1
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Kelly SD, Williams DM, Zhu S, Kim T, Jana M, Nothof J, Thota VN, Lowary TL, Whitfield C. Klebsiella pneumoniae O-polysaccharide biosynthesis highlights the diverse organization of catalytic modules in ABC transporter-dependent glycan assembly. J Biol Chem 2024; 300:107420. [PMID: 38815868 PMCID: PMC11231755 DOI: 10.1016/j.jbc.2024.107420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 05/10/2024] [Accepted: 05/19/2024] [Indexed: 06/01/2024] Open
Abstract
Klebsiella pneumoniae provides influential prototypes for lipopolysaccharide O antigen (OPS) biosynthesis in Gram-negative bacteria. Sequences of OPS-biosynthesis gene clusters in serotypes O4 and O7 suggest fundamental differences in the organization of required enzyme modules compared to other serotypes. Furthermore, some required activities were not assigned by homology shared with characterized enzymes. The goal of this study was therefore to resolve the serotype O4 and O7 pathways to expand our broader understanding of glycan polymerization and chain termination processes. The O4 and O7 antigens were produced from cloned genetic loci in recombinant Escherichia coli. Systematic in vivo and in vitro approaches were then applied to assign each enzyme in each of the pathways, defining the necessary components for polymerization and chain termination. OPS assembly is accomplished by multiprotein complexes formed by interactions between polymerase components variably distributed in single and multimodule proteins. In each complex, a terminator function is present in a protein containing a characteristic coiled-coil molecular ruler, which determines glycan chain length. In serotype O4, we discovered a CMP-α-3-deoxy-ᴅ-manno-octulosonic acid-dependent chain-terminating glycosyltransferase that is the founding member of a new glycosyltransferase family (GT137) and potentially identifies a new glycosyltransferase fold. The O7 OPS is terminated by a methylphosphate moiety, like the K. pneumoniae O3 antigen, but the methyltransferase-kinase enzyme pairs responsible for termination in these serotypes differ in sequence and predicted structures. Together, the characterization of O4 and O7 has established unique enzyme activities and provided new insight into glycan-assembly strategies that are widely distributed in bacteria.
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Affiliation(s)
- Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Danielle M Williams
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Shawna Zhu
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Taeok Kim
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Manas Jana
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jeremy Nothof
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | | | - Todd L Lowary
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada; Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.
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2
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Ravinath R, Usha T, Das AJ, Sarangi AN, Sarvashiva Kiran N, Kumar Goyal A, Krishnareddy Prasannakumar M, Ramesh N, Middha SK. Pomegranate Rhizosphere Microbial Diversity Revealed by Metagenomics: Toward Organic Farming, Plant Growth Promotion and Biocontrol? OMICS : A JOURNAL OF INTEGRATIVE BIOLOGY 2024; 28:303-318. [PMID: 38805323 DOI: 10.1089/omi.2023.0272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Food production must undergo systems change to meet the sustainable development goals (SDGs). For example, organic farming can be empowered by soil microorganisms with plant growth promotion (PGP) and biocontrol features. In this context, there have been limited studies on pomegranate. We investigated microbial diversity in rhizosphere of the pomegranate "Bhagwa" variety and its potential role in PGP and biocontrol. Both bulk and rhizosphere soil samples were analyzed for their physicochemical properties. Whole metagenome sequencing was conducted using the Illumina NovaSeq6000 platform. Surprisingly, we found that bulk and rhizosphere soil samples had comparable microbial diversity. Metagenome sequencing revealed the abundance of Streptomyces indicus, Bradyrhizobium kalamazoonesis, and Pseudomonas cellulosum in the rhizosphere that are reported here for the first time in agricultural literature. Pathway prediction analysis using KEGG (Kyoto Encyclopedia for Genes and Genomes) and COG (clusters of orthologous genes) databases identified metabolic pathways associated with biocontrol properties against pathogens. We confirmed the metagenome data in vitro, which demonstrated their PGP potential and antimicrobial properties. For instance, S. indicus produced high concentration of indole-3-acetic acid, a PGP phytohormone, that can stimulate plant growth. In addition, an antimicrobial susceptibility assay suggested that bacterial extracts displayed activity against Xanthomonas, a primary pathogen causing the pomegranate wilt disease. In conclusion, this study suggests that S. indicus, B. kalamazoonesis, and P. cellulosum can potentially be PGP and biocontrol agents that may contribute to increased crop productivity in pomegranate cultivation. These agents and their combinations warrant future research with an eye on SDGs and so as to enable and innovate organic farming and pomegranate agricultural practices.
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Affiliation(s)
- Renuka Ravinath
- Department of Biotechnology, School of Applied Sciences, REVA University, Bengaluru, India
| | - Talambedu Usha
- Department of Biochemistry, Maharani Lakshmi Ammanni College for Women, Bengaluru, India
| | - Anupam J Das
- Department of Biotechnology, School of Applied Sciences, REVA University, Bengaluru, India
| | | | | | | | | | - Nijalingappa Ramesh
- Department of Biotechnology, School of Applied Sciences, REVA University, Bengaluru, India
| | - Sushil Kumar Middha
- Department of Biotechnology, Maharani Lakshmi Ammanni College for Women, Bengaluru, India
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3
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Liu W, Cong B, Lin J, Liu S, Deng A, Zhao L. Taxonomic identification and temperature stress tolerance mechanisms of Aequorivita marisscotiae sp. nov. Commun Biol 2023; 6:1186. [PMID: 37990058 PMCID: PMC10663628 DOI: 10.1038/s42003-023-05559-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 11/08/2023] [Indexed: 11/23/2023] Open
Abstract
The deep sea harbours microorganisms with unique life characteristics and activities due to adaptation to particular environmental conditions, but the limited sample collection and pure culture techniques available constrain the study of deep-sea microorganisms. In this study, strain Ant34-E75 was isolated from Antarctic deep-sea sediment samples and showed the highest 16 S rRNA gene sequence similarity (97.18%) with the strain Aequorivita viscosa 8-1bT. Strain Ant34-E75 is psychrotrophic and can effectively increase the cold tolerance of Chlamydomonas reinhardtii (a model organism). Subsequent transcriptome analysis revealed multiple mechanisms involved in the Ant34-E75 response to temperature stress, and weighted gene co-expression network analysis (WGCNA) showed that the peptidoglycan synthesis pathway was the key component. Overall, this study provides insights into the characteristics of a deep-sea microorganism and elucidates mechanisms of temperature adaptation at the molecular level.
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Affiliation(s)
- Wenqi Liu
- First Institute of Oceanography, Ministry of Natural Resources, Qingdao, 266061, China
| | - Bailin Cong
- First Institute of Oceanography, Ministry of Natural Resources, Qingdao, 266061, China.
| | - Jing Lin
- First Institute of Oceanography, Ministry of Natural Resources, Qingdao, 266061, China
| | - Shenghao Liu
- First Institute of Oceanography, Ministry of Natural Resources, Qingdao, 266061, China
| | - Aifang Deng
- First Institute of Oceanography, Ministry of Natural Resources, Qingdao, 266061, China
| | - Linlin Zhao
- First Institute of Oceanography, Ministry of Natural Resources, Qingdao, 266061, China
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4
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Kelly SD, Ovchinnikova OG, Müller F, Steffen M, Braun M, Sweeney RP, Kowarik M, Follador R, Lowary TL, Serventi F, Whitfield C. Identification of a second glycoform of the clinically prevalent O1 antigen from Klebsiella pneumoniae. Proc Natl Acad Sci U S A 2023; 120:e2301302120. [PMID: 37428935 PMCID: PMC10629545 DOI: 10.1073/pnas.2301302120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 05/15/2023] [Indexed: 07/12/2023] Open
Abstract
Carbapenemase and extended β-lactamase-producing Klebsiella pneumoniae isolates represent a major health threat, stimulating increasing interest in immunotherapeutic approaches for combating Klebsiella infections. Lipopolysaccharide O antigen polysaccharides offer viable targets for immunotherapeutic development, and several studies have described protection with O-specific antibodies in animal models of infection. O1 antigen is produced by almost half of clinical Klebsiella isolates. The O1 polysaccharide backbone structure is known, but monoclonal antibodies raised against the O1 antigen showed varying reactivity against different isolates that could not be explained by the known structure. Reinvestigation of the structure by NMR spectroscopy revealed the presence of the reported polysaccharide backbone (glycoform O1a), as well as a previously unknown O1b glycoform composed of the O1a backbone modified with a terminal pyruvate group. The activity of the responsible pyruvyltransferase (WbbZ) was confirmed by western immunoblotting and in vitro chemoenzymatic synthesis of the O1b terminus. Bioinformatic data indicate that almost all O1 isolates possess genes required to produce both glycoforms. We describe the presence of O1ab-biosynthesis genes in other bacterial species and report a functional O1 locus on a bacteriophage genome. Homologs of wbbZ are widespread in genetic loci for the assembly of unrelated glycostructures in bacteria and yeast. In K. pneumoniae, simultaneous production of both O1 glycoforms is enabled by the lack of specificity of the ABC transporter that exports the nascent glycan, and the data reported here provide mechanistic understanding of the capacity for evolution of antigenic diversity within an important class of biomolecules produced by many bacteria.
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Affiliation(s)
- Steven D. Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ONN1G 2W1, Canada
| | - Olga G. Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ONN1G 2W1, Canada
| | | | | | - Martin Braun
- LimmaTech Biologics AG, Schlieren8952, Switzerland
| | - Ryan P. Sweeney
- Department of Chemistry, University of Alberta, Edmonton, ABT6G 2G2, Canada
| | | | | | - Todd L. Lowary
- Department of Chemistry, University of Alberta, Edmonton, ABT6G 2G2, Canada
- Institute of Biological Chemistry, Academia Sinica, Taipei, Nangang11529, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei10617, Taiwan
| | | | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ONN1G 2W1, Canada
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5
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Molecular basis for polysaccharide recognition and modulated ATP hydrolysis by the O antigen ABC transporter. Nat Commun 2022; 13:5226. [PMID: 36064941 PMCID: PMC9445017 DOI: 10.1038/s41467-022-32597-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 08/08/2022] [Indexed: 11/08/2022] Open
Abstract
O antigens are ubiquitous protective extensions of lipopolysaccharides in the extracellular leaflet of the Gram-negative outer membrane. Following biosynthesis in the cytosol, the lipid-linked polysaccharide is transported to the periplasm by the WzmWzt ABC transporter. Often, O antigen secretion requires the chemical modification of its elongating terminus, which the transporter recognizes via a carbohydrate-binding domain (CBD). Here, using components from A. aeolicus, we identify the O antigen structure with methylated mannose or rhamnose as its cap. Crystal and cryo electron microscopy structures reveal how WzmWzt recognizes this cap between its carbohydrate and nucleotide-binding domains in a nucleotide-free state. ATP binding induces drastic conformational changes of its CBD, terminating interactions with the O antigen. ATPase assays and site directed mutagenesis reveal reduced hydrolytic activity upon O antigen binding, likely to facilitate polymer loading into the ABC transporter. Our results elucidate critical steps in the recognition and translocation of polysaccharides by ABC transporters.
