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Hu S, Zhou S, Wang Y, Chen W, Yin G, Chen J, Du G, Kang Z. Coordinated optimization of the polymerization and transportation processes to enhance the yield of exopolysaccharide heparosan. Carbohydr Polym 2024; 333:121983. [PMID: 38494235 DOI: 10.1016/j.carbpol.2024.121983] [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: 12/18/2023] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/19/2024]
Abstract
Heparosan as the precursor for heparin biosynthesis has attracted intensive attention while Escherichia coli Nissle 1917 (EcN) has been applied as a chassis for heparosan biosynthesis. Here, after uncovering the pivotal role of KfiB in heparosan biosynthesis, we further demonstrate KfiB is involved in facilitating KpsT to translocate the nascent heparosan polysaccharide chain. As a result, an artificial expression cassette KfiACB was constructed with optimized RBS elements, resulting in 0.77 g/L heparosan in shake flask culture. Moreover, in view of the intracellular accumulation of heparosan, we further investigated the effects of overexpression of the ABC transport system proteins on heparosan biosynthesis. By co-overexpressing KfiACB with KpsTME, the heparosan production in flask cultures was increased to 1.03 g/L with an extracellular concentration of 0.96 g/L. Eventually, the engineered strain EcN/pET-kfiACB3-galU-kfiD-glmM/pCDF-kpsTME produced 12.2 g/L heparosan in 5-L fed-batch cultures while the extracellular heparosan was about 11.2 g/L. The results demonstrate the high-efficiency of the strategy for co-optimizing the polymerization and transportation for heparosan biosynthesis. Moreover, this strategy should be also available for enhancing the production of other polysaccharides.
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Affiliation(s)
- Shan Hu
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; The Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Siyan Zhou
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; The Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Yang Wang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; The Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Wuxia Chen
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; The Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Guobin Yin
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; The Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Jian Chen
- The Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Guocheng Du
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; The Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Zhen Kang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; The Science Center for Future Foods, Jiangnan University, Wuxi 214122, China.
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Sheng LL, Cai YM, Li Y, Huang SL, Sheng JZ. Advancements in heparosan production through metabolic engineering and improved fermentation. Carbohydr Polym 2024; 331:121881. [PMID: 38388039 DOI: 10.1016/j.carbpol.2024.121881] [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: 11/26/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024]
Abstract
Heparin is one of the most widely used natural drugs, and has been the preferred anticoagulant and antithrombotic agent in the clinical setting for nearly a century. Heparin also shows increasing therapeutic potential for treating inflammation, cancer, and microbial and viral diseases, including COVID-19. With advancements in synthetic biology, heparin production through microbial engineering of heparosan offers a cost-effective and scalable alternative to traditional extraction from animal tissues. Heparosan serves as the starting carbon backbone for the chemoenzymatic synthesis of bioengineered heparin, possessing a chain length that is critically important for the production of heparin-based therapeutics with specific molecular weight (MW) distributions. Recent advancements in metabolic engineering of microbial cell factories have resulted in high-yield heparosan production. This review systematically analyzes the key modules involved in microbial heparosan biosynthesis and the latest metabolic engineering strategies for enhancing production, regulating MW, and optimizing the fermentation scale-up of heparosan. It also discusses future studies, remaining challenges, and prospects in the field.
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Affiliation(s)
- Li-Li Sheng
- Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Yi-Min Cai
- Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Yi Li
- Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China
| | - Si-Ling Huang
- Bloomage BioTechnology Corp., Ltd., Jinan 250010, China
| | - Ju-Zheng Sheng
- Key Laboratory of Chemical Biology of Natural Products, Ministry of Education, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan 250012, China; The State Key Laboratory of Microbial Technology, Shandong University, Qingdao 250100, China.
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Pang M, Tu T, Wang Y, Zhang P, Ren M, Yao X, Luo Y, Yang Z. Design of a multi-epitope vaccine against Haemophilus parasuis based on pan-genome and immunoinformatics approaches. Front Vet Sci 2022; 9:1053198. [PMID: 36644533 PMCID: PMC9835091 DOI: 10.3389/fvets.2022.1053198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Accepted: 11/30/2022] [Indexed: 12/30/2022] Open
Abstract
Background Glässer's disease, caused by Haemophilus parasuis (HPS), is responsible for economic losses in the pig industry worldwide. However, the existing commercial vaccines offer poor protection and there are significant barriers to the development of effective vaccines. Methods In the current study, we aimed to identify potential vaccine candidates and design a multi-epitope vaccine against HPS by performing pan-genomic analysis of 121 strains and using a reverse vaccinology approach. Results The designed vaccine constructs consist of predicted epitopes of B and T cells derived from the outer membrane proteins of the HPS core genome. The vaccine was found to be highly immunogenic, non-toxic, and non-allergenic as well as have stable physicochemical properties. It has a high binding affinity to Toll-like receptor 2. In addition, in silico immune simulation results showed that the vaccine elicited an effective immune response. Moreover, the mouse polyclonal antibody obtained by immunizing the vaccine protein can be combined with different serotypes and non-typable Haemophilus parasuis in vitro. Conclusion The overall results of the study suggest that the designed multi-epitope vaccine is a promising candidate for pan-prophylaxis against different strains of HPS.
