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Newman KE, Tindall SN, Mader SL, Khalid S, Thomas GH, Van Der Woude MW. A novel fold for acyltransferase-3 (AT3) proteins provides a framework for transmembrane acyl-group transfer. eLife 2023; 12:e81547. [PMID: 36630168 PMCID: PMC9833829 DOI: 10.7554/elife.81547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 12/04/2022] [Indexed: 01/12/2023] Open
Abstract
Acylation of diverse carbohydrates occurs across all domains of life and can be catalysed by proteins with a membrane bound acyltransferase-3 (AT3) domain (PF01757). In bacteria, these proteins are essential in processes including symbiosis, resistance to viruses and antimicrobials, and biosynthesis of antibiotics, yet their structure and mechanism are largely unknown. In this study, evolutionary co-variance analysis was used to build a computational model of the structure of a bacterial O-antigen modifying acetyltransferase, OafB. The resulting structure exhibited a novel fold for the AT3 domain, which molecular dynamics simulations demonstrated is stable in the membrane. The AT3 domain contains 10 transmembrane helices arranged to form a large cytoplasmic cavity lined by residues known to be essential for function. Further molecular dynamics simulations support a model where the acyl-coA donor spans the membrane through accessing a pore created by movement of an important loop capping the inner cavity, enabling OafB to present the acetyl group close to the likely catalytic resides on the extracytoplasmic surface. Limited but important interactions with the fused SGNH domain in OafB are identified, and modelling suggests this domain is mobile and can both accept acyl-groups from the AT3 and then reach beyond the membrane to reach acceptor substrates. Together this new general model of AT3 function provides a framework for the development of inhibitors that could abrogate critical functions of bacterial pathogens.
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Affiliation(s)
- Kahlan E Newman
- School of Chemistry, University of SouthamptonSouthamptonUnited Kingdom
| | - Sarah N Tindall
- Department of Biology and the York Biomedical Research Institute, University of YorkYorkUnited Kingdom
| | - Sophie L Mader
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - Syma Khalid
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
| | - Gavin H Thomas
- Department of Biology and the York Biomedical Research Institute, University of YorkYorkUnited Kingdom
| | - Marjan W Van Der Woude
- Hull York Medical School and the York Biomedical Research Institute, University of YorkYorkUnited Kingdom
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Palusinska-Szysz M, Luchowski R, Gruszecki WI, Choma A, Szuster-Ciesielska A, Lück C, Petzold M, Sroka-Bartnicka A, Kowalczyk B. The Role of Legionella pneumophila Serogroup 1 Lipopolysaccharide in Host-Pathogen Interaction. Front Microbiol 2019; 10:2890. [PMID: 31921066 PMCID: PMC6927915 DOI: 10.3389/fmicb.2019.02890] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Accepted: 12/02/2019] [Indexed: 11/13/2022] Open
Abstract
The Legionella pneumophila TF3/1 mutant of the Corby strain, which possesses a point mutation in the active site of the O-acetyltransferase, synthesized the polysaccharide chain with a reduced degree of substitution with O-acetyl groups. The mutant did not produce a high-molecular-weight lipopolysaccharide (LPS) fraction above 12 kDa. The disturbances in LPS synthesis have an effect on the composition of other macromolecules (lipids and proteins), as indicated by differences in the infrared absorption spectra between the L. pneumophila Corby strain and its TF3/1 mutant. The wild-type strain contained less N+-CH3 and C-N groups as well as more CH3 groups than the mutant. The fatty acid composition showed that the wild type strain synthesized more branched acyl residues (a15:0, i16:0, and a17:0), a less unsaturated acid (16:1), and a straight-chain acid (18:0) than the mutant. The mutant synthesized approximately twice more a long-chain fatty acid (20:0) than the wild type. The main differences in the phospholipids between both strains were found in the classes of phosphatidylcholines and phosphatidylglycerols (PG). Substantial differences in the cell surface topography of these bacteria and their nanomechanical properties were shown by atomic force microscopy (AFM). The wild type strain had no undulated surface and produced numerous vesicles. In the case of the mutant type, the vesicles were not numerous, but there were grooves on the cell surface. The average roughness of the cell surface of the mutant was approximately twofold higher than in the wild-type strain. In turn, the wild-type strain exhibited much better adhesive properties than the mutant. The kinetic study of the interaction between the L. pneumophila strains and Acanthamoeba castellanii monitored by Förster resonance energy transfer revealed a pronounced difference, i.e., almost instantaneous and highly efficient binding of the L. pneumophila Corby strain to the amoeba surface, followed by penetration into the amoeba cells. This process was clearly not as efficient in the case of the mutant. The results point to LPS and, in particular, to the length of the polysaccharide fraction as an important L. pneumophila determinant involved in the process of adhesion to the host cell.
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Affiliation(s)
- Marta Palusinska-Szysz
- Department of Genetics and Microbiology, Faculty of Biology and Biotechnology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Lublin, Poland
| | - Rafal Luchowski
- Department of Biophysics, Faculty of Mathematics, Physics and Computer Science, Institute of Physics, Maria Curie-Skłodowska University, Lublin, Poland
| | - Wieslaw I Gruszecki
- Department of Biophysics, Faculty of Mathematics, Physics and Computer Science, Institute of Physics, Maria Curie-Skłodowska University, Lublin, Poland
| | - Adam Choma
- Department of Genetics and Microbiology, Faculty of Biology and Biotechnology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Lublin, Poland
| | - Agnieszka Szuster-Ciesielska
- Department of Virology and Immunology, Faculty of Biology and Biotechnology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Lublin, Poland
| | - Christian Lück
- National Reference Laboratory for Legionella, Institute of Medical Microbiology and Hygiene, University of Technology Dresden, Dresden, Germany
| | - Markus Petzold
- Department of Infectious Diseases, Medical Microbiology and Hygiene, Heidelberg University Hospital, Heidelberg, Germany
| | - Anna Sroka-Bartnicka
- Department of Genetics and Microbiology, Faculty of Biology and Biotechnology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Lublin, Poland.,Department of Biopharmacy, Medical University of Lublin, Lublin, Poland
| | - Bozena Kowalczyk
- Department of Genetics and Microbiology, Faculty of Biology and Biotechnology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Lublin, Poland
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Petzold M, Thürmer A, Menzel S, Mouton JW, Heuner K, Lück C. A structural comparison of lipopolysaccharide biosynthesis loci of Legionella pneumophila serogroup 1 strains. BMC Microbiol 2013; 13:198. [PMID: 24069939 PMCID: PMC3766260 DOI: 10.1186/1471-2180-13-198] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Accepted: 08/31/2013] [Indexed: 01/21/2023] Open
Abstract
Background The lipopolysaccharide (LPS) is the major immuno-dominant antigen of all Legionella species including L. pneumophila. Its diversity is the basis for the classification of L. pneumophila into serogroups and monoclonal subgroups and is thought to be involved in strain specific virulence. The understanding of the genetic basis of the LPS-antigen is incomplete. Thus, we analyzed the genetic locus involved in LPS-biosynthesis of L. pneumophila serogroup 1 (Sg1) strains with the focus on strain specific gene composition. Results The LPS-biosynthesis loci of 14 L. pneumophila Sg1 strains comprise two distinct regions: A 15 kb region containing LPS-biosynthesis genes that can be found in all L. pneumophila strains and a Sg1-specific 18 kb region. The 15 kb region is highly conserved among Sg1 strains as reflected by high homologies of single ORFs and by a consistent ORF arrangement. In contrast, the Sg1 specific 18 kb region is variable and partially disrupted by phage related genes. We propose that the region spanning from ORF 6 to ORF 11 of the Sg1-specific region is likely involved in late LPS-modification. Due to the high variability of this small region and various combinations of single ORFs within this region a strain specific LPS-structure could be synthesized including modifications of legionaminic acid derivates. Conclusions Our data clearly demonstrate that the gene structure of the LPS-biosynthesis locus of L. pneumophila Sg1 strains show significant interstrain variability. These data can be used for further functional analysis of the LPS synthesis to understand pathogenesis and reactivity with monoclonal antibodies. Moreover, variable but strain specific regions can serve as basis for the development of novel genotyping assays.
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Affiliation(s)
- Markus Petzold
- Institute of Medical Microbiology and Hygiene, Faculty of Medicine 'Carl Gustav Carus', University of Technology Dresden, Fetscherstraße 74, Dresden D-01307, Germany.
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Abstract
The lipopolysaccharide(LPS) of Legionella spp. is an immuno-dominant antigen and the basis for Legionella pneumophila serogroup classification. The LPS shows a peculiar structure composed of a very hydrophobic lipid A acylated by long chain fatty acids and an O-antigen-specific chain consisting of homopolymeric legionaminic acid. In this chapter we describe a method for the isolation of LPS from L. pneumophila. In the first part we describe the chemical purification, in the second part we outline the application of monoclonal antibody (mAb) in Western blot and immuno-localization by indirect immunofluorescence. This report does not describe physico-chemical methods that analyze the structure of lipopolysaccharide entities.
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Affiliation(s)
- Christian Lück
- Institute for Medical Microbiology and Hygiene, University of Technology, Dresden, Germany.