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6
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Mena-Bueno S, Poveda-Urkixo I, Irazoki O, Palacios L, Cava F, Zabalza-Baranguá A, Grilló MJ. Brucella melitensis Wzm/Wzt System: Changes in the Bacterial Envelope Lead to Improved Rev1Δwzm Vaccine Properties. Front Microbiol 2022; 13:908495. [PMID: 35875565 PMCID: PMC9306315 DOI: 10.3389/fmicb.2022.908495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 05/26/2022] [Indexed: 11/13/2022] Open
Abstract
The lipopolysaccharide (LPS) O-polysaccharide (O-PS) is the main virulence factor in Brucella. After synthesis in the cytoplasmic membrane, O-PS is exported to the periplasm by the Wzm/Wzt system, where it is assembled into a LPS. This translocation also engages a bactoprenol carrier required for further biosynthesis pathways, such as cell wall biogenesis. Targeting O-PS export by blockage holds great potential for vaccine development, but little is known about the biological implications of each Wzm/Wzt moiety. To improve this knowledge and to elucidate its potential application as a vaccine, we constructed and studied wzm/wzt single- and double-deletion mutants, using the attenuated strain Brucella melitensis Rev1 as the parental strain. This allowed us to describe the composition of Brucella peptidoglycan for the first time. We observed that these mutants lack external O-PS yet trigger changes in genetic transcription and in phenotypic properties associated with the outer membrane and cell wall. The three mutants are highly attenuated; unexpectedly, Rev1Δwzm also excels as an immunogenic and effective vaccine against B. melitensis and Brucella ovis in mice, revealing that low persistence is not at odds with efficacy. Rev1Δwzm is attenuated in BeWo trophoblasts, does not infect mouse placentas, and is safe in pregnant ewes. Overall, these attributes and the minimal serological interference induced in sheep make Rev1Δwzm a highly promising vaccine candidate.
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Affiliation(s)
- Sara Mena-Bueno
- Animal Health Department, Instituto de Agrobiotecnología (IdAB, CSIC-Gobierno de Navarra), Pamplona, Spain
- Agronomy, Biotecnology and Food Department, Universidad Pública de Navarra (UPNA), Pamplona, Spain
| | - Irati Poveda-Urkixo
- Animal Health Department, Instituto de Agrobiotecnología (IdAB, CSIC-Gobierno de Navarra), Pamplona, Spain
| | - Oihane Irazoki
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Leyre Palacios
- Animal Health Department, Instituto de Agrobiotecnología (IdAB, CSIC-Gobierno de Navarra), Pamplona, Spain
| | - Felipe Cava
- Laboratory for Molecular Infection Medicine Sweden, Department of Molecular Biology, Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Ana Zabalza-Baranguá
- Animal Health Department, Instituto de Agrobiotecnología (IdAB, CSIC-Gobierno de Navarra), Pamplona, Spain
| | - María Jesús Grilló
- Animal Health Department, Instituto de Agrobiotecnología (IdAB, CSIC-Gobierno de Navarra), Pamplona, Spain
- *Correspondence: María Jesús Grilló,
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7
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Lam MMC, Wick RR, Judd LM, Holt KE, Wyres KL. Kaptive 2.0: updated capsule and lipopolysaccharide locus typing for the Klebsiella pneumoniae species complex. Microb Genom 2022; 8:000800. [PMID: 35311639 PMCID: PMC9176290 DOI: 10.1099/mgen.0.000800] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 02/12/2022] [Indexed: 11/18/2022] Open
Abstract
The outer polysaccharide capsule and lipopolysaccharide (LPS) antigens are key targets for novel control strategies targeting Klebsiella pneumoniae and related taxa from the K. pneumoniae species complex (KpSC), including vaccines, phage and monoclonal antibody therapies. Given the importance and growing interest in these highly diverse surface antigens, we had previously developed Kaptive, a tool for rapidly identifying and typing capsule (K) and outer LPS (O) loci from whole genome sequence data. Here, we report two significant updates, now freely available in Kaptive 2.0 (https://github.com/katholt/kaptive): (i) the addition of 16 novel K locus sequences to the K locus reference database following an extensive search of >17 000 KpSC genomes; and (ii) enhanced O locus typing to enable prediction of the clinically relevant O2 antigen (sub)types, for which the genetic determinants have been recently described. We applied Kaptive 2.0 to a curated dataset of >12 000 public KpSC genomes to explore for the first time, to the best of our knowledge, the distribution of predicted O (sub)types across species, sampling niches and clones, which highlighted key differences in the distributions that warrant further investigation. As the uptake of genomic surveillance approaches continues to expand globally, the application of Kaptive 2.0 will generate novel insights essential for the design of effective KpSC control strategies.
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Affiliation(s)
- Margaret M. C. Lam
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria 3004, Australia
| | - Ryan R. Wick
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria 3004, Australia
| | - Louise M. Judd
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria 3004, Australia
| | - Kathryn E. Holt
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria 3004, Australia
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Kelly L. Wyres
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria 3004, Australia
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8
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Bes T, Nagano D, Martins R, Marchi AP, Perdigão-Neto L, Higashino H, Prado G, Guimaraes T, Levin AS, Costa S. Bloodstream Infections caused by Klebsiella pneumoniae and Serratia marcescens isolates co-harboring NDM-1 and KPC-2. Ann Clin Microbiol Antimicrob 2021; 20:57. [PMID: 34461917 PMCID: PMC8404334 DOI: 10.1186/s12941-021-00464-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 08/16/2021] [Indexed: 11/10/2022] Open
Abstract
Carbapenem-resistant Enterobacteriaceae are a worldwide health problem and isolates carrying both blaKPC-2 and blaNDM-1 are unusual. Here we describe the microbiological and clinical characteristics of five cases of bloodstream infections (BSI) caused by carbapenem-resistant Klebsiella pneumoniae and Serratia marcescens having both blaKPC-2 and blaNDM-1. Of the five blood samples, three are from hematopoietic stem cell transplantation patients, one from a renal transplant patient, and one from a surgical patient. All patients lived in low-income neighbourhoods and had no travel history. Despite antibiotic treatment, four out of five patients died. The phenotypic susceptibility assays showed that meropenem with the addition of either EDTA, phenylboronic acid (PBA), or both, increased the zone of inhibition in comparison to meropenem alone. Molecular tests showed the presence of blaKPC-2 and blaNDM-1 genes. K. pneumoniae isolates were assigned to ST258 or ST340 by whole genome sequencing. This case-series showed a high mortality among patients with BSI caused by Enterobacteriae harbouring both carbapenemases. The detection of carbapenemase-producing isolates carrying both blaKPC-2 and blaNDM-1 remains a challenge when using only phenotypic assays. Microbiology laboratories must be alert for K. pneumoniae isolates producing both KPC-2 and NDM-1.
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Affiliation(s)
- Taniela Bes
- Infectious Diseases Division, Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brazil. .,Institute of Tropical Medicine of the University of São Paulo, Avenida Dr. Enéas Carvalho de Aguiar, 470; LIM 49, São Paulo, CEP 05403-000, Brazil.
| | - Debora Nagano
- Institute of Tropical Medicine of the University of São Paulo, Avenida Dr. Enéas Carvalho de Aguiar, 470; LIM 49, São Paulo, CEP 05403-000, Brazil
| | - Roberta Martins
- Institute of Tropical Medicine of the University of São Paulo, Avenida Dr. Enéas Carvalho de Aguiar, 470; LIM 49, São Paulo, CEP 05403-000, Brazil
| | - Ana Paula Marchi
- Institute of Tropical Medicine of the University of São Paulo, Avenida Dr. Enéas Carvalho de Aguiar, 470; LIM 49, São Paulo, CEP 05403-000, Brazil
| | - Lauro Perdigão-Neto
- Infectious Diseases Division, Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brazil.,Institute of Tropical Medicine of the University of São Paulo, Avenida Dr. Enéas Carvalho de Aguiar, 470; LIM 49, São Paulo, CEP 05403-000, Brazil.,Infection Control, Hospital das Clínicas Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Hermes Higashino
- Infectious Diseases Division, Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brazil
| | - Gladys Prado
- Institute of Tropical Medicine of the University of São Paulo, Avenida Dr. Enéas Carvalho de Aguiar, 470; LIM 49, São Paulo, CEP 05403-000, Brazil
| | - Thais Guimaraes
- Infectious Diseases Division, Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brazil.,Infection Control, Hospital das Clínicas Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Anna S Levin
- Infectious Diseases Division, Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brazil.,Institute of Tropical Medicine of the University of São Paulo, Avenida Dr. Enéas Carvalho de Aguiar, 470; LIM 49, São Paulo, CEP 05403-000, Brazil.,Infection Control, Hospital das Clínicas Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
| | - Silvia Costa
- Infectious Diseases Division, Hospital das Clínicas da Universidade de São Paulo, São Paulo, Brazil.,Institute of Tropical Medicine of the University of São Paulo, Avenida Dr. Enéas Carvalho de Aguiar, 470; LIM 49, São Paulo, CEP 05403-000, Brazil.,Infection Control, Hospital das Clínicas Faculdade de Medicina da Universidade de Sao Paulo, Sao Paulo, Brazil
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9
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Cryo-EM structure of the full-length WzmWzt ABC transporter required for lipid-linked O antigen transport. Proc Natl Acad Sci U S A 2020; 118:2016144118. [PMID: 33443152 DOI: 10.1073/pnas.2016144118] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
O antigens are important cell surface polysaccharides in gram-negative bacteria where they extend core lipopolysaccharides in the extracellular leaflet of the outer membrane. O antigen structures are serotype specific and form extended cell surface barriers endowing many pathogens with survival benefits. In the ABC transporter-dependent biosynthesis pathway, O antigens are assembled on the cytosolic side of the inner membrane on a lipid anchor and reoriented to the periplasmic leaflet by the channel-forming WzmWzt ABC transporter for ligation to the core lipopolysaccharides. In many cases, this process depends on the chemical modification of the O antigen's nonreducing terminus, sensed by WzmWzt via a carbohydrate-binding domain (CBD) that extends its nucleotide-binding domain (NBD). Here, we provide the cryo-electron microscopy structure of the full-length WzmWzt transporter from Aquifex aeolicus bound to adenosine triphosphate (ATP) and in a lipid environment, revealing a highly asymmetric transporter organization. The CBDs dimerize and associate with only one NBD. Conserved loops at the CBD dimer interface straddle a conserved peripheral NBD helix. The CBD dimer is oriented perpendicularly to the NBDs and its putative ligand-binding sites face the transporter to likely modulate ATPase activity upon O antigen binding. Further, our structure reveals a closed WzmWzt conformation in which an aromatic belt near the periplasmic channel exit seals the transporter in a resting, ATP-bound state. The sealed transmembrane channel is asymmetric, with one open and one closed cytosolic and periplasmic portal. The structure provides important insights into O antigen recruitment to and translocation by WzmWzt and related ABC transporters.
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10
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Jayaraman J, Jones WT, Harvey D, Hemara LM, McCann HC, Yoon M, Warring SL, Fineran PC, Mesarich CH, Templeton MD. Variation at the common polysaccharide antigen locus drives lipopolysaccharide diversity within the Pseudomonas syringae species complex. Environ Microbiol 2020; 22:5356-5372. [PMID: 32985740 PMCID: PMC7820976 DOI: 10.1111/1462-2920.15250] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 09/22/2020] [Accepted: 09/22/2020] [Indexed: 12/19/2022]
Abstract
The common polysaccharide antigen (CPA) of the lipopolysaccharide (LPS) from Pseudomonas syringae is highly variable, but the genetic basis for this is poorly understood. We have characterized the CPA locus from P. syringae pv. actinidiae (Psa). This locus has genes for l- and d-rhamnose biosynthesis and an operon coding for ABC transporter subunits, a bifunctional glycosyltransferase and an o-methyltransferase. This operon is predicted to have a role in the transport, elongation and termination of the CPA oligosaccharide and is referred to as the TET operon. Two alleles of the TET operon were present in different biovars (BV) of Psa and lineages of the closely related pathovar P. syringae pv. actinidifoliorum. This allelic variation was reflected in the electrophoretic properties of purified LPS from the different isolates. Gene knockout of the TET operon allele from BV1 and replacement with that from BV3, demonstrated the link between the genetic locus and the biochemical properties of the LPS molecules in Psa. Sequence analysis of the TET operon from a range of P. syringae and P. viridiflava isolates displayed a phylogenetic history incongruent with core gene phylogeny but correlates with previously reported tailocin sensitivity, suggesting a functional relationship between LPS structure and tailocin susceptibility.