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Affiliation(s)
- Maonan Pang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Chengdu, Sichuan, China
| | - Teng Tu
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Chengdu, Sichuan, China
| | - Yin Wang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Chengdu, Sichuan, China,*Correspondence: Yin Wang
| | - Pengfei Zhang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Chengdu, Sichuan, China
| | - Meishen Ren
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Chengdu, Sichuan, China
| | - Xueping Yao
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Chengdu, Sichuan, China
| | - Yan Luo
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Chengdu, Sichuan, China
| | - Zexiao Yang
- College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China,Key Laboratory of Animal Diseases and Human Health of Sichuan Province, Chengdu, Sichuan, China
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Saïdi F, Mahanta U, Panda A, Kezzo AA, Jolivet NY, Bitazar R, John G, Martinez M, Mellouk A, Calmettes C, Chang YW, Sharma G, Islam ST. Bacterial Outer Membrane Polysaccharide Export (OPX) Proteins Occupy Three Structural Classes with Selective β-Barrel Porin Requirements for Polymer Secretion. Microbiol Spectr 2022; 10:e0129022. [PMID: 36200915 PMCID: PMC9603273 DOI: 10.1128/spectrum.01290-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 09/08/2022] [Indexed: 12/30/2022] Open
Abstract
Secretion of high-molecular-weight polysaccharides across the bacterial envelope is ubiquitous, as it enhances prokaryotic survival in (a)biotic settings. Such polymers are often assembled by Wzx/Wzy- or ABC transporter-dependent schemes implicating outer membrane (OM) polysaccharide export (OPX) proteins in cell-surface polymer translocation. In the social predatory bacterium Myxococcus xanthus, the exopolysaccharide (EPS) pathway WzaX, major spore coat (MASC) pathway WzaS, and biosurfactant polysaccharide (BPS) pathway WzaB were herein found to be truncated OPX homologues of Escherichia coli Wza lacking OM-spanning α-helices. Comparative genomics across all bacteria (>91,000 OPX proteins identified and analyzed), complemented with cryo-electron tomography cell-envelope analyses, revealed such "truncated" WzaX/S/B architecture to be the most common among three defined OPX-protein structural classes independent of periplasm thickness. Fold recognition and deep learning revealed the conserved M. xanthus proteins MXAN_7418/3226/1916 (encoded beside wzaX/S/B, respectively) to be integral OM β-barrels, with structural homology to the poly-N-acetyl-d-glucosamine synthase-dependent pathway porin PgaA. Such bacterial porins were identified near numerous genes for all three OPX protein classes. Interior MXAN_7418/3226/1916 β-barrel electrostatics were found to match properties of their associated polymers. With MXAN_3226 essential for MASC export, and MXAN_7418 herein shown to mediate EPS translocation, we have designated this new secretion machinery component "Wzp" (i.e., Wz porin), with the final step of M. xanthus EPS/MASC/BPS secretion across the OM now proposed to be mediated by WzpX/S/B (i.e., MXAN_7418/3226/1916). Importantly, these data support a novel and widespread secretion paradigm for polysaccharide biosynthesis pathways in which those containing OPX components that cannot span the OM instead utilize β-barrel porins to mediate polysaccharide transport across the OM. IMPORTANCE Diverse bacteria assemble and secrete polysaccharides that alter their physiologies through modulation of motility, biofilm formation, and host immune system evasion. Most such pathways require outer membrane (OM) polysaccharide export (OPX) proteins for sugar-polymer transport to the cell surface. In the prototypic Escherichia coli Group-1-capsule biosynthesis system, eight copies of this canonical OPX protein cross the OM with an α-helix, forming a polysaccharide-export pore. Herein, we instead reveal that most OPX proteins across all bacteria lack this α-helix, raising questions as to the manner by which most secreted polysaccharides actually exit cells. In the model developmental bacterium Myxococcus xanthus, we show this process to depend on OPX-coupled OM-spanning β-barrel porins, with similar porins encoded near numerous OPX genes in diverse bacteria. Knowledge of the terminal polysaccharide secretion step will enable development of antimicrobial compounds targeted to blocking polymer export from outside the cell, thus bypassing any requirements for antimicrobial compound uptake by the cell.
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Affiliation(s)
- Fares Saïdi
- Institut National de la Recherche Scientifique (INRS), Centre Armand-Frappier Santé Biotechnologie, Université du Québec, Institut Pasteur International Network, Laval, Quebec, Canada
- PROTEO, the Quebec Network for Research on Protein Function, Engineering, and Applications, Université Laval, Québec, Quebec, Canada
| | - Utkarsha Mahanta
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bengaluru, Karnataka, India
| | - Adyasha Panda
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bengaluru, Karnataka, India
| | - Ahmad A. Kezzo
- Institut National de la Recherche Scientifique (INRS), Centre Armand-Frappier Santé Biotechnologie, Université du Québec, Institut Pasteur International Network, Laval, Quebec, Canada
- PROTEO, the Quebec Network for Research on Protein Function, Engineering, and Applications, Université Laval, Québec, Quebec, Canada
| | - Nicolas Y. Jolivet
- Institut National de la Recherche Scientifique (INRS), Centre Armand-Frappier Santé Biotechnologie, Université du Québec, Institut Pasteur International Network, Laval, Quebec, Canada
- PROTEO, the Quebec Network for Research on Protein Function, Engineering, and Applications, Université Laval, Québec, Quebec, Canada
| | - Razieh Bitazar
- Institut National de la Recherche Scientifique (INRS), Centre Armand-Frappier Santé Biotechnologie, Université du Québec, Institut Pasteur International Network, Laval, Quebec, Canada
- PROTEO, the Quebec Network for Research on Protein Function, Engineering, and Applications, Université Laval, Québec, Quebec, Canada
| | - Gavin John
- Department of Pediatrics, Division of Infectious Diseases, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Matthew Martinez
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Abdelkader Mellouk
- Institut National de la Recherche Scientifique (INRS), Centre Armand-Frappier Santé Biotechnologie, Université du Québec, Institut Pasteur International Network, Laval, Quebec, Canada
- PROTEO, the Quebec Network for Research on Protein Function, Engineering, and Applications, Université Laval, Québec, Quebec, Canada
| | - Charles Calmettes
- Institut National de la Recherche Scientifique (INRS), Centre Armand-Frappier Santé Biotechnologie, Université du Québec, Institut Pasteur International Network, Laval, Quebec, Canada
- PROTEO, the Quebec Network for Research on Protein Function, Engineering, and Applications, Université Laval, Québec, Quebec, Canada
| | - Yi-Wei Chang
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Gaurav Sharma
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bengaluru, Karnataka, India
| | - Salim T. Islam
- Institut National de la Recherche Scientifique (INRS), Centre Armand-Frappier Santé Biotechnologie, Université du Québec, Institut Pasteur International Network, Laval, Quebec, Canada
- PROTEO, the Quebec Network for Research on Protein Function, Engineering, and Applications, Université Laval, Québec, Quebec, Canada
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Structural and Functional Variation in Outer Membrane Polysaccharide Export (OPX) Proteins from the Two Major Capsule Assembly Pathways Present in Escherichia coli. J Bacteriol 2019; 201:JB.00213-19. [PMID: 31036729 DOI: 10.1128/jb.00213-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 04/26/2019] [Indexed: 11/20/2022] Open
Abstract
Capsular polysaccharides (CPSs) are virulence factors for many important pathogens. In Escherichia coli, CPSs are synthesized via two distinct pathways, but both require proteins from the outer membrane polysaccharide export (OPX) family to complete CPS export from the periplasm to the cell surface. In this study, we compare the properties of the OPX proteins from the prototypical group 1 (Wzy-dependent) and group 2 (ABC transporter-dependent) pathways in E. coli K30 (Wza) and E. coli K2 (KpsD), respectively. In addition, we compare an OPX from Salmonella enterica serovar Typhi (VexA), which shares structural properties with Wza, while operating in an ABC transporter-dependent pathway. These proteins differ in distribution in the cell envelope and formation of stable multimers, but these properties do not align with acylation or the interfacing biosynthetic pathway. In E. coli K2, murein lipoprotein (Lpp) plays a role in peptidoglycan association of KpsD, and loss of this interaction correlates with impaired group 2 capsule production. VexA also depends on Lpp for peptidoglycan association, but CPS production is unaffected in an lpp mutant. In contrast, Wza and group 1 capsule production is unaffected by the absence of Lpp. These results point to complex structure-function relationships between different OPX proteins.IMPORTANCE Capsules are protective layers of polysaccharides that surround the cell surface of many bacteria, including that of Escherichia coli isolates and Salmonella enterica serovar Typhi. Capsular polysaccharides (CPSs) are often essential for virulence because they facilitate evasion of host immune responses. The attenuation of unencapsulated mutants in animal models and the involvement of protein families with conserved features make the CPS export pathway a novel candidate for therapeutic strategies. However, appropriate "antivirulence" strategies require a fundamental understanding of the underpinning cellular processes. Investigating export proteins that are conserved across different biosynthesis strategies will give important insight into how CPS is transported to the cell surface.