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Abstract
In this chapter we describe the methods currently used for subgrouping Legionella pneumophila and other non-pneumophila species. In the first part we describe monoclonal antibody (mAb) subgrouping, either by indirect immunofluorescence or indirect ELISA methods. These monoclonal antibodies are not commercially available but can be obtained for noncommercial purposes from one of the authors. Further, we describe pulsed-field gel electrophoresis (PFGE), amplified fragment length polymorphism (AFLP) and sequence-based typing (SBT) as well standardized and reproducible methods for genotyping. The SBT schema is currently available for L. pneumophila whereas PFGE and AFLP can be used for all Legionella species. For certain applications it might be useful to use spoligotyping to distinguish strains belonging to the same sequence type (ST).
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Affiliation(s)
- Christian Lück
- Institute for Medical Microbiology and Hygiene, University of Technology, Dresden, Germany.
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Lucas CE, Taylor TH, Fields BS. Accuracy and precision of Legionella isolation by US laboratories in the ELITE program pilot study. WATER RESEARCH 2011; 45:4428-4436. [PMID: 21726887 DOI: 10.1016/j.watres.2011.05.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 03/28/2011] [Accepted: 05/26/2011] [Indexed: 05/31/2023]
Abstract
A pilot study for the Environmental Legionella Isolation Techniques Evaluation (ELITE) Program, a proficiency testing scheme for US laboratories that culture Legionella from environmental samples, was conducted September 1, 2008 through March 31, 2009. Participants (n=20) processed panels consisting of six sample types: pure and mixed positive, pure and mixed negative, pure and mixed variable. The majority (93%) of all samples (n=286) were correctly characterized, with 88.5% of samples positive for Legionella and 100% of negative samples identified correctly. Variable samples were incorrectly identified as negative in 36.9% of reports. For all samples reported positive (n=128), participants underestimated the cfu/ml by a mean of 1.25 logs with standard deviation of 0.78 logs, standard error of 0.07 logs, and a range of 3.57 logs compared to the CDC re-test value. Centering results around the interlaboratory mean yielded a standard deviation of 0.65 logs, standard error of 0.06 logs, and a range of 3.22 logs. Sampling protocol, treatment regimen, culture procedure, and laboratory experience did not significantly affect the accuracy or precision of reported concentrations. Qualitative and quantitative results from the ELITE pilot study were similar to reports from a corresponding proficiency testing scheme available in the European Union, indicating these results are probably valid for most environmental laboratories worldwide. The large enumeration error observed suggests that the need for remediation of a water system should not be determined solely by the concentration of Legionella observed in a sample since that value is likely to underestimate the true level of contamination.
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Affiliation(s)
- Claressa E Lucas
- Division of Bacterial Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd NE MS G03, Atlanta, GA 30333, USA.
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Gosselin F, Duval JFL, Simonet J, Ginevra C, Gaboriaud F, Jarraud S, Mathieu L. Impact of the virulence-associated MAb3/1 epitope on the physicochemical surface properties of Legionella pneumophila sg1: An issue to explain infection potential? Colloids Surf B Biointerfaces 2010; 82:283-90. [PMID: 20889314 DOI: 10.1016/j.colsurfb.2010.08.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Accepted: 08/26/2010] [Indexed: 11/25/2022]
Abstract
The relationship between the presence/absence of the virulence-associated MAb3/1 epitope of sixteen Legionella pneumophila serogroup 1 strains and their respective surface physicochemical properties is evidenced from electrokinetic measurements (microelectrophoresis) performed as a function of KNO(3) electrolyte concentration (range 1-100mM, pH∼6.5). Among the bacteria selected, nine original strains constitute the Dresden reference panel and differ according to the presence/absence of the virulence-associated monoclonal antibody MAb3/1 of the O-specific chain of the lipopolysaccharides (LPS). Five isogenic Lens strains, also investigated in the current study, present the epitope MAb3/1 of their LPS and were involved to some extent in the outbreak that stroke the Nord Pas-de-Calais region (France) in 2004. All bacteria exhibit the typical electrokinetic features of soft (permeable) particles. On the basis of Ohshima's model, analysis of the electrophoretic mobility data allows evaluating the intraparticular flow penetration length 1/λ(0) and the (negative) volume charge density ρ(0) that both reflect the structure and chemical composition of the soft bacterial component. Our results show that the virulent MAb3/1 positive strains are characterized on average by 1/λ(0) and ǀρ(0)ǀ values that are about 1.5 times larger and 5 times lower, respectively, than those derived for lesser virulent (MAb3/1 negative) strains. In other words, on average the soft surface layer of MAb3/1 positive strains is significantly less charged and more permeable than those of MAb3/1 negative strains. The intimate correlation between virulence-associated MAb3/1 epitope and charge density carried by the bacterial envelop was further confirmed by lower 1/λ(0) and greater ǀρ(0)ǀ values for lag-1 mutant CS332 strain, lacking the MAb3/1 epitope, compared to the parental strain AM511. A closer inspection of the dispersion in 1/λ(0) and ǀρ(0)ǀ data over the ensemble of analysed bacteria together with the reported number of Legionnaires' disease cases they are responsible for, points out the charge density ǀρ(0)ǀ as the parameter that is most suitable for discriminating highly virulent (MAb3/1 positive) from less virulent (MAb3/1 negative) strains. Although short-range interaction determines infection process, our results suggest that the infection potential of Legionella pneumophila serogroup 1 may be also controlled significantly by non-specific long-range electrostatic repulsion the bacteria undergo when approaching negatively charged host cells to be infected.
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Affiliation(s)
- F Gosselin
- Ecole Pratique des Hautes Etudes, UMR 7564 CNRS/Nancy Université, Pôle de l'Eau, F-54505 Vandoeuvre-lès-Nancy, France
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Pannier K, Heuner K, Lück C. Variable genetic element typing: a quick method for epidemiological subtyping of Legionella pneumophila. Eur J Clin Microbiol Infect Dis 2010; 29:481-7. [PMID: 20119676 DOI: 10.1007/s10096-009-0872-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2009] [Accepted: 12/27/2009] [Indexed: 11/29/2022]
Abstract
A total of 57 isolates of Legionella pneumophila were randomly selected from the German National Legionella strain collection and typed by monoclonal antibody subgrouping, seven-gene locus sequence-based typing (SBT) scheme and a newly developed variable element typing (VET) system based on the presence or absence of ten variable genetic elements. These elements were detected while screening a genomic library of strain Corby, as well as being taken from published data for PAI-1 (pathogenicity island) from strain Philadelphia. Specific primers were designed and used in gel-based polymerase chain reaction (PCR) assays. PCR amplification of the mip gene served as a control. The end-point was the presence/absence of a PCR product on an ethidium bromide-strained gel. In the present study, the index of discrimination was somewhat lower than that of the SBT (0.87 versus 0.97). Nevertheless, the results obtained showed as a 'proof of principle' that this simple and quick typing assay might be useful for the epidemiological characterisation of L. pneumophila strains.
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Affiliation(s)
- K Pannier
- Institute of Medical Microbiology and Hygiene, TU Dresden, Dresden, Germany
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Thürmer A, Helbig JH, Jacobs E, Lück PC. PCR-based 'serotyping' of Legionella pneumophila. J Med Microbiol 2009; 58:588-595. [PMID: 19369520 DOI: 10.1099/jmm.0.008508-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Currently, several PCR assays based on 16S rRNA and virulence-associated genes are available for detection of Legionella pneumophila. So far, no genotyping method has been published that can discriminate between serogroups and monoclonal subgroups of the most common L. pneumophila serogroup 1. Our first approach was to analyse LPS-associated genes of seven L. pneumophila serogroup 1 strains, and we developed two PCR-based methods specific for serogroup 1. Specific DNA fragments could be amplified from all the serogroup 1 strains (n=43) including the strains from the American Type Culture Collection. In contrast, none of the strains from serogroups 2-15 (n=41) contained these specific gene regions. In a second approach, primers specific for the lag-1 gene, encoding an O-acetyltransferase, which is responsible for the presence of the LPS epitope recognized by mAb 3/1, were designed and tested for their ability to differentiate between mAb 3/1-positive and -negative strains. All mAb 3/1-positive strains (n=30) contained the lag-1 gene, but in turn 4 of 13 tested mAb 3/1-negative strains were also positive in the PCR. Thus, the discrimination between mAb 3/1-positive and mAb 3/1-negative subgroups could not be achieved for all strains. In a third approach, two intergenic regions expected to be specific for monoclonal subgroup Knoxville and closely related subgroups Benidorm/Bellingham were identified and used for selective genotyping. These intergenic regions could not only be amplified in every tested strain belonging to the subgroups Knoxville, Benidorm and Bellingham, but also in some strains of other unrelated subgroups. The two PCR approaches with primers specific for serogroup 1 genes definitely represent a valuable tool in outbreak investigations and for risk assessment. They also might be used for culture-independent diagnosis of legionellosis caused by L. pneumophila serogroup 1.
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Affiliation(s)
- Alexander Thürmer
- Institute of Medical Microbiology and Hygiene, Technische Universität Dresden, Fiedlerstrasse 42, D-01307 Dresden, Germany
| | - Jürgen Herbert Helbig
- Institute of Medical Microbiology and Hygiene, Technische Universität Dresden, Fiedlerstrasse 42, D-01307 Dresden, Germany
| | - Enno Jacobs
- Institute of Medical Microbiology and Hygiene, Technische Universität Dresden, Fiedlerstrasse 42, D-01307 Dresden, Germany
| | - Paul Christian Lück
- Institute of Medical Microbiology and Hygiene, Technische Universität Dresden, Fiedlerstrasse 42, D-01307 Dresden, Germany
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