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Vassen V, Valotteau C, Feuillie C, Formosa-Dague C, Dufrêne YF, De Bolle X. Localized incorporation of outer membrane components in the pathogen Brucella abortus. EMBO J 2019; 38:e100323. [PMID: 30635335 PMCID: PMC6396147 DOI: 10.15252/embj.2018100323] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 11/29/2018] [Accepted: 12/04/2018] [Indexed: 12/21/2022] Open
Abstract
The zoonotic pathogen Brucella abortus is part of the Rhizobiales, which are alpha-proteobacteria displaying unipolar growth. Here, we show that this bacterium exhibits heterogeneity in its outer membrane composition, with clusters of rough lipopolysaccharide co-localizing with the essential outer membrane porin Omp2b, which is proposed to allow facilitated diffusion of solutes through the porin. We also show that the major outer membrane protein Omp25 and peptidoglycan are incorporated at the new pole and the division site, the expected growth sites. Interestingly, lipopolysaccharide is also inserted at the same growth sites. The absence of long-range diffusion of main components of the outer membrane could explain the apparent immobility of the Omp2b clusters, as well as unipolar and mid-cell localizations of newly incorporated outer membrane proteins and lipopolysaccharide. Unipolar growth and limited mobility of surface structures also suggest that new surface variants could arise in a few generations without the need of diluting pre-existing surface antigens.
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Affiliation(s)
- Victoria Vassen
- Research Unit in Biology of Microorganisms (URBM), Narilis University of Namur (UNamur), Namur, Belgium
| | - Claire Valotteau
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Cécile Feuillie
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Cécile Formosa-Dague
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
| | - Yves F Dufrêne
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain (UCL), Louvain-la-Neuve, Belgium
- Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Wavre, Belgium
| | - Xavier De Bolle
- Research Unit in Biology of Microorganisms (URBM), Narilis University of Namur (UNamur), Namur, Belgium
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2
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Gram-negative trimeric porins have specific LPS binding sites that are essential for porin biogenesis. Proc Natl Acad Sci U S A 2016; 113:E5034-43. [PMID: 27493217 DOI: 10.1073/pnas.1602382113] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The outer membrane (OM) of gram-negative bacteria is an unusual asymmetric bilayer with an external monolayer of lipopolysaccharide (LPS) and an inner layer of phospholipids. The LPS layer is rigid and stabilized by divalent cation cross-links between phosphate groups on the core oligosaccharide regions. This means that the OM is robust and highly impermeable to toxins and antibiotics. During their biogenesis, OM proteins (OMPs), which function as transporters and receptors, must integrate into this ordered monolayer while preserving its impermeability. Here we reveal the specific interactions between the trimeric porins of Enterobacteriaceae and LPS. Isolated porins form complexes with variable numbers of LPS molecules, which are stabilized by calcium ions. In earlier studies, two high-affinity sites were predicted to contain groups of positively charged side chains. Mutation of these residues led to the loss of LPS binding and, in one site, also prevented trimerization of the porin, explaining the previously observed effect of LPS mutants on porin folding. The high-resolution X-ray crystal structure of a trimeric porin-LPS complex not only helps to explain the mutagenesis results but also reveals more complex, subtle porin-LPS interactions and a bridging calcium ion.
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3
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Thaipisuttikul I, Hittle LE, Chandra R, Zangari D, Dixon CL, Garrett TA, Rasko DA, Dasgupta N, Moskowitz SM, Malmström L, Goodlett DR, Miller SI, Bishop RE, Ernst RK. A divergent Pseudomonas aeruginosa palmitoyltransferase essential for cystic fibrosis-specific lipid A. Mol Microbiol 2013; 91:158-74. [PMID: 24283944 DOI: 10.1111/mmi.12451] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2013] [Indexed: 12/25/2022]
Abstract
Strains of Pseudomonas aeruginosa (PA) isolated from the airways of cystic fibrosis patients constitutively add palmitate to lipid A, the membrane anchor of lipopolysaccharide. The PhoPQ regulated enzyme PagP is responsible for the transfer of palmitate from outer membrane phospholipids to lipid A. This enzyme had previously been identified in many pathogenic Gram-negative bacteria, but in PA had remained elusive, despite abundant evidence that its lipid A contains palmitate. Using a combined genetic and biochemical approach, we identified PA1343 as the PA gene encoding PagP. Although PA1343 lacks obvious primary structural similarity with known PagP enzymes, the β-barrel tertiary structure with an interior hydrocarbon ruler appears to be conserved. PA PagP transfers palmitate to the 3' position of lipid A, in contrast to the 2 position seen with the enterobacterial PagP. Palmitoylated PA lipid A alters host innate immune responses, including increased resistance to some antimicrobial peptides and an elevated pro-inflammatory response, consistent with the synthesis of a hexa-acylated structure preferentially recognized by the TLR4/MD2 complex. Palmitoylation commonly confers resistance to cationic antimicrobial peptides, however, increased cytokine production resulting in inflammation is not seen with other palmitoylated lipid A, indicating a unique role for this modification in PA pathogenesis.