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Peptidoglycan Association of Murein Lipoprotein Is Required for KpsD-Dependent Group 2 Capsular Polysaccharide Expression and Serum Resistance in a Uropathogenic Escherichia coli Isolate. mBio 2017; 8:mBio.00603-17. [PMID: 28536290 PMCID: PMC5442458 DOI: 10.1128/mbio.00603-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Murein lipoprotein (Lpp) and peptidoglycan-associated lipoprotein (Pal) are major outer membrane lipoproteins in Escherichia coli. Their roles in cell-envelope integrity have been documented in E. coli laboratory strains, and while Lpp has been linked to serum resistance in vitro, the underlying mechanism has not been established. Here, lpp and pal mutants of uropathogenic E. coli strain CFT073 showed reduced survival in a mouse bacteremia model, but only the lpp mutant was sensitive to serum killing in vitro. The peptidoglycan-bound Lpp form was specifically required for preventing complement-mediated bacterial lysis in vitro and complement-mediated clearance in vivo. Compared to the wild-type strain, the lpp mutant had impaired K2 capsular polysaccharide production and was unable to respond to exposure to serum by elevating capsular polysaccharide amounts. These properties correlated with altered cellular distribution of KpsD, the predicted outer membrane translocon for “group 2” capsular polysaccharides. We identified a novel Lpp-dependent association between functional KpsD and peptidoglycan, highlighting important interplay between cell envelope components required for resistance to complement-mediated lysis in uropathogenic E. coli isolates. Uropathogenic E. coli (UPEC) isolates represent a significant cause of nosocomial urinary tract and bloodstream infections. Many UPEC isolates are resistant to serum killing. Here, we show that a major cell-envelope lipoprotein (murein lipoprotein) is required for serum resistance in vitro and for complement-mediated bacterial clearance in vivo. This is mediated, in part, through a novel mechanism by which murein lipoprotein affects the proper assembly of a key component of the machinery involved in production of “group 2” capsules. The absence of murein lipoprotein results in impaired production of the capsule layer, a known participant in complement resistance. These results demonstrate an important role for murein lipoprotein in complex interactions between different outer membrane biogenesis pathways and further highlight the importance of lipoprotein assembly and transport in bacterial pathogenesis.
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Schmid J, Sieber V. Enzymatic Transformations Involved in the Biosynthesis of Microbial Exo-polysaccharides Based on the Assembly of Repeat Units. Chembiochem 2015; 16:1141-7. [DOI: 10.1002/cbic.201500035] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Indexed: 12/12/2022]
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Topology of Streptococcus pneumoniae CpsC, a polysaccharide copolymerase and bacterial protein tyrosine kinase adaptor protein. J Bacteriol 2014; 197:120-7. [PMID: 25313397 DOI: 10.1128/jb.02106-14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Gram-positive bacteria, tyrosine kinases are split into two proteins, the cytoplasmic tyrosine kinase and a transmembrane adaptor protein. In Streptococcus pneumoniae, this transmembrane adaptor is CpsC, with the C terminus of CpsC critical for interaction and subsequent tyrosine kinase activity of CpsD. Topology predictions suggest that CpsC has two transmembrane domains, with the N and C termini present in the cytoplasm. In order to investigate CpsC topology, we used a chromosomal hemagglutinin (HA)-tagged Cps2C protein in S. pneumoniae strain D39. Incubation of both protoplasts and membranes with carboxypeptidase B (CP-B) resulted in complete degradation of HA-Cps2C in all cases, indicating that the C terminus of Cps2C was likely extracytoplasmic and hence that the protein's topology was not as predicted. Similar results were seen with membranes from S. pneumoniae strain TIGR4, indicating that Cps4C also showed similar topology. A chromosomally encoded fusion of HA-Cps2C and Cps2D was not degraded by CP-B, suggesting that the fusion fixed the C terminus within the cytoplasm. However, capsule synthesis was unaltered by this fusion. Detection of the CpsC C terminus by flow cytometry indicated that it was extracytoplasmic in approximately 30% of cells. Interestingly, a mutant in the protein tyrosine phosphatase CpsB had a significantly greater proportion of positive cells, although this effect was independent of its phosphatase activity. Our data indicate that CpsC possesses a varied topology, with the C terminus flipping across the cytoplasmic membrane, where it interacts with CpsD in order to regulate tyrosine kinase activity.
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Yuan B, Cheng A, Wang M. Polysaccharide export outer membrane proteins in Gram-negative bacteria. Future Microbiol 2013; 8:525-35. [DOI: 10.2217/fmb.13.13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Polysaccharide export outer membrane proteins of Gram-negative bacteria are involved in the export of polysaccharides across the outer membrane. The mechanisms of polysaccharide export across the outer membrane in Gram-negative bacteria are not yet completely clear. However, the mechanisms of polysaccharide assembly in Escherichia coli have been intensively investigated. Here, we mainly review the current understanding of the assembly mechanisms of group 1 capsular polysaccharide, group 2 capsular polysaccharide and lipopolysaccharide of E. coli, and the current structures and interactions of some polysaccharide export outer membrane proteins with other proteins involved in polysaccharide export in Gram-negative bacteria. In addition, LptD may be targeted by peptidomimetic antibiotics in Gram-negative bacteria. We also give insights into the directions of future research regarding the mechanisms of polysaccharide export.
