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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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Sun JX, Xia QD, Zhong XY, Liu Z, Wang SG. The bladder microbiome of NMIBC and MIBC patients revealed by 2bRAD-M. Front Cell Infect Microbiol 2023; 13:1182322. [PMID: 37351184 PMCID: PMC10282653 DOI: 10.3389/fcimb.2023.1182322] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/15/2023] [Indexed: 06/24/2023] Open
Abstract
Background Bladder cancer (BCa) is the most common malignancy of the urinary tract which can be divided into non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC), and their microbial differences are not fully understood. This study was conducted by performing 2bRAD sequencing for Microbiome (2bRAD-M) on NMIBC and MIBC tissue samples to investigate the microbiota differences between NMIBC and MIBC individuals. Methods A total of 22 patients with BCa, including 7 NMIBC and 15 MIBC, were recruited. Tumor tissues were surgically removed as samples and DNA was extracted. Type IIB restriction endonucleases were used to enzymatically cleave the microbial genome for each microbe's tag and map it to species-specific 2bRAD markers to enable qualitative and quantitative studies of microbes between MIBC and NMIBC tissues. Results A total of 527 species were detected. The microbial diversity of NMIBC tissues was significantly higher than that of MIBC tissues. Microbial composition of the two tumor tissues was similar, where Ralstonia_sp000620465 was the most dominant species. 4 species (Acinetobacter_guillouiae, Anoxybacillus_A_rupiensis, Brevibacillus_agri and Staphylococcus_lugdunensis) were enriched in NMIBC, while Ralstonia_mannitolilytica, Ralstonia_pickettii, and Ralstonia_sp000620465 were overrepresented in MIBC. 252 discriminatory character taxa were also revealed by linear discriminant analysis effect sizea (LEfSe). Species importance point plots identified Ralstonia_sp000620465, Cutibacterium_acnes and Ralstonia_pickettii as the three most important species between the two groups. Meanwhile, functional annotation analysis showed 3011 different COGs and 344 related signaling pathways between MIBC and NMIBC microbiome. Conclusion This first 2bRAD-M microbiome study on MIBC and NMIBC tissues revealed significant differences in the microbial environment between the two groups, which implies a potential association between tumor microbial dysbiosis and BCa, and provides a possible target and basis for subsequent studies on the mechanisms of BCa development and progression.
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Affiliation(s)
| | | | | | - Zheng Liu
- Department and Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shao-Gang Wang
- Department and Institute of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Liu K, Guo L, Chen X, Liu L, Gao C. Microbial synthesis of glycosaminoglycans and their oligosaccharides. Trends Microbiol 2023; 31:369-383. [PMID: 36517300 DOI: 10.1016/j.tim.2022.11.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 12/15/2022]
Abstract
Compared with chemical synthesis and tissue extraction methods, microbial synthesis of glycosaminoglycans (GAGs) is attractive because of the advantages of eco-friendly processes, production safety, and sustainable development. However, boosting the efficiency of microbial cell factories, precisely regulating GAG molecular weights, and rationally controlling the sulfation degree of GAGs remain challenging. To address these issues, various strategies, including genetic, enzymatic, metabolic, and fermentation engineering, have been developed. In this review, we summarize the recent progress in the construction of efficient GAG-producing microbial cell factories, regulation of the molecular weight of GAGs, and modification of GAG chains. Moreover, future studies, remaining challenges, and potential solutions in this field are discussed.
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Affiliation(s)
- Kaifang Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Liang Guo
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Xiulai Chen
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Liming Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Cong Gao
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, Wuxi, Jiangsu 214122, China.
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Stephens Z, Wilson LFL, Zimmer J. Diverse mechanisms of polysaccharide biosynthesis, assembly and secretion across kingdoms. Curr Opin Struct Biol 2023; 79:102564. [PMID: 36870276 DOI: 10.1016/j.sbi.2023.102564] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/16/2023] [Accepted: 01/28/2023] [Indexed: 03/06/2023]
Abstract
Polysaccharides are essential biopolymers produced in all kingdoms of life. On the cell surface, they represent versatile architectural components, forming protective capsules and coats, cell walls, or adhesives. Extracellular polysaccharide (EPS) biosynthesis mechanisms differ based on the cellular localization of polymer assembly. Some polysaccharides are first synthesized in the cytosol and then extruded by ATP powered transporters [1]. In other cases, the polymers are assembled outside the cell [2], synthesized and secreted in a single step [3], or deposited on the cell surface via vesicular trafficking [4]. This review focuses on recent insights into the biosynthesis, secretion, and assembly of EPS in microbes, plants and vertebrates. We focus on comparing the sites of biosynthesis, secretion mechanisms, and higher-order EPS assemblies.
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Affiliation(s)
- Zachery Stephens
- Howard Hughes Medical Institute, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
| | - Louis F L Wilson
- Howard Hughes Medical Institute, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
| | - Jochen Zimmer
- Howard Hughes Medical Institute, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA.
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Bali K, Guffick C, McCoy R, Lu Z, Kaminski CF, Mela I, Owens RM, van Veen HW. Biosensor for Multimodal Characterization of an Essential ABC Transporter for Next-Generation Antibiotic Research. ACS APPLIED MATERIALS & INTERFACES 2023; 15:12766-12776. [PMID: 36866935 PMCID: PMC10020959 DOI: 10.1021/acsami.2c21556] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 02/15/2023] [Indexed: 05/21/2023]
Abstract
As the threat of antibiotic resistance increases, there is a particular focus on developing antimicrobials against pathogenic bacteria whose multidrug resistance is especially entrenched and concerning. One such target for novel antimicrobials is the ATP-binding cassette (ABC) transporter MsbA that is present in the plasma membrane of Gram-negative pathogenic bacteria where it is fundamental to the survival of these bacteria. Supported lipid bilayers (SLBs) are useful in monitoring membrane protein structure and function since they can be integrated with a variety of optical, biochemical, and electrochemical techniques. Here, we form SLBs containing Escherichia coli MsbA and use atomic force microscopy (AFM) and structured illumination microscopy (SIM) as high-resolution microscopy techniques to study the integrity of the SLBs and incorporated MsbA proteins. We then integrate these SLBs on microelectrode arrays (MEA) based on the conducting polymer poly(3,4-ethylenedioxy-thiophene) poly(styrene sulfonate) (PEDOT:PSS) using electrochemical impedance spectroscopy (EIS) to monitor ion flow through MsbA proteins in response to ATP hydrolysis. These EIS measurements can be correlated with the biochemical detection of MsbA-ATPase activity. To show the potential of this SLB approach, we observe not only the activity of wild-type MsbA but also the activity of two previously characterized mutants along with quinoline-based MsbA inhibitor G907 to show that EIS systems can detect changes in ABC transporter activity. Our work combines a multitude of techniques to thoroughly investigate MsbA in lipid bilayers as well as the effects of potential inhibitors of this protein. We envisage that this platform will facilitate the development of next-generation antimicrobials that inhibit MsbA or other essential membrane transporters in microorganisms.
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Affiliation(s)
- Karan Bali
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, CB3 0AS Cambridge, U. K.
| | - Charlotte Guffick
- Department
of Pharmacology, University of Cambridge, CB2 1PD Cambridge, U. K.
| | - Reece McCoy
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, CB3 0AS Cambridge, U. K.
| | - Zixuan Lu
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, CB3 0AS Cambridge, U. K.
| | - Clemens F. Kaminski
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, CB3 0AS Cambridge, U. K.
| | - Ioanna Mela
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, CB3 0AS Cambridge, U. K.
| | - Róisín M. Owens
- Department
of Chemical Engineering and Biotechnology, University of Cambridge, CB3 0AS Cambridge, U. K.
| | - Hendrik W. van Veen
- Department
of Pharmacology, University of Cambridge, CB2 1PD Cambridge, U. K.
