1
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Zhou Y, Rernglit W, Fukamizo T, Sucharitakul J, Suginta W. A three-step "ping-pong" mechanism of a GH20 β-N-acetylglucosaminidase from Vibrio campbellii belonging to a major Clade A-I of the phylogenetic tree of the enzyme superfamily. Biochem Biophys Res Commun 2024; 729:150357. [PMID: 39002194 DOI: 10.1016/j.bbrc.2024.150357] [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: 06/24/2024] [Accepted: 07/04/2024] [Indexed: 07/15/2024]
Abstract
β-N-acetylglucosaminidase (GlcNAcase) is an essential biocatalyst in chitin assimilation by marine Vibrio species, which rely on chitin as their main carbon source. Structure-based phylogenetic analysis of the GlcNAcase superfamily revealed that a GlcNAcase from Vibrio campbellii, formerly named V. harveyi, (VhGlcNAcase) belongs to a major clade, Clade A-I, of the phylogenetic tree. Pre-steady-state and steady-state kinetic analysis of the reaction catalysed by VhGlcNAcase with the fluorogenic substrate 4-methylumbelliferyl N-acetyl-β-D-glucosaminide suggested the following mechanism: (1) the Michaelis-Menten complex is formed in a rapid enzyme-substrate equilibrium with a Kd of 99.1 ± 1 μM. (2) The glycosidic bond is cleaved by the action of the catalytic residue Glu438, followed by the rapid release of the aglycone product with a rate constant (k2) of 53.3 ± 1 s-1. (3) After the formation of an oxazolinium ion intermediate with the assistance of Asp437, the anomeric carbon of the transition state is attacked by a catalytic water, followed by release of the glycone product with a rate constant (k3) of 14.6 s-1, which is rate-limiting. The result clearly indicated a three-step "ping-pong" mechanism for VhGlcNAcase.
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Affiliation(s)
- Yong Zhou
- School of Biomolecular Science and Engineering (BSE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, 21210, Thailand
| | - Waraporn Rernglit
- School of Chemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand
| | - Tamo Fukamizo
- School of Biomolecular Science and Engineering (BSE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, 21210, Thailand.
| | - Jeerus Sucharitakul
- Department of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand.
| | - Wipa Suginta
- School of Biomolecular Science and Engineering (BSE), Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, 21210, Thailand.
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2
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Moran CL, Debowski A, Vrielink A, Stubbs K, Sarkar-Tyson M. N-acetyl-β-hexosaminidase activity is important for chitooligosaccharide metabolism and biofilm formation in Burkholderia pseudomallei. Environ Microbiol 2024; 26:e16571. [PMID: 38178319 DOI: 10.1111/1462-2920.16571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 12/18/2023] [Indexed: 01/06/2024]
Abstract
Burkholderia pseudomallei is a saprophytic Gram-negative bacillus that can cause the disease melioidosis. Although B. pseudomallei is a recognised member of terrestrial soil microbiomes, little is known about its contribution to the saprophytic degradation of polysaccharides within its niche. For example, while chitin is predicted to be abundant within terrestrial soils the chitinolytic capacity of B. pseudomallei is yet to be defined. This study identifies and characterises a putative glycoside hydrolase, bpsl0500, which is expressed by B. pseudomallei K96243. Recombinant BPSL0500 was found to exhibit activity against substrate analogues and GlcNAc disaccharides relevant to chitinolytic N-acetyl-β-d-hexosaminidases. In B. pseudomallei, bpsl0500 was found to be essential for both N-acetyl-β-d-hexosaminidase activity and chitooligosaccharide metabolism. Furthermore, bpsl0500 was also observed to significantly affect biofilm deposition. These observations led to the identification of BPSL0500 activity against model disaccharide linkages that are present in biofilm exopolysaccharides, a feature that has not yet been described for chitinolytic enzymes. The results in this study indicate that chitinolytic N-acetyl-β-d-hexosaminidases like bpsl0500 may facilitate biofilm disruption as well as chitin assimilation, providing dual functionality for saprophytic bacteria such as B. pseudomallei within the competitive soil microbiome.
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Affiliation(s)
- Clare L Moran
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, The University of Western Australia, Nedlands, Australia
| | - Aleksandra Debowski
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, The University of Western Australia, Nedlands, Australia
| | - Alice Vrielink
- School of Molecular Sciences, The University of Western Australia, Crawley, Australia
| | - Keith Stubbs
- School of Molecular Sciences, The University of Western Australia, Crawley, Australia
- ARC Training Centre for Next-Gen Technologies in Biomedical Analysis, School of Molecular Sciences, University of Western Australia, Crawley, Australia
| | - Mitali Sarkar-Tyson
- Marshall Centre for Infectious Disease Research and Training, School of Biomedical Sciences, The University of Western Australia, Nedlands, Australia
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3
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Nguyen VH, Wemheuer B, Song W, Bennett H, Palladino G, Burgsdorf I, Sizikov S, Steindler L, Webster NS, Thomas T. Functional characterization and taxonomic classification of novel gammaproteobacterial diversity in sponges. Syst Appl Microbiol 2023; 46:126401. [PMID: 36774720 DOI: 10.1016/j.syapm.2023.126401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 01/18/2023] [Accepted: 01/22/2023] [Indexed: 01/26/2023]
Abstract
Sponges harbour exceptionally diverse microbial communities, whose members are largely uncultured. The class Gammaproteobacteria often dominates the microbial communities of various sponge species, but most of its diversity remains functional and taxonomically uncharacterised. Here we reconstructed and characterised 32 metagenome-assembled genomes (MAGs) derived from three sponge species. These MAGs represent ten novel species and belong to seven orders, of which one is new. We propose nomenclature for all these taxa. These new species comprise sponge-specific bacteria with varying levels of host specificity. Functional gene profiling highlights significant differences in metabolic capabilities across the ten species, though each also often exhibited a large degree of metabolic diversity involving various nitrogen- and sulfur-based compounds. The genomic features of the ten species suggest they have evolved to form symbiotic interaction with their hosts or are well-adapted to survive within the sponge environment. These Gammaproteobacteria are proposed to scavenge substrates from the host environment, including metabolites or cellular components of the sponge. Their diverse metabolic capabilities may allow for efficient cycling of organic matter in the sponge environment, potentially to the benefit of the host and other symbionts.
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Affiliation(s)
- Viet Hung Nguyen
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Bernd Wemheuer
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Weizhi Song
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Holly Bennett
- Australian Institute of Marine Science, Townsville, Queensland, Australia; Cawthron Institute, Nelson, New Zealand
| | - Giorgia Palladino
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia; Unit of Microbiome Science and Biotechnology, Department of Pharmacy and Biotechnology, University of Bologna, via Belmeloro 6, 40126 Bologna, Italy
| | | | | | | | - Nicole S Webster
- Australian Institute of Marine Science, Townsville, Queensland, Australia; Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, Australia; Australian Antarctic Division, Kingston, Tasmania, Australia
| | - Torsten Thomas
- Centre for Marine Science and Innovation, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia.
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4
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Mathew BJ, Gupta P, Naaz T, Rai R, Gupta S, Gupta S, Chaurasiya SK, Purwar S, Biswas D, Vyas AK, Singh AK. Role of Streptococcus pneumoniae extracellular glycosidases in immune evasion. Front Cell Infect Microbiol 2023; 13:1109449. [PMID: 36816580 PMCID: PMC9937060 DOI: 10.3389/fcimb.2023.1109449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Accepted: 01/16/2023] [Indexed: 02/05/2023] Open
Abstract
Streptococcus pneumoniae (pneumococcus) typically colonizes the human upper airway asymptomatically but upon reaching other sites of the host body can cause an array of diseases such as pneumonia, bacteremia, otitis media, and meningitis. Be it colonization or progression to disease state, pneumococcus faces multiple challenges posed by host immunity ranging from complement mediated killing to inflammation driven recruitment of bactericidal cells for the containment of the pathogen. Pneumococcus has evolved several mechanisms to evade the host inflicted immune attack. The major pneumococcal virulence factor, the polysaccharide capsule helps protect the bacteria from complement mediated opsonophagocytic killing. Another important group of pneumococcal proteins which help bacteria to establish and thrive in the host environment is surface associated glycosidases. These enzymes can hydrolyze host glycans on glycoproteins, glycolipids, and glycosaminoglycans and consequently help bacteria acquire carbohydrates for growth. Many of these glycosidases directly or indirectly facilitate bacterial adherence and are known to modulate the function of host defense/immune proteins likely by removing glycans and thereby affecting their stability and/or function. Furthermore, these enzymes are known to contribute the formation of biofilms, the bacterial communities inherently resilient to antimicrobials and host immune attack. In this review, we summarize the role of these enzymes in host immune evasion.
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Affiliation(s)
- Bijina J. Mathew
- Department of Biological Science and Engineering, Maulana Azad National Institute of Technology, Bhopal, India
| | - Priyal Gupta
- Department of Microbiology, All India Institute of Medical Sciences, Bhopal, India
| | - Tabassum Naaz
- Department of Microbiology, All India Institute of Medical Sciences, Bhopal, India
| | - Rupal Rai
- Department of Biological Science and Engineering, Maulana Azad National Institute of Technology, Bhopal, India
| | - Sudheer Gupta
- Research and Development, 3B Blackbio Biotech India Ltd., Bhopal, India
| | - Sudipti Gupta
- Abigail Wexner Research Institute, Nationwide Children’s Hospital, Columbus, OH, United States
| | - Shivendra K. Chaurasiya
- Department of Biological Science and Engineering, Maulana Azad National Institute of Technology, Bhopal, India
| | - Shashank Purwar
- Department of Microbiology, All India Institute of Medical Sciences, Bhopal, India
| | - Debasis Biswas
- Department of Microbiology, All India Institute of Medical Sciences, Bhopal, India
| | - Ashish Kumar Vyas
- John C Martin Centre for Liver Research and Innovation, Liver Foundation Sonarpur, Kolkata, India
| | - Anirudh K. Singh
- School of Sciences, SAM Global University, Raisen, India,*Correspondence: Anirudh K. Singh,
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5
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Temporal analysis of N-acetylglucosamine extension of N-glycans in the middle silk gland of silkworm Bombyx mori. J Biosci Bioeng 2022; 133:533-540. [PMID: 35397991 DOI: 10.1016/j.jbiosc.2022.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 02/27/2022] [Accepted: 03/02/2022] [Indexed: 12/30/2022]
Abstract
N-glycosylation of proteins is an important post-translational modification in eukaryotic cells. One of the key modifications in protein N-glycosylation is N-acetylglucosamine (GlcNAc) extension mediated by N-acetylglucosaminyltransferase I (GNTI), which triggers N-glycan maturation from high-mannose-type to hybrid- and complex-type structures in Golgi. However, the temporal contributions of GNTI to GlcNAc extension and the resultant N-glycan structures in insects have not been analyzed. Here, focusing on GlcNAc extension of N-glycan in the silkworm Bombyx mori, we analyzed the temporal N-glycan alterations in the middle silk gland (MSG) and characterized the property of key enzyme for complex-type N-glycan biosynthesis, B. mori GNTI (BmGNTI). N-glycan analysis of N-glycoproteins in the MSG demonstrated that BmGNTI identified and characterized in this study consistently contributed to GlcNAc extension of N-glycans, which led to the accumulation of GlcNAc-extended N-glycans as predominant structures throughout the MSG development. The expression profile of GlcNAc extension-related genes revealed that the enzymes contributing to the hydrolysis of GlcNAc showed stage-specific expressions, thereby resulting in accumulations of the end product N-glycans of the enzyme. These results lead to the speculation that not BmGNTI but rather glycosylhydrolases critically influenced the structural formations and the changes in the ratio of N-glycans with GlcNAc residue(s) in MSG.
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6
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Wang X, Shang Y, Wei Q, Wu X, Dou H, Zhang H, Zhou S, Sha W, Sun G, Ma S, Zhang H. Comparative Analyses of the Gut Microbiome of Two Fox Species, the Red Fox (Vulpes Vulpes) and Corsac Fox (Vulpes Corsac), that Occupy Different Ecological Niches. MICROBIAL ECOLOGY 2022; 83:753-765. [PMID: 34189610 DOI: 10.1007/s00248-021-01806-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
The gut microbiome is integral for the host's living and environmental adaptation and crucially important for understanding host adaptive mechanisms. The red fox (Vulpes vulpes) dominates a wider ecological niche and more complicated habitat than that of the corsac fox (V. corsac). However, the adaptive mechanisms (in particular, the gut microbiome responsible for this kind of difference) are still unclear. Therefore, we investigated the gut microbiome of these two species in the Hulunbuir grassland, China, and evaluated their microbiome composition, function, and adaptive mechanisms. We profiled the gut microbiome and metabolism function of red and corsac foxes via 16S rRNA gene and metagenome sequencing. The foxes harbored species-specific microbiomes and functions that were related to ecological niche and habitat. The red fox had abundant Bacteroides, which leads to significant enrichment of metabolic pathways (K12373 and K21572) and enzymes related to chitin and carbohydrate degradation that may help the red fox adapt to a wider niche. The corsac fox harbored large proportions of Blautia, Terrisporobacter, and ATP-binding cassette (ABC) transporters (K01990, K02003, and K06147) that can help maintain corsac fox health, allowing it to live in harsh habitats. These results indicate that the gut microbiome of the red and corsac foxes may have different abilities which may provide these species with differing capabilities to adapt to different ecological niches and habitats, thus providing important microbiome data for understanding the mechanisms of host adaptation to different niches and habitats.
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Affiliation(s)
- Xibao Wang
- College of Life Science, Qufu Normal University, Qufu, China
| | - Yongquan Shang
- College of Life Science, Qufu Normal University, Qufu, China
| | - Qinguo Wei
- College of Life Science, Qufu Normal University, Qufu, China
| | - Xiaoyang Wu
- College of Life Science, Qufu Normal University, Qufu, China
| | - Huashan Dou
- Hulunbuir Academy of Inland Lakes in Northern Cold & Arid Areas, Hulunbuir, China
| | - Huanxin Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Shengyang Zhou
- College of Life Science, Qufu Normal University, Qufu, China
| | - Weilai Sha
- College of Life Science, Qufu Normal University, Qufu, China
| | - Guolei Sun
- College of Life Science, Qufu Normal University, Qufu, China
| | - Shengchao Ma
- College of Life Science, Qufu Normal University, Qufu, China
| | - Honghai Zhang
- College of Life Science, Qufu Normal University, Qufu, China.
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7
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Mechanism of cooperative N-glycan processing by the multi-modular endoglycosidase EndoE. Nat Commun 2022; 13:1137. [PMID: 35241669 PMCID: PMC8894350 DOI: 10.1038/s41467-022-28722-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 02/04/2022] [Indexed: 11/29/2022] Open
Abstract
Bacteria produce a remarkably diverse range of glycoside hydrolases to metabolize glycans from the environment as a primary source of nutrients, and to promote the colonization and infection of a host. Here we focus on EndoE, a multi-modular glycoside hydrolase secreted by Enterococcus faecalis, one of the leading causes of healthcare-associated infections. We provide X-ray crystal structures of EndoE, which show an architecture composed of four domains, including GH18 and GH20 glycoside hydrolases connected by two consecutive three α-helical bundles. We determine that the GH20 domain is an exo-β-1,2-N-acetylglucosaminidase, whereas the GH18 domain is an endo-β-1,4-N-acetylglucosaminidase that exclusively processes the central core of complex-type or high-mannose-type N-glycans. Both glycoside hydrolase domains act in a concerted manner to process diverse N-glycans on glycoproteins, including therapeutic IgG antibodies. EndoE combines two enzyme domains with distinct functions and glycan specificities to play a dual role in glycan metabolism and immune evasion. EndoE is a multi-domain glycoside hydrolase of the human pathogen Enterococcus faecalis. Here, the authors present crystal structures of EndoE and provide biochemical insights into the molecular basis of EndoE’s substrate specificity and catalytic mechanism.
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8
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Robertsson C, Svensäter G, Blum Z, Jakobsson ME, Wickström C. Proteomic response in Streptococcus gordonii DL1 biofilm cells during attachment to salivary MUC5B. J Oral Microbiol 2021; 13:1967636. [PMID: 34447490 PMCID: PMC8386731 DOI: 10.1080/20002297.2021.1967636] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background Salivary mucin MUC5B seems to promote biodiversity in dental biofilms, and thereby oral health, for example, by inducing synergistic ‘mucolytic’ activities in a variety of microbial species that need to cooperate for the release of nutrients from the complex glycoprotein. Knowledge of how early colonizers interact with host salivary proteins is integral to better understand the maturation of putatively harmful oral biofilms and could provide key insights into biofilm physiology. Methods The early oral colonizer Streptococcus gordonii DL1 was grown planktonically and in biofilm flow cell systems with uncoated, MUC5B or low-density salivary protein (LDP) coated surfaces. Bacterial cell proteins were extracted and analyzed using a quantitative mass spectrometry-based workflow, and differentially expressed proteins were identified. Results and conclusions Overall, the proteomic profiles of S. gordonii DL1 were similar across conditions. Six novel biofilm cell proteins and three planktonic proteins absent in all biofilm cultures were identified. These differences may provide insights into mechanisms for adaptation to biofilm growth in this species. Salivary MUC5B also elicited specific responses in the biofilm cell proteome. These regulations may represent mechanisms by which this mucin could promote colonization of the commensal S. gordonii in oral biofilms.
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Affiliation(s)
- Carolina Robertsson
- Department of Oral Biology and Pathology, Faculty of Odontology, Malmö University, Malmö, Sweden
| | - Gunnel Svensäter
- Department of Oral Biology and Pathology, Faculty of Odontology, Malmö University, Malmö, Sweden
| | - Zoltan Blum
- Department of Biomedical Science, Faculty of Health and Society, Malmö University, Malmö, Sweden
| | | | - Claes Wickström
- Department of Oral Biology and Pathology, Faculty of Odontology, Malmö University, Malmö, Sweden
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9
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Andreassen PR, Trappetti C, Minhas V, Nielsen FD, Pakula K, Paton JC, Jørgensen MG. Host-glycan metabolism is regulated by a species-conserved two-component system in Streptococcus pneumoniae. PLoS Pathog 2020; 16:e1008332. [PMID: 32130269 PMCID: PMC7075642 DOI: 10.1371/journal.ppat.1008332] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 03/16/2020] [Accepted: 01/18/2020] [Indexed: 12/16/2022] Open
Abstract
Pathogens of the Streptococcus genus inhabit many different environmental niches during the course of an infection in a human host and the bacteria must adjust their metabolism according to available nutrients. Despite their lack of the citric-acid cycle, some streptococci proliferate in niches devoid of a readily available carbohydrate source. Instead they rely on carbohydrate scavenging for energy acquisition, which are obtained from the host. Here we discover a two-component system (TCS07) of Streptococcus pneumoniae that responds to glycoconjugated structures on proteins present on the host cells. Using next-generation RNA sequencing we find that the uncharacterized TCS07 regulon encodes proteins important for host-glycan processing and transporters of the released glycans, as well as intracellular carbohydrate catabolizing enzymes. We find that a functional TCS07 allele is required for growth on the glycoconjugated model protein fetuin. Consistently, we see a TCS07-dependent activation of the glycan degradation pathway. Thus, we pinpoint the molecular constituents responsible for sensing host derived glycans and link this to the induction of the proteins necessary for glycan degradation. Furthermore, we connect the TCS07 regulon to virulence in a mouse model, thereby establishing that host-derived glycan-metabolism is important for infection in vivo. Finally, a comparative phylogenomic analysis of strains from the Streptococcus genus reveal that TCS07 and most of its regulon is specifically conserved in species that utilize host-glycans for growth. Worldwide, Streptococcus pneumoniae is the most common cause of community acquired pneumonia with high mortality rates. Interestingly, S. pneumoniae strictly relies on carbohydrate scavenging for energy acquisition, which are obtained from the host. This is a critical step in pathogenesis and a common mechanism among Streptococcal species. In this study, we discover an uncharacterized two-component system that responds to the carbohydrate structures present on the host cells. These are important findings as we describe the molecular mechanism responsible for sensing these host derived glycans, and how this mechanism is linked to virulence, thus highlighting that glycan metabolism is important for infection in vivo, thereby posing a novel target for intervention. Our phylogenetic analysis reveals that the two-component system and the genetic regulon co-occur and are specifically conserved among Streptococcal species capable of degrading host-glycans.
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Affiliation(s)
| | - Claudia Trappetti
- Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia
| | - Vikrant Minhas
- Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia
| | | | - Kevin Pakula
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - James C. Paton
- Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, Australia
| | - Mikkel Girke Jørgensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- * E-mail:
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10
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Meekrathok P, Thongsom S, Aunkham A, Kaewmaneewat A, Kitaoku Y, Choowongkomon K, Suginta W. Novel GH-20 β-N-acetylglucosaminidase inhibitors: Virtual screening, molecular docking, binding affinity, and anti-tumor activity. Int J Biol Macromol 2020; 142:503-512. [DOI: 10.1016/j.ijbiomac.2019.09.122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 09/15/2019] [Accepted: 09/16/2019] [Indexed: 01/05/2023]
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11
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Hobbs JK, Pluvinage B, Robb M, Smith SP, Boraston AB. Two complementary α-fucosidases from Streptococcus pneumoniae promote complete degradation of host-derived carbohydrate antigens. J Biol Chem 2019; 294:12670-12682. [PMID: 31266803 DOI: 10.1074/jbc.ra119.009368] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/24/2019] [Indexed: 12/13/2022] Open
Abstract
An important aspect of the interaction between the opportunistic bacterial pathogen Streptococcus pneumoniae and its human host is its ability to harvest host glycans. The pneumococcus can degrade a variety of complex glycans, including N- and O-linked glycans, glycosaminoglycans, and carbohydrate antigens, an ability that is tightly linked to the virulence of S. pneumoniae Although S. pneumoniae is known to use a sophisticated enzyme machinery to attack the human glycome, how it copes with fucosylated glycans, which are primarily histo-blood group antigens, is largely unknown. Here, we identified two pneumococcal enzymes, SpGH29C and SpGH95C, that target α-(1→3/4) and α-(1→2) fucosidic linkages, respectively. X-ray crystallography studies combined with functional assays revealed that SpGH29C is specific for the LewisA and LewisX antigen motifs and that SpGH95C is specific for the H(O)-antigen motif. Together, these enzymes could defucosylate LewisY and LewisB antigens in a complementary fashion. In vitro reconstruction of glycan degradation cascades disclosed that the individual or combined activities of these enzymes expose the underlying glycan structure, promoting the complete deconstruction of a glycan that would otherwise be resistant to pneumococcal enzymes. These experiments expand our understanding of the extensive capacity of S. pneumoniae to process host glycans and the likely roles of α-fucosidases in this. Overall, given the importance of enzymes that initiate glycan breakdown in pneumococcal virulence, such as the neuraminidase NanA and the mannosidase SpGH92, we anticipate that the α-fucosidases identified here will be important factors in developing more refined models of the S. pneumoniae-host interaction.
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Affiliation(s)
- Joanne K Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Melissa Robb
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Steven P Smith
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
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12
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Hobbs JK, Pluvinage B, Boraston AB. Glycan-metabolizing enzymes in microbe-host interactions: the Streptococcus pneumoniae paradigm. FEBS Lett 2018; 592:3865-3897. [PMID: 29608212 DOI: 10.1002/1873-3468.13045] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 12/31/2022]
Abstract
Streptococcus pneumoniae is a frequent colonizer of the upper airways; however, it is also an accomplished pathogen capable of causing life-threatening diseases. To colonize and cause invasive disease, this bacterium relies on a complex array of factors to mediate the host-bacterium interaction. The respiratory tract is rich in functionally important glycoconjugates that display a vast range of glycans, and, thus, a key component of the pneumococcus-host interaction involves an arsenal of bacterial carbohydrate-active enzymes to depolymerize these glycans and carbohydrate transporters to import the products. Through the destruction of host glycans, the glycan-specific metabolic machinery deployed by S. pneumoniae plays a variety of roles in the host-pathogen interaction. Here, we review the processing and metabolism of the major host-derived glycans, including N- and O-linked glycans, Lewis and blood group antigens, proteoglycans, and glycogen, as well as some dietary glycans. We discuss the role of these metabolic pathways in the S. pneumoniae-host interaction, speculate on the potential of key enzymes within these pathways as therapeutic targets, and relate S. pneumoniae as a model system to glycan processing in other microbial pathogens.
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Affiliation(s)
- Joanne K Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, Canada
| | - Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, Canada
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, Canada
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Wang M, Zhang XY, Guo RR, Cai ZP, Hu XC, Chen H, Wei S, Voglmeir J, Liu L. Cloning, purification and biochemical characterization of two β- N -acetylhexosaminidases from the mucin-degrading gut bacterium Akkermansia muciniphila. Carbohydr Res 2018; 457:1-7. [DOI: 10.1016/j.carres.2017.12.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 12/13/2017] [Accepted: 12/18/2017] [Indexed: 12/15/2022]
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14
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Cell Surface Glycoside Hydrolases of Streptococcus gordonii Promote Growth in Saliva. Appl Environ Microbiol 2016; 82:5278-86. [PMID: 27316967 DOI: 10.1128/aem.01291-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 06/14/2016] [Indexed: 02/05/2023] Open
Abstract
UNLABELLED The growth of the oral commensal Streptococcus gordonii in saliva may depend on a number of glycoside hydrolases (GHs), including three cell wall-anchored proteins that are homologs of pneumococcal β-galactosidase (BgaA), β-N-acetylglucosaminidase (StrH), and endo-β-N-acetylglucosaminidase D (EndoD). In the present study, we introduced unmarked in-frame deletions into the corresponding genes of S. gordonii DL1, verified the presence (or absence) of the encoded proteins on the resulting mutant strains, and compared these strains with wild-type strain DL1 for growth and glycan foraging in saliva. The overnight growth of wild-type DL1 was reduced 3- to 10-fold by the deletion of any one or two genes and approximately 20-fold by the deletion of all three genes. The only notable change in the salivary proteome associated with this reduction of growth was a downward shift in the apparent molecular masses of basic proline-rich glycoproteins (PRG), which was accompanied by the loss of lectin binding sites for galactose-specific Erythrina cristagalli agglutinin (ECA) and mannose-specific Galanthus nivalis agglutinin (GNA). The binding of ECA to PRG was also abolished in saliva cultures of mutants that expressed cell surface BgaA alone or together with either StrH or EndoD. However, the subsequent loss of GNA binding was seen only in saliva cocultures of different mutants that together expressed all three cell surface GHs. The findings indicate that the growth of S. gordonii DL1 in saliva depends to a significant extent on the sequential actions of first BgaA and then StrH and EndoD on N-linked glycans of PRG. IMPORTANCE The ability of oral bacteria to grow on salivary glycoproteins is critical for dental plaque biofilm development. Little is known, however, about how specific salivary components are attacked and utilized by different members of the biofilm community, such as Streptococcus gordonii. Streptococcus gordonii DL1 has three cell wall-anchored glycoside hydrolases that are predicted to act on host glycans. In the present study, we introduced unmarked in-frame deletions in the corresponding genes, verified the presence (or absence) of encoded proteins on the resulting mutant strains, and compared these strains with wild-type DL1 for growth and glycan foraging in saliva. The results indicate that the growth of S. gordonii DL1 depends to a significant extent on sequential action of these cell surface GHs on N-linked glycans of basic proline-rich salivary glycoproteins, which appears to be an essential first step in salivary glycan foraging.
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Robb M, Robb CS, Higgins MA, Hobbs JK, Paton JC, Boraston AB. A Second β-Hexosaminidase Encoded in the Streptococcus pneumoniae Genome Provides an Expanded Biochemical Ability to Degrade Host Glycans. J Biol Chem 2015; 290:30888-900. [PMID: 26491009 DOI: 10.1074/jbc.m115.688630] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Indexed: 12/19/2022] Open
Abstract
An important facet of the interaction between the pathogen Streptococcus pneumoniae (pneumococcus) and its human host is the ability of this bacterium to process host glycans. To achieve cleavage of the glycosidic bonds in host glycans, S. pneumoniae deploys a wide array of glycoside hydrolases. Here, we identify and characterize a new family 20 glycoside hydrolase, GH20C, from S. pneumoniae. Recombinant GH20C possessed the ability to hydrolyze the β-linkages joining either N-acetylglucosamine or N-acetylgalactosamine to a wide variety of aglycon residues, thus revealing this enzyme to be a generalist N-acetylhexosaminidase in vitro. X-ray crystal structures were determined for GH20C in a ligand-free form, in complex with the N-acetylglucosamine and N-acetylgalactosamine products of catalysis and in complex with both gluco- and galacto-configured inhibitors O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenyl carbamate (PUGNAc), O-(2-acetamido-2-deoxy-D-galactopyranosylidene)amino N-phenyl carbamate (GalPUGNAc), N-acetyl-D-glucosamine-thiazoline (NGT), and N-acetyl-D-galactosamine-thiazoline (GalNGT) at resolutions from 1.84 to 2.7 Å. These structures showed N-acetylglucosamine and N-acetylgalactosamine to be recognized via identical sets of molecular interactions. Although the same sets of interaction were maintained with the gluco- and galacto-configured inhibitors, the inhibition constants suggested preferred recognition of the axial O4 when an aglycon moiety was present (Ki for PUGNAc > GalPUGNAc) but preferred recognition of an equatorial O4 when the aglycon was absent (Ki for GalNGT > NGT). Overall, this study reveals GH20C to be another tool that is unique in the arsenal of S. pneumoniae and that it may implement the effort of the bacterium to utilize and/or destroy the wide array of host glycans that it may encounter.
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Affiliation(s)
- Melissa Robb
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6 and
| | - Craig S Robb
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6 and
| | - Melanie A Higgins
- the Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, South Australia 5005, Australia
| | - Joanne K Hobbs
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6 and
| | - James C Paton
- the Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, South Australia 5005, Australia
| | - Alisdair B Boraston
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6 and
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16
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Ekin IH, Gurturk K, Ilhan Z, Arabaci C, Gulaydin O. Detection of enzyme activities and their relation to serotypes of bovine and human group B streptococci. J Med Microbiol 2015; 64:985-989. [PMID: 26297151 DOI: 10.1099/jmm.0.000124] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Enzymatic properties of group B streptococci (GBS) serotypes from bovine milk and human routine vaginal specimens were investigated. Out of the 56 human and 66 bovine GBS, 35 and 30 could be classified serologically by a co-agglutination test with type-specific antisera, respectively. Hyaluronidase (HYAL), streptokinase (SK) and protease activities were detected using culture media. HYAL activity was observed mostly in typable human GBS, and serotypes Ia, Ic and II comprised 77.3% of the typable strains producing HYAL. Bovine GBS serotypes II, III and VII comprised 87.5% of typable bovine strains exhibiting HYAL activity. SK activity was detected only in three human GBS. Human GBS serotypes Ia, Ic, II, III, VII and almost all typable bovine GBS strains showed protease activity. β-D-glucosidase activity was frequently observed in human GBS, whereas N-acetyl-β-D-glucosaminidase activity was mostly detected in non-typable GBS from humans. These results indicate that different GBS serotypes could vary in their virulence properties, and bovine and human GBS isolates could not be differentiated by their enzyme activities. Use of the culture media appeared to be a simple-to-apply and useful method for the detection of extracellular enzyme activity such as HYAL, protease and SK.
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Affiliation(s)
- Ismail Hakki Ekin
- Faculty of Veterinary Medicine, University of Yuzuncu Yil, Van, Turkey
| | - Kemal Gurturk
- Faculty of Veterinary Medicine, University of Yuzuncu Yil, Van, Turkey
| | - Ziya Ilhan
- Faculty of Veterinary Medicine, University of Yuzuncu Yil, Van, Turkey
| | - Cigdem Arabaci
- Department of Microbiology, Okmeydani Education and Research Hospital, Istanbul, Turkey
| | - Ozgul Gulaydin
- Faculty of Veterinary Medicine, University of Yuzuncu Yil, Van, Turkey
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17
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Sjögren J, Collin M. Bacterial glycosidases in pathogenesis and glycoengineering. Future Microbiol 2015; 9:1039-51. [PMID: 25340834 DOI: 10.2217/fmb.14.71] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Glycosylation is a common post-translational protein modification and many key proteins of the immune system are glycosylated. As the true experts of our immune system, pathogenic bacteria produce enzymes that can modify the carbohydrates (glycans) of the defense mechanisms in order to favor bacterial survival and persistence. At the intersection between bacterial pathogenesis and glycobiology, there is an increased interest in studying the bacterial enzymes that modify the protein glycosylation of their colonized or infected hosts. This is of great importance in order to fully understand bacterial pathogenesis, but it also presents itself as a valuable source for glycoengineering and glycoanalysis tools. This article highlights the role of bacterial glycosidases during infections, introduces the use of such enzymes as glycoengineering tools and discusses the potential of further studies in this emerging field.
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Affiliation(s)
- Jonathan Sjögren
- Department of Clinical Sciences, Division of Infection Medicine, Lund University, BMC B14, SE-221 84 Lund, Sweden
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Paixão L, Oliveira J, Veríssimo A, Vinga S, Lourenço EC, Ventura MR, Kjos M, Veening JW, Fernandes VE, Andrew PW, Yesilkaya H, Neves AR. Host glycan sugar-specific pathways in Streptococcus pneumoniae: galactose as a key sugar in colonisation and infection [corrected]. PLoS One 2015; 10:e0121042. [PMID: 25826206 PMCID: PMC4380338 DOI: 10.1371/journal.pone.0121042] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Accepted: 02/12/2015] [Indexed: 01/13/2023] Open
Abstract
The human pathogen Streptococcus pneumoniae is a strictly fermentative organism that relies on glycolytic metabolism to obtain energy. In the human nasopharynx S. pneumoniae encounters glycoconjugates composed of a variety of monosaccharides, which can potentially be used as nutrients once depolymerized by glycosidases. Therefore, it is reasonable to hypothesise that the pneumococcus would rely on these glycan-derived sugars to grow. Here, we identified the sugar-specific catabolic pathways used by S. pneumoniae during growth on mucin. Transcriptome analysis of cells grown on mucin showed specific upregulation of genes likely to be involved in deglycosylation, transport and catabolism of galactose, mannose and N acetylglucosamine. In contrast to growth on mannose and N-acetylglucosamine, S. pneumoniae grown on galactose re-route their metabolic pathway from homolactic fermentation to a truly mixed acid fermentation regime. By measuring intracellular metabolites, enzymatic activities and mutant analysis, we provide an accurate map of the biochemical pathways for galactose, mannose and N-acetylglucosamine catabolism in S. pneumoniae. Intranasal mouse infection models of pneumococcal colonisation and disease showed that only mutants in galactose catabolic genes were attenuated. Our data pinpoint galactose as a key nutrient for growth in the respiratory tract and highlights the importance of central carbon metabolism for pneumococcal pathogenesis.
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Affiliation(s)
- Laura Paixão
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Joana Oliveira
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - André Veríssimo
- Centre for Intelligent Systems, LAETA, IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Susana Vinga
- Centre for Intelligent Systems, LAETA, IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - Eva C. Lourenço
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - M. Rita Ventura
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Morten Kjos
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Groningen, The Netherlands
| | - Jan-Willem Veening
- Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, Groningen, The Netherlands
| | - Vitor E. Fernandes
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
| | - Peter W. Andrew
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
| | - Hasan Yesilkaya
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
| | - Ana Rute Neves
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- * E-mail:
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Kantsø B, Green N, Goldblatt D, Benfield T. Antibody Response is More Likely to Pneumococcal Proteins Than to Polysaccharide After HIV-associated Invasive Pneumococcal Disease. J Infect Dis 2015; 212:1093-9. [PMID: 25762789 DOI: 10.1093/infdis/jiv158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Accepted: 03/06/2015] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Human immunodeficiency virus (HIV)-infected individuals are at increased risk of invasive pneumococcal disease (IPD). In order to assess the immunogenicity of pneumococcal proteins and polysaccharide, we investigated protein and serotype-specific antibody responses after HIV-associated IPD. METHODS Specific antipneumococcal immunoglobulin G to 27 pneumococcal protein antigens and 30 serotype polysaccharides was measured in plasma before and after IPD in HIV-infected individuals and compared to HIV-infected individuals without IPD. RESULTS Over time, 81% of IPD cases responded to at least 1 protein compared to 51% of non-IPD controls. HIV IPD cases responded to more proteins than non-IPD controls (8.6 ± 8.4 vs 4.2 ± 7.6 proteins; P = .01), and had a significantly higher probability of yielding an antibody response to the proteins PiaA, PsaA, and PcpA. Twenty-two percent of HIV-infected individuals with IPD had a serotype-specific antibody response. Younger age at the time of IPD was the only predictor of a serotype-specific pneumococcal antibody response, whereas we did not identify predictors of a protein-specific antibody response. CONCLUSIONS Antibody responses occurred more frequently to pneumococcal proteins than to polysaccharide, and protein antibodies persisted for longer than polysaccharide-specific antibodies. PcpA, PiaA, and PsaA were the most immunogenic proteins.
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Affiliation(s)
- Bjørn Kantsø
- Department of Microbiological Diagnostics and Virology, Statens Serum Institut, Copenhagen, Denmark
| | - Nicola Green
- Immunobiology Unit, Institute of Child Health, University College London, United Kingdom
| | - David Goldblatt
- Immunobiology Unit, Institute of Child Health, University College London, United Kingdom
| | - Thomas Benfield
- Department of Infectious Diseases Clinical Research Centre, Hvidovre Hospital Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
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20
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Singh AK, Pluvinage B, Higgins MA, Dalia AB, Woodiga SA, Flynn M, Lloyd AR, Weiser JN, Stubbs KA, Boraston AB, King SJ. Unravelling the multiple functions of the architecturally intricate Streptococcus pneumoniae β-galactosidase, BgaA. PLoS Pathog 2014; 10:e1004364. [PMID: 25210925 PMCID: PMC4161441 DOI: 10.1371/journal.ppat.1004364] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/28/2014] [Indexed: 11/18/2022] Open
Abstract
Bacterial cell-surface proteins play integral roles in host-pathogen interactions. These proteins are often architecturally and functionally sophisticated and yet few studies of such proteins involved in host-pathogen interactions have defined the domains or modules required for specific functions. Streptococcus pneumoniae (pneumococcus), an opportunistic pathogen that is a leading cause of community acquired pneumonia, otitis media and bacteremia, is decorated with many complex surface proteins. These include β-galactosidase BgaA, which is specific for terminal galactose residues β-1-4 linked to glucose or N-acetylglucosamine and known to play a role in pneumococcal growth, resistance to opsonophagocytic killing, and adherence. This study defines the domains and modules of BgaA that are required for these distinct contributions to pneumococcal pathogenesis. Inhibitors of β-galactosidase activity reduced pneumococcal growth and increased opsonophagocytic killing in a BgaA dependent manner, indicating these functions require BgaA enzymatic activity. In contrast, inhibitors increased pneumococcal adherence suggesting that BgaA bound a substrate of the enzyme through a distinct module or domain. Extensive biochemical, structural and cell based studies revealed two newly identified non-enzymatic carbohydrate-binding modules (CBMs) mediate adherence to the host cell surface displayed lactose or N-acetyllactosamine. This finding is important to pneumococcal biology as it is the first adhesin-carbohydrate receptor pair identified, supporting the widely held belief that initial pneumococcal attachment is to a glycoconjugate. Perhaps more importantly, this is the first demonstration that a CBM within a carbohydrate-active enzyme can mediate adherence to host cells and thus this study identifies a new class of carbohydrate-binding adhesins and extends the paradigm of CBM function. As other bacterial species express surface-associated carbohydrate-active enzymes containing CBMs these findings have broad implications for bacterial adherence. Together, these data illustrate that comprehending the architectural sophistication of surface-attached proteins can increase our understanding of the different mechanisms by which these proteins can contribute to bacterial pathogenesis.
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Affiliation(s)
- Anirudh K. Singh
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Benjamin Pluvinage
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Melanie A. Higgins
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Ankur B. Dalia
- Department of Microbiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Shireen A. Woodiga
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Matthew Flynn
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
| | - Audrey R. Lloyd
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
| | - Jeffrey N. Weiser
- Department of Microbiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Keith A. Stubbs
- School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Alisdair B. Boraston
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
- * E-mail: (ABB); (SJK)
| | - Samantha J. King
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail: (ABB); (SJK)
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21
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Nagae M, Morita-Matsumoto K, Arai S, Wada I, Matsumoto Y, Saito K, Hashimoto Y, Yamaguchi Y. Structural change of N-glycan exposes hydrophobic surface of human transferrin. Glycobiology 2014; 24:693-702. [PMID: 24780636 DOI: 10.1093/glycob/cwu033] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Transferrin is an iron-transport protein which possesses N-glycans at Asn432 and Asn630 in humans. Transferrin glycoforms Tf-1 and Tf-2, previously identified in human cerebrospinal fluid, are defined as the lower and upper bands in gel electrophoresis, respectively. Importantly, the Tf-2/Tf-1 ratio is raised in idiopathic normal pressure hydrocephalus patients and is useful as a clinical marker. In order to gain insight into the relationship between transferrin glycoform and biological function, we performed comparative characterization of Tf-1, Tf-2 and serum transferrin (sTf). Mass spectrometric analyses confirmed that Tf-2 is modified with disialylated biantennary glycans at both of the two N-glycosylation sites, which are similar to the N-glycans of sTf. On the other hand, Tf-1 is site-specifically modified: Asn630 has biantennary agalacto-complex-type glycan with bisecting N-acetylglucosamine (GlcNAc) and core fucose while Asn432 is modified with complex/high mannose-type glycans and possibly single GlcNAc. Size exclusion chromatography and fluorescence correlation spectroscopy analysis revealed that the hydration volume of Tf-1 is slightly smaller than that of sTf. Our striking finding is that Tf-1 has an exposed hydrophobic surface as monitored by the fluorescence intensity and wavelength of a hydrophobic probe, 1-anilino-8-naphthalene sulfonate, whereas Tf-2 does not. These results suggest that the different N-glycan structure of Tf-1 lowers the apparent hydration volume and reveals a patch of hydrophobic surface on transferrin which is otherwise covered with sialoglycan in sTf and Tf-2. The carbohydrate deficiency in certain pathological conditions may also expose hydrophobic surface which may modulate the function and/or stability of transferrin.
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Affiliation(s)
- Masamichi Nagae
- Structural Glycobiology Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Kana Morita-Matsumoto
- Structural Glycobiology Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Seisuke Arai
- Department of Cell Science, Institute of Biomedical Sciences
| | - Ikuo Wada
- Department of Cell Science, Institute of Biomedical Sciences
| | | | | | - Yasuhiro Hashimoto
- Department of Biochemistry, Fukushima Medical University School of Medicine, 1 Hikarigaoka, Fukushima 960-1295, Japan
| | - Yoshiki Yamaguchi
- Structural Glycobiology Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, RIKEN Global Research Cluster, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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EndoE from Enterococcus faecalis hydrolyzes the glycans of the biofilm inhibiting protein lactoferrin and mediates growth. PLoS One 2014; 9:e91035. [PMID: 24608122 PMCID: PMC3946673 DOI: 10.1371/journal.pone.0091035] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 02/10/2014] [Indexed: 11/24/2022] Open
Abstract
Glycosidases are widespread among bacteria. The opportunistic human pathogen Enterococcus faecalis encodes several putative glycosidases but little is known about their functions. The identified endo-β-N-acetylglucosaminidase EndoE has activity on the N-linked glycans of the human immunoglobulin G (IgG). In this report we identified the human glycoprotein lactoferrin (hLF) as a new substrate for EndoE. Hydrolysis of the N-glycans from hLF was investigated using lectin blot, UHPLC and mass spectrometry, showing that EndoE releases major glycoforms from this protein. hLF was shown to inhibit biofilm formation of E. faecalis in vitro. Glycans of hLF influence the binding to E. faecalis, and EndoE-hydrolyzed hLF inhibits biofilm formation to lesser extent than intact hLF indicating that EndoE prevents the inhibition of biofilm. In addition, hLF binds to a surface-associated enolase of E. faecalis. Culture experiments showed that the activity of EndoE enables E. faecalis to use the glycans derived from lactoferrin as a carbon source indicating that they could be used as nutrients in vivo when no other preferred carbon source is available. This report adds important information about the enzymatic activity of EndoE from the commensal and opportunist E. faecalis. The activity on the human glycoprotein hLF, and the functional consequences with reduced inhibition of biofilm formation highlights both innate immunity functions of hLF and a bacterial mechanism to evade this innate immunity function. Taken together, our results underline the importance of glycans in the interplay between bacteria and the human host, with possible implications for both commensalism and opportunism.
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Jeong KH, Nguyen V, Kim JH. Human milk oligosaccharides: the novel modulator of intestinal microbiota. BMB Rep 2012; 45:433-41. [DOI: 10.5483/bmbrep.2012.45.8.168] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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Pérez-Dorado I, Galan-Bartual S, Hermoso JA. Pneumococcal surface proteins: when the whole is greater than the sum of its parts. Mol Oral Microbiol 2012; 27:221-45. [PMID: 22759309 DOI: 10.1111/j.2041-1014.2012.00655.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Surface-exposed proteins of pathogenic bacteria are considered as potential virulence factors through their direct contribution to host-pathogen interactions. Four families of surface proteins decorate the cell surface of the human pathogen Streptococcus pneumoniae. Besides lipoproteins and LPXTG proteins, also present in other gram-positive bacteria, the pneumococcus presents the choline-binding protein (CBP) family and the non-classical surface proteins (NCSPs). The CBPs present specific structural features that allow their anchorage to the cell envelope through non-covalent interaction with choline residues of lipoteichoic acid and teichoic acid. NCSP is an umbrella term for less characterized proteins displaying moonlighting functions on the pneumococcal surface that lack a leader peptide and membrane-anchor motif. Considering the unceasing evolution of microbial species under the selective pressure of antibiotic use, detailed understanding of the interaction between pathogen and the host cells is required for the development of novel therapeutic strategies to combat pneumococcal infections. This article reviews recent progress in the investigation of the three-dimensional structures of surface-exposed pneumococcal proteins. The modular nature of some of them produces a great versatility and sophistication of the virulence functions that, in most cases, cannot be deduced by the structural analysis of the isolated modules.
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Affiliation(s)
- I Pérez-Dorado
- Department of Crystallography and Structural Biology, Instituto de Química-Física Rocasolano, CSIC, Madrid, Spain
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25
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Konno N, Takahashi H, Nakajima M, Takeda T, Sakamoto Y. Characterization of β-N-acetylhexosaminidase (LeHex20A), a member of glycoside hydrolase family 20, from Lentinula edodes (shiitake mushroom). AMB Express 2012; 2:29. [PMID: 22656067 PMCID: PMC3430601 DOI: 10.1186/2191-0855-2-29] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Accepted: 05/13/2012] [Indexed: 01/29/2023] Open
Abstract
We purified and cloned a β-N-acetylhexosaminidase, LeHex20A, with a molecular mass of 79 kDa from the fruiting body of Lentinula edodes (shiitake mushroom). The gene lehex20a gene had 1,659 nucleotides, encoding 553 amino acid residues. Sequence analysis indicated that LeHex20A belongs to glycoside hydrolase (GH) family 20, and homologues of lehex20a are broadly represented in the genomes of basidiomycetes. Purified LeHex20A hydrolyzed the terminal monosaccharide residues of β-N-acetylgalactosaminides and β-N-acetylglucosaminides, indicating that LeHex20A is a β-N-acetylhexosaminidase classified into EC 3.2.1.52. The maximum LeHex20A activity was observed at pH 4.0 and 50°C. The kinetic constants were estimated using chitooligosaccharides with degree of polymerization 2-6. GH20 β-N-acetylhexosaminidases generally prefer chitobiose among natural substrates. However, LeHex20A had the highest catalytic efficiency (kcat/Km) for chitotetraose, and the Km values for GlcNAc6 were 3.9-fold lower than for chitobiose. Furthermore, the enzyme partially hydrolyzed amorphous chitin polymers. These results indicate that LeHex20A can produce N-acetylglucosamine from long-chain chitomaterials.
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Affiliation(s)
- Naotake Konno
- Iwate Biotechnology Research Center, 22-174-4 Narita, Kitakami-shi, Iwate 024-0003, Japan
| | - Hideyuki Takahashi
- Iwate Biotechnology Research Center, 22-174-4 Narita, Kitakami-shi, Iwate 024-0003, Japan
| | - Masahiro Nakajima
- Iwate Biotechnology Research Center, 22-174-4 Narita, Kitakami-shi, Iwate 024-0003, Japan
| | - Takumi Takeda
- Iwate Biotechnology Research Center, 22-174-4 Narita, Kitakami-shi, Iwate 024-0003, Japan
| | - Yuichi Sakamoto
- Iwate Biotechnology Research Center, 22-174-4 Narita, Kitakami-shi, Iwate 024-0003, Japan
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Nguyen HA, Nguyen TH, Křen V, Eijsink VGH, Haltrich D, Peterbauer CK. Heterologous expression and characterization of an N-acetyl-β-D-hexosaminidase from Lactococcus lactis ssp. lactis IL1403. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:3275-3281. [PMID: 22356128 DOI: 10.1021/jf204915e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The lnbA gene of Lactococcus lactis ssp. lactis IL1403 encodes a polypeptide with similarity to lacto-N-biosidases and N-acetyl-β-D-hexosaminidases. The gene was cloned into the expression vector pET-21d and overexpressed in Escherichia coli BL21* (DE3). The recombinant purified enzyme (LnbA) was a monomer with a molecular weight of approximately 37 kDa. Studies with chromogenic substrates including p-nitrophenyl N-acetyl-β-D-glucosamine (pNP-GlcNAc) and p-nitrophenyl N-acetyl-β-D-galactosamine (pNP-GalNAc) showed that the enzyme had both N-acetyl-β-D-glucosaminidase and N-acetyl-β-D-galactosaminidase activity, thus indicating that the enzyme is an N-acetyl-β-D-hexosaminidase. K(m) and k(cat) for pNP-GlcNAc were 2.56 mM and 26.7 s(-1), respectively, whereas kinetic parameters for pNP-GalNAc could not be determined due to the K(m) being very high (>10 mM). The optimal temperature and pH of the enzyme were 37 °C and 5.5, respectively, for both substrates. The half-life of activity at 37 °C and pH 6.0 was 53 h, but activity was completely abolished after 30 min at 50 °C, meaning that the enzyme has relatively low temperature stability. The enzyme was stable in the pH 5.5-8 range and was unstable at pH below 5.5. Studies with natural substrates showed hydrolytic activity on chito-oligosaccharides but not on colloidal chitin or chitosan. Transglycosylation products were not detected. In all, the data suggest that LnbA's role may be to degrade chito-oligosaccharides that are produced by the previously described chitinolytic system of L. lactis.
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Affiliation(s)
- Hoang Anh Nguyen
- Food Biotechnology Laboratory, Department of Food Sciences and Technology, University of Natural Resources and Life Sciences, Vienna, Austria
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27
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Garbe J, Collin M. Bacterial hydrolysis of host glycoproteins - powerful protein modification and efficient nutrient acquisition. J Innate Immun 2012; 4:121-31. [PMID: 22222876 DOI: 10.1159/000334775] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 11/01/2011] [Indexed: 12/30/2022] Open
Abstract
Glycoproteins are ubiquitous in nature and fundamental to most biological processes, including the human immune system. The glycoprotein carbohydrate moieties, or glycans, are very diverse in their structure and composition, and have major effects on the chemical, physical and biological properties of these glycoproteins. The hydrolysis of glycoprotein glycans by bacterial glycosidases can have dramatic effects on glycoprotein function and, thereby, be beneficial for the bacteria in different ways. This review gives an introduction to the expanding field of extracellular glycosidases from bacterial pathogens with activity on host glycoproteins, describes some known and proposed consequences for the host and the bacteria and discusses some evolutionary and regulatory aspects of bacterial glycosidases.
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Affiliation(s)
- Julia Garbe
- Department of Clinical Sciences, Division of Infection Medicine, Lund University Biomedical Center B14, Lund, Sweden. julia.garbe @ med.lu.se
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Jiang YL, Yu WL, Zhang JW, Frolet C, Di Guilmi AM, Zhou CZ, Vernet T, Chen Y. Structural basis for the substrate specificity of a novel β-N-acetylhexosaminidase StrH protein from Streptococcus pneumoniae R6. J Biol Chem 2011; 286:43004-12. [PMID: 22013074 PMCID: PMC3234876 DOI: 10.1074/jbc.m111.256578] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Revised: 10/05/2011] [Indexed: 11/06/2022] Open
Abstract
The β-N-acetylhexosaminidase (EC 3.2.1.52) from glycoside hydrolase family 20 (GH20) catalyzes the hydrolysis of the β-N-acetylglucosamine (NAG) group from the nonreducing end of various glycoconjugates. The putative surface-exposed N-acetylhexosaminidase StrH/Spr0057 from Streptococcus pneumoniae R6 was proved to contribute to the virulence by removal of β(1,2)-linked NAG on host defense molecules following the cleavage of sialic acid and galactose by neuraminidase and β-galactosidase, respectively. StrH is the only reported GH20 enzyme that contains a tandem repeat of two 53% sequence-identical catalytic domains (designated as GH20-1 and GH20-2, respectively). Here, we present the 2.1 Å crystal structure of the N-terminal domain of StrH (residues Glu-175 to Lys-642) complexed with NAG. It adopts an overall structure similar to other GH20 enzymes: a (β/α)(8) TIM barrel with the active site residing at the center of the β-barrel convex side. The kinetic investigation using 4-nitrophenyl N-acetyl-β-d-glucosaminide as the substrate demonstrated that GH20-1 had an enzymatic activity (k(cat)/K(m)) of one-fourth compared with GH20-2. The lower activity of GH20-1 could be attributed to the substitution of active site Cys-469 of GH20-1 to the counterpart Tyr-903 of GH20-2. A complex model of NAGβ(1,2)Man at the active site of GH20-1 combined with activity assays of the corresponding site-directed mutants characterized two key residues Trp-443 and Tyr-482 at subsite +1 of GH20-1 (Trp-876 and Tyr-914 of GH20-2) that might determine the β(1,2) substrate specificity. Taken together, these findings shed light on the mechanism of catalytic specificity toward the β(1,2)-linked β-N-acetylglucosides.
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Affiliation(s)
- Yong-Liang Jiang
- From the Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | - Wei-Li Yu
- From the Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | - Jun-Wei Zhang
- From the Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | - Cecile Frolet
- the Laboratoire d'Ingénierie des Macromolécules, Institut de Biologie Structurale Jean-Pierre Ebel, 38027 Grenoble, France
| | - Anne-Marie Di Guilmi
- the Laboratoire d'Ingénierie des Macromolécules, Institut de Biologie Structurale Jean-Pierre Ebel, 38027 Grenoble, France
| | - Cong-Zhao Zhou
- From the Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | - Thierry Vernet
- the Laboratoire d'Ingénierie des Macromolécules, Institut de Biologie Structurale Jean-Pierre Ebel, 38027 Grenoble, France
| | - Yuxing Chen
- From the Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
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Inhibition of the Pneumococcal Virulence Factor StrH and Molecular Insights into N-Glycan Recognition and Hydrolysis. Structure 2011; 19:1603-14. [DOI: 10.1016/j.str.2011.08.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 08/15/2011] [Accepted: 08/17/2011] [Indexed: 11/21/2022]
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Higgins MA, Ficko-Blean E, Meloncelli PJ, Lowary TL, Boraston AB. The overall architecture and receptor binding of pneumococcal carbohydrate-antigen-hydrolyzing enzymes. J Mol Biol 2011; 411:1017-36. [PMID: 21767550 DOI: 10.1016/j.jmb.2011.06.035] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Revised: 06/16/2011] [Accepted: 06/20/2011] [Indexed: 11/19/2022]
Abstract
The TIGR4 and SP3-BS71 strains of Streptococcus pneumoniae each produce family 98 glycoside hydrolases, called Sp4GH98 and Sp3GH98, respectively, which have different modular architectures and substrate specificities. Sp4GH98 degrades the Lewis(Y) antigen and possesses three C-terminal family 47 carbohydrate-binding modules (CBMs) that bind to this substrate. Sp3GH98 degrades the blood group A/B antigens and has two N-terminal family 51 CBMs that are of unknown function. Here, we examine the complex carbohydrate-binding specificity of the family 51 CBMs from Sp3GH98 (referred to as CBM51-1 and CBM51-2), the structural basis of this interaction, and the overall solution conformations of both Sp3GH98 and Sp4GH98, which are shown to be fully secreted proteins. Through glycan microarray binding analysis and isothermal titration calorimetry, CBM51-1 is found to bind specifically to the blood group A/B antigens. However, due to a series of relatively small structural rearrangements that were revealed in structures determined by X-ray crystallography, CBM51-2 appears to be incapable of binding carbohydrates. Analysis of small-angle X-ray scattering data in combination with the available high-resolution X-ray crystal structures of the Sp3GH98 and Sp4GH98 catalytic modules and their CBMs yielded models of the biological solution structures of the full-length enzymes. These studies reveal the complex architectures of the two enzymes and suggest that carbohydrate recognition by the CBMs and the activity of the catalytic modules are not directly coupled.
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Affiliation(s)
- Melanie A Higgins
- Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, Canada V8W 3P6
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Limoli DH, Sladek JA, Fuller LA, Singh AK, King SJ. BgaA acts as an adhesin to mediate attachment of some pneumococcal strains to human epithelial cells. MICROBIOLOGY-SGM 2011; 157:2369-2381. [PMID: 21602213 PMCID: PMC3167885 DOI: 10.1099/mic.0.045609-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Streptococcus pneumoniae colonization of the respiratory tract is an essential precursor for pneumococcal disease. To colonize efficiently, bacteria must adhere to the epithelial-cell surface. S. pneumoniae possesses surface-associated exoglycosidases that are capable of sequentially deglycosylating human glycans. Two exoglycosidases, neuraminidase (NanA) and β-galactosidase (BgaA), have previously been shown to contribute to S. pneumoniae adherence to human epithelial cells, as deletion of either of these genes results in reduced adherence. It has been suggested that these enzymes may modulate adherence by cleaving sugars to reveal a receptor on host cells. Pretreatment of epithelial cells with exogenous neuraminidase restores the adherence of a nanA mutant, whereas pretreatment with β-galactosidase does not restore the adherence of a bgaA mutant. These data suggest that BgaA may not function to reveal a receptor, and implicate an alternative role for BgaA in adherence. Here we demonstrate that β-galactosidase activity is not required for BgaA-mediated adherence. Addition of recombinant BgaA (rBgaA) to adherence assays and pretreatment of epithelial cells with rBgaA both significantly reduced the level of adherence of the parental strain, but not the BgaA mutant. One possible explanation of these data is that BgaA is acting as an adhesin and that rBgaA is binding to the receptor, preventing bacterial binding. A bead-binding assay demonstrated that BgaA can bind directly to human epithelial cells, supporting the hypothesis that BgaA is an adhesin. Preliminary characterization of the epithelial-cell receptor suggests that it is a glycan in the context of a glycosphingolipid. To further establish the relevance of this adherence mechanism, we demonstrated that BgaA-mediated adherence contributed to adherence of a recent clinical isolate to primary human epithelial cells. Together, these data suggest a novel role for BgaA as an adhesin and suggest that this mechanism could contribute to adherence of at least some pneumococcal strains in vivo.
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Affiliation(s)
- Dominique H. Limoli
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital, OH 43205, USA
| | - Julie A. Sladek
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital, OH 43205, USA
- The Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - Lindsey A. Fuller
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital, OH 43205, USA
| | - Anirudh K. Singh
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital, OH 43205, USA
| | - Samantha J. King
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital, OH 43205, USA
- The Ohio State University College of Medicine, Columbus, OH 43210, USA
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Watanabe S, Misawa M, Matsuzaki T, Sakurai T, Muramatsu T, Sato M. A novel glycosylation signal regulates transforming growth factor beta receptors as evidenced by endo-beta-galactosidase C expression in rodent cells. Glycobiology 2010; 21:482-92. [PMID: 21062784 DOI: 10.1093/glycob/cwq186] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The αGal (Galα1-3Gal) epitope is a xenoantigen that is responsible for hyperacute rejection in xenotransplantation. This epitope is expressed on the cell surface in the cells of all mammals except humans and Old World monkeys. It can be digested by the enzyme endo-β-galactosidase C (EndoGalC), which is derived from Clostridium perfringens. Previously, we produced EndoGalC transgenic mice to identify the phenotypes that would be induced following EndoGalC overexpression. The mice lacked the αGal epitope in all tissues and exhibited abnormal phenotypes such as postnatal death, growth retardation, skin lesion and abnormal behavior. Interestingly, skin lesions caused by increased proliferation of keratinocytes suggest the role of a glycan structure [in which the αGal epitope has been removed or the N-acetylglucosamine (GlcNAc) residue is newly exposed] as a regulator of signal transduction. To verify this hypothesis, we introduced an EndoGalC expression vector into cultured mouse NIH3T3 cells and obtained several EndoGalC-expressing transfectants. These cells lacked αGal epitope expression and exhibited 1.8-fold higher proliferation than untransfected parental cells. We then used several cytokine receptor inhibitors to assess the signal transduction cascades that were affected. Only SB431542 and LY364947, both of which are transforming growth factor β (TGFβ) receptor type-I (TβR-I) inhibitors, were found to successfully reverse the enhanced cell proliferation rate of EndoGalC transfectants, indicating that the glycan structure is a regulator of TβRs. Biochemical analysis demonstrated that the glycan altered association between TβR-I and TβR-II in the absence of ligands.
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Affiliation(s)
- Satoshi Watanabe
- Animal Genome Research Unit, Division of Animal Science, National Institute of Agrobiological Sciences, 2 Ikenodai, Tsukuba, Ibaraki 305-0901, Japan.
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Frolet C, Beniazza M, Roux L, Gallet B, Noirclerc-Savoye M, Vernet T, Di Guilmi AM. New adhesin functions of surface-exposed pneumococcal proteins. BMC Microbiol 2010; 10:190. [PMID: 20624274 PMCID: PMC2911433 DOI: 10.1186/1471-2180-10-190] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2009] [Accepted: 07/12/2010] [Indexed: 12/02/2022] Open
Abstract
Background Streptococcus pneumoniae is a widely distributed commensal Gram-positive bacteria of the upper respiratory tract. Pneumococcal colonization can progress to invasive disease, and thus become lethal, reason why antibiotics and vaccines are designed to limit the dramatic effects of the bacteria in such cases. As a consequence, pneumococcus has developed efficient antibiotic resistance, and the use of vaccines covering a limited number of serotypes such as Pneumovax® and Prevnar® results in the expansion of non-covered serotypes. Pneumococcal surface proteins represent challenging candidates for the development of new therapeutic targets against the bacteria. Despite the number of described virulence factors, we believe that the majority of them remain to be characterized. This is the reason why pneumococcus invasion processes are still largely unknown. Results Availability of genome sequences facilitated the identification of pneumococcal surface proteins bearing characteristic motifs such as choline-binding proteins (Cbp) and peptidoglycan binding (LPXTG) proteins. We designed a medium throughput approach to systematically test for interactions between these pneumococcal surface proteins and host proteins (extracellular matrix proteins, circulating proteins or immunity related proteins). We cloned, expressed and purified 28 pneumococcal surface proteins. Interactions were tested in a solid phase assay, which led to the identification of 23 protein-protein interactions among which 20 are new. Conclusions We conclude that whether peptidoglycan binding proteins do not appear to be major adhesins, most of the choline-binding proteins interact with host proteins (elastin and C reactive proteins are the major Cbp partners). These newly identified interactions open the way to a better understanding of host-pneumococcal interactions.
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Affiliation(s)
- Cécile Frolet
- Institut de Biologie Structurale, UMR, Université Joseph Fourier, CNRS, CEA, Grenoble, France
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Lysosomal storage of oligosaccharide and glycosphingolipid in imino sugar treated cells. Glycoconj J 2010; 27:297-308. [DOI: 10.1007/s10719-010-9278-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 01/08/2010] [Accepted: 01/12/2010] [Indexed: 10/19/2022]
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Three surface exoglycosidases from Streptococcus pneumoniae, NanA, BgaA, and StrH, promote resistance to opsonophagocytic killing by human neutrophils. Infect Immun 2010; 78:2108-16. [PMID: 20160017 DOI: 10.1128/iai.01125-09] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Streptococcus pneumoniae (the pneumococcus) is a major human pathogen and a leading cause of inflammatory infections such as pneumonia and otitis media. An important mechanism for host defense against S. pneumoniae is opsonophagocytic killing by neutrophils. To persist in the human host, the pneumococcus has developed strategies to evade opsonization and subsequent neutrophil-mediated killing. Utilizing a genomic approach, we identified NanA, the major pneumococcal neuraminidase, as a factor important for resistance to opsonophagocytic killing in ex vivo killing assays using human neutrophils. The effect of NanA was shown using both type 4 (TIGR4) and type 6A clinical isolates. NanA promotes this resistance by acting in conjunction with two other surface-associated exoglycosidases, BgaA, a beta-galactosidase, and StrH, an N-acetylglucosaminidase. Experiments using human serum showed that these exoglycosidases reduced deposition of complement component C3 on the pneumococcal surface, providing a mechanism for this resistance. Additionally, we have shown that antibodies in human serum do not contribute to this phenotype. These results demonstrate that deglycosylation of a human serum glycoconjugate(s) by the combined effects of NanA, BgaA, and StrH, is important for resistance to complement deposition and subsequent phagocytic killing of S. pneumoniae.
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King S. Pneumococcal modification of host sugars: a major contributor to colonization of the human airway? Mol Oral Microbiol 2010; 25:15-24. [DOI: 10.1111/j.2041-1014.2009.00564.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Nobbs AH, Lamont RJ, Jenkinson HF. Streptococcus adherence and colonization. Microbiol Mol Biol Rev 2009; 73:407-50, Table of Contents. [PMID: 19721085 PMCID: PMC2738137 DOI: 10.1128/mmbr.00014-09] [Citation(s) in RCA: 431] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Streptococci readily colonize mucosal tissues in the nasopharynx; the respiratory, gastrointestinal, and genitourinary tracts; and the skin. Each ecological niche presents a series of challenges to successful colonization with which streptococci have to contend. Some species exist in equilibrium with their host, neither stimulating nor submitting to immune defenses mounted against them. Most are either opportunistic or true pathogens responsible for diseases such as pharyngitis, tooth decay, necrotizing fasciitis, infective endocarditis, and meningitis. Part of the success of streptococci as colonizers is attributable to the spectrum of proteins expressed on their surfaces. Adhesins enable interactions with salivary, serum, and extracellular matrix components; host cells; and other microbes. This is the essential first step to colonization, the development of complex communities, and possible invasion of host tissues. The majority of streptococcal adhesins are anchored to the cell wall via a C-terminal LPxTz motif. Other proteins may be surface anchored through N-terminal lipid modifications, while the mechanism of cell wall associations for others remains unclear. Collectively, these surface-bound proteins provide Streptococcus species with a "coat of many colors," enabling multiple intimate contacts and interplays between the bacterial cell and the host. In vitro and in vivo studies have demonstrated direct roles for many streptococcal adhesins as colonization or virulence factors, making them attractive targets for therapeutic and preventive strategies against streptococcal infections. There is, therefore, much focus on applying increasingly advanced molecular techniques to determine the precise structures and functions of these proteins, and their regulatory pathways, so that more targeted approaches can be developed.
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Affiliation(s)
- Angela H Nobbs
- Oral Microbiology Unit, Department of Oral and Dental Science, University of Bristol, Bristol BS1 2LY, United Kingdom
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Abstract
Some thirty years ago, work on mammalian tissues suggested the presence of two cytosolic hexosaminidases in mammalian cells; one of these has been more recently characterized in a recombinant form and has an important role in cellular function due to its ability to cleave beta-N-acetylglucosamine residues from a variety of nuclear and cytoplasmic proteins. However, the molecular nature of the second cytosolic hexosaminidase, named hexosaminidase D, has remained obscure. In the present study, we molecularly characterize for the first time the human and murine recombinant forms of enzymes, encoded by HEXDC genes, which appear to correspond to hexosaminidase D in terms of substrate specificity, pH dependency and temperature stability. Furthermore, a Myc-tagged form of this novel hexosaminidase displays a nucleocytoplasmic localization. Transcripts of the corresponding gene are expressed in a number of murine tissues. On the basis of its sequence, this enzyme represents, along with the lysosomal hexosaminidase subunits encoded by the HEXA and HEXB genes, the third class 20 glycosidase to be identified from mammalian sources.
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Abstract
Colonization of the airway by Streptococcus pneumoniae is typically asymptomatic; however, progression of bacteria beyond the oronasopharynx can cause diseases including otitis media and pneumonia. The mechanisms by which S. pneumoniae establishes and maintains colonization remain poorly understood. Both N-linked and O-linked glycans are abundant in the airway. Our previous research demonstrated that S. pneumoniae can sequentially deglycosylate N-linked glycans and suggested that this modification of sugar structures may aid in colonization. There is published evidence that S. pneumoniae expresses a secreted O-glycosidase that cleaves galactose beta1-3 N-acetylgalactosamine (Galbeta1-3GalNAc) from core-1 O-linked glycans; however, the biological function of this enzyme has not previously been determined. We established that the activity is not secreted but is instead surface associated in a sortase-dependent manner. Genome analysis revealed an open reading frame predicted to encode a sortase-dependent surface protein with sequence similarity to the O-glycosidase of Bifidobacterium longum. Deletion of this pneumococcal open reading frame confirmed that this gene encodes an O-glycosidase. Experiments using a model glycoconjugate demonstrated that this O-glycosidase, together with the neuraminidase NanA, is required for S. pneumoniae to cleave sialylated core-1 O-linked glycans. The ability of the O-glycosidase mutant to cleave this glycan structure was restored by both genetic complementation and the addition of O-glycosidase. The mutant showed a reduction in adherence to human airway epithelial cells and a significantly decreased ability to colonize the upper respiratory tract, suggesting that cleavage of core-1 O-linked glycans enhances the ability of S. pneumoniae to colonize the human airway.
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41
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Layec S, Decaris B, Leblond-Bourget N. Diversity of Firmicutes peptidoglycan hydrolases and specificities of those involved in daughter cell separation. Res Microbiol 2008; 159:507-15. [PMID: 18656532 DOI: 10.1016/j.resmic.2008.06.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 06/04/2008] [Accepted: 06/10/2008] [Indexed: 11/29/2022]
Abstract
Within Streptococcus thermophilus, Cse was identified as the major cell disconnecting peptidoglycan hydrolase (PGH) and was demonstrated to be species-specific. To identify cell disconnecting PGHs encoded by other Streptococcus genomes, we explored the diversity of domains carried by Firmicutes PGHs, and especially that of enzymes involved in daughter cell separation. This work brings to light the diversity of PGHs and reveals that each species recruits its own cell-separating enzyme distinct from that of the others. This specificity is probably correlated with the diversity of substrates found in the bacterial cell wall.
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Affiliation(s)
- Séverine Layec
- Laboratoire de Génétique et Microbiologie, UMR INRA/UHP 1128, IFR 110, Faculté des Sciences et Techniques, Nancy-Université, BP 239, 54506 Vandoeuvre-lès-Nancy, France
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IgG glycan hydrolysis by a bacterial enzyme as a therapy against autoimmune conditions. Proc Natl Acad Sci U S A 2008; 105:4265-70. [PMID: 18332429 DOI: 10.1073/pnas.0711271105] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
EndoS from Streptococcus pyogenes efficiently hydrolyzes the functionally important and conserved N-linked glycan of IgG in human blood. Repeated i.v. administration of EndoS in rabbits completely hydrolyzes the glycans of the whole IgG pool, despite the generation of anti-EndoS antibodies. EndoS administration had no apparent effects on the health of the animals. EndoS hydrolysis of the IgG glycan has profound effects on IgG effector functions, such as complement activation and Fc receptor binding, suggesting that the enzyme could be used as an immunomodulatory therapeutic agent against IgG-mediated diseases. We demonstrate here that EndoS indeed has a protective effect in a mouse model of lethal IgG-driven immune (or idiopathic) thrombocytopenic purpura. EndoS pretreatment of pathogenic antibodies inhibits the development of disease, and the enzyme also rescues mice from already established disease when severe thrombocytopenia and s.c. bleeding have developed. These results identify EndoS as a potential therapeutic agent against diseases where pathogenic IgG antibodies are important and further emphasize antibody glycans as possible targets in future therapies against antibody-mediated autoimmune conditions.
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Ramos-Montañez S, Tsui HCT, Wayne KJ, Morris JL, Peters LE, Zhang F, Kazmierczak KM, Sham LT, Winkler ME. Polymorphism and regulation of the spxB (pyruvate oxidase) virulence factor gene by a CBS-HotDog domain protein (SpxR) in serotype 2 Streptococcus pneumoniae. Mol Microbiol 2007; 67:729-46. [PMID: 18179423 DOI: 10.1111/j.1365-2958.2007.06082.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
spxB-encoded pyruvate oxidase is a major virulence factor of Streptococcus pneumoniae. During aerobic growth, SpxB synthesizes H2O2 and acetyl phosphate, which play roles in metabolism, signalling, and oxidative stress. We report here the first cis- and trans-acting regulatory elements for spxB transcription. These elements were identified in a genetic screen for spontaneous mutations that caused colonies of strain D39 to change from a semitransparent to an opaque appearance. Six of the seven opaque colonies recovered (frequency approximately 3 x 10(-5)) were impaired for SpxB function or expression. Two mutations changed amino acids in SpxB likely required for cofactor or subunit binding. One mutation defined a cis-acting adjacent direct repeat required for optimal spxB transcription. The other three spontaneous mutations created the same frameshift near the start of the trans-acting spxR regulatory gene. The SpxR protein contains helix-turn-helix, CBS and HotDog domains implicated in binding DNA, adenosyl compounds, and CoA-containing compounds respectively, and suggest that SpxR positively regulates spxB transcription in response to energy and metabolic state. Microarray analyses unexpectedly demonstrated that SpxR also positively regulates the strH exoglycosidase gene, which, like spxB, has been implicated in colonization. Finally, SpxR is required for full virulence in a murine model of infection.
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Growth of Streptococcus pneumoniae on human glycoconjugates is dependent upon the sequential activity of bacterial exoglycosidases. J Bacteriol 2007; 190:221-30. [PMID: 17981977 DOI: 10.1128/jb.01251-07] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the human host, Streptococcus pneumoniae encounters a variety of glycoconjugates, including mucin, host defense molecules, and glycans associated with the epithelial surface. S. pneumoniae is known to encode a number of glycosidases that may modify these glycoconjugates in vivo. Three exoglycosidases, a neuraminidase (NanA), beta-galactosidase (BgaA), and N-acetylglucosaminidase (StrH), have been previously demonstrated to sequentially deglycosylate N-linked glycans on host defense molecules, which coat the pneumococcal surface in vivo. This cleavage is proposed to alter the clearance function of these molecules, allowing pneumococci to persist in the airway. However, we propose that the exoglycosidase-dependent liberation of monosaccharides from these glycoconjugates in close proximity to the pneumococcal surface provides S. pneumoniae with a convenient source of fermentable carbohydrate in vivo. In this study, we demonstrate that S. pneumoniae is able to utilize complex N-linked human glycoconjugates as a sole source of carbon to sustain growth and that efficient growth is dependent upon the sequential deglycosylation of the glycoconjugate substrate by pneumococcal exoglycosidases. In addition to demonstrating a role for NanA, BgaA, and StrH, we have identified a function for the second pneumococcal neuraminidase, NanB, in the deglycosylation of host glycoconjugates and have demonstrated that NanB activity can partially compensate for the loss or dysfunction of NanA. To date, all known functions of pneumococcal neuraminidase have been attributed to NanA. Thus, this study describes the first proposed role for NanB by which it may contribute to S. pneumoniae colonization and pathogenesis.
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Gutternigg M, Kretschmer-Lubich D, Paschinger K, Rendić D, Hader J, Geier P, Ranftl R, Jantsch V, Lochnit G, Wilson IBH. Biosynthesis of truncated N-linked oligosaccharides results from non-orthologous hexosaminidase-mediated mechanisms in nematodes, plants, and insects. J Biol Chem 2007; 282:27825-40. [PMID: 17636254 PMCID: PMC2850174 DOI: 10.1074/jbc.m704235200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In many invertebrates and plants, the N-glycosylation profile is dominated by truncated paucimannosidic N-glycans, i.e. glycans consisting of a simple trimannosylchitobiosyl core often modified by core fucose residues. Even though they lack antennal N-acetylglucosamine residues, the biosynthesis of these glycans requires the sequential action of GlcNAc transferase I, Golgi mannosidase II, and, finally, beta-N-acetylglucosaminidases. In Drosophila, the recently characterized enzyme encoded by the fused lobes (fdl) gene specifically removes the non-reducing N-acetylglucosamine residue from the alpha1,3-antenna of N-glycans. In the present study, we examined the products of five beta-N-acetylhexosaminidase genes from Caenorhabditis elegans (hex-1 to hex-5, corresponding to reading frames T14F9.3, C14C11.3, Y39A1C.4, Y51F10.5, and Y70D2A.2) in addition to three from Arabidopsis thaliana (AtHEX1, AtHEX2, and AtHEX3, corresponding to reading frames At1g65590, At3g55260, and At1g05590). Based on homology, the Caenorhabditis HEX-1 and all three Arabidopsis enzymes are members of the same sub-family as the aforementioned Drosophila fused lobes enzyme but either act as chitotriosidases or non-specifically remove N-acetylglucosamine from both N-glycan antennae. The other four Caenorhabditis enzymes are members of a distinct sub-family; nevertheless, two of these enzymes displayed the same alpha1,3-antennal specificity as the fused lobes enzyme. Furthermore, a deletion of part of the Caenorhabditis hex-2 gene drastically reduces the native N-glycan-specific hexosaminidase activity in mutant worm extracts and results in a shift in the N-glycan profile, which is a demonstration of its in vivo enzymatic relevance. Based on these data, it is hypothesized that the genetic origin of paucimannosidic glycans in nematodes, plants, and insects involves highly divergent members of the same hexosaminidase gene family.
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Affiliation(s)
- Martin Gutternigg
- Department für Chemie, Universität für Bodenkultur, Muthgasse 18, A-1190 Wien, Austria
| | | | - Katharina Paschinger
- Department für Chemie, Universität für Bodenkultur, Muthgasse 18, A-1190 Wien, Austria
| | - Dubravko Rendić
- Department für Chemie, Universität für Bodenkultur, Muthgasse 18, A-1190 Wien, Austria
| | - Josef Hader
- Department für Chemie, Universität für Bodenkultur, Muthgasse 18, A-1190 Wien, Austria
| | - Petra Geier
- Department für Chemie, Universität für Bodenkultur, Muthgasse 18, A-1190 Wien, Austria
| | - Ramona Ranftl
- Department für Chemie, Universität für Bodenkultur, Muthgasse 18, A-1190 Wien, Austria
| | - Verena Jantsch
- Abteilung für Chromosomenbiologie, Vienna Biocenter II, A-1030 Wien, Austria
| | - Günter Lochnit
- Institut für Biochemie, Justus-Liebig-Universität, D-35292 Gießen, Germany
| | - Iain B. H. Wilson
- Department für Chemie, Universität für Bodenkultur, Muthgasse 18, A-1190 Wien, Austria
- To whom correspondence should be addressed: ; Tel: +43-1-36006-6541; Fax: +43-1-36006-6076
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King SJ, Hippe KR, Weiser JN. Deglycosylation of human glycoconjugates by the sequential activities of exoglycosidases expressed by Streptococcus pneumoniae. Mol Microbiol 2006; 59:961-74. [PMID: 16420364 DOI: 10.1111/j.1365-2958.2005.04984.x] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Streptococcus pneumoniae produces three surface-associated exoglycosidases; a neuraminidase, NanA, a beta-galactosidase, BgaA, and a beta-N-acetylglucosaminidase, StrH. the proposed functions of NanA, which removes terminal sialic acid, include revealing receptors for adherence, affecting the function of glycosylated host clearance molecules, modifying the surface of other bacteria coinhabiting the same niche, and providing a nutrient source. However, it is unclear whether following desialylation S. pneumoniae can further deglycosylate human targets through the activity of BgaA or StrH. We demonstrate that NanA, BgaA and StrH act sequentially to remove sialic acid, galactose and N-acetylglucosamine and expose mannose on human glycoproteins that bind to the pneumococcus and protect the airway. In addition, both BgaA and NanA were shown to contribute to the adherence of unencapsulated pneumococci, to human epithelial cells. Despite these findings, triple exoglycosidase mutants colonized mice as well as their parental strains, suggesting that any effect of these genes on colonization and disease may be host species-specific. These studies highlight the importance of considering the complete ability of S. pneumoniae to deglycosylate human targets and suggest that in addition to NanA, BgaA and StrH also contribute to pneumococcal colonization and/or pathogenesis.
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Affiliation(s)
- Samantha J King
- Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
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Bruce AF, Gounaris K. Characterisation of a secreted N-acetyl-β-hexosaminidase from Trichinella spiralis. Mol Biochem Parasitol 2006; 145:84-93. [PMID: 16242793 DOI: 10.1016/j.molbiopara.2005.09.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2005] [Revised: 09/19/2005] [Accepted: 09/21/2005] [Indexed: 11/18/2022]
Abstract
A thorough investigation was conducted for glycoside hydrolase activities in the secreted proteins of Trichinella spiralis. The data demonstrated that the only secreted glycosidase with significant activity was an exo-beta-hexosaminidase with catalysis of the substrates N-acetyl-beta-D-glucosamine, N-acetyl-beta-D-galactosamine and N-acetyl-beta-D-glucosamine-6-sulphate proceeding with an efficiency similar to the human isozyme beta-hexosaminidase A (Hex A). The hydrolysis of N-acetyl-beta-D-glucosamine followed Michaelis-Menten kinetics with a K(m) of 0.187+/-0.025 mM, and catalysis was inhibited competitively by both N-acetyl-beta-d-glucosamine and N-acetyl-beta-D-galactosamine, with K(i) values of 15.75+/-0.99 and 1.17+/-0.24 mM, respectively. The enzyme was maximally active at pH 4.4, had a temperature optimum at 54 degrees C and was thermolabile. We observed no cleavage of N-acetylglucosamine beta1-4 linkages in N-acetylchitooligosaccharides, but significant hydrolysis of N-acetylglucosamine beta1-2 linked to mannose in glycans was detected indicating that the secreted enzyme is linkage specific. The enzyme was partially purified and identified by SDS-PAGE and Western blotting as a protein with an apparent molecular mass of 50 kDa. We established that the protein was glycosylated and showed that the glycan was decorated with tyvelose (3,6-dideoxy-D-arabino-hexose). Matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS) analysis demonstrated that the carbohydrate moeity was a tyvelose capped tetra-antennary N-glycan corresponding to the structure Tyv(4)Fuc(5)HexNAc(10)Hex(3). All our studies suggest that this is a novel variant of a secreted N-acetyl-beta-hexosaminidase.
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Affiliation(s)
- Alexandra F Bruce
- Division of Cell and Molecular Biology, Biochemistry Building, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
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Tendolkar PM, Baghdayan AS, Shankar N. The N-terminal domain of enterococcal surface protein, Esp, is sufficient for Esp-mediated biofilm enhancement in Enterococcus faecalis. J Bacteriol 2005; 187:6213-22. [PMID: 16109963 PMCID: PMC1196143 DOI: 10.1128/jb.187.17.6213-6222.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Enterococci have emerged as one of the leading causes of nosocomial bloodstream, surgical site, and urinary tract infections. More recently, enterococci have been associated with biofilms, which are bacterial communities attached to a surface and encased in an extracellular polymeric matrix. The enterococcal cell surface-associated protein, Esp, enhances biofilm formation by Enterococcus faecalis in a glucose-dependent manner. Mature Esp consists of a nonrepeat N-terminal domain and a central region made up of two types of tandem repeats followed by a C-terminal membrane-spanning and anchor domain. This study was undertaken to localize the specific domain(s) of Esp that plays a role in Esp-mediated biofilm enhancement. To achieve this objective, we constructed in-frame deletion mutants expressing truncated forms of Esp in an isogenic background. By comparing strains expressing the mutant forms of Esp to those expressing wild-type Esp, we found that the strain expressing Esp lacking the N-terminal domain formed biofilms that were quantitatively less in biovolume than the strain expressing wild-type Esp. Furthermore, an E. faecalