. Not surprisingly, the modification of the LPS pattern is a virulence strategy of several pathogens to evade the innate immune system. Yersinia enterocolitica causes food-borne infections in animals and humans (yersiniosis). Temperature regulates most, if not all, virulence factors of yersiniae including the structure of the LPS lipid A. At 21°C, lipid A is mainly hexa-acylated and may be modified with aminoarabinose or palmitate. In contrast, at 37°C, Y. enterocolitica expresses a unique tetra-acylated lipid A. In this work, we establish that Y. enterocolitica encodes a lipid A deacylase, LpxR, responsible for the lipid A structure expressed by the pathogen at 37°C, the host temperature. Our findings also revealed that the low inflammatory response associated to Y. enterocolitica infections is the sum of the anti-inflammatory action exerted by a Yersinia protein translocated into the cytosol of macrophages and the reduced activation of the LPS receptor complex due to the expression of a LpxR-dependent deacylated LPS.
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Affiliation(s)
- Mar Reinés
- Laboratory Microbial Pathogenesis, Fundació d'Investigació Sanitària de les Illes Balears (FISIB), Recinto Hospital Joan March, Bunyola, Spain
- Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Enrique Llobet
- Laboratory Microbial Pathogenesis, Fundació d'Investigació Sanitària de les Illes Balears (FISIB), Recinto Hospital Joan March, Bunyola, Spain
| | - Käthe M. Dahlström
- Structural Bioinformatics Laboratory, Department of Biosciences, Åbo Akademi University, Turku, Finland
| | - Camino Pérez-Gutiérrez
- Laboratory Microbial Pathogenesis, Fundació d'Investigació Sanitària de les Illes Balears (FISIB), Recinto Hospital Joan March, Bunyola, Spain
| | - Catalina M. Llompart
- Laboratory Microbial Pathogenesis, Fundació d'Investigació Sanitària de les Illes Balears (FISIB), Recinto Hospital Joan March, Bunyola, Spain
| | - Nuria Torrecabota
- Laboratory Microbial Pathogenesis, Fundació d'Investigació Sanitària de les Illes Balears (FISIB), Recinto Hospital Joan March, Bunyola, Spain
| | - Tiina A. Salminen
- Structural Bioinformatics Laboratory, Department of Biosciences, Åbo Akademi University, Turku, Finland
| | - José A. Bengoechea
- Laboratory Microbial Pathogenesis, Fundació d'Investigació Sanitària de les Illes Balears (FISIB), Recinto Hospital Joan March, Bunyola, Spain
- Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- * E-mail:
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Islam ST, Lam JS. Wzx flippase-mediated membrane translocation of sugar polymer precursors in bacteria. Environ Microbiol 2012; 15:1001-15. [PMID: 23016929 DOI: 10.1111/j.1462-2920.2012.02890.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 08/13/2012] [Accepted: 08/18/2012] [Indexed: 11/29/2022]
Abstract
Bacterial cell surface polysaccharides confer resistance to external stress and promote survival in biotic and abiotic environments. Glycan assembly often occurs at the periplasmic leaflet of the inner membrane (IM) from undecaprenyl pyrophosphate (UndPP)-linked polysaccharide units via the Wzx/Wzy-dependent pathway. Wzx is an integral IM protein found in Gram-negative and Gram-positive bacteria that mediates IM translocation of UndPP-linked sugar repeats from the cytoplasmic to the periplasmic leaflet; interaction of Wzx with other assembly proteins is indirectly supported by genetic evidence. Topological mapping has indicated 12 α-helical transmembrane segments (TMS), with the number of charged TMS residues fluctuating based on the mapping method used. A novel Wzx tertiary structure model has been built, allowing for substrate-binding or energy-coupling roles to be proposed for functionally important charged and aromatic TMS residues. It has also led to a proposed antiport-like mechanism of Wzx function. Exquisite substrate specificity of Wzx proteins was recently revealed in distinguishing between UndPP-linked substrates with identical main-chain sugar repeats, but differing in the chemical composition of a terminal sugar side-branch cap. The objective of this review is to synthesize the most up-to-date knowledge concerning Wzx flippases and to provide perspective for future investigations in this burgeoning field.
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Affiliation(s)
- Salim T Islam
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
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13
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Production of Coturnix quail immunoglobulins Y (IgYs) against Vibrio parahaemolyticus and Vibrio vulnificus. Food Sci Biotechnol 2011. [DOI: 10.1007/s10068-011-0218-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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14
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Islam ST, Gold AC, Taylor VL, Anderson EM, Ford RC, Lam JS. Dual conserved periplasmic loops possess essential charge characteristics that support a catch-and-release mechanism of O-antigen polymerization by Wzy in Pseudomonas aeruginosa PAO1. J Biol Chem 2011; 286:20600-5. [PMID: 21498511 PMCID: PMC3121466 DOI: 10.1074/jbc.c110.204651] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heteropolymeric B-band lipopolysaccharide in Pseudomonas aeruginosa PAO1 is synthesized via the so-called Wzy-dependent pathway, requiring a functional Wzy for polymerization of O-antigen repeat units in the periplasm. Wzy is an integral inner membrane protein for which the detailed topology has been mapped in a recent investigation (Islam, S. T., Taylor, V. L., Qi, M., and Lam, J. S. (2010) mBio 1, e00189-10), revealing two principal periplasmic loops (PL), PL3 and PL5, each containing an RX10G motif. Despite considerable sequence conservation between the two loops, the isoelectric point for each peptide displayed marked differences, with PL3 exhibiting a net-positive charge and PL5 showing a net-negative charge. Data from site-directed mutagenesis of amino acids in each PL have led to the identification of several key Arg residues within the two RX10G motifs that are important for Wzy function, of which Arg176, Arg290, and Arg291 could not be functionally substituted with Lys. These observations support the proposed role of each PL in a catch-and-release mechanism for Wzy-mediated O-antigen polymerization.
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Affiliation(s)
- Salim T Islam
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Aguilar HN, Zielnik B, Tracey CN, Mitchell BF. Quantification of rapid Myosin regulatory light chain phosphorylation using high-throughput in-cell Western assays: comparison to Western immunoblots. PLoS One 2010; 5:e9965. [PMID: 20376358 PMCID: PMC2848601 DOI: 10.1371/journal.pone.0009965] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Accepted: 02/18/2010] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Quantification of phospho-proteins (PPs) is crucial when studying cellular signaling pathways. Western immunoblotting (WB) is commonly used for the measurement of relative levels of signaling intermediates in experimental samples. However, WB is in general a labour-intensive and low-throughput technique. Because of variability in protein yield and phospho-signal preservation during protein harvesting, and potential loss of antigen during protein transfer, WB provides only semi-quantitative data. By comparison, the "in-cell western" (ICW) technique has high-throughput capacity and requires less extensive sample preparation. Thus, we compared the ICW technique to WB for measuring phosphorylated myosin regulatory light chain (PMLC(20)) in primary cultures of uterine myocytes to assess their relative specificity, sensitivity, precision, and quantification of biologically relevant responses. METHODOLOGY/PRINCIPAL FINDINGS ICWs are cell-based microplate assays for quantification of protein targets in their cellular context. ICWs utilize a two-channel infrared (IR) scanner (Odyssey(R)) to quantify signals arising from near-infrared (NIR) fluorophores conjugated to secondary antibodies. One channel is dedicated to measuring the protein of interest and the second is used for data normalization of the signal in each well of the microplate. Using uterine myocytes, we assessed oxytocin (OT)-stimulated MLC(20) phosphorylation measured by ICW and WB, both using NIR fluorescence. ICW and WB data were comparable regarding signal linearity, signal specificity, and time course of phosphorylation response to OT. CONCLUSION/SIGNIFICANCE ICW and WB yield comparable biological data. The advantages of ICW over WB are its high-throughput capacity, improved precision, and reduced sample preparation requirements. ICW might provide better sensitivity and precision with low-quantity samples or for protocols requiring large numbers of samples. These features make the ICW technique an excellent tool for the study of phosphorylation endpoints. However, the drawbacks of ICW include the need for a cell culture format and the lack of utility where protein purification, concentration or stoichiometric analyses are required.
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Affiliation(s)
- Hector N. Aguilar
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Barbara Zielnik
- Department of Obstetrics and Gynecology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Curtis N. Tracey
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Bryan F. Mitchell
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- Department of Obstetrics and Gynecology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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Kaur J, Bachhawat AK. A modified Western blot protocol for enhanced sensitivity in the detection of a membrane protein. Anal Biochem 2009; 384:348-9. [DOI: 10.1016/j.ab.2008.10.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 09/15/2008] [Accepted: 10/07/2008] [Indexed: 11/25/2022]
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Abeyrathne PD, Lam JS. WaaL of Pseudomonas aeruginosa utilizes ATP in in vitro ligation of O antigen onto lipid A-core. Mol Microbiol 2008; 65:1345-59. [PMID: 17697256 DOI: 10.1111/j.1365-2958.2007.05875.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
waaL has been implicated as the gene that encodes the O-antigen ligase. To date, in vitro biochemical evidence to prove that WaaL possesses ligase activity has been lacking due to the difficulty of purifying WaaL and unavailability of substrates. Here we describe the purification of WaaL, a membrane protein with 11 potential transmembrane segments from Pseudomonas aeruginosa, and the development of an in vitro O-antigen ligase assay. WaaL was expressed in a P. aeruginosa wbpL knockout strain, which is defective in its initial glycosyltransferase for O-antigen biosynthesis. This approach allowed the purification of WaaL without contaminating O-antigen-undecaprenol-phosphate (Und-P) molecules. Purified WaaL resolved to a monomer (35 kDa) and a dimer (70 kDa) band in SDS-PAGE. The substrates for the O-antigen ligase assay, O-antigen-Und-P and lipid A-core were prepared from a waaL mutant. ATP at 2-4 mM is optimum for the O-ligase activity, and ATP hydrolysis by WaaL follows Michaelis-Menten kinetics. Site-directed mutagenesis analysis indicated that the periplasmic loop region of WaaL is important for ligase activity. A waaL mutant of P. aeruginosa could not be cross-complemented by waaL of Escherichia coli, which suggested that each of these proteins has specificity for its cognate core oligosaccharide.
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Affiliation(s)
- Priyanka D Abeyrathne
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
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Han XX, Jia HY, Wang YF, Lu ZC, Wang CX, Xu WQ, Zhao B, Ozaki Y. Analytical Technique for Label-Free Multi-Protein Detection Based on Western Blot and Surface-Enhanced Raman Scattering. Anal Chem 2008; 80:2799-804. [DOI: 10.1021/ac702390u] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiao X. Han
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China
| | - Hui Y. Jia
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China
| | - Yan F. Wang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China
| | - Zhi C. Lu
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China
| | - Chun X. Wang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China
| | - Wei Q. Xu
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China
| | - Bing Zhao
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China
| | - Yukihiro Ozaki
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012, P. R. China
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