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Zhang Y, Cui R, Shi G, Dai Y, Dong J, Wu Q, Zhang H, Dai J. Dioxin-like polychlorinated biphenyl 126 (PCB126) disrupts gut microbiota-host metabolic dysfunction in mice via aryl hydrocarbon receptor activation. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 236:113448. [PMID: 35367886 DOI: 10.1016/j.ecoenv.2022.113448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 03/17/2022] [Accepted: 03/20/2022] [Indexed: 05/15/2023]
Abstract
Exposure to environmental pollutants, including dioxin-like pollutants, can cause numerous health issues. A common exposure route to pollutants is through contaminated foods, and thus the gastrointestinal system and gut microbiota are often exposed to high amounts of pollutants. Multiple studies have focused on the imbalance in intestinal microbiota composition caused by dioxin-like pollutants. Here, we examined the effects of polychlorinated biphenyl 126 (PCB126) on the composition and functions of gut microbes through metagenomic sequencing, and explored the correlations between microflora dysbiosis and aryl hydrocarbon receptor (AHR) signaling. Adult male wild-type and Ahr-/- mice with a C57BL/6 background were weekly exposed to 50 μg/kg body weight of PCB126 for 8 weeks. Results showed that PCB126 had the opposite effect on gut microbiota composition and diversity in the wild-type and Ahr-/- mice. Functional prediction found that PCB126 exposure mainly altered carbon metabolism and signal regulatory pathways in wild-type mice but impacted DNA replication and lipopolysaccharide biosynthesis in Ahr-/- mice. In wild-type mice, PCB126 exposure induced liver injury, decreased serum lipid content, and delayed gastrointestinal motility, which were significantly correlated to several specific bacterial taxa, such as Helicobacter. Following AHR knockout, however, the holistic effects of PCB126 on the host were lessened or abolished. These results suggest that PCB126 may disrupt host metabolism and gut microbiota dynamics via AHR activation. Overall, our findings provide new insight into the complex interactions between host metabolism and gut microbiota, which may contribute to grouped assessment of environmental pollutants in the future.
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Affiliation(s)
- Yaran Zhang
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Ruina Cui
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Guohui Shi
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Yi Dai
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Jiuhong Dong
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qi Wu
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hongxia Zhang
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jiayin Dai
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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7
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Sharma N, Lavania M, Lal B. Biosurfactant: A Next-Generation Tool for Sustainable Remediation of Organic Pollutants. Front Microbiol 2022; 12:821531. [PMID: 35265051 PMCID: PMC8899659 DOI: 10.3389/fmicb.2021.821531] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 12/20/2021] [Indexed: 12/04/2022] Open
Abstract
Petroleum hydrocarbons are energy resources that majorly contribute pollutants to the environment. These pollutants may cause serious health issues, and hence, for the regulation of these contaminants, the development of sustainable alternative technologies has been considered, without causing further harm to the environment. One such alternative is biosurfactants (having low toxicity and being biodegradable) produced by numerous microbial species that have a tendency to remediate organic pollutants. Biosurfactants are amphiphilic compounds that are categorized into two types based on their molecular mass. Biosurfactants can be generated extracellularly or as a part of the cell membrane of microorganisms (bacteria, fungi, and algae). This review provides a detailed view of the types of biosurfactants, their properties, and the mechanism involved in the degradation of oil spills.