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Affiliation(s)
- Biao Yuan
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, China.
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, China
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46 Xinkang Road, Ya’an, Sichuan 625014, China
- Key Laboratory of Animal Disease & Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu city, Sichuan 611130, China
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Chengdu City, Sichuan 611130, China
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, 46 Xinkang Road, Ya’an, Sichuan 625014, China
- Key Laboratory of Animal Disease & Human Health of Sichuan Province, Sichuan Agricultural University, Wenjiang, Chengdu city, Sichuan 611130, China
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Lewis VG, Ween MP, McDevitt CA. The role of ATP-binding cassette transporters in bacterial pathogenicity. PROTOPLASMA 2012; 249:919-942. [PMID: 22246051 DOI: 10.1007/s00709-011-0360-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Accepted: 11/29/2011] [Indexed: 05/31/2023]
Abstract
The ATP-binding cassette transporter superfamily is present in all three domains of life. This ubiquitous class of integral membrane proteins have diverse biological functions, but their fundamental role involves the unidirectional translocation of compounds across cellular membranes in an ATP coupled process. The importance of this class of proteins in eukaryotic systems is well established as typified by their association with genetic diseases and roles in the multi-drug resistance of cancer. In stark contrast, the ABC transporters of prokaryotes have not been exhaustively investigated due to the sheer number of different roles and organisms in which they function. In this review, we examine the breadth of functions associated with microbial ABC transporters in the context of their contribution to bacterial pathogenicity and virulence.
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Affiliation(s)
- Victoria G Lewis
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, 5005, Australia
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Bhaskar U, Sterner E, Hickey AM, Onishi A, Zhang F, Dordick JS, Linhardt RJ. Engineering of routes to heparin and related polysaccharides. Appl Microbiol Biotechnol 2011; 93:1-16. [PMID: 22048616 DOI: 10.1007/s00253-011-3641-4] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 09/23/2011] [Accepted: 10/08/2011] [Indexed: 10/16/2022]
Abstract
Anticoagulant heparin has been shown to possess important biological functions that vary according to its fine structure. Variability within heparin's structure occurs owing to its biosynthesis and animal tissue-based recovery and adds another dimension to its complex polymeric structure. The structural variations in chain length and sulfation patterns mediate its interaction with many heparin-binding proteins, thereby eliciting complex biological responses. The advent of novel chemical and enzymatic approaches for polysaccharide synthesis coupled with high throughput combinatorial approaches for drug discovery have facilitated an increased effort to understand heparin's structure-activity relationships. An improved understanding would offer potential for new therapeutic development through the engineering of polysaccharides. Such a bioengineering approach requires the amalgamation of several different disciplines, including carbohydrate synthesis, applied enzymology, metabolic engineering, and process biochemistry.
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Affiliation(s)
- Ujjwal Bhaskar
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
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Wang Z, Dordick JS, Linhardt RJ. Escherichia coli K5 heparosan fermentation and improvement by genetic engineering. Bioeng Bugs 2011; 2:63-7. [PMID: 21636991 DOI: 10.4161/bbug.2.1.14201] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
N-acetyl heparosan is the precursor for the biosynthesis of the important anticoagulant drug heparin. The E. coli K5 capsular heparosan polysaccharide provides a promising precursor for in vitro chemoenzymatic production of bioengineered heparin. This article explores the improvements of heparosan production for bioengineered heparin by fermentation process engineering and genetic engineering.
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Affiliation(s)
- Zhenyu Wang
- Department of Biology, Center for Biotechnology & Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, USA
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Larue K, Ford RC, Willis LM, Whitfield C. Functional and structural characterization of polysaccharide co-polymerase proteins required for polymer export in ATP-binding cassette transporter-dependent capsule biosynthesis pathways. J Biol Chem 2011; 286:16658-68. [PMID: 21454677 PMCID: PMC3089508 DOI: 10.1074/jbc.m111.228221] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 03/17/2011] [Indexed: 11/06/2022] Open
Abstract
Neisseria meningitidis serogroup B and Escherichia coli K1 bacteria produce a capsular polysaccharide (CPS) that is composed of α2,8-linked polysialic acid (PSA). Biosynthesis of PSA in these bacteria occurs via an ABC (ATP-binding cassette) transporter-dependent pathway. In N. meningitidis, export of PSA to the surface of the bacterium requires two proteins that form an ABC transporter (CtrC and CtrD) and two additional proteins, CtrA and CtrB, that are proposed to form a cell envelope-spanning export complex. CtrA is a member of the outer membrane polysaccharide export (OPX) family of proteins, which are proposed to form a pore to mediate export of CPSs across the outer membrane. CtrB is an inner membrane protein belonging to the polysaccharide co-polymerase (PCP) family. PCP proteins involved in other bacterial polysaccharide assembly systems form structures that extend into the periplasm from the inner membrane. There is currently no structural information available for PCP or OPX proteins involved in an ABC transporter-dependent CPS biosynthesis pathway to support their proposed roles in polysaccharide export. Here, we report cryo-EM images of purified CtrB reconstituted into lipid bilayers. These images contained molecular top and side views of CtrB and showed that it formed a conical oligomer that extended ∼125 Å from the membrane. This structure is consistent with CtrB functioning as a component of an envelope-spanning complex. Cross-complementation of CtrA and CtrB in E. coli mutants with defects in genes encoding the corresponding PCP and OPX proteins show that PCP-OPX pairs require interactions with their cognate partners to export polysaccharide. These experiments add further support for the model of an ABC transporter-PCP-OPX multiprotein complex that functions to export CPS across the cell envelope.
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Affiliation(s)
- Kane Larue
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 and
| | - Robert C. Ford
- the Faculty of Life Science, University of Manchester, Manchester M60 1QD, United Kingdom
| | - Lisa M. Willis
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 and
| | - Chris Whitfield
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1 and
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Wang Z, Ly M, Zhang F, Zhong W, Suen A, Hickey AM, Dordick JS, Linhardt RJ. E. coli K5 fermentation and the preparation of heparosan, a bioengineered heparin precursor. Biotechnol Bioeng 2011; 107:964-73. [PMID: 20717972 DOI: 10.1002/bit.22898] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Heparosan is an acidic polysaccharide natural product, which serves as the critical precursor in heparin biosynthesis and in the chemoenzymatic synthesis of bioengineered heparin. Heparosan is also the capsular polysaccharide of Escherichia coli K5 strain. The current study was focused on the examination of the fermentation of E. coli K5 with the goal of producing heparosan in high yield and volumetric productivity. The structure and molecular weight properties of this bacterial heparosan were determined using polyacrylamide gel electrophoresis (PAGE) and Fourier transform mass spectrometry. Fermentation of E. coli K5 in a defined medium using exponential fed-batch glucose addition with oxygen enrichment afforded heparosan at 15 g/L having a number average molecular weight of 58,000 Da and a weight average molecular weight of 84,000 Da.