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Affiliation(s)
- Iyarit Thaipisuttikul
- Department of Microbial Pathogenesis, University of Maryland, School of Dentistry, University of Maryland, Baltimore, MD, 21201, USA; Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Prannok Road, Bangkoknoi, Bangkok, 10700, Thailand
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4
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Baboolal TG, Conroy MJ, Gill K, Ridley H, Visudtiphole V, Bullough PA, Lakey JH. Colicin N binds to the periphery of its receptor and translocator, outer membrane protein F. Structure 2008; 16:371-9. [PMID: 18334212 PMCID: PMC2581486 DOI: 10.1016/j.str.2007.12.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 12/20/2007] [Accepted: 12/21/2007] [Indexed: 11/24/2022]
Abstract
Colicins kill Escherichia coli after translocation across the outer membrane. Colicin N displays an unusually simple translocation pathway, using the outer membrane protein F (OmpF) as both receptor and translocator. Studies of this binary complex may therefore reveal a significant component of the translocation pathway. Here we show that, in 2D crystals, colicin is found outside the porin trimer, suggesting that translocation may occur at the protein-lipid interface. The major lipid of the outer leaflet interface is lipopolysaccharide (LPS). It is further shown that colicin N binding displaces OmpF-bound LPS. The N-terminal helix of the pore-forming domain, which is not required for pore formation, rearranges and binds to OmpF. Colicin N also binds artificial OmpF dimers, indicating that trimeric symmetry plays no part in the interaction. The data indicate that colicin is closely associated with the OmpF-lipid interface, providing evidence that this peripheral pathway may play a role in colicin transmembrane transport.
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Affiliation(s)
- Thomas G Baboolal
- The Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle-upon-Tyne, NE2 4HH, United Kingdom
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5
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Lukáčová M, Barák I, Kazár J. Role of structural variations of polysaccharide antigens in the pathogenicity of Gram-negative bacteria. Clin Microbiol Infect 2008; 14:200-6. [DOI: 10.1111/j.1469-0691.2007.01876.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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6
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Siroy A, Cosette P, Seyer D, Lemaître-Guillier C, Vallenet D, Van Dorsselaer A, Boyer-Mariotte S, Jouenne T, Dé E. Global Comparison of the Membrane Subproteomes between a Multidrug-ResistantAcinetobacterbaumanniiStrain and a Reference Strain. J Proteome Res 2006; 5:3385-98. [PMID: 17137340 DOI: 10.1021/pr060372s] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Acinetobacter baumannii causes severe infections in compromised patients. We combined SDS-PAGE, two-dimensional gel electrophoresis and mass spectrometry (LC-MS/MS and MALDI-TOF) to separate and characterize the proteins of the cell envelope of this bacterium. In total, 135 proteins (inner and outer membrane proteins) were identified. In this analysis, we described the expression by this bacterium of RND-type efflux systems and some potential virulence factors. We then compared the membrane subproteome of a clinical multidrug-resistant (MDR) isolate with that of a reference strain. We found that the MDR strain expressed lower levels of the penicillin-binding-protein 1b, produced a CarO protein having different primary and quaternary structures to that of the reference strain, and expressed OmpW isoforms. We also showed that the clinical strain has a high ability to form biofilms consistent with the accumulation of some outer membrane proteins (OMPs) such as NlpE or CsuD that have already been described as involved in bacterial adhesion. These features may partly explain the MDR emergence of the clinical isolate.
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Affiliation(s)
- Axel Siroy
- IBBR Group, Laboratory Polymères, Biopolymères, Membranes, UMR 6522 CNRS, University of Rouen, France
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7
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Tabatabai LB, Zehr ES. Identification of five outer membrane-associated proteins among cross-protective factor proteins of Pasteurella multocida. Infect Immun 2004; 72:1195-8. [PMID: 14742575 PMCID: PMC321617 DOI: 10.1128/iai.72.2.1195-1198.2004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fowl cholera is caused by Pasteurella multocida serovars A:1, A:3, and A:4. The 39-kDa cross-protective factor protein and four other membrane proteins of the membrane proteome of P. multocida were identified. We determined that the 39-kDa cross-protective protein was Pasteurella lipoprotein B, or PlpB.