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Affiliation(s)
- Jay Jayaraman
- Bioprotection TechnologiesThe New Zealand Institute for Plant and Food Research LimitedAucklandNew Zealand
- Bioprotection Centre for Research ExcellenceNew Zealand
| | - William T. Jones
- Bioprotection TechnologiesThe New Zealand Institute for Plant and Food Research LimitedPalmerston NorthNew Zealand
| | - Dawn Harvey
- Bioprotection TechnologiesThe New Zealand Institute for Plant and Food Research LimitedPalmerston NorthNew Zealand
| | - Lauren M. Hemara
- Bioprotection TechnologiesThe New Zealand Institute for Plant and Food Research LimitedAucklandNew Zealand
- Bioprotection Centre for Research ExcellenceNew Zealand
- School of Biological SciencesUniversity of AucklandNew Zealand
| | - Honour C. McCann
- Institute of Advanced StudiesMassey UniversityAucklandNew Zealand
| | - Minsoo Yoon
- Bioprotection TechnologiesThe New Zealand Institute for Plant and Food Research LimitedAucklandNew Zealand
| | - Suzanne L. Warring
- Department of Microbiology and ImmunologyUniversity of OtagoDunedinNew Zealand
| | - Peter C. Fineran
- Bioprotection Centre for Research ExcellenceNew Zealand
- Department of Microbiology and ImmunologyUniversity of OtagoDunedinNew Zealand
| | - Carl H. Mesarich
- Bioprotection Centre for Research ExcellenceNew Zealand
- School of Agriculture and EnvironmentMassey UniversityPalmerston NorthNew Zealand
| | - Matthew D. Templeton
- Bioprotection TechnologiesThe New Zealand Institute for Plant and Food Research LimitedAucklandNew Zealand
- Bioprotection Centre for Research ExcellenceNew Zealand
- School of Biological SciencesUniversity of AucklandNew Zealand
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11
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Liu B, Furevi A, Perepelov AV, Guo X, Cao H, Wang Q, Reeves PR, Knirel YA, Wang L, Widmalm G. Structure and genetics of Escherichia coli O antigens. FEMS Microbiol Rev 2020; 44:655-683. [PMID: 31778182 PMCID: PMC7685785 DOI: 10.1093/femsre/fuz028] [Citation(s) in RCA: 121] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 11/22/2019] [Indexed: 02/07/2023] Open
Abstract
Escherichia coli includes clonal groups of both commensal and pathogenic strains, with some of the latter causing serious infectious diseases. O antigen variation is current standard in defining strains for taxonomy and epidemiology, providing the basis for many serotyping schemes for Gram-negative bacteria. This review covers the diversity in E. coli O antigen structures and gene clusters, and the genetic basis for the structural diversity. Of the 187 formally defined O antigens, six (O31, O47, O67, O72, O94 and O122) have since been removed and three (O34, O89 and O144) strains do not produce any O antigen. Therefore, structures are presented for 176 of the 181 E. coli O antigens, some of which include subgroups. Most (93%) of these O antigens are synthesized via the Wzx/Wzy pathway, 11 via the ABC transporter pathway, with O20, O57 and O60 still uncharacterized due to failure to find their O antigen gene clusters. Biosynthetic pathways are given for 38 of the 49 sugars found in E. coli O antigens, and several pairs or groups of the E. coli antigens that have related structures show close relationships of the O antigen gene clusters within clades, thereby highlighting the genetic basis of the evolution of diversity.
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Affiliation(s)
- Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Axel Furevi
- Department of Organic Chemistry, Arrhenius Laboratory, Svante Arrhenius väg 16C, Stockholm University, S-106 91 Stockholm, Sweden
| | - Andrei V Perepelov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect, 47, Moscow, Russia
| | - Xi Guo
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Hengchun Cao
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Quan Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Peter R Reeves
- School of Molecular and Microbial Bioscience, University of Sydney, 2 Butilin Ave, Darlington NSW 2008, Sydney, Australia
| | - Yuriy A Knirel
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect, 47, Moscow, Russia
| | - Lei Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory, Svante Arrhenius väg 16C, Stockholm University, S-106 91 Stockholm, Sweden
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Patro LPP, Sudhakar KU, Rathinavelan T. K-PAM: a unified platform to distinguish Klebsiella species K- and O-antigen types, model antigen structures and identify hypervirulent strains. Sci Rep 2020; 10:16732. [PMID: 33028855 PMCID: PMC7541508 DOI: 10.1038/s41598-020-73360-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 08/11/2020] [Indexed: 12/14/2022] Open
Abstract
A computational method has been developed to distinguish the Klebsiella species serotypes to aid in outbreak surveillance. A reliability score (estimated based on the accuracy of a specific K-type prediction against the dataset of 141 distinct K-types) average (ARS) that reflects the specificity between the Klebsiella species capsular polysaccharide biosynthesis and surface expression proteins, and their K-types has been established. ARS indicates the following order of potency in accurate serotyping: Wzx (ARS = 98.5%),Wzy (ARS = 97.5%),WbaP (ARS = 97.2%),Wzc (ARS = 96.4%),Wzb (ARS = 94.3%),WcaJ (ARS = 93.8%),Wza (ARS = 79.9%) and Wzi (ARS = 37.1%). Thus, Wzx, Wzy and WbaP can give more reliable K-typing compared with other proteins. A fragment-based approach has further increased the Wzi ARS from 37.1% to 80.8%. The efficacy of these 8 proteins in accurate K-typing has been confirmed by a rigorous testing and the method has been automated as K-PAM (www.iith.ac.in/K-PAM/). Testing also indicates that the use of multiple genes/proteins helps in reducing the K-type multiplicity, distinguishing the K-types that have identical K-locus (like KN3 and K35) and identifying the ancestral serotypes of Klebsiella spp. K-PAM has the facilities to O-type using Wzm (ARS = 85.7%) and Wzt (ARS = 85.7%) and identifies the hypervirulent Klebsiella species by the use of rmpA, rmpA2, iucA, iroB and peg-344 marker genes. Yet another highlight of the server is the repository of the modeled 11 O- and 79 K- antigen 3D structures.
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Affiliation(s)
- L Ponoop Prasad Patro
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, 502285, India
| | - Karpagam Uma Sudhakar
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Telangana, 502285, India
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13
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Identification of the Pseudomonas aeruginosa O17 and O15 O-Specific Antigen Biosynthesis Loci Reveals an ABC Transporter-Dependent Synthesis Pathway and Mechanisms of Genetic Diversity. J Bacteriol 2020; 202:JB.00347-20. [PMID: 32690555 DOI: 10.1128/jb.00347-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 07/13/2020] [Indexed: 02/07/2023] Open
Abstract
Many bacterial cell surface glycans, such as the O antigen component of lipopolysaccharide (LPS), are produced via the so-called Wzx/Wzy- or ABC transporter-dependent pathways. O antigens are highly diverse polysaccharides that protect bacteria from their environment and engage in important host-pathogen interactions. The specific structure and composition of O antigens are the basis of classifying bacteria into O serotypes. In the opportunistic pathogen Pseudomonas aeruginosa, there are currently 20 known O-specific antigen (OSA) structures. The clusters of genes responsible for 18 of these O antigens have been identified, all of which follow the Wzx/Wzy-dependent pathway and are located at a common locus. In this study, we located the two unidentified O antigen biosynthesis clusters responsible for the synthesis of the O15 and the O17 OSA structures by analyzing published whole-genome sequence data. Intriguingly, these clusters were found outside the conserved OSA biosynthesis locus and were likely acquired through multiple horizontal gene transfer events. Based on data from knockout and overexpression studies, we determined that the synthesis of these O antigens follows an ABC transporter-dependent rather than a Wzx/Wzy-dependent pathway. In addition, we collected evidence to show that the O15 and O17 polysaccharide chain lengths are regulated by molecular rulers with distinct and variable domain architectures. The findings in this report are critical for a comprehensive understanding of O antigen biosynthesis in P. aeruginosa and provide a framework for future studies.IMPORTANCE P. aeruginosa is a problematic opportunistic pathogen that causes diseases in those with compromised host defenses, such as those suffering from cystic fibrosis. This bacterium produces a number of virulence factors, including a serotype-specific O antigen. Here, we identified and characterized the gene clusters that produce the O15 and O17 O antigens and show that they utilize a pathway for synthesis that is distinct from that of the 18 other known serotypes. We also provide evidence that these clusters have acquired mutations in specific biosynthesis genes and have undergone extensive horizontal gene transfer within the P. aeruginosa population. These findings expand on our understanding of O antigen biosynthesis in Gram-negative bacteria and the mechanisms that drive O antigen diversity.
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14
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Abstract
Cordyceps is a parasitic edible fungus with a variety of metabolically active ingredients. The main active ingredient, extracellular polysaccharide (EPS), shows favourable application prospects in prevention and treatment of certain diseases. EPS extracted from different parts of various Cordyceps species can be used in health foods or medicinal preparations because of the structural diversity and multiple bioactivities. In terms of the complexity of composition and structure, researchers have speculated on the anabolic pathways of EPSs and the genes involved in the synthesis process. Studies to increase the yield of polysaccharides are limited because the synthesis pathways and anabolic regulation mechanisms of Cordyceps exopolysaccharide remain unknown. This review summarises the current researches in the yield of Cordyceps polysaccharides. A mechanism for the biosynthesis of Cordyceps polysaccharides was proposed by referring to the polysaccharide synthesis in other species. Furthermore, we also discuss the future perspective and ongoing challenges of EPS in uses of health foods and pharmaceutics.
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Affiliation(s)
- Shengli Yang
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Xi Yang
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou, China
| | - Hui Zhang
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, China
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15
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Caffalette CA, Kuklewicz J, Spellmon N, Zimmer J. Biosynthesis and Export of Bacterial Glycolipids. Annu Rev Biochem 2020; 89:741-768. [DOI: 10.1146/annurev-biochem-011520-104707] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Complex carbohydrates are essential for many biological processes, from protein quality control to cell recognition, energy storage, and cell wall formation. Many of these processes are performed in topologically extracellular compartments or on the cell surface; hence, diverse secretion systems evolved to transport the hydrophilic molecules to their sites of action. Polyprenyl lipids serve as ubiquitous anchors and facilitators of these transport processes. Here, we summarize and compare bacterial biosynthesis pathways relying on the recognition and transport of lipid-linked complex carbohydrates. In particular, we compare transporters implicated in O antigen and capsular polysaccharide biosyntheses with those facilitating teichoic acid and N-linked glycan transport. Further, we discuss recent insights into the generation, recognition, and recycling of polyprenyl lipids.