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Affiliation(s)
- Zhenyu Wang
- Department of Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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15
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Abstract
Complex glycoconjugates play critical roles in the biology of microorganisms. Despite the remarkable diversity in glycan structures and the bacteria that produce them, conserved themes are evident in the biosynthesis-export pathways. One of the primary pathways involves representatives of the ATP-binding cassette (ABC) transporter superfamily. These proteins are responsible for the export of a wide variety of cell surface oligo- and polysaccharides in both Gram-positive and Gram-negative bacteria. Recent investigations of the structure and function of ABC transporters involved in the export of lipopolysaccharide O antigens have revealed two fundamentally different strategies for coupling glycan polymerization to export. These mechanisms are distinguished by the presence (or absence) of characteristic nonreducing terminal modifications on the export substrates, which serve as chain termination and/or export signals, and by the presence (or absence) of a discrete substrate-binding domain in the nucleotide-binding domain polypeptide of the ABC transporter. A bioinformatic survey examining ABC exporters from known oligo- and polysaccharide biosynthesis loci identifies conserved nucleotide-binding domain protein families that correlate well with themes in the structures and assembly of glycans. The familial relationships among the ABC exporters generate hypotheses concerning the biosynthesis of structurally diverse oligo- and polysaccharides, which play important roles in the biology of bacteria with different lifestyles.
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16
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Janssen PJ, Van Houdt R, Moors H, Monsieurs P, Morin N, Michaux A, Benotmane MA, Leys N, Vallaeys T, Lapidus A, Monchy S, Médigue C, Taghavi S, McCorkle S, Dunn J, van der Lelie D, Mergeay M. The complete genome sequence of Cupriavidus metallidurans strain CH34, a master survivalist in harsh and anthropogenic environments. PLoS One 2010; 5:e10433. [PMID: 20463976 PMCID: PMC2864759 DOI: 10.1371/journal.pone.0010433] [Citation(s) in RCA: 199] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 03/29/2010] [Indexed: 11/21/2022] Open
Abstract
Many bacteria in the environment have adapted to the presence of toxic heavy metals. Over the last 30 years, this heavy metal tolerance was the subject of extensive research. The bacterium Cupriavidus metallidurans strain CH34, originally isolated by us in 1976 from a metal processing factory, is considered a major model organism in this field because it withstands milli-molar range concentrations of over 20 different heavy metal ions. This tolerance is mostly achieved by rapid ion efflux but also by metal-complexation and -reduction. We present here the full genome sequence of strain CH34 and the manual annotation of all its genes. The genome of C. metallidurans CH34 is composed of two large circular chromosomes CHR1 and CHR2 of, respectively, 3,928,089 bp and 2,580,084 bp, and two megaplasmids pMOL28 and pMOL30 of, respectively, 171,459 bp and 233,720 bp in size. At least 25 loci for heavy-metal resistance (HMR) are distributed over the four replicons. Approximately 67% of the 6,717 coding sequences (CDSs) present in the CH34 genome could be assigned a putative function, and 9.1% (611 genes) appear to be unique to this strain. One out of five proteins is associated with either transport or transcription while the relay of environmental stimuli is governed by more than 600 signal transduction systems. The CH34 genome is most similar to the genomes of other Cupriavidus strains by correspondence between the respective CHR1 replicons but also displays similarity to the genomes of more distantly related species as a result of gene transfer and through the presence of large genomic islands. The presence of at least 57 IS elements and 19 transposons and the ability to take in and express foreign genes indicates a very dynamic and complex genome shaped by evolutionary forces. The genome data show that C. metallidurans CH34 is particularly well equipped to live in extreme conditions and anthropogenic environments that are rich in metals.
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Affiliation(s)
- Paul J Janssen
- Molecular and Cellular Biology, Belgian Nuclear Research Center SCK*CEN, Mol, Belgium.
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17
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Bacterial Adaptor Membrane Fusion Proteins and the Structurally Dissimilar Outer Membrane Auxiliary Proteins Have Exchanged Central Domains in alpha-Proteobacteria. Int J Microbiol 2010; 2010:589391. [PMID: 20379386 PMCID: PMC2850547 DOI: 10.1155/2010/589391] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 01/31/2010] [Indexed: 12/03/2022] Open
Abstract
Transport systems frequently include auxiliary proteins that perform subfunctions within the transporter protein complex. Two such proteins found in Gram-negative bacteria are the Membrane Fusion Proteins (MFPs) and the Outer Membrane Auxiliary (OMA) proteins. We here demonstrate that OMAs present in α-proteobacteria (but not in other bacterial types) contain a long α-helical region that is homologous to corresponding regions in the MFPs. The results suggest that during their evolution, OMAs, specifically from α-proteobacteria, exchanged their own α-helical domain for one derived from an MFP. The structural and functional implications of these findings are discussed.
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18
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Ferrero MA, Aparicio LR. Biosynthesis and production of polysialic acids in bacteria. Appl Microbiol Biotechnol 2010; 86:1621-35. [PMID: 20349183 DOI: 10.1007/s00253-010-2531-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 02/25/2010] [Accepted: 02/25/2010] [Indexed: 01/30/2023]
Abstract
Polysialic acids (PA) are protective capsular sialohomopolymers present in some bacteria which can invade the mammalian host and cause lethal bacteremia and meningitis. Biosynthesis and translocation of PA to the cell surface are equivalent in different species and bacterial strains which are produced. The diversity in PA structure is derived from the PA linkages and is a consequence of the specific sialyltransferase activities. The monomer acetylation and the polymer length could be important factors in the potential virulence. In vivo PA production is affected by different physical and chemical factors. The temperature of cellular growth strictly regulates PA genesis through a molecular complex and multifactorial mechanism that operate to transcription level.
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Affiliation(s)
- Miguel Angel Ferrero
- Departamento de Biología Molecular, Universidad de León, Campus de Vegazana, 24071, León, Spain.