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Affiliation(s)
- Louisa B Tabatabai
- National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa 50010, USA.
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8
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El Hamel C, Freulet MA, Jaquinod M, Dé E, Molle G, Orange N. Involvement of the C-terminal part of Pseudomonas fluorescens OprF in the modulation of its pore-forming properties. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1509:237-44. [PMID: 11118535 DOI: 10.1016/s0005-2736(00)00300-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The major outer-membrane protein, OprF, from the psychrotrophic bacterium Pseudomonas fluorescens undergoes a reduction of its conductance value (from 250 pS to 80 pS) when the growth temperature is shifted from 28 degrees C to 8 degrees C. The involvement of changes in tertiary or quaternary structure in this behaviour, was implied by enzymatic digestion experiments in which OprFs purified from 8 degrees C and 28 degrees C cultures showed different accessibility to pronase. Resistant proteolytic fragments of 19 kDa, obtained from both OprF preparations, were identified as the N-terminal half of the native protein. These 19 kDa fragments induced ion channels in planar lipid bilayers with similar conductance values of 65-75 pS in 1 M NaCl, in contrast to the native proteins. Thus, the C-terminal part of the protein is required for the growth temperature-dependent modulation of OprF channel-forming properties. LPS was not detected on the proteolytic fragments while it was found in similar amounts on the native OprFs. These results suggest the LPS/porin association occurs through the C-terminal part of the porin. Radiolabelling experiments showed different phosphorylation levels of LPS for 8 degrees C and 28 degrees C cultures. Thus, in response to growth temperature, the structural modification of the LPS could be associated to the modulation of OprF pore size.
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Affiliation(s)
- C El Hamel
- UMR 6522, CNRS, IFRMP 23, Faculté des Sciences, Mont-Sanit-Aignan, France
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Freulet-Marrière MA, El Hamel C, Chevalier S, Dé E, Molle G, Orange N. Evidence for association of lipopolysaccharide with Pseudomonas fluorescens strain MF0 porin OprF. Res Microbiol 2000; 151:873-6. [PMID: 11191813 DOI: 10.1016/s0923-2508(00)01154-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Lipopolysaccharide (LPS) was found to be associated with the major outer membrane protein OprF of the psychrotrophic bacterium Pseudomonas fluorescens MF0, using two OprF purification procedures. OprF, purified under mild conditions, presented two types of association with LPS: tight (tLPS) and slight (sLPS), both of type R. LPS protected OprF from heat modification and trypsin degradation and facilitated the reincorporation of purified OprF into an artificial lipid bilayer without affecting its pore-forming activity. The size of the OprF channel depended on cell growth temperature, as did the extent of LPS phosphorylation: we suggest that LPS may be involved in modifications of OprF pore formation.
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Affiliation(s)
- M A Freulet-Marrière
- Laboratoire de microbiologie du froid, Upres 2123, Université de Rouen, Evreux, France
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10
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Berlanga M, Ruiz N, Hernandez-Borrell J, Montero T, Viñas M. Role of the outer membrane in the accumulation of quinolones bySerratia marcescens. Can J Microbiol 2000. [DOI: 10.1139/w00-052] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Accumulation of four quinolones by Serratia marcescens was measured fluorometrically. The passage of quinolones through the outer membrane was studied in both lipopolysaccharide-deficient and porin-deficient mutants. The lipopolysaccharide (LPS) layer formed a partially effective barrier for highly hydrophobic quinolones such as nalidixic acid. Quinolones with a low relative hydrophobicity coefficient seemed to pass preferentially through the water-filled Omp3 porin channels. Results were confirmed when Omp3 was cloned in a porin-defective Escherichia coli.