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Affiliation(s)
- Christopher A. Caffalette
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Jeremi Kuklewicz
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Nicholas Spellmon
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA
| | - Jochen Zimmer
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, USA
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16
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Whitfield C, Williams DM, Kelly SD. Lipopolysaccharide O-antigens-bacterial glycans made to measure. J Biol Chem 2020; 295:10593-10609. [PMID: 32424042 DOI: 10.1074/jbc.rev120.009402] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/17/2020] [Indexed: 01/05/2023] Open
Abstract
Lipopolysaccharides are critical components of bacterial outer membranes. The more conserved lipid A part of the lipopolysaccharide molecule is a major element in the permeability barrier imposed by the outer membrane and offers a pathogen-associated molecular pattern recognized by innate immune systems. In contrast, the long-chain O-antigen polysaccharide (O-PS) shows remarkable structural diversity and fulfills a range of functions, depending on bacterial lifestyles. O-PS production is vital for the success of clinically important Gram-negative pathogens. The biological properties and functions of O-PSs are mostly independent of specific structures, but the size distribution of O-PS chains is particularly important in many contexts. Despite the vast O-PS chemical diversity, most are produced in bacterial cells by two assembly strategies, and the different mechanisms employed in these pathways to regulate chain-length distribution are emerging. Here, we review our current understanding of the mechanisms involved in regulating O-PS chain-length distribution and discuss their impact on microbial cell biology.
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Affiliation(s)
- Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Danielle M Williams
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
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17
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Li Y, Huang J, Wang X, Xu C, Han T, Guo X. Genetic Characterization of the O-Antigen and Development of a Molecular Serotyping Scheme for Enterobacter cloacae. Front Microbiol 2020; 11:727. [PMID: 32411106 PMCID: PMC7198725 DOI: 10.3389/fmicb.2020.00727] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 03/27/2020] [Indexed: 11/13/2022] Open
Abstract
Enterobacter cloacae is a well-characterized opportunistic pathogen that is closely associated with various nosocomial infections. The O-antigen, which is one of the most variable constituents on the cell surface, has been used widely and traditionally for serological classification of many gram-negative bacteria. E. cloacae is divided into 30 serotypes, based on its O-antigen diversity. In this study, by using genomic and comparative-genomic approaches, we analyzed the O-antigen gene clusters of 26 E. cloacae serotypes in depth. We also identified the sero-specific gene for each serotype and developed a multiplex polymerase chain reaction (PCR) method. The sensitivity of the assay was 0.1 ng for genomic DNA and 103 colony forming units for pure cultures. The assay reliability was evaluated by double-blinded testing with 81 clinical strains. Furthermore, we established a valid, genome-based tool for in silico serotyping of E. cloacae. By screening 431 E. cloacae genomes deposited in GenBank, 304 were classified into current antigenic scheme, and 112 were allocated into 55 putative novel serotypes. Our results represent the first genetic basis of the O-antigen diversity and variation of E. cloacae, providing a rationale for studying the O-antigen associated evolution and pathogenesis of this bacterium. In addition, we extended the current serotyping system for E. cloacae, which is important for detection and epidemiological surveillance purposes for this important pathogen.
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Affiliation(s)
- Yayue Li
- The Third Central Hospital of Tianjin, Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin Institute of Hepatobiliary Disease, Tianjin, China
| | - Junjie Huang
- Department of Vascular Surgery, Tianjin Hospital, Tianjin, China
| | - Xiaotong Wang
- Tianjin Children's Hospital, Third Central Clinical College of Tianjin Medical University, Tianjin, China
| | - Cong Xu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Tao Han
- The Third Central Hospital of Tianjin, Tianjin Key Laboratory of Extracorporeal Life Support for Critical Diseases, Tianjin Institute of Hepatobiliary Disease, Tianjin, China
| | - Xi Guo
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
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18
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Mann E, Kimber MS, Whitfield C. Bioinformatics analysis of diversity in bacterial glycan chain-termination chemistry and organization of carbohydrate-binding modules linked to ABC transporters. Glycobiology 2020; 29:822-838. [PMID: 31504498 DOI: 10.1093/glycob/cwz066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/19/2019] [Accepted: 08/19/2019] [Indexed: 12/22/2022] Open
Abstract
The structures of bacterial cell surface glycans are remarkably diverse. In spite of this diversity, the general strategies used for their assembly are limited. In one of the major processes, found in both Gram-positive and Gram-negative bacteria, the glycan is polymerized in the cytoplasm on a polyprenol lipid carrier and exported from the cytoplasm by an ATP-binding cassette (ABC) transporter. The ABC transporter actively participates in determining the chain length of the glycan substrate, which impacts functional properties of the glycoconjugate products. A subset of these systems employs an additional elaborate glycan capping strategy that dictates the size distribution of the products. The hallmarks of prototypical capped glycan systems are a chain-terminating enzyme possessing a coiled-coil molecular ruler and an ABC transporter possessing a carbohydrate-binding module, which recognizes the glycan cap. To date, detailed investigations are limited to a small number of prototypes, and here, we used our current understanding of these processes for a bioinformatics census of other examples in available genome sequences. This study not only revealed additional instances of existing terminators but also predicted new chemistries as well as systems that diverge from the established prototypes. These analyses enable some new functional hypotheses and offer a roadmap for future research.
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Affiliation(s)
- Evan Mann
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Rd. East, Guelph, Ontario N1G 2W1, Canada
| | - Matthew S Kimber
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Rd. East, Guelph, Ontario N1G 2W1, Canada
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Rd. East, Guelph, Ontario N1G 2W1, Canada
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19
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Bi Y, Zimmer J. Structure and Ligand-Binding Properties of the O Antigen ABC Transporter Carbohydrate-Binding Domain. Structure 2019; 28:252-258.e2. [PMID: 31879128 DOI: 10.1016/j.str.2019.11.020] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 11/13/2019] [Accepted: 11/27/2019] [Indexed: 10/25/2022]
Abstract
A hallmark of Gram-negative bacteria is an asymmetric outer membrane containing lipopolysaccharides (LPSs) in the extracellular leaflet. LPS molecules consist of lipid A, which is connected to the inner and outer core oligosaccharides. This LPS core structure is extended in the periplasm by the O antigen, a variable and serotype-defining polysaccharide. In the ABC transporter-dependent LPS biosynthesis pathway, the WzmWzt transporter secretes the complete O antigen across the inner membrane for ligation to the LPS core. In some O antigen transporters, the nucleotide-binding domain of Wzt is fused C-terminally to a carbohydrate-binding domain (CBD) that interacts with the O antigen chain. Here, we present the crystal structure of the Aquifex aeolicus CBD that reveals a conserved flat and a variable twisted jelly-roll surface. The CBD dimer is stabilized by mutual β strand exchange. Microbial glycan array binding studies with the isolated CBD provide insights into its interaction with complex carbohydrates.
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Affiliation(s)
- Yunchen Bi
- School of Medicine, Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22903, USA
| | - Jochen Zimmer
- School of Medicine, Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22903, USA.
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20
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Patro LPP, Rathinavelan T. Targeting the Sugary Armor of Klebsiella Species. Front Cell Infect Microbiol 2019; 9:367. [PMID: 31781512 PMCID: PMC6856556 DOI: 10.3389/fcimb.2019.00367] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Accepted: 10/09/2019] [Indexed: 12/25/2022] Open
Abstract
The emergence of multidrug-resistant strains of Gram-negative Klebsiella species is an urgent global threat. The World Health Organization has listed Klebsiella pneumoniae as one of the global priority pathogens in critical need of next-generation antibiotics. Compared to other Gram-negative pathogens, K. pneumoniae accumulates a greater diversity of antimicrobial-resistant genes at a higher frequency. The evolution of a hypervirulent phenotype of K. pneumoniae is yet another concern. It has a broad ecological distribution affecting humans, agricultural animals, plants, and aquatic animals. Extracellular polysaccharides of Klebsiella, such as lipopolysaccharides, capsular polysaccharides, and exopolysaccharides, play crucial roles in conferring resistance against the host immune response, as well as in colonization, surface adhesion, and for protection against antibiotics and bacteriophages. These extracellular polysaccharides are major virulent determinants and are highly divergent with respect to their antigenic properties. Wzx/Wzy-, ABC-, and synthase-dependent proteinaceous nano-machineries are involved in the biosynthesis, transport, and cell surface expression of these sugar molecules. Although the proteins involved in the biosynthesis and surface expression of these sugar molecules represent potential drug targets, variation in the amino acid sequences of some of these proteins, in combination with diversity in their sugar composition, poses a major challenge to the design of a universal drug for Klebsiella infections. This review discusses the challenges in universal Klebsiella vaccine and drug development from the perspective of antigen sugar compositions and the proteins involved in extracellular antigen transport.
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21
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Mann E, Kelly SD, Al-Abdul-Wahid MS, Clarke BR, Ovchinnikova OG, Liu B, Whitfield C. Substrate recognition by a carbohydrate-binding module in the prototypical ABC transporter for lipopolysaccharide O-antigen from Escherichia coli O9a. J Biol Chem 2019; 294:14978-14990. [PMID: 31416837 DOI: 10.1074/jbc.ra119.010323] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 08/14/2019] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli serotype O9a provides a model for export of lipopolysaccharide (LPS) O-antigen polysaccharide (O-PS) via ABC transporters. In O9a biosynthesis, a chain-terminator enzyme, WbdD, caps the nonreducing end of the glycan with a methylphosphate moiety and thereby establishes chain-length distribution. A carbohydrate-binding module (CBM) in the ABC transporter recognizes terminated glycans, ensuring that only mature O-PS is exported and incorporated into LPS. Here, we addressed two questions arising from this model. Are both residues in the binary terminator necessary for termination and export? And is a terminal methylphosphate moiety sufficient for export of heterologous glycans? To answer the first question, we uncoupled WbdD kinase and methyltransferase activities. WbdD mutants revealed that although the kinase activity is solely responsible for chain-length regulation, both activities are essential for CBM recognition and export. Consistent with this observation, a saturation transfer difference NMR experiment revealed a direct interaction between the CBM and the terminal methyl group. To determine whether methylphosphate is the sole determinant of substrate recognition by the CBM, we exploited Klebsiella pneumoniae O7, whose O-PS repeat-unit structure differs from O9a, but, as shown here, offers the second confirmed example of a terminal methylphosphate serving in substrate recognition. In vitro and in vivo experiments indicated that each CBM can bind the O-PS only with the native repeat unit, revealing that methylphosphate is essential but not sufficient for substrate recognition and export. Our findings provide important new insight into the structural determinants in a prototypical quality control system for glycan assembly and export.
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Affiliation(s)
- Evan Mann
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | | | - Bradley R Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Olga G Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 3 Hongda St. TEDA, Tianjin 300457, China
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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22
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Pérez-Burgos M, García-Romero I, Jung J, Valvano MA, Søgaard-Andersen L. Identification of the lipopolysaccharide O-antigen biosynthesis priming enzyme and the O-antigen ligase in Myxococcus xanthus: critical role of LPS O-antigen in motility and development. Mol Microbiol 2019; 112:1178-1198. [PMID: 31332863 DOI: 10.1111/mmi.14354] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2019] [Indexed: 01/03/2023]
Abstract
Myxococcus xanthus is a model bacterium to study social behavior. At the cellular level, the different social behaviors of M. xanthus involve extensive cell-cell contacts. Here, we used bioinformatics, genetics, heterologous expression and biochemical experiments to identify and characterize the key enzymes in M. xanthus implicated in O-antigen and lipopolysaccharide (LPS) biosynthesis and examined the role of LPS O-antigen in M. xanthus social behaviors. We identified WbaPMx (MXAN_2922) as the polyisoprenyl-phosphate hexose-1-phosphate transferase responsible for priming O-antigen synthesis. In heterologous expression experiments, WbaPMx complemented a Salmonella enterica mutant lacking the endogenous WbaP that primes O-antigen synthesis, indicating that WbaPMx transfers galactose-1-P to undecaprenyl-phosphate. We also identified WaaLMx (MXAN_2919), as the O-antigen ligase that joins O-antigen to lipid A-core. Our data also support the previous suggestion that WzmMx (MXAN_4622) and WztMx (MXAN_4623) form the Wzm/Wzt ABC transporter. We show that mutations that block different steps in LPS O-antigen synthesis can cause pleiotropic phenotypes. Also, using a wbaPMx deletion mutant, we revisited the role of LPS O-antigen and demonstrate that it is important for gliding motility, conditionally important for type IV pili-dependent motility and required to complete the developmental program leading to the formation of spore-filled fruiting bodies.