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Affiliation(s)
- Neha Sharma
- Microbial Biotechnology, Environmental and Industrial Biotechnology Division, The Energy and Resources Institute (TERI), New Delhi, India
| | - Meeta Lavania
- Microbial Biotechnology, Environmental and Industrial Biotechnology Division, The Energy and Resources Institute (TERI), New Delhi, India
| | - Banwari Lal
- Microbial Biotechnology, Environmental and Industrial Biotechnology Division, The Energy and Resources Institute (TERI), New Delhi, India
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Hua M, Liu J, Du P, Liu X, Li M, Wang H, Chen C, Xu X, Jiang Y, Wang Y, Zeng H, Li A. The novel outer membrane protein from OprD/Occ family is associated with hypervirulence of carbapenem resistant Acinetobacter baumannii ST2/KL22. Virulence 2021; 12:1-11. [PMID: 33258407 PMCID: PMC7781578 DOI: 10.1080/21505594.2020.1856560] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 01/04/2023] Open
Abstract
Acinetobacter baumannii has become a major healthcare threat that causes nosocomial infections, especially in critically ill patients. The spread of carbapenem-resistant A. baumannii (CRAB) strains has long been a clinical concern. It is important to study the epidemiology and virulence characteristics of different CRAB isolates in order to tailor infection prevention and antibiotic prescribing. In this study, a total of 71 CRAB isolates were collected in the hospital, and clinical characteristics of infections were analyzed. The genomic characteristics and phylogenetic relationships were elucidated based on genome sequencing and analysis. The isolates were assigned to three sequence types (STs, Pasteur) and nine capsular polysaccharide (KL) types, among which ST2/KL22 was the most prevalent CRAB in the hospital. Even though all the ST2/KL22 isolates contained the same reported virulence genes, one specific clade of ST2/KL22 showed more pathogenic in mouse infection model. Complete genomic analysis revealed differences at the oprD locus between the low- and high-virulent isolates. More specifically, a premature stop codon in the low-virulence strains resulted in truncated OprD expression. By evaluating pathogenicity in C57BL/6 J mice, knock-out of oprD in high-virulent isolate resulted in virulence attenuation, and complementing the avirulent strain with full-length oprD from high-virulent isolate enhanced virulence of the former. The oprD gene may be associated with the enhanced virulence of the specific ST2/KL22 clone, which provides a potential molecular marker for screening the hypervirulent A. baumannii strains.
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Affiliation(s)
- Mingxi Hua
- Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing
| | - Jingyuan Liu
- Department of Critical Care Medicine, Beijing Ditan Hospital, Capital Medical University, Beijing
| | - Pengcheng Du
- Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing
| | - Xinzhe Liu
- Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing
| | - Min Li
- Clinical Laboratory, Beijing Ditan Hospital, Capital Medical University, Beijing, China
| | - Huizhu Wang
- Clinical Laboratory, Beijing Ditan Hospital, Capital Medical University, Beijing, China
| | - Chen Chen
- Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing
| | - Xinmin Xu
- Clinical Laboratory, Beijing Ditan Hospital, Capital Medical University, Beijing, China
| | - Yu Jiang
- Department of Stomatology, Beijing Children’s Hospital, Capital Medical University, Beijing
| | - Yajie Wang
- Clinical Laboratory, Beijing Ditan Hospital, Capital Medical University, Beijing, China
| | - Hui Zeng
- Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing
- Beijing Key Laboratory of Emerging Infectious Diseases, Beijing
| | - Ang Li
- Department of Critical Care Medicine, Beijing Ditan Hospital, Capital Medical University, Beijing
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Abstract
The outer membrane of Gram-negative bacteria is essential for their survival in harsh environments and provides intrinsic resistance to many antibiotics. This membrane is remarkable; it is a highly asymmetric lipid bilayer. The inner leaflet of the outer membrane contains phospholipids, whereas the fatty acyl chains attached to lipopolysaccharide (LPS) comprise the hydrophobic portion of the outer leaflet. This lipid asymmetry, and in particular the exclusion of phospholipids from the outer leaflet, is key to creating an almost impenetrable barrier to hydrophobic molecules that can otherwise pass through phospholipid bilayers. It has long been known that these lipids are not made in the outer membrane. It is now believed that conserved multisubunit protein machines extract these lipids after their synthesis is completed at the inner membrane and transport them to the outer membrane. A longstanding question is how the cell builds and maintains this asymmetric lipid bilayer in coordination with the assembly of the other components of the cell envelope. This Review describes the trans-envelope lipid transport systems that have been identified to participate in outer-membrane biogenesis: LPS transport via the Lpt machine, and phospholipid transport via the Mla pathway and several recently proposed transporters.
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Affiliation(s)
| | - Daniel Kahne
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
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Bhatt P, Verma A, Gangola S, Bhandari G, Chen S. Microbial glycoconjugates in organic pollutant bioremediation: recent advances and applications. Microb Cell Fact 2021; 20:72. [PMID: 33736647 PMCID: PMC7977309 DOI: 10.1186/s12934-021-01556-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 02/27/2021] [Indexed: 02/06/2023] Open
Abstract
The large-scale application of organic pollutants (OPs) has contaminated the air, soil, and water. Persistent OPs enter the food supply chain and create several hazardous effects on living systems. Thus, there is a need to manage the environmental levels of these toxicants. Microbial glycoconjugates pave the way for the enhanced degradation of these toxic pollutants from the environment. Microbial glycoconjugates increase the bioavailability of these OPs by reducing surface tension and creating a solvent interface. To date, very little emphasis has been given to the scope of glycoconjugates in the biodegradation of OPs. Glycoconjugates create a bridge between microbes and OPs, which helps to accelerate degradation through microbial metabolism. This review provides an in-depth overview of glycoconjugates, their role in biofilm formation, and their applications in the bioremediation of OP-contaminated environments.
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Affiliation(s)
- Pankaj Bhatt
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Laboratory for Lingnan Modern Agriculture, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, 510642, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, China
| | - Amit Verma
- Department of Biochemistry, College of Basic Science and Humanities, SD Agricultural University, Gujarat, 385506, India
| | - Saurabh Gangola
- School of Agriculture, Graphic Era Hill University, Bhimtal Campus, Dehradun, Uttarakhand, 248002, India
| | - Geeta Bhandari
- Department of Biotechnology, Sardar Bhagwan Singh University, Dehradun, Uttarakhand, 248161, India
| | - Shaohua Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Laboratory for Lingnan Modern Agriculture, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, 510642, China.
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou, 510642, China.
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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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12
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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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Whitfield C, Wear SS, Sande C. Assembly of Bacterial Capsular Polysaccharides and Exopolysaccharides. Annu Rev Microbiol 2020; 74:521-543. [PMID: 32680453 DOI: 10.1146/annurev-micro-011420-075607] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Polysaccharides are dominant features of most bacterial surfaces and are displayed in different formats. Many bacteria produce abundant long-chain capsular polysaccharides, which can maintain a strong association and form a capsule structure enveloping the cell and/or take the form of exopolysaccharides that are mostly secreted into the immediate environment. These polymers afford the producing bacteria protection from a wide range of physical, chemical, and biological stresses, support biofilms, and play critical roles in interactions between bacteria and their immediate environments. Their biological and physical properties also drive a variety of industrial and biomedical applications. Despite the immense variation in capsular polysaccharide and exopolysaccharide structures, patterns are evident in strategies used for their assembly and export. This review describes recent advances in understanding those strategies, based on a wealth of biochemical investigations of select prototypes, supported by complementary insight from expanding structural biology initiatives. This provides a framework to identify and distinguish new systems emanating from genomic studies.
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Affiliation(s)
- Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada;
| | - Samantha S Wear
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada;
| | - Caitlin Sande
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada;
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14
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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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15
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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: 87] [Impact Index Per Article: 21.8] [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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16
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Budde I, Litschko C, Führing JI, Gerardy-Schahn R, Schubert M, Fiebig T. An enzyme-based protocol for cell-free synthesis of nature-identical capsular oligosaccharides from Actinobacillus pleuropneumoniae serotype 1. J Biol Chem 2020; 295:5771-5784. [PMID: 32152227 PMCID: PMC7186170 DOI: 10.1074/jbc.ra120.012961] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/09/2020] [Indexed: 11/06/2022] Open
Abstract
Actinobacillus pleuropneumoniae (App) is the etiological agent of acute porcine pneumonia and responsible for severe economic losses worldwide. The capsule polymer of App serotype 1 (App1) consists of [4)-GlcNAc-β(1,6)-Gal-α-1-(PO4-] repeating units that are O-acetylated at O-6 of the GlcNAc. It is a major virulence factor and was used in previous studies in the successful generation of an experimental glycoconjugate vaccine. However, the application of glycoconjugate vaccines in the animal health sector is limited, presumably because of the high costs associated with harvesting the polymer from pathogen culture. Consequently, here we exploited the capsule polymerase Cps1B of App1 as an in vitro synthesis tool and an alternative for capsule polymer provision. Cps1B consists of two catalytic domains, as well as a domain rich in tetratricopeptide repeats (TPRs). We compared the elongation mechanism of Cps1B with that of a ΔTPR truncation (Cps1B-ΔTPR). Interestingly, the product profiles displayed by Cps1B suggested processive elongation of the nascent polymer, whereas Cps1B-ΔTPR appeared to work in a more distributive manner. The dispersity of the synthesized products could be reduced by generating single-action transferases and immobilizing them on individual columns, separating the two catalytic activities. Furthermore, we identified the O-acetyltransferase Cps1D of App1 and used it to modify the polymers produced by Cps1B. Two-dimensional NMR analyses of the products revealed O-acetylation levels identical to those of polymer harvested from App1 culture supernatants. In conclusion, we have established a protocol for the pathogen-free in vitro synthesis of tailored, nature-identical App1 capsule polymers.
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Affiliation(s)
- Insa Budde
- Institute of Clinical Biochemistry, Hannover Medical School, Carl-Neuberg Strasse 1, 30625 Hannover, Germany
| | - Christa Litschko
- Institute of Clinical Biochemistry, Hannover Medical School, Carl-Neuberg Strasse 1, 30625 Hannover, Germany
| | - Jana I Führing
- Institute of Clinical Biochemistry, Hannover Medical School, Carl-Neuberg Strasse 1, 30625 Hannover, Germany; Fraunhofer International Consortium for Anti-Infective Research (iCAIR), 30625 Hannover, Germany
| | - Rita Gerardy-Schahn
- Institute of Clinical Biochemistry, Hannover Medical School, Carl-Neuberg Strasse 1, 30625 Hannover, Germany; Fraunhofer International Consortium for Anti-Infective Research (iCAIR), 30625 Hannover, Germany
| | - Mario Schubert
- Department of Biosciences, University of Salzburg, 5020 Salzburg, Austria
| | - Timm Fiebig
- Institute of Clinical Biochemistry, Hannover Medical School, Carl-Neuberg Strasse 1, 30625 Hannover, Germany.
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17
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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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18
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Analysis of the Topology and Active-Site Residues of WbbF, a Putative O-Polysaccharide Synthase from Salmonella enterica Serovar Borreze. J Bacteriol 2020; 202:JB.00625-19. [PMID: 31792013 DOI: 10.1128/jb.00625-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 11/22/2019] [Indexed: 02/06/2023] Open
Abstract
Bacterial lipopolysaccharides are major components and contributors to the integrity of Gram-negative outer membranes. The more conserved lipid A-core part of this complex glycolipid is synthesized separately from the hypervariable O-antigenic polysaccharide (OPS) part, and they are joined in the periplasm prior to translocation to the outer membrane. Three different biosynthesis strategies are recognized for OPS biosynthesis, and one, the synthase-dependent pathway, is currently confined to a single example: the O:54 antigen from Salmonella enterica serovar Borreze. Synthases are complex enzymes that have the capacity to both polymerize and export bacterial polysaccharides. Although synthases like cellulose synthase are widespread, they typically polymerize a glycan without employing a lipid-linked intermediate, unlike the O:54 synthase (WbbF), which produces an undecaprenol diphosphate-linked product. This raises questions about the overall similarity between WbbF and conventional synthases. In this study, we examine the topology of WbbF, revealing four membrane-spanning helices, compared to the eight in cellulose synthase. Molecular modeling of the glycosyltransferase domain of WbbF indicates a similar architecture, and site-directed mutagenesis confirmed that residues important for catalysis and processivity in cellulose synthase are conserved in WbbF and required for its activity. These findings indicate that the glycosyltransferase mechanism of WbbF and classic synthases are likely conserved despite the use of a lipid acceptor for chain extension by WbbF.IMPORTANCE Glycosyltransferases play a critical role in the synthesis of a wide variety of bacterial polysaccharides. These include O-antigenic polysaccharides, which form the distal component of lipopolysaccharides and provide a protective barrier important for survival and host-pathogen interactions. Synthases are a subset of glycosyltransferases capable of coupled synthesis and export of glycans. Currently, the O:54 antigen of Salmonella enterica serovar Borreze involves the only example of an O-polysaccharide synthase, and its generation of a lipid-linked product differentiates it from classical synthases. Here, we explore features conserved in the O:54 enzyme and classical synthases to shed light on the structure and function of the unusual O:54 enzyme.