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11
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Arockiasamy A, Krishnaswamy S. Purification of integral outer-membrane protein OmpC, a surface antigen from Salmonella typhi for structure-function studies: a method applicable to enterobacterial major outer-membrane protein. Anal Biochem 2000; 283:64-70. [PMID: 10929809 DOI: 10.1006/abio.2000.4634] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Extraction of the outer-membrane porin, OmpC, from Salmonella typhi Ty21a was done by using a modified salt-extraction procedure. It was possible to extract only the major outer-membrane protein (OMP) from the crude membrane using this method. Aberrant lipopolysaccharide (LPS) production in the galE mutant Ty21a has resulted in more isoforms of OmpC and subsequently led to anomalous mobility in SDS-PAGE. The purity of the preparation was confirmed by denaturing urea SDS-PAGE and N-terminal sequencing. The major OMP extracts had LPS of both bound and free forms. The free form of LPS could be removed by gel filtration and the bound form, largely, was removed using ion-exchange chromatography and by passing through ultrafiltration devices. This method has been used to extract the native trimer of OmpC, the major OMP, in a large scale, for structure-function studies. S. typhi Ty21a OmpC preparation yielded reproducible diffraction-quality crystals. Extracts of porin from wild-type Escherichia coli HB101, grown under high osmolarity conditions, showed a single species of OMP on SDS-PAGE. This suggests the possible application of the method to other gram-negative bacterial porins.
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Affiliation(s)
- A Arockiasamy
- Bioinformatics Centre, School of Biotechnology, Madurai Kamaraj University, India
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12
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Guina T, Yi EC, Wang H, Hackett M, Miller SI. A PhoP-regulated outer membrane protease of Salmonella enterica serovar typhimurium promotes resistance to alpha-helical antimicrobial peptides. J Bacteriol 2000; 182:4077-86. [PMID: 10869088 PMCID: PMC94595 DOI: 10.1128/jb.182.14.4077-4086.2000] [Citation(s) in RCA: 255] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The outer membrane protein contents of Salmonella enterica serovar Typhimurium strains with PhoP/PhoQ regulon mutations were compared by two-dimensional gel electrophoresis. At least 26 species of outer membrane proteins (OMPs) were identified as being regulated by PhoP/PhoQ activation. One PhoP/PhoQ-activated OMP was identified by semiautomated tandem mass spectrometry coupled with electronic database searching as PgtE, a member of the Escherichia coli OmpT and Yersinia pestis Pla family of outer membrane proteases. Salmonella PgtE expression promoted resistance to alpha-helical cationic antimicrobial peptides (alpha-CAMPs). Strains expressing PgtE cleaved C18G, an 18-residue alpha-CAMP present in culture medium, indicating that protease activity is likely to be the mechanism of OmpT-mediated resistance to alpha-CAMPs. PhoP/PhoQ did not regulate the transcription or export of PgtE, indicating that another PhoP/PhoQ-dependent mechanism is required for PgtE outer membrane localization. PgtE is a posttranscriptionally regulated component of the PhoP/PhoQ regulon that contributes to Salmonella resistance to innate immunity.
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Affiliation(s)
- T Guina
- Departments of Microbiology, University of Washington, Seattle 98195, USA
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13
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Dahan D, Srikumar R, Laprade R, Coulton JW. Purification and refolding of recombinant Haemophilus influenzae type b porin produced in Bacillus subtilis. FEBS Lett 1996; 392:304-8. [PMID: 8774868 DOI: 10.1016/0014-5793(96)00841-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The major diffusion channel in the outer membrane of Haemophilus influenzae type b (Hib) is porin (341 amino acids; Mr 37 782). The Hib porin gene was cloned and overexpressed in Bacillus subtilis. Recombinant Hib porin (Bac porin), having aggregated into inclusion bodies, was purified under denaturing conditions and subsequently refolded. To compare Bac porin that is intrinsically devoid of lipooligosaccharides versus native Hib porin, the properties of Bac porin were assessed by the following four criteria: circular dichroism spectroscopy, channel formation in planar bilayers, resistance to trypsin digestion and formation of the conformational epitope recognized by an anti-Hib porin monoclonal antibody. We conclude that in the absence of lipooligosaccharides, Bac porin was refolded into a functional form which closely resembled the structure of Hib porin.