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Affiliation(s)
- María Pérez-Burgos
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Str. 10, 35043, Marburg, Germany
| | - Inmaculada García-Romero
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, UK
| | - Jana Jung
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Str. 10, 35043, Marburg, Germany
| | - Miguel A Valvano
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7BL, UK
| | - Lotte Søgaard-Andersen
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Str. 10, 35043, Marburg, Germany
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23
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Düzgün AÖ, Saral A. Next-generation sequencing of plasmid carrying blaOXA-48 in Klebsiella pneumoniae from Turkey. Acta Microbiol Immunol Hung 2019; 66:261-272. [PMID: 30803252 DOI: 10.1556/030.66.2019.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A carbapenem-resistant Klebsiella pneumoniae strain was isolated in Turkey in 2012 and blaNDM-1 and blaOXA-48 genes were observed in this strain. The aim of this study was to investigate transferability of plasmid bearing blaOXA-48 in K. pneumoniae and to use whole-genome sequencing in order to understand the genetic context of plasmid. K. pneumoniae strain was used as donor in conjugation experiments. Antibiotic susceptibility profile of selected transconjugant was determined. Plasmid was isolated from transconjugant colony and was named as pKPT. Complete sequencing of the pKPT was conducted using a next-generation sequencing. Annotation of the contigs was performed using the Geneious R9, followed by finding open reading frames (ORFs) with selected web-based tools. BLAST analysis was performed at the NCBI BLAST server to determine genes showing more than 90% similarity with these ORFs. Results of antibiotic susceptibility test showed that transconjugant colony was resistant to ampicillin/sulbactam, piperacillin, and piperacillin/tazobactam. The pKPT plasmid had a length of 45,217 bp and an average G + C content of 49%. Blast analysis revealed that pKPT was included in the IncL/M incompatibility group. The pKPT was found to contain blaOXA-48 within Tn1999.2 transposon without any other antibiotic resistance gene.
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Affiliation(s)
- Azer Özad Düzgün
- 1 Department of Genetics and Bioengineering, Faculty of Engineering and Natural Sciences, Gümüşhane University, Gümüşhane, Turkey
- 2 Medicinal Plants, Traditional Medicine Practice and Research Center, Gümüşhane University, Gümüşhane, Turkey
| | - Ayşegül Saral
- 3 Department of Nutrition and Dietetics, Faculty of Health Sciences, Artvin Coruh University, Artvin, Turkey
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24
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Kelly SD, Clarke BR, Ovchinnikova OG, Sweeney RP, Williamson ML, Lowary TL, Whitfield C. Klebsiella pneumoniae O1 and O2ac antigens provide prototypes for an unusual strategy for polysaccharide antigen diversification. J Biol Chem 2019; 294:10863-10876. [PMID: 31138653 DOI: 10.1074/jbc.ra119.008969] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 05/21/2019] [Indexed: 12/17/2022] Open
Abstract
A limited range of different structures is observed in O-antigenic polysaccharides (OPSs) from Klebsiella pneumoniae lipopolysaccharides. Among these, several are based on modifications of a conserved core element of serotype O2a OPS, which has a disaccharide repeat structure [→3)-α-d-Galp-(1→3)-β-d-Galf-(1→]. Here, we describe the enzymatic pathways for a highly unusual modification strategy involving the attachment of a second glycan repeat-unit structure to the nonreducing terminus of O2a. This occurs by the addition of the O1 [→3)-α-d-Galp-(1→3)-β-d-Galp-(1→] or O2c [→3)-β-d-GlcpNAc-(1→5)-β-d-Galf-(1→] antigens. The organization of the enzyme activities performing these modifications differs, with the enzyme WbbY possessing two glycosyltransferase catalytic sites solely responsible for O1 antigen polymerization and forming a complex with the O2a glycosyltransferase WbbM. In contrast, O2c polymerization requires glycosyltransferases WbmV and WbmW, which interact with one another but apparently not with WbbM. Using defined synthetic acceptors and site-directed mutants to assign the activities of the WbbY catalytic sites, we found that the C-terminal WbbY domain is a UDP-Galp-dependent GT-A galactosyltransferase adding β-(1→3)-linked d-Galp, whereas the WbbY N terminus includes a GT-B enzyme adding α-(1→3)-linked d-Galp These activities build the O1 antigen on a terminal Galp in the O2a domain. Using similar approaches, we identified WbmV as the UDP-GlcNAc transferase and noted that WbmW represents a UDP-Galf-dependent enzyme and that both are GT-A members. WbmVW polymerizes the O2c antigen on a terminal Galf. Our results provide mechanistic and conceptual insights into an important strategy for polysaccharide antigen diversification in bacteria.
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Affiliation(s)
- Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and
| | - Bradley R Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and
| | - Olga G Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and
| | - Ryan P Sweeney
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Monica L Williamson
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and
| | - Todd L Lowary
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and.
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25
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Perez C, Mehdipour AR, Hummer G, Locher KP. Structure of Outward-Facing PglK and Molecular Dynamics of Lipid-Linked Oligosaccharide Recognition and Translocation. Structure 2019; 27:669-678.e5. [PMID: 30799077 DOI: 10.1016/j.str.2019.01.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/29/2018] [Accepted: 01/25/2019] [Indexed: 12/21/2022]
Abstract
PglK is a lipid-linked oligosaccharide (LLO) flippase essential for asparagine-linked protein glycosylation in Campylobacter jejuni. Previously we have proposed a non-alternating-access LLO translocation mechanism, where postulated outward-facing states play a primary role. To investigate this unusual mechanistic proposal, we have determined a high-resolution structure of PglK that displays an outward semi-occluded state with the two nucleotide binding domains forming an asymmetric closed dimer with two bound ATPγS molecules. Based on this structure, we performed extensive molecular dynamics simulations to investigate LLO recognition and flipping. Our results suggest that PglK may employ a "substrate-hunting" mechanism to locally increase the LLO concentration and facilitate its jump into the translocation pathway, for which sugars from the LLO head group are essential. We further conclude that the release of LLO to the outside occurs before ATP hydrolysis and is followed by the closing of the periplasmic cavity of PglK.
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Affiliation(s)
- Camilo Perez
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland; Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Ahmad Reza Mehdipour
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany; Institute of Biophysics, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany.
| | - Kaspar P Locher
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland.
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26
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Caffalette CA, Corey RA, Sansom MSP, Stansfeld PJ, Zimmer J. A lipid gating mechanism for the channel-forming O antigen ABC transporter. Nat Commun 2019; 10:824. [PMID: 30778065 PMCID: PMC6379404 DOI: 10.1038/s41467-019-08646-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 01/23/2019] [Indexed: 12/15/2022] Open
Abstract
Extracellular glycan biosynthesis is a widespread microbial protection mechanism. In Gram-negative bacteria, the O antigen polysaccharide represents the variable region of outer membrane lipopolysaccharides. Fully assembled lipid-linked O antigens are translocated across the inner membrane by the WzmWzt ABC transporter for ligation to the lipopolysaccharide core, with the transporter forming a continuous transmembrane channel in a nucleotide-free state. Here, we report its structure in an ATP-bound conformation. Large structural changes within the nucleotide-binding and transmembrane regions push conserved hydrophobic residues at the substrate entry site towards the periplasm and provide a model for polysaccharide translocation. With ATP bound, the transporter forms a large transmembrane channel with openings toward the membrane and periplasm. The channel's periplasmic exit is sealed by detergent molecules that block solvent permeation. Molecular dynamics simulation data suggest that, in a biological membrane, lipid molecules occupy this periplasmic exit and prevent water flux in the transporter's resting state.
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Affiliation(s)
- Christopher A Caffalette
- Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Robin A Corey
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | | | - Jochen Zimmer
- Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
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27
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Current Progress in the Structural and Biochemical Characterization of Proteins Involved in the Assembly of Lipopolysaccharide. Int J Microbiol 2018; 2018:5319146. [PMID: 30595696 PMCID: PMC6286764 DOI: 10.1155/2018/5319146] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 10/29/2018] [Indexed: 12/25/2022] Open
Abstract
The lipid component of the outer leaflet of the outer membrane of Gram-negative bacteria is primarily composed of the glycolipid lipopolysaccharide (LPS), which serves to form a protective barrier against hydrophobic toxins and many antibiotics. LPS is comprised of three regions: the lipid A membrane anchor, the nonrepeating core oligosaccharide, and the repeating O-antigen polysaccharide. The lipid A portion is also referred to as endotoxin as its overstimulation of the toll-like receptor 4 during systemic infection precipitates potentially fatal septic shock. Because of the importance of LPS for the viability and virulence of human pathogens, understanding how LPS is synthesized and transported to the outer leaflet of the outer membrane is important for developing novel antibiotics to combat resistant Gram-negative strains. The following review describes the current state of our understanding of the proteins responsible for the synthesis and transport of LPS with an emphasis on the contribution of protein structures to our understanding of their functions. Because the lipid A portion of LPS is relatively well conserved, a detailed description of the biosynthetic enzymes in the Raetz pathway of lipid A synthesis is provided. Conversely, less well-conserved biosynthetic enzymes later in LPS synthesis are described primarily to demonstrate conserved principles of LPS synthesis. Finally, the conserved LPS transport systems are described in detail.
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28
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Bi Y, Mann E, Whitfield C, Zimmer J. Architecture of a channel-forming O-antigen polysaccharide ABC transporter. Nature 2018; 553:361-365. [PMID: 29320481 PMCID: PMC5978415 DOI: 10.1038/nature25190] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 12/01/2017] [Indexed: 11/23/2022]
Abstract
O-antigens are cell surface polysaccharides of many Gram-negative pathogens that aid in escaping innate immune responses. A widespread O-antigen biosynthesis mechanism involves the synthesis of the lipid-anchored polymer on the cytosolic face of the inner membrane, followed by transport to the periplasmic side where it is ligated to the lipid A core to complete a lipopolysaccharide molecule. In this pathway, transport to the periplasm is mediated by an ATP-binding cassette (ABC) transporter, called Wzm-Wzt. Here we present the crystal structure of the Wzm-Wzt homologue from Aquifex aeolicus in an open conformation. The transporter forms a transmembrane channel that is sufficiently wide to accommodate a linear polysaccharide. Its nucleotide-binding domain and a periplasmic extension form 'gate helices' at the cytosolic and periplasmic membrane interfaces that probably serve as substrate entry and exit points. Site-directed mutagenesis of the gates impairs in vivo O-antigen secretion in the Escherichia coli prototype. Combined with a closed structure of the isolated nucleotide-binding domains, our structural and functional analyses suggest a processive O-antigen translocation mechanism, which stands in contrast to the classical alternating access mechanism of ABC transporters.