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19
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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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20
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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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21
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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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22
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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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23
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Periplasmic depolymerase provides insight into ABC transporter-dependent secretion of bacterial capsular polysaccharides. Proc Natl Acad Sci U S A 2018; 115:E4870-E4879. [PMID: 29735649 PMCID: PMC6003464 DOI: 10.1073/pnas.1801336115] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Capsules are critical virulence determinants for bacterial pathogens. They are composed of capsular polysaccharides (CPSs) with diverse structures, whose assembly on the cell surface is often powered by a conserved ABC transporter. Current capsule-assembly models include a contiguous trans-envelope channel directing nascent CPSs from the transporter to the cell surface. This conserved apparatus is an attractive target for antivirulence antimicrobial development. This work describes a CPS depolymerizing lyase enzyme found in the Burkholderiales and unique structural features that define its mechanism, CPS specificity, and evolution to function in the periplasm in a noncatabolic role. The activity of this enzyme provides evidence that CPS assembled in an ABC transporter-dependent system is exposed to periplasm during translocation to the cell surface. Capsules are surface layers of hydrated capsular polysaccharides (CPSs) produced by many bacteria. The human pathogen Salmonella enterica serovar Typhi produces “Vi antigen” CPS, which contributes to virulence. In a conserved strategy used by bacteria with diverse CPS structures, translocation of Vi antigen to the cell surface is driven by an ATP-binding cassette (ABC) transporter. These transporters are engaged in heterooligomeric complexes proposed to form an enclosed translocation conduit to the cell surface, allowing the transporter to power the entire process. We identified Vi antigen biosynthesis genetic loci in genera of the Burkholderiales, which are paradoxically distinguished from S. Typhi by encoding VexL, a predicted pectate lyase homolog. Biochemical analyses demonstrated that VexL is an unusual metal-independent endolyase with an acidic pH optimum that is specific for O-acetylated Vi antigen. A 1.22-Å crystal structure of the VexL-Vi antigen complex revealed features which distinguish common secreted catabolic pectate lyases from periplasmic VexL, which participates in cell-surface assembly. VexL possesses a right-handed parallel β-superhelix, of which one face forms an electropositive glycan-binding groove with an extensive hydrogen bonding network that includes Vi antigen acetyl groups and confers substrate specificity. VexL provided a probe to interrogate conserved features of the ABC transporter-dependent export model. When introduced into S. Typhi, VexL localized to the periplasm and degraded Vi antigen. In contrast, a cytosolic derivative had no effect unless export was disrupted. These data provide evidence that CPS assembled in ABC transporter-dependent systems is actually exposed to the periplasm during envelope translocation.
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Dibutyl phthalate alters the metabolic pathways of microbes in black soils. Sci Rep 2018; 8:2605. [PMID: 29422490 PMCID: PMC5805725 DOI: 10.1038/s41598-018-21030-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 01/29/2018] [Indexed: 01/08/2023] Open
Abstract
Dibutyl phthalate (DBP) is well known as a high-priority pollutant. This study explored the impacts of DBP on the metabolic pathways of microbes in black soils in the short term (20 days). The results showed that the microbial communities were changed in black soils with DBP. In nitrogen cycling, the abundances of the genes were elevated by DBP. DBP contamination facilitated 3'-phosphoadenosine-5'-phosphosulfate (PAPS) formation, and the gene flux of sulfate metabolism was increased. The total abundances of ABC transporters and the gene abundances of the monosaccharide-transporting ATPases MalK and MsmK were increased by DBP. The total abundance of two-component system (TCS) genes and the gene abundances of malate dehydrogenase, histidine kinase and citryl-CoA lyase were increased after DBP contamination. The total abundance of phosphotransferase system (PTS) genes and the gene abundances of phosphotransferase, Crr and BglF were raised by DBP. The increased gene abundances of ABC transporters, TCS and PTS could be the reasons for the acceleration of nitrogen, carbon and sulfate metabolism. The degrading-genes of DBP were increased markedly in soil exposed to DBP. In summary, DBP contamination altered the microbial community and enhanced the gene abundances of the carbon, nitrogen and sulfur metabolism in black soils in the short term.
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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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