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Affiliation(s)
- D Dahan
- Department of Microbiology and Immunology, McGill University, Montreal, Canada
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14
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15
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de Cock H, van Blokland S, Tommassen J. In vitro insertion and assembly of outer membrane protein PhoE of Escherichia coli K-12 into the outer membrane. Role of Triton X-100. J Biol Chem 1996; 271:12885-90. [PMID: 8662743 DOI: 10.1074/jbc.271.22.12885] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The assembly of the in vitro synthesized outer membrane protein PhoE into purified outer membranes was investigated. The assembly appeared to be strongly stimulated by the presence of low amounts of Triton X-100 (optimal 0.08%, w/v). The role of Triton X-100 in the in vitro system was further examined. Pretreating outer membranes with Triton X-100 did not make the membranes competent for correct assembly, indicating that the detergent did not act on the membrane but at the protein level. PhoE became assembly-incompetent with a half-life of approximately 12 min and 90 s at 37 degrees C in the absence and presence, respectively, of 0.08% Triton X-100. Apparently, Triton X-100 induces an assembly-competent state in the PhoE protein with a very short half-life. Furthermore, the efficiency of correct assembly of PhoE was greatly reduced when outer membranes of deep rough lipopolysaccharide mutants were used, indicating an important role of lipopolysaccharides in the assembly of the porin.
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Affiliation(s)
- H de Cock
- Institute of Biomembranes and the Department of Molecular Cell Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
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16
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Gadó I, Pászti J, László VG. Effect of precultivation conditions on colicin susceptibility in Escherichia coli. J Chemother 1995; 7:100-5. [PMID: 7545223 DOI: 10.1179/joc.1995.7.2.100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The effect of 20 colicins and cloacin was studied after various precultivations. Nutrient agar supplemented with subinhibitory concentration of EDTA used for precultivation or elevating the growth-temperature of the inoculum from 37 degrees C to 42 degrees C increased the susceptibility of wild-type (smooth) Escherichia coli strains to the inhibitory action of some colicins. There were great differences among the colicins in respect to these effects. In case of rough mutants, their sensitivities did not change or eventually decrease after EDTA or heat pretreatment. The LPS pattern in SDS-PAGE of smooth cells grown in EDTA-containing nutrient medium changed in some degree towards the rough character. In case of precultivation at 42 degrees C this change was less considerable. It is supposed that both factors applied during precultivation have influence on colicin sensitivity by means of the change of receptor activity caused by LPS modification.
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Affiliation(s)
- I Gadó
- B. Johan National Institute of Hygiene, Budapest, Hungary
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17
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Export and assembly of outer membrane proteins in E. coli. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s1874-5172(06)80011-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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18
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Fourel D, Bernadac A, Pagès JM. Involvement of exposed polypeptide loops in trimeric stability and membrane insertion of Escherichia coli OmpF porin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 222:625-30. [PMID: 8020499 DOI: 10.1111/j.1432-1033.1994.tb18905.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Different ompF-ompC gene fusions were used to analyse the regions involved in the stable trimerization and membrane insertion of the Escherichia coli OmpF porin. The stability of the trimers formed from the various hybrids was analysed. Three classes of trimer instability are observed related to the presence of different exposed polypeptide loops of OmpF. In all cases, amino acids located between residue 115 and residue 144 of OmpF are necessary to promote a correct and stable trimeric conformation. However, immunogold labelling studies indicate the correct insertion of the protein in the outer membrane despite a marked instability of some hybrid porins. The location of the residues involved in trimer stability is discussed with regards to both the three-dimensional structure and the folding of OmpF.
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Affiliation(s)
- D Fourel
- Centre de Biochimie et de Biologie, Marseille, France
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19
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Gratia JP. Ufr/s variation in Escherichia coli K12: a reversible double-mutation or alternate chromosome expression in non-complementing diploids? Res Microbiol 1994; 145:309-25. [PMID: 7997644 DOI: 10.1016/0923-2508(94)90186-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
A novel form of bacterial variation found in an FhuA- mutant of Escherichia coli K12 was characterized by the alternation of (1) simultaneous resistance to lipopolysaccharide-specific phage U3 and to FhuA-specific agents (Ufr phenotype); and (2) a return to the sensitivity pattern of the initial strain (Ufs). In Ufr cells, loss of the U3 receptor permitted C21 adsorption without modifying the sensitivity to other tested phages or colicins. Genetic analysis revealed that Ufr variants were altered at two distinct loci. Ufr bacteria, though derived from a strain F- devoid of classical gene transfer mechanisms, were transiently able to promote mating between themselves and, to some extent, with other bacteria, including Rec-. Heterogenic matings resulted in the formation of persistent heterozygotes segregating Ufr- and Ufs-like bacteria. Pedigree analysis and subcloning of heterozygotic isolates indicate that they were diploids, as was the initial Ufr strain. Functional genetic complementation between these two genomes was only transient and the alternative forms were likely to result from the expression of a single chromosome of the heterozygotes. Mutation occurred in either form without causing any change in the alternative form.
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Affiliation(s)
- J P Gratia
- Microbial Genetics and Ecology Unit, Brussels University School of Medicine
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20
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Laird MW, Kloser AW, Misra R. Assembly of LamB and OmpF in deep rough lipopolysaccharide mutants of Escherichia coli K-12. J Bacteriol 1994; 176:2259-64. [PMID: 8157594 PMCID: PMC205347 DOI: 10.1128/jb.176.8.2259-2264.1994] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Assembly of the OmpF and LamB proteins was kinetically retarded in deep rough lipopolysaccharide mutants of Escherichia coli K-12. OmpF assembly was affected at the step of conversion of metastable trimers to stable trimers, whereas LamB assembly was influenced both at the monomer-to-metastable trimer and metastable-to-stable trimer steps. These assembly defects were reversed in the presence of the sfaA1 and sfaB3 suppressor alleles, which were isolated by using ompF assembly mutants.
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Affiliation(s)
- M W Laird
- Department of Microbiology, Arizona State University, Tempe 85287-2701
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21
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Papp-Szabò E, Sutherland CL, Josephy PD. Superoxide dismutase and the resistance of Escherichia coli to phagocytic killing by human neutrophils. Infect Immun 1993; 61:1442-6. [PMID: 8454348 PMCID: PMC281383 DOI: 10.1128/iai.61.4.1442-1446.1993] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Transformation of Escherichia coli K-12-derived strains with a plasmid carrying the genetic determinants for synthesis of lipopolysaccharide O antigen by Shigella dysenteriae allows the construction of phenotypically smooth derivatives. We show that such E. coli K-12 derivatives are highly resistant to killing by human serum. Isogenic wild-type and sodB mutant (Fe superoxide dismutase-deficient) strains were constructed. The results of experiments on phagocytic killing of these strains by human neutrophils are reported. We observed no difference between the sensitivities of wild-type and sodB mutant strains to phagocytic killing, in contrast to the results reported by other researchers who used species other than E. coli or strains other than K-12.
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Affiliation(s)
- E Papp-Szabò
- Guelph-Waterloo Centre for Graduate Work in Chemistry, Department of Chemistry and Biochemistry, University of Guelph, Canada
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Butz S, Benz R, Wacker T, Welte W, Lustig A, Plapp R, Weckesser J. Biochemical characterization and crystallization of porin from Rhodopseudomonas blastica. Arch Microbiol 1993. [DOI: 10.1007/bf00290911] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Tigyi Z, Kishore AR, Maeland JA, Forsgren A, Naidu AS. Lactoferrin-binding proteins in Shigella flexneri. Infect Immun 1992; 60:2619-26. [PMID: 1319403 PMCID: PMC257212 DOI: 10.1128/iai.60.7.2619-2626.1992] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The ability of Shigella flexneri to interact with lactoferrin (Lf) was examined with a 125I-labeled protein-binding assay. The percent binding of human lactoferrin (HLf) and bovine lactoferrin (BLf) to 45 S. flexneri strains was 19 +/- 3 and 21 +/- 3 (mean +/- standard error of the mean), respectively. 125I-labeled HLf and BLf binding to strain M90T reached an equilibrium within 2 h. Unlabeled HLf and BLf displaced the 125I-HLf-bacteria interaction in a dose-dependent manner. The Lf-bacterium complex was uncoupled by KSCN or urea, but not by NaCl. The interaction was specific, and approximately 4,800 HLf binding sites (affinity constant [Ka], 690 nM) or approximately 5,700 BLf binding sites (Ka, 104 nM) per cell were estimated in strain M90T by a Scatchard plot analysis. The native cell envelope (CE) and outer membrane (OM) did not reveal Lf-binding components in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, after being boiled, the CE and OM preparations showed three distinct horseradish peroxidase-Lf reactive bands of about 39, 22, and 16 kDa. The 39-kDa component was also reactive to a monoclonal antibody specific for porin (PoI) proteins of members of the family Enterobacteriaceae. The Lf-binding protein pattern was similar with BLf or HLf, for Crb+ and Crb- strains. The protein-Lf complex was dissociable by KSCN or urea and was stable after treatment with NaCl. Variation (loss) in the O chain of lipopolysaccharide (LPS) markedly enhanced the Lf-binding capacity in the isogenic rough strain SFL1070-15 compared with its smooth parent strain, SFL1070. These data establish that Lf binds to specific components in the bacterial OM; the heat-modifiable, anti-PoI-reactive, and LPS-associated properties suggested that the Lf-binding proteins are porins in S. flexneri.
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Affiliation(s)
- Z Tigyi
- Department of Medical Microbiology, Malmö General Hospital, Sweden
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24
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Fourel D, Mizushima S, Pagès JM. Dynamics of the exposure of epitopes on OmpF, an outer membrane protein of Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 206:109-14. [PMID: 1375155 DOI: 10.1111/j.1432-1033.1992.tb16907.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The OmpF protein is the major outer membrane trimeric porin of Escherichia coli B. The exposure of several cell-surface-exposed epitopes, that are recognized by various monoclonal antibodies directed against the protein, is investigated. Kinetic analyses show that two epitopes (E18 and E19) appear early during the in-vivo assembly on the folded monomer, just after the removal of the signal peptide, and are conserved in the native trimer. The trimerization that immediately follows or occurs in conjunction with the folding of monomers exposes another antigenic site (E21) at the surface of metastable forms. The binding of nascent lipopolysaccharide promotes the conversion of the heat-modifiable intermediate to a stable trimer and ensures the exposure of E20, E1, E3, E4 and E7. Late epitopes, E1, E3, E4 and E7 are only detected in the outer membrane fraction. These results suggest that different steps induce the sequential exposure of native antigenic sites. The detection of these epitopes depends on conformational changes occurring during the OmpF insertion into the outer membrane.
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Affiliation(s)
- D Fourel
- Centre de Biochimie et de Biologie Moléculaire, Centre National de la Recherche Scientifique, Marseille, France
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25
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Abstract
Porins and specific channels both produce water-filled pores that allow the transmembrane diffusion of small solutes, but the latter contain specific ligand-binding sites within the channels. Recent structural studies show that many or most of these proteins exist as beta-barrels with the beta-strands traversing the thickness of the outer membrane. The channels often have diameters in the range of 1 nm, and thus the penetration rates of solutes through porin channels are likely to be affected strongly by what appear to be minor differences in the size, shape, hydrophobicity or charge of the solute molecule. With the specific channels, the presence of binding sites can accelerate very significantly the diffusion of some ligands when they are present at low concentrations. Thus these simple channels can sometimes achieve a surprising degree of real or apparent specificity. Recent data tend to favour the idea that these proteins are first exported into the periplasm, and then inserted into the outer membrane. Although lipopolysaccharides seem to play a significant role in the final assembly of the trimeric porins, the details of the targeting process still remain to be elucidated.
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Affiliation(s)
- H Nikaido
- Department of Molecular and Cell Biology, University of California, Berkeley 94720
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26
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Parker CT, Kloser AW, Schnaitman CA, Stein MA, Gottesman S, Gibson BW. Role of the rfaG and rfaP genes in determining the lipopolysaccharide core structure and cell surface properties of Escherichia coli K-12. J Bacteriol 1992; 174:2525-38. [PMID: 1348243 PMCID: PMC205891 DOI: 10.1128/jb.174.8.2525-2538.1992] [Citation(s) in RCA: 185] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Deletions which removed rfa genes involved in lipopolysaccharide (LPS) core synthesis were constructed in vitro and inserted into the chromosome by linear transformation. The deletion delta rfa1, which removed rfaGPBI, resulted in a truncated LPS core containing two heptose residues but no hexose and a deep rought phenotype including decreased expression of major outer membrane proteins, hypersensitivity to novobiocin, and resistance to phage U3. In addition, delta rfa1 resulted in the loss of flagella and pili and a mucoid colony morphology. Measurement of the synthesis of beta-galactosidase from a cps-lacZ fusion showed that the mucoid phenotype was due to rcsC-dependent induction of colanic acid capsular polysaccharide synthesis. Complementation of delta rfa1 with rfaG+ DNA fragments resulted in a larger core and restored the synthesis of flagella and pili but did not reverse the deep rough phenotype or the induction of cps-lacZ, while complementation with a fragment carrying only rfaP+ reversed the deep rough phenotype but not the loss of flagella and pili. A longer deletion which removed rfaQGPBIJ was also constructed, and complementation studies with this deletion showed that the product of rfaQ was not required for the functions of rfaG and rfaP. Thus, the function of rfaQ remains unknown. Tandem mass spectrometric analysis of LPS core oligosaccharides from complemented delta rfa1 strains indicated that rfaP+ was necessary for the addition of either phosphoryl (P) or pyrophosphorylethanolamine (PPEA) substituents to the heptose I residue, as well as for the partial branch substitution of heptose II by heptose III. The substitution of heptose II is independent of the type of P substituent present on heptose I, and this results in four different core structures. A model is presented which relates the deep rough phenotype to the loss of heptose-linked P and PPEA.
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Affiliation(s)
- C T Parker
- Department of Microbiology, Arizona State University, Tempe 85287
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27
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Stein MA, McAllister SA, Torian BE, Diedrich DL. Acquisition of apparently intact and unmodified lipopolysaccharides from Escherichia coli by Bdellovibrio bacteriovorus. J Bacteriol 1992; 174:2858-64. [PMID: 1373716 PMCID: PMC205937 DOI: 10.1128/jb.174.9.2858-2864.1992] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The ability of Bdellovibrio bacteriovorus to relocalize the OmpF major outer membrane porins from its Escherichia coli prey to its own outer membranes is diminished in prey expressing smooth lipopolysaccharide (S-LPS). Since porins exist in the membrane complexed with LPS, we examined the LPS associated with relocalized porin to determine whether it had been acquired intact, mixed or replaced with Bdellovibrio LPS, or derivatized by the bdellovibrios. The relocalized trimers were found associated with the same LPS originally bound to them in the E. coli. The bulk-phase LPS from bdellovibrios grown on various chemotypes of rough prey was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis to determine whether more than the trimer-bound LPS was acquired by the bdellovibrios. This analysis revealed bands of Bdellovibrio LPS matching the LPS chemotype of the prey. One or two other bands were identical in migration to the LPS of prey-independent mutants of B. bacteriovorus and represented bdellovibrio-synthesized LPS. The LPS of bdellovibrios grown on prey with radiolabeled lipid A showed radioactivity only in gel band positions identical with those of the prey's LPS. The amount of this prey-derived LPS was shown by enzyme-linked immunosorbent assay to reach a constant value during the purification of the bdellovibrios, and it represented approximately 25% of the total Bdellovibrio LPS. Immunoelectron microscopy confirmed the presence of prey-derived LPS on the cell surface of bdellovibrios, and no evidence could be found for bdellovibrio-induced modifications of the relocalized prey LPS.
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Affiliation(s)
- M A Stein
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Medical Center, New Orleans 70112-1393
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28
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Gadó I, Erdei J, Laszlo VG, Pászti J, Czirók E, Kontrohr T, Tóth I, Forsgren A, Naidu AS. Correlation between human lactoferrin binding and colicin susceptibility in Escherichia coli. Antimicrob Agents Chemother 1991; 35:2538-43. [PMID: 1810187 PMCID: PMC245427 DOI: 10.1128/aac.35.12.2538] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Escherichia coli H10407 demonstrated low 125I-human lactoferrin (HLf) binding (7%) and was insusceptible to group A (A, E1, E2, E3, E6, and K) and group B (B, D, Ia, Ib, and V) colicins. Conversely, a spontaneous HLf high-binding (44%) variant, H10407(Lf), demonstrated an increase susceptibility to both colicin groups. Colicin-insusceptible E. coli wild-type strains 75ColT, 84ColT, and 981ColT showed a low degree of HLf binding, i.e., 4, 8, and 10%, respectively. The HLf binding capacity was high in the corresponding colicin-susceptible mutants 75ColS (43%), 84ColS (32%), and 981ColS (43%). Furthermore, HLf low- (less than 5%) and high- (greater than 35%) binding E. coli clinical isolates (10 in each category) were tested for susceptibility against 11 colicins. Colicin V susceptibility did not correlate with HLf binding in either categories. However, with the remaining colicins, three distinct HLf-binding, colicin susceptibility patterns were observed; (i) 10 of 10 HLf low-binding strains were colicin insusceptible, (ii) 6 of 10 HLf high-binding strains were also colicin insusceptible, and (iii) the remaining HLf high binders were highly colicin susceptible. Certain proteins in the cell envelope and outer membrane of wild-type H10407 (HLf low binder, colicin insusceptible) showed a lower mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis compared to the corresponding proteins of mutant H10407(Lf) (HLf high binder, colicin susceptible). These mobility differences were also associated with HLf-binding proteins in Western blot (ligand blot) analysis. The wild type showed a smooth form of lipopolysaccharide (LPS) with a distinct ladder of O-chains, compared to the rough LPS of the mutant.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- I Gadó
- Department of Medical Microbiology, Malmö General Hospital, University of Lund, Sweden
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