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Affiliation(s)
- Yunchen Bi
- Molecular Physiology and Biological Physics, University of Virginia
School of Medicine, Charlottesville, VA 22908, USA
| | - Evan Mann
- Department of Molecular and Cellular Biology, University of Guelph,
Guelph, Ontario, N1G 2W1, Canada
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph,
Guelph, Ontario, N1G 2W1, Canada
| | - Jochen Zimmer
- Molecular Physiology and Biological Physics, University of Virginia
School of Medicine, Charlottesville, VA 22908, USA
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29
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X-ray crystallographic structure of a bacterial polysialyltransferase provides insight into the biosynthesis of capsular polysialic acid. Sci Rep 2017; 7:5842. [PMID: 28724897 PMCID: PMC5517516 DOI: 10.1038/s41598-017-05627-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 05/31/2017] [Indexed: 12/21/2022] Open
Abstract
Polysialic acid (polySia) is a homopolymeric saccharide that is associated with some neuroinvasive pathogens and is found on selective cell types in their eukaryotic host. The presence of a polySia capsule on these bacterial pathogens helps with resistance to phagocytosis, cationic microbial peptides and bactericidal antibody production. The biosynthesis of bacterial polySia is catalysed by a single polysialyltransferase (PST) transferring sialic acid from a nucleotide-activated donor to a lipid-linked acceptor oligosaccharide. Here we present the X-ray structure of the bacterial PST from Mannheimia haemolytica serotype A2, thereby defining the architecture of this class of enzymes representing the GT38 family. The structure reveals a prominent electropositive groove between the two Rossmann-like domains forming the GT-B fold that is suitable for binding of polySia chain products. Complex structures of PST with a sugar donor analogue and an acceptor mimetic combined with kinetic studies of PST active site mutants provide insight into the principles of substrate binding and catalysis. Our results are the basis for a molecular understanding of polySia biosynthesis in bacteria and might assist the production of polysialylated therapeutic reagents and the development of novel antibiotics.
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Single polysaccharide assembly protein that integrates polymerization, termination, and chain-length quality control. Proc Natl Acad Sci U S A 2017; 114:E1215-E1223. [PMID: 28137848 DOI: 10.1073/pnas.1613609114] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Lipopolysaccharides (LPS) are essential outer membrane glycolipids in most gram-negative bacteria. Biosynthesis of the O-antigenic polysaccharide (OPS) component of LPS follows one of three widely distributed strategies, and similar processes are used to assemble other bacterial surface glycoconjugates. This study focuses on the ATP-binding cassette (ABC) transporter-dependent pathway, where glycans are completed on undecaprenyl diphosphate carriers at the cytosol:membrane interface, before export by the ABC transporter. We describe Raoultella terrigena WbbB, a prototype for a family of proteins that, remarkably, integrates several key activities in polysaccharide biosynthesis into a single polypeptide. WbbB contains three glycosyltransferase (GT) modules. Each of the GT102 and GT103 modules characterized here represents a previously unrecognized GT family. They form a polymerase, generating a polysaccharide of [4)-α-Rhap-(1→3)-β-GlcpNAc-(1→] repeat units. The polymer chain is terminated by a β-linked Kdo (3-deoxy-d-manno-oct-2-ulosonic acid) residue added by a third GT module belonging to the recently discovered GT99 family. The polymerase GT modules are separated from the GT99 chain terminator by a coiled-coil structure that forms a molecular ruler to determine product length. Different GT modules in the polymerase domains of other family members produce diversified OPS structures. These findings offer insight into glycan assembly mechanisms and the generation of antigenic diversity as well as potential tools for glycoengineering.
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31
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Glycolipid substrates for ABC transporters required for the assembly of bacterial cell-envelope and cell-surface glycoconjugates. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:1394-1403. [PMID: 27793707 DOI: 10.1016/j.bbalip.2016.10.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/19/2016] [Accepted: 10/20/2016] [Indexed: 01/07/2023]
Abstract
Glycoconjugates, molecules that contain sugar components, are major components of the cell envelopes of bacteria and cover much of their exposed surfaces. These molecules are involved in interactions with the surrounding environment and, in pathogens, play critical roles in the interplay with the host immune system. Despite the remarkable diversity in glycoconjugate structures, most are assembled by glycosyltransferases that act on lipid acceptors at the cytosolic membrane. The resulting glycolipids are then transported to the cell surface in processes that frequently begin with ATP-binding cassette transporters. This review summarizes current understanding of the structure and biosynthesis of glycolipid substrates and the structure and functions of their transporters. This article is part of a Special Issue entitled: Bacterial Lipids edited by Russell E. Bishop.
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32
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Mohammad MM, Tomita N, Ohta M, Movileanu L. The Transmembrane Domain of a Bicomponent ABC Transporter Exhibits Channel-Forming Activity. ACS Chem Biol 2016; 11:2506-18. [PMID: 27379442 PMCID: PMC5026576 DOI: 10.1021/acschembio.6b00383] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that expresses two unique forms of lipopolysaccharides (LPSs) on its bacterial surface, the A- and B-bands. The A-band polysaccharides (A-band PSs) are thought to be exported into the periplasm via a bicomponent ATP-binding cassette (ABC) transporter located within the inner membrane. This ABC protein complex consists of the transmembrane (TMD) Wzm and nucleotide-binding (NBD) Wzt domain proteins. Here, we were able to probe ∼1.36 nS-average conductance openings of the Wzm-based protein complex when reconstituted into a lipid membrane buffered by a 200 mM KCl solution, demonstrating the large-conductance, channel-forming ability of the TMDs. In agreement with this finding, transmission electron microscopy (TEM) imaging revealed the ring-shaped structure of the transmembrane Wzm protein complex. As hypothesized, using liposomes, we demonstrated that Wzm interacts with Wzt. Further, the Wzt polypeptide indeed hydrolyzed ATP but exhibited a ∼75% reduction in the ATPase activity when its Walker A domain was deleted. The distribution and average unitary conductance of the TMD Wzm protein complex were altered by the presence of the NBD Wzt protein, confirming the regulatory role of the latter polypeptide. To our knowledge, the large-conductance, channel-like activity of the Wzm protein complex, although often hypothesized, has not previously been demonstrated. These results constitute a platform for future structural, biophysical, and functional explorations of this bicomponent ABC transporter.
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Affiliation(s)
- Mohammad M. Mohammad
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
| | - Noriko Tomita
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Makoto Ohta
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
| | - Liviu Movileanu
- Department of Physics, Syracuse University, 201 Physics Building, Syracuse, New York 13244-1130, USA
- Structural Biology, Biochemistry, and Biophysics Program, Syracuse University, 111 College Place, Syracuse, New York 13244-4100, USA
- The Syracuse Biomaterials Institute, Syracuse University, 121 Link Hall, Syracuse, New York 13244, USA
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33
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Follador R, Heinz E, Wyres KL, Ellington MJ, Kowarik M, Holt KE, Thomson NR. The diversity of Klebsiella pneumoniae surface polysaccharides. Microb Genom 2016; 2:e000073. [PMID: 28348868 PMCID: PMC5320592 DOI: 10.1099/mgen.0.000073] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 06/09/2016] [Indexed: 11/24/2022] Open
Abstract
Klebsiella pneumoniae is considered an urgent health concern due to the emergence of multi-drug-resistant strains for which vaccination offers a potential remedy. Vaccines based on surface polysaccharides are highly promising but need to address the high diversity of surface-exposed polysaccharides, synthesized as O-antigens (lipopolysaccharide, LPS) and K-antigens (capsule polysaccharide, CPS), present in K. pneumoniae. We present a comprehensive and clinically relevant study of the diversity of O- and K-antigen biosynthesis gene clusters across a global collection of over 500 K. pneumoniae whole-genome sequences and the seroepidemiology of human isolates from different infection types. Our study defines the genetic diversity of O- and K-antigen biosynthesis cluster sequences across this collection, identifying sequences for known serotypes as well as identifying novel LPS and CPS gene clusters found in circulating contemporary isolates. Serotypes O1, O2 and O3 were most prevalent in our sample set, accounting for approximately 80 % of all infections. In contrast, K serotypes showed an order of magnitude higher diversity and differ among infection types. In addition we investigated a potential association of O or K serotypes with phylogenetic lineage, infection type and the presence of known virulence genes. K1 and K2 serotypes, which are associated with hypervirulent K. pneumoniae, were associated with a higher abundance of virulence genes and more diverse O serotypes compared to other common K serotypes.
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Affiliation(s)
| | - Eva Heinz
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Kelly L. Wyres
- Centre for Systems Genomics, University of Melbourne, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | | | | | - Kathryn E. Holt
- Centre for Systems Genomics, University of Melbourne, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Nicholas R. Thomson
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
- London School of Hygiene and Tropical Medicine, London, UK
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34
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Unique lipid anchor attaches Vi antigen capsule to the surface of Salmonella enterica serovar Typhi. Proc Natl Acad Sci U S A 2016; 113:6719-24. [PMID: 27226298 DOI: 10.1073/pnas.1524665113] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Polysaccharide capsules are surface structures that are critical for the virulence of many Gram-negative pathogenic bacteria. Salmonella enterica serovar Typhi is the etiological agent of typhoid fever. It produces a capsular polysaccharide known as "Vi antigen," which is composed of nonstoichiometrically O-acetylated α-1,4-linked N-acetylgalactosaminuronic acid residues. This glycan is a component of currently available vaccines. The genetic locus for Vi antigen production is also present in soil bacteria belonging to the genus Achromobacter Vi antigen assembly follows a widespread general strategy with a characteristic glycan export step involving an ATP-binding cassette transporter. However, Vi antigen producers lack the enzymes that build the conserved terminal glycolipid characterizing other capsules using this method. Achromobacter species possess a Vi antigen-specific depolymerase enzyme missing in S enterica Typhi, and we exploited this enzyme to isolate acylated Vi antigen termini. Mass spectrometry analysis revealed a reducing terminal N-acetylhexosamine residue modified with two β-hydroxyl acyl chains. This terminal structure resembles one half of lipid A, the hydrophobic portion of bacterial lipopolysaccharides. The VexE protein encoded in the Vi antigen biosynthesis locus shares similarity with LpxL, an acyltransferase from lipid A biosynthesis. In the absence of VexE, Vi antigen is produced, but its physical properties are altered, its export is impaired, and a Vi capsule structure is not assembled on the cell surface. The structure of the lipidated terminus dictates a unique assembly mechanism and has potential implications in pathogenesis and vaccine production.
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35
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Mann E, Mallette E, Clarke BR, Kimber MS, Whitfield C. The Klebsiella pneumoniae O12 ATP-binding Cassette (ABC) Transporter Recognizes the Terminal Residue of Its O-antigen Polysaccharide Substrate. J Biol Chem 2016; 291:9748-61. [PMID: 26934919 DOI: 10.1074/jbc.m116.719344] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Indexed: 11/06/2022] Open
Abstract
Export of the Escherichia coli serotype O9a O-antigenic polysaccharides (O-PS) involves an ATP-binding cassette (ABC) transporter. The process requires a non-reducing terminal residue, which is recognized by a carbohydrate-binding module (CBM) appended to the C terminus of the nucleotide-binding domain of the transporter. Here, we investigate the process in Klebsiella pneumoniae serotype O12 (and Raoultella terrigena ATCC 33257). The O12 polysaccharide is terminated at the non-reducing end by a β-linked 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) residue. The O12 ABC transporter also binds its cognate O-PS via a CBM, and export is dependent on the presence of the terminal β-Kdo residue. The overall structural architecture of the O12 CBM resembles the O9a prototype, but they share only weak sequence similarity, and the putative binding pocket for the O12 glycan is different. Removal of the CBM abrogated O-PS transport, but export was restored when the CBM was expressed in trans with the mutant CBM-deficient ABC transporter. These results demonstrate that the CBM-mediated substrate-recognition mechanism is evolutionarily conserved and can operate with glycans of widely differing structures.