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19
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Abstract
The capsule is a cell surface structure composed of long-chain polysaccharides that envelops many isolates of Escherichia coli. It protects the cell against host defenses or physical environmental stresses, such as desiccation. The component capsular polysaccharides (CPSs) are major surface antigens in E. coli. They are named K antigens (after the German word Kapsel). Due to variations in CPS structures, more than 80 serologically unique K antigens exist in E. coli. Despite the hypervariability in CPS structures, only two capsule-assembly strategies exist in E. coli. These have led to the assignment of group 1 and group 2 capsules, and many of the key elements of the corresponding assembly pathways have been resolved. Structural features, as well as genetic and regulatory variations, give rise to additional groups 3 and 4. These employ the same biosynthesis processes described in groups 2 and 1, respectively. Each isolate possesses a distinctive set of cytosolic and inner-membrane enzymes, which generate a precise CPS structure, defining a given K serotype. Once synthesized, a multiprotein complex is needed to translocate the nascent CPS across the Gram-negative cell envelope to the outer surface of the outer membrane, where the capsule structure is assembled. While the translocation machineries for group 1 and group 2 CPSs are fundamentally different from one another, they possess no specificity for a given CPS structure. Each is conserved in all isolates producing capsules belonging to a particular group.
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20
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Pivotal roles of the outer membrane polysaccharide export and polysaccharide copolymerase protein families in export of extracellular polysaccharides in gram-negative bacteria. Microbiol Mol Biol Rev 2009; 73:155-77. [PMID: 19258536 PMCID: PMC2650888 DOI: 10.1128/mmbr.00024-08] [Citation(s) in RCA: 185] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Many bacteria export extracellular polysaccharides (EPS) and capsular polysaccharides (CPS). These polymers exhibit remarkably diverse structures and play important roles in the biology of free-living, commensal, and pathogenic bacteria. EPS and CPS production represents a major challenge because these high-molecular-weight hydrophilic polymers must be assembled and exported in a process spanning the envelope, without compromising the essential barrier properties of the envelope. Emerging evidence points to the existence of molecular scaffolds that perform these critical polymer-trafficking functions. Two major pathways with different polymer biosynthesis strategies are involved in the assembly of most EPS/CPS: the Wzy-dependent and ATP-binding cassette (ABC) transporter-dependent pathways. They converge in an outer membrane export step mediated by a member of the outer membrane auxiliary (OMA) protein family. OMA proteins form outer membrane efflux channels for the polymers, and here we propose the revised name outer membrane polysaccharide export (OPX) proteins. Proteins in the polysaccharide copolymerase (PCP) family have been implicated in several aspects of polymer biogenesis, but there is unequivocal evidence for some systems that PCP and OPX proteins interact to form a trans-envelope scaffold for polymer export. Understanding of the precise functions of the OPX and PCP proteins has been advanced by recent findings from biochemistry and structural biology approaches and by parallel studies of other macromolecular trafficking events. Phylogenetic analyses reported here also contribute important new insight into the distribution, structural relationships, and function of the OPX and PCP proteins. This review is intended as an update on progress in this important area of microbial cell biology.
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21
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A recombinant E. coli bioprocess for hyaluronan synthesis. Appl Microbiol Biotechnol 2009; 84:63-9. [DOI: 10.1007/s00253-009-1963-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 03/11/2009] [Accepted: 03/12/2009] [Indexed: 10/21/2022]
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22
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Morona R, Purins L, Tocilj A, Matte A, Cygler M. Sequence-structure relationships in polysaccharide co-polymerase (PCP) proteins. Trends Biochem Sci 2008; 34:78-84. [PMID: 19058968 DOI: 10.1016/j.tibs.2008.11.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2008] [Revised: 10/30/2008] [Accepted: 11/03/2008] [Indexed: 10/21/2022]
Abstract
Polysaccharides are ubiquitously distributed on the cell surface of bacteria. These polymers are involved in many processes, including immune avoidance and bacteria-host interactions, which are especially important for pathogenic organisms. In many instances, the lengths of these polysaccharides are not random, but rather distribute around some mean value, termed the modal length. A large family of proteins, called polysaccharide co-polymerases (PCPs), found in both Gram-negative and Gram-positive species regulate polysaccharide modal length. Recent crystal structures of Wzz proteins from Escherichia coli and Salmonella typhimurium provide the first atomic-resolution information for one family of PCPs, the PCP1 group. These crystal structures have important implications for the structures of other PCP families.
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Affiliation(s)
- Renato Morona
- Australian Bacterial Pathogenesis Program, School of Molecular and Biomedical Science, Discipline of Microbiology and Immunology, University of Adelaide, North Terrace, Adelaide, SA 5005, Australia.
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23
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Steenbergen SM, Vimr ER. Biosynthesis of the Escherichia coli K1 group 2 polysialic acid capsule occurs within a protected cytoplasmic compartment. Mol Microbiol 2008; 68:1252-67. [PMID: 18435708 PMCID: PMC2408645 DOI: 10.1111/j.1365-2958.2008.06231.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2008] [Indexed: 11/28/2022]
Abstract
Capsular polysaccharides are important virulence determinants in a wide range of invasive infectious diseases. Although capsule synthesis has been extensively investigated, understanding polysaccharide export from the cytoplasm to the external environment has been more difficult. Here we present the results of a novel protection assay indicating that synthesis and export of the Escherichia coli K1 group 2 capsular polysialic acid (K1 antigen) occur within a protected subcellular compartment designated the sialisome. In addition to the polymerase encoded by neuS, localization and complementation analyses indicated that the sialisome includes the accessory membrane protein NeuE. The requirement for NeuE was suppressed by overproducing NeuS, suggesting that NeuE functions by stabilizing the polymerase or facilitating its assembly in the sialisome. Although an interaction between NeuE and NeuS could not be demonstrated with a bacterial two-hybrid system that reconstitutes an intracellular cell-signalling pathway, interactions between NeuS and KpsC as well as other sialisome components were detected. The combined results provide direct evidence for specific protein-protein interactions in the synthesis and export of group 2 capsular polysaccharides under in vivo conditions. The approaches developed here will facilitate further dissection of the sialisome, suggesting similar methodology for understanding the biosynthesis of other group 2 capsules.
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Affiliation(s)
- Susan M Steenbergen
- Laboratory of Sialobiology and Comparative Metabolomics, Department of Pathobiology, University of Illinois at Urbana-ChampaignUrbana, IL 61802, USA
| | - Eric R Vimr
- Laboratory of Sialobiology and Comparative Metabolomics, Department of Pathobiology, University of Illinois at Urbana-ChampaignUrbana, IL 61802, USA
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24
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Corbett D, Roberts IS. Capsular Polysaccharides in Escherichia coli. ADVANCES IN APPLIED MICROBIOLOGY 2008; 65:1-26. [DOI: 10.1016/s0065-2164(08)00601-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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25
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Bachtiar BM, Coloe PJ, Fry BN. Knockout mutagenesis of the kpsE gene of Campylobacter jejuni 81116 and its involvement in bacterium-host interactions. FEMS IMMUNOLOGY AND MEDICAL MICROBIOLOGY 2007; 49:149-54. [PMID: 17266722 DOI: 10.1111/j.1574-695x.2006.00182.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Campylobacter jejuni is a common cause of bacterial enteritis. The surface capsular polysaccharides are important for this bacterium to survive in the environment, but little is known about their involvement in bacterium-host interactions. This study showed that the C. jejuni capsular polysaccharides play an important role in adherence to and invasion of human embryonic epithelial cells. However, no significant role of capsular polysaccharides was shown in colonization of the chicken gut.
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Affiliation(s)
- Boy M Bachtiar
- Biotechnology and Environmental Biology, RMIT University, Melbourne, Australia
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26
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Abstract
Capsules are protective structures on the surfaces of many bacteria. The remarkable structural diversity in capsular polysaccharides is illustrated by almost 80 capsular serotypes in Escherichia coli. Despite this variation, the range of strategies used for capsule biosynthesis and assembly is limited, and E. coli isolates provide critical prototypes for other bacterial species. Related pathways are also used for synthesis and export of other bacterial glycoconjugates and some enzymes/processes have counterparts in eukaryotes. In gram-negative bacteria, it is proposed that biosynthesis and translocation of capsular polysaccharides to the cell surface are temporally and spatially coupled by multiprotein complexes that span the cell envelope. These systems have an impact on both a general understanding of membrane trafficking in bacteria and on bacterial pathogenesis.
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Affiliation(s)
- Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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27
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McNulty C, Thompson J, Barrett B, Lord L, Andersen C, Roberts IS. The cell surface expression of group 2 capsular polysaccharides in Escherichia coli: the role of KpsD, RhsA and a multi-protein complex at the pole of the cell. Mol Microbiol 2006; 59:907-22. [PMID: 16420360 DOI: 10.1111/j.1365-2958.2005.05010.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The export of large negatively charged capsular polysaccharides across the outer membrane represents a significant challenge to Gram negative bacteria. In the case of Escherichia coli group 2 capsular polysaccharides, the mechanism of export across the outer membrane was unknown, with no identified candidate outer membrane proteins. In this paper we demonstrate that the KpsD protein, previously believed to be a periplasmic protein, is an outer membrane protein involved in the export of group 2 capsular polysaccharides across the outer membrane. We demonstrate that KpsD and KpsE are located at the poles of the cell and that polysaccharide biosynthesis and export occurs at these polar sites. By in vivo chemical cross-linking and MALDI-TOF-MS analysis we demonstrate the presence of a multi-protein biosynthetic/export complex in which cytoplasmic proteins involved in polysaccharide biosynthesis could be cross-linked to proteins involved in export across the inner and outer membranes. In addition, we show that the RhsA protein, of previously unknown function, could be cross-linked to the complex and that a rhsA mutation reduces K5 biosynthesis suggesting a role for RhsA in coupling biosynthesis and export.
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Affiliation(s)
- Clodagh McNulty
- Faculty of Life Sciences, 1.800 Stopford Building, The University of Manchester, Oxford Road, Manchester M13 9PT, UK
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28
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Yip ES, Grublesky BT, Hussa EA, Visick KL. A novel, conserved cluster of genes promotes symbiotic colonization and sigma-dependent biofilm formation by Vibrio fischeri. Mol Microbiol 2005; 57:1485-98. [PMID: 16102015 DOI: 10.1111/j.1365-2958.2005.04784.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Vibrio fischeri is the exclusive symbiont residing in the light organ of the squid Euprymna scolopes. To understand the genetic requirements for this association, we searched a library of V. fischeri transposon insertion mutants for those that failed to colonize E. scolopes. We identified four mutants that exhibited severe defects in initiating colonization. Sequence analysis revealed that the strains contained insertions in four different members of a cluster of 21 genes oriented in the same direction. The predicted gene products are similar to proteins involved in capsule, exopolysaccharide or lipopolysaccharide biosynthesis, including six putative glycosyltransferases. We constructed mutations in five additional genes and found that they also were required for symbiosis. Therefore, we have termed this region syp, for symbiosis polysaccharide. Homologous clusters also exist in Vibrio parahaemolyticus and Vibrio vulnificus, and thus these genes may represent a common mechanism for promoting bacteria-host interactions. Using lacZ reporter fusions, we observed that transcription of the syp genes did not occur under standard laboratory conditions, but could be induced by multicopy expression of sypG, which encodes a response regulator with a predicted sigma54 interaction domain. This induction depended on sigma54, as a mutation in rpoN abolished syp transcription. Primer extension analysis supported the use of putative sigma54 binding sites upstream of sypA, sypI and sypM as promoters. Finally, we found that multicopy expression of sypG resulted in robust biofilm formation. This work thus reveals a novel group of genes that V. fischeri controls through a sigma54-dependent response regulator and uses to promote symbiotic colonization.
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Affiliation(s)
- Emily S Yip
- Department of Microbiology and Immunology, Loyola University Chicago, 2160 S. First Ave. Bldg. 105, Maywood, IL 60153, USA
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29
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Schwan WR, Beck MT, Hultgren SJ, Pinkner J, Woolever NL, Larson T. Down-regulation of the kps region 1 capsular assembly operon following attachment of Escherichia coli type 1 fimbriae to D-mannose receptors. Infect Immun 2005; 73:1226-31. [PMID: 15664970 PMCID: PMC547067 DOI: 10.1128/iai.73.2.1226-1231.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Revised: 09/17/2004] [Accepted: 09/30/2004] [Indexed: 11/20/2022] Open
Abstract
A differential-display PCR procedure identified the capsular assembly gene kpsD after Escherichia coli type 1 fimbrial binding to mannose-coated Sepharose beads. Limiting-dilution reverse-transcribed PCRs confirmed down-regulation of the kpsD gene, and Northern blot and lacZ fusion analyses showed down-regulation of the kpsFEDUCS region 1 operon. KpsD protein levels fell, and an agglutination test showed less K capsular antigen on the surface following the bacterial ligand-receptor interaction. These data show that binding of type 1 fimbriae (pili) to d-mannose receptors triggers a cross talk that leads to down-regulation of the capsule assembly region 1 operon in uropathogenic E. coli.
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Affiliation(s)
- William R Schwan
- Department of Microbiology, University of Wisconsin-La Crosse, 1725 State Street, La Crosse, WI 54601, USA.
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30
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Abstract
Gram-negative bacteria characteristically are surrounded by an additional membrane layer, the outer membrane. Although outer membrane components often play important roles in the interaction of symbiotic or pathogenic bacteria with their host organisms, the major role of this membrane must usually be to serve as a permeability barrier to prevent the entry of noxious compounds and at the same time to allow the influx of nutrient molecules. This review summarizes the development in the field since our previous review (H. Nikaido and M. Vaara, Microbiol. Rev. 49:1-32, 1985) was published. With the discovery of protein channels, structural knowledge enables us to understand in molecular detail how porins, specific channels, TonB-linked receptors, and other proteins function. We are now beginning to see how the export of large proteins occurs across the outer membrane. With our knowledge of the lipopolysaccharide-phospholipid asymmetric bilayer of the outer membrane, we are finally beginning to understand how this bilayer can retard the entry of lipophilic compounds, owing to our increasing knowledge about the chemistry of lipopolysaccharide from diverse organisms and the way in which lipopolysaccharide structure is modified by environmental conditions.
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Affiliation(s)
- Hiroshi Nikaido
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202, USA.
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31
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Steenbergen SM, Vimr ER. Functional relationships of the sialyltransferases involved in expression of the polysialic acid capsules of Escherichia coli K1 and K92 and Neisseria meningitidis groups B or C. J Biol Chem 2003; 278:15349-59. [PMID: 12578835 DOI: 10.1074/jbc.m208837200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Polysialic acid (PSA) capsules are cell-associated homopolymers of alpha2,8-, alpha2,9-, or alternating alpha2,8/2,9-linked sialic acid residues that function as essential virulence factors in neuroinvasive diseases caused by certain strains of Escherichia coli and Neisseria meningitidis. PSA chains structurally identical to the bacterial alpha2,8-linked capsular polysaccharides are also synthesized by the mammalian central nervous system, where they regulate neuronal function in association with the neural cell adhesion molecule (NCAM). Despite the structural identity between bacterial and NCAM PSAs, the respective polysialyltransferases (polySTs) responsible for polymerizing sialyl residues from donor CMP-sialic acid are not homologous glycosyltransferases. To better define the mechanism of capsule biosynthesis, we established the functional interchangeability of bacterial polySTs by complementation of a polymerase-deficient E. coli K1 mutant with the polyST genes from groups B or C N. meningitidis and the control E. coli K92 polymerase gene. The biochemical and immunochemical results demonstrated that linkage specificity is dictated solely by the source of the polymerase structural gene. To determine the molecular basis for linkage specificity, we created chimeras of the K1 and K92 polySTs by overlap extension PCR. Exchanging the first 52 N-terminal amino acids of the K1 NeuS with the C terminus of the K92 homologue did not alter specificity of the resulting chimera, whereas exchanging the first 85 or reciprocally exchanging the first 100 residues did. These results demonstrated that linkage specificity is dependent on residues located between positions 53 and 85 from the N terminus. Site-directed mutagenesis of the K92 polyST N terminus indicated that no single residue alteration was sufficient to affect specificity, consistent with the proposed function of this domain in orienting the acceptor. The combined results provide the first evidence for residues critical to acceptor binding and elongation in polysialyltransferase.
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Affiliation(s)
- Susan M Steenbergen
- Laboratory of Sialobiology, Department of Pathobiology, University of Illinois, Urbana, Illinois 61802, USA.
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32
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Zhai Y, Saier MH. The beta-barrel finder (BBF) program, allowing identification of outer membrane beta-barrel proteins encoded within prokaryotic genomes. Protein Sci 2002; 11:2196-207. [PMID: 12192075 PMCID: PMC2373602 DOI: 10.1110/ps.0209002] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Many outer membrane proteins (OMPs) in Gram-negative bacteria possess known beta-barrel three-dimensional (3D) structures. These proteins, including channel-forming transmembrane porins, are diverse in sequence but exhibit common structural features. We here report computational analyses of six outer membrane proteins of known 3D structures with respect to (1) secondary structure, (2) hydropathy, and (3) amphipathicity. Using these characteristics, as well as the presence of an N-terminal targeting sequence, a program was developed allowing prediction of integral membrane beta-barrel proteins encoded within any completely sequenced prokaryotic genome. This program, termed the beta-barrel finder (BBF) program, was used to analyze the proteins encoded within the Escherichia coli genome. Out of 4290 sequences examined, 118 (2.8%) were retrieved. Of these, almost all known outer membrane proteins with established beta-barrel structures as well as many probable outer membrane proteins were identified. This program should be useful for predicting the occurrence of outer membrane proteins in bacteria with completely sequenced genomes.
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Affiliation(s)
- Yufeng Zhai
- Department of Biology, University of California at San Diego, La Jolla, California 92093-0116, USA
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Phoenix DA, Brandenburg K, Harris F, Seydel U, Hammerton T, Roberts IS. An investigation into the membrane-interactive potential of the Escherichia coli KpsE C-terminus. Biochem Biophys Res Commun 2001; 285:976-80. [PMID: 11467848 DOI: 10.1006/bbrc.2001.5266] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Membrane binding via C-terminal amphiphilic alpha-helical structure is a novel anchoring mechanism, which has been characterised in a number of prokaryotic carboxypeptidases. Here, we have used graphical and DWIH analyses to ascertain if a similar anchoring mechanism may be utilised by the Escherichia coli KpsE protein in its binding to the periplasmic face of the inner membrane. The results of these analyses have been compared to those obtained for similar analyses of the C-terminal sequences of E. coli penicillin-binding proteins (PBPs) PBP5 and PBP6 which, are known to function as amphiphilic alpha-helical membrane anchors, and of melittin, a known membrane-interactive toxin. We have also used FTIR spectroscopy and lipid phase transition temperature analysis to investigate the interaction of a peptide homologue of KpsE C-terminal region with membrane lipid. Our results suggest that the KpsE C-terminal sequence has the potential to form an amphiphilic alpha-helix and that this alpha-helix could feature in the membrane binding of the protein.
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Affiliation(s)
- D A Phoenix
- Centre for Forensic Science, University of Central Lancashire, Preston, PR1 2HE, United Kingdom.
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