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Affiliation(s)
- Evan Mann
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Evan Mallette
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Bradley R Clarke
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Matthew S Kimber
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Chris Whitfield
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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36
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Perez C, Gerber S, Boilevin J, Bucher M, Darbre T, Aebi M, Reymond JL, Locher KP. Structure and mechanism of an active lipid-linked oligosaccharide flippase. Nature 2015; 524:433-8. [PMID: 26266984 DOI: 10.1038/nature14953] [Citation(s) in RCA: 164] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 07/15/2015] [Indexed: 02/06/2023]
Abstract
The flipping of membrane-embedded lipids containing large, polar head groups is slow and energetically unfavourable, and is therefore catalysed by flippases, the mechanisms of which are unknown. A prominent example of a flipping reaction is the translocation of lipid-linked oligosaccharides that serve as donors in N-linked protein glycosylation. In Campylobacter jejuni, this process is catalysed by the ABC transporter PglK. Here we present a mechanism of PglK-catalysed lipid-linked oligosaccharide flipping based on crystal structures in distinct states, a newly devised in vitro flipping assay, and in vivo studies. PglK can adopt inward- and outward-facing conformations in vitro, but only outward-facing states are required for flipping. While the pyrophosphate-oligosaccharide head group of lipid-linked oligosaccharides enters the translocation cavity and interacts with positively charged side chains, the lipidic polyprenyl tail binds and activates the transporter but remains exposed to the lipid bilayer during the reaction. The proposed mechanism is distinct from the classical alternating-access model applied to other transporters.
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Affiliation(s)
- Camilo Perez
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Sabina Gerber
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Monika Bucher
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Markus Aebi
- Institute of Microbiology, ETH Zürich, CH-8093 Zürich, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland
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37
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The sweet tooth of bacteria: common themes in bacterial glycoconjugates. Microbiol Mol Biol Rev 2015; 78:372-417. [PMID: 25184559 DOI: 10.1128/mmbr.00007-14] [Citation(s) in RCA: 106] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Humans have been increasingly recognized as being superorganisms, living in close contact with a microbiota on all their mucosal surfaces. However, most studies on the human microbiota have focused on gaining comprehensive insights into the composition of the microbiota under different health conditions (e.g., enterotypes), while there is also a need for detailed knowledge of the different molecules that mediate interactions with the host. Glycoconjugates are an interesting class of molecules for detailed studies, as they form a strain-specific barcode on the surface of bacteria, mediating specific interactions with the host. Strikingly, most glycoconjugates are synthesized by similar biosynthesis mechanisms. Bacteria can produce their major glycoconjugates by using a sequential or an en bloc mechanism, with both mechanistic options coexisting in many species for different macromolecules. In this review, these common themes are conceptualized and illustrated for all major classes of known bacterial glycoconjugates, with a special focus on the rather recently emergent field of glycosylated proteins. We describe the biosynthesis and importance of glycoconjugates in both pathogenic and beneficial bacteria and in both Gram-positive and -negative organisms. The focus lies on microorganisms important for human physiology. In addition, the potential for a better knowledge of bacterial glycoconjugates in the emerging field of glycoengineering and other perspectives is discussed.
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Zhang H, Rahman S, Li W, Fu G, Kaur P. Characterization of a novel domain 'GATE' in the ABC protein DrrA and its role in drug efflux by the DrrAB complex. Biochem Biophys Res Commun 2015; 459:148-53. [PMID: 25721665 DOI: 10.1016/j.bbrc.2015.02.086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 02/13/2015] [Indexed: 12/27/2022]
Abstract
A novel domain, GATE (Glycine-loop And Transducer Element), is identified in the ABC protein DrrA. This domain shows sequence and structural conservation among close homologs of DrrA as well as distantly-related ABC proteins. Among the highly conserved residues in this domain are three glycines, G215, G221 and G231, of which G215 was found to be critical for stable expression of the DrrAB complex. Other conserved residues, including E201, G221, K227 and G231, were found to be critical for the catalytic and transport functions of the DrrAB transporter. Structural analysis of both the previously published crystal structure of the DrrA homolog MalK and the modeled structure of DrrA showed that G215 makes close contacts with residues in and around the Walker A motif, suggesting that these interactions may be critical for maintaining the integrity of the ATP binding pocket as well as the complex. It is also shown that G215A or K227R mutation diminishes some of the atomic interactions essential for ATP catalysis and overall transport function. Therefore, based on both the biochemical and structural analyses, it is proposed that the GATE domain, located outside of the previously identified ATP binding and hydrolysis motifs, is an additional element involved in ATP catalysis.
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Affiliation(s)
- Han Zhang
- Department of Biology, Georgia State University, Atlanta, GA, 30303, USA
| | - Sadia Rahman
- Department of Biology, Georgia State University, Atlanta, GA, 30303, USA
| | - Wen Li
- Department of Biology, Georgia State University, Atlanta, GA, 30303, USA
| | - Guoxing Fu
- Department of Biology, Georgia State University, Atlanta, GA, 30303, USA
| | - Parjit Kaur
- Department of Biology, Georgia State University, Atlanta, GA, 30303, USA.
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Hagelueken G, Clarke BR, Huang H, Tuukkanen A, Danciu I, Svergun DI, Hussain R, Liu H, Whitfield C, Naismith JH. A coiled-coil domain acts as a molecular ruler to regulate O-antigen chain length in lipopolysaccharide. Nat Struct Mol Biol 2015; 22:50-56. [PMID: 25504321 PMCID: PMC4650267 DOI: 10.1038/nsmb.2935] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 11/20/2014] [Indexed: 11/22/2022]
Abstract
Long-chain bacterial polysaccharides have important roles in pathogenicity. In Escherichia coli O9a, a model for ABC transporter-dependent polysaccharide assembly, a large extracellular carbohydrate with a narrow size distribution is polymerized from monosaccharides by a complex of two proteins, WbdA (polymerase) and WbdD (terminating protein). Combining crystallography and small-angle X-ray scattering, we found that the C-terminal domain of WbdD contains an extended coiled-coil that physically separates WbdA from the catalytic domain of WbdD. The effects of insertions and deletions in the coiled-coil region were analyzed in vivo, revealing that polymer size is controlled by varying the length of the coiled-coil domain. Thus, the coiled-coil domain of WbdD functions as a molecular ruler that, along with WbdA:WbdD stoichiometry, controls the chain length of a model bacterial polysaccharide.
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Affiliation(s)
- Gregor Hagelueken
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Bradley R. Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Hexian Huang
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - Anne Tuukkanen
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestraße 85, 22603 Hamburg, Germany
| | - Iulia Danciu
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestraße 85, 22603 Hamburg, Germany
| | - Dmitri I. Svergun
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestraße 85, 22603 Hamburg, Germany
| | | | - Huanting Liu
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - James H. Naismith
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
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40
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Cooper CA, Mainprize IL, Nickerson NN. Genetic, Biochemical, and Structural Analyses of Bacterial Surface Polysaccharides. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 883:295-315. [PMID: 26621474 DOI: 10.1007/978-3-319-23603-2_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Surface polysaccharides are an often essential component of the outer surface of bacteria. They may serve to protect organisms from harsh environmental conditions and to increase virulence. The focus of this review will be to introduce polysaccharide biosynthesis and export from the cell, and the associated techniques used to determine these glycostructures. Protein interactions and proteomics will then be discussed while introducing systems biology approaches used to determine protein-protein and protein-polysaccharide interactions. The final section will address related screening methods used to study gene regulation in bacteria relating to polysaccharide gene clusters and their associated regulators. The goal of this review will be to highlight key studies that have increased our knowledge of glycobiology and discuss novel methods that examine this field at the cellular level using systems biology.
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Affiliation(s)
- Colin A Cooper
- Agriculture and Food Laboratory, Laboratory Services, University of Guelph, 95 Stone Rd. W., Guelph, ON, N1H 8J7, Canada.
| | - Iain L Mainprize
- Department of Molecular and Cellular Biology, University of Guelph, 95 Stone Road, Guelph, ON, N1H 8J7, Canada
| | - Nicholas N Nickerson
- Department of Molecular and Cellular Biology, University of Guelph, 95 Stone Road, Guelph, ON, N1H 8J7, Canada.,Department of Infectious Diseases, Genentech Inc., South San Francisco, CA, 94080, USA
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41
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Liston SD, Clarke BR, Greenfield LK, Richards MR, Lowary TL, Whitfield C. Domain interactions control complex formation and polymerase specificity in the biosynthesis of the Escherichia coli O9a antigen. J Biol Chem 2014; 290:1075-85. [PMID: 25422321 DOI: 10.1074/jbc.m114.622480] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli O9a O-polysaccharide (O-PS) is a prototype for bacterial glycan synthesis and export by an ATP-binding cassette transporter-dependent pathway. The O9a O-PS possesses a tetrasaccharide repeat unit comprising two α-(1→2)- and two α-(1→3)-linked mannose residues and is extended on a polyisoprenoid lipid carrier by the action of a polymerase (WbdA) containing two glycosyltransferase active sites. The N-terminal domain of WbdA possesses α-(1→2)-mannosyltransferase activity, and we demonstrate in this study that the C-terminal domain is an α-(1→3)-mannosyltransferase. Previous studies established that the size of the O9a polysaccharide is determined by the chain-terminating dual kinase/methyltransferase (WbdD) that is tethered to the membrane and recruits WbdA into an active enzyme complex by protein-protein interactions. Here, we used bacterial two-hybrid analysis to identify a surface-exposed α-helix in the C-terminal mannosyltransferase domain of WbdA as the site of interaction with WbdD. However, the C-terminal domain was unable to interact with WbdD in the absence of its N-terminal partner. Through deletion analysis, we demonstrated that the α-(1→2)-mannosyltransferase activity of the N-terminal domain is regulated by the activity of the C-terminal α-(1→3)-mannosyltransferase. In mutants where the C-terminal catalytic site was deleted but the WbdD-interaction site remained, the N-terminal mannosyltransferase became an unrestricted polymerase, creating a novel polymer comprising only α-(1→2)-linked mannose residues. The WbdD protein therefore orchestrates critical localization and coordination of activities involved in chain extension and termination. Complex domain interactions are needed to position the polymerase components appropriately for assembly into a functional complex located at the cytoplasmic membrane.
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Affiliation(s)
- Sean D Liston
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1 and
| | - Bradley R Clarke
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1 and
| | - Laura K Greenfield
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1 and
| | - Michele R Richards
- the Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Todd L Lowary
- the Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Chris Whitfield
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1 and
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42
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Abstract
Prokaryotic glycosylation fulfills an important role in maintaining and protecting the structural integrity and function of the bacterial cell wall, as well as serving as a flexible adaption mechanism to evade environmental and host-induced pressure. The scope of bacterial and archaeal protein glycosylation has considerably expanded over the past decade(s), with numerous examples covering the glycosylation of flagella, pili, glycosylated enzymes, as well as surface-layer proteins. This article addresses structure, analysis, function, genetic basis, biosynthesis, and biomedical and biotechnological applications of cell-envelope glycoconjugates, S-layer glycoprotein glycans, and "nonclassical" secondary-cell wall polysaccharides. The latter group of polymers mediates the important attachment and regular orientation of the S-layer to the cell wall. The structures of these glycopolymers reveal an enormous diversity, resembling the structural variability of bacterial lipopolysaccharides and capsular polysaccharides. While most examples are presented for Gram-positive bacteria, the S-layer glycan of the Gram-negative pathogen Tannerella forsythia is also discussed. In addition, archaeal S-layer glycoproteins are briefly summarized.
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Affiliation(s)
- Paul Messner
- Department of NanoBiotechnology, NanoGlycobiology Unit, University of Natural Resources and Life Sciences, Vienna, Austria
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43
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ABC Transporters Involved in the Biogenesis of the Outer Membrane in Gram-Negative Bacteria. Biosci Biotechnol Biochem 2014; 75:1044-54. [DOI: 10.1271/bbb.110115] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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44
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Lipopolysaccharide O antigen size distribution is determined by a chain extension complex of variable stoichiometry in Escherichia coli O9a. Proc Natl Acad Sci U S A 2014; 111:6407-12. [PMID: 24733938 DOI: 10.1073/pnas.1400814111] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The lengths of bacterial polysaccharides can be critical for their biological function. Unlike DNA or protein synthesis, where polymer length is implicit in the nucleic acid template, the molecular mechanisms for regulating polysaccharide length are poorly understood. Two models are commonly cited: a "molecular clock" regulates length by controlling the duration of the polymer extension process, whereas a "molecular ruler" determines length by measurement against a physical structure in the biosynthetic complex. Escherichia coli O9a is a prototype for the biosynthesis of O polysaccharides by ATP-binding cassette transporter-dependent processes. The length of the O9a polysaccharide is determined by two proteins: an extension enzyme, WbdA, and a termination enzyme, WbdD. WbdD is known to self-oligomerize and also to interact with WbdA. Changing either enzyme's concentration can alter the polysaccharide length. We quantified the O9a polysaccharide length distribution and the enzyme concentration dependence in vivo, then made mathematical models to predict the polymer length distributions resulting from hypothetical length-regulation mechanisms. Our data show qualitative features that cannot be explained by either a molecular clock or a molecular ruler model. Therefore, we propose a "variable geometry" model, in which a postulated biosynthetic WbdA-WbdD complex assembles with variable stoichiometry dependent on relative enzyme concentration. Each stoichiometry produces polymers with a distinct, geometrically determined, modal length. This model reproduces the enzyme concentration dependence and modality of the observed polysaccharide length distributions. Our work highlights limitations of previous models and provides new insight into the mechanisms of length control in polysaccharide biosynthesis.
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45
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Yan S, Wang N, Chen Z, Wang Y, He N, Peng Y, Li Q, Deng X. Genes encoding the production of extracellular polysaccharide bioflocculant are clustered on a 30-kb DNA segment in Bacillus licheniformis. Funct Integr Genomics 2013; 13:425-34. [DOI: 10.1007/s10142-013-0333-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 07/18/2013] [Accepted: 08/12/2013] [Indexed: 10/26/2022]
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46
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Singh DR, Mohammad MM, Patowary S, Stoneman MR, Oliver JA, Movileanu L, Raicu V. Determination of the quaternary structure of a bacterial ATP-binding cassette (ABC) transporter in living cells. Integr Biol (Camb) 2013; 5:312-23. [PMID: 23223798 DOI: 10.1039/c2ib20218b] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pseudomonas aeruginosa is a pathogenic Gram-negative bacterium that affects patients with cystic fibrosis and immunocompromised individuals. This bacterium coexpresses two unique forms of lipopolysaccharides (LPSs) on its surface, the A- and B-band LPS, which are among the main virulence factors that contribute to its pathogenicity. The polysaccharides in A-band LPSs are synthesized in the cytoplasm and translocated into the periplasm via an ATP-binding cassette (ABC) transporter consisting of a transmembrane protein, Wzm, and a cytoplasmic nucleotide-binding protein, Wzt. Most of the biochemical studies of A-band PSs in Pseudomonas aeruginosa are focused on the stages of the synthesis and ligation of PS, leaving the export stage involving the ABC transporter mostly unexplored. This difficulty is compounded by the fact that the subunit composition and structure of this bi-component ABC transporter are still unknown. Here we propose a simple but powerful method, based on Förster Resonance Energy Transfer (FRET) and optical micro-spectroscopy technology, to probe the structure of dynamic (as opposed to static) protein complexes in living cells. We use this method to determine the association stoichiometry and quaternary structure of the Wzm-Wzt complex in living cells. It is found that Wzt forms a rhombus-shaped homo-tetramer which becomes a square upon co-expression with Wzm, and that Wzm forms a square-shaped homo-tetramer both in the presence and absence of Wzt. Based on these results, we propose a structural model for the double-tetramer complex formed by the bi-component ABC transporter in living cells. An understanding of the structure and behavior of this ABC transporter will help develop antibiotics targeting the biosynthesis of the A-band LPS endotoxin.
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Affiliation(s)
- Deo R Singh
- Physics Department, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
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47
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Bodelón G, Palomino C, Fernández LÁ. Immunoglobulin domains inEscherichia coliand other enterobacteria: from pathogenesis to applications in antibody technologies. FEMS Microbiol Rev 2013; 37:204-50. [DOI: 10.1111/j.1574-6976.2012.00347.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 06/07/2012] [Accepted: 06/14/2012] [Indexed: 11/28/2022] Open
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48
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Five new genes are important for common polysaccharide antigen biosynthesis in Pseudomonas aeruginosa. mBio 2013; 4:e00631-12. [PMID: 23341552 PMCID: PMC3560663 DOI: 10.1128/mbio.00631-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Common polysaccharide antigen (CPA) is a conserved cell surface polysaccharide produced by Pseudomonas aeruginosa. It contains a rhamnan homopolymer and is one of the two forms of O polysaccharide attached to P. aeruginosa lipopolysaccharide (LPS). Our laboratory has previously characterized an eight-gene cluster (pa5447-pa5454 in P. aeruginosa PAO1) required for biosynthesis of CPA. Here we demonstrate that an adjacent five-gene cluster pa5455-pa5459 is also involved. Using reverse transcriptase PCR (RT-PCR), we showed that the original eight-gene cluster and the new five-gene cluster are both organized as operons. We have analyzed the LPS phenotypes of in-frame deletion mutants made in each of the five genes, and the results verified that these five genes are indeed required for CPA biosynthesis, extending the CPA biosynthesis locus to contain 13 contiguous genes. By performing overexpression experiments of different sets of these biosynthesis genes, we were able to obtain information about their possible functions in CPA biosynthesis. Lipopolysaccharide (LPS) is an important cell surface structure of Gram-negative bacteria. The human opportunistic pathogen Pseudomonas aeruginosa simultaneously produces an O-antigen-specific (OSA) form and a common polysaccharide antigen (CPA) form of LPS. CPA, the focus of this study, is composed of α-1-2, α1-3-linked d-rhamnose sugars and has been shown to be important for attachment of the bacteria to human airway epithelial cells. Genome sequencing of this species revealed a new five-gene cluster that we predicted to be involved in CPA biosynthesis and modification. In this study, we have generated chromosomal knockouts by performing in-frame deletions and allelic replacements. Characterizing the function of each of the five genes is important for us to better understand CPA biosynthesis and the mechanisms of chain length termination and regulation of this unique D-rhamnan polysaccharide.
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49
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Greenfield LK, Richards MR, Vinogradov E, Wakarchuk WW, Lowary TL, Whitfield C. Domain organization of the polymerizing mannosyltransferases involved in synthesis of the Escherichia coli O8 and O9a lipopolysaccharide O-antigens. J Biol Chem 2012; 287:38135-49. [PMID: 22989876 PMCID: PMC3488083 DOI: 10.1074/jbc.m112.412577] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 09/16/2012] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli O9a and O8 polymannose O-polysaccharides (O-PSs) serve as model systems for the biosynthesis of bacterial polysaccharides by ATP-binding cassette transporter-dependent pathways. Both O-PSs contain a conserved primer-adaptor domain at the reducing terminus and a serotype-specific repeat unit domain. The repeat unit domain is polymerized by the serotype-specific WbdA mannosyltransferase. In serotype O9a, WbdA is a bifunctional α-(1→2)-, α-(1→3)-mannosyltransferase, and its counterpart in serotype O8 is trifunctional (α-(1→2), α-(1→3), and β-(1→2)). Little is known about the detailed structures or mechanisms of action of the WbdA polymerases, and here we establish that they are multidomain enzymes. WbdA(O9a) contains two separable and functionally active domains, whereas WbdA(O8) possesses three. In WbdC(O9a) and WbdB(O9a), substitution of the first Glu of the EX(7)E motif had detrimental effects on the enzyme activity, whereas substitution of the second had no significant effect on activity in vivo. Mutation of the Glu residues in the EX(7)E motif of the N-terminal WbdA(O9a) domain resulted in WbdA variants unable to synthesize O-PS. In contrast, mutation of the Glu residues in the motif of the C-terminal WbdA(O9a) domain generated an enzyme capable of synthesizing an altered O-PS repeat unit consisting of only α-(1→2) linkages. In vitro assays with synthetic acceptors unequivocally confirmed that the N-terminal domain of WbdA(O9a) possesses α-(1→2)-mannosyltransferase activity. Together, these studies form a framework for detailed structure-function studies on individual domains and a strategy applicable for dissection and analysis of other multidomain glycosyltransferases.
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Affiliation(s)
- Laura K. Greenfield
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1
| | - Michele R. Richards
- the Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, and
| | - Evgeny Vinogradov
- the Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Warren W. Wakarchuk
- the Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Todd L. Lowary
- the Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, and
| | - Chris Whitfield
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1
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50
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Hagelueken G, Huang H, Clarke BR, Lebl T, Whitfield C, Naismith JH. Structure of WbdD: a bifunctional kinase and methyltransferase that regulates the chain length of the O antigen in Escherichia coli O9a. Mol Microbiol 2012; 86:730-42. [PMID: 22970759 PMCID: PMC3482155 DOI: 10.1111/mmi.12014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2012] [Indexed: 02/05/2023]
Abstract
The Escherichia coli serotype O9a O-antigen polysaccharide (O-PS) is a model for glycan biosynthesis and export by the ATP-binding cassette transporter-dependent pathway. The polymannose O9a O-PS is synthesized as a polyprenol-linked glycan by mannosyltransferase enzymes located at the cytoplasmic membrane. The chain length of the O9a O-PS is tightly regulated by the WbdD enzyme. WbdD first phosphorylates the terminal non-reducing mannose of the O-PS and then methylates the phosphate, stopping polymerization. The 2.2 Å resolution structure of WbdD reveals a bacterial methyltransferase domain joined to a eukaryotic kinase domain. The kinase domain is again fused to an extended C-terminal coiled-coil domain reminiscent of eukaryotic DMPK (Myotonic Dystrophy Protein Kinase) family kinases such as Rho-associated protein kinase (ROCK). WbdD phosphorylates 2-α-d-mannosyl-d-mannose (2α-MB), a short mimic of the O9a polymer. Mutagenesis identifies those residues important in catalysis and substrate recognition and the in vivo phenotypes of these mutants are used to dissect the termination reaction. We have determined the structures of co-complexes of WbdD with two known eukaryotic protein kinase inhibitors. Although these are potent inhibitors in vitro, they do not show any in vivo activity. The structures reveal new insight into O-PS chain-length regulation in this important model system.
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Affiliation(s)
- Gregor Hagelueken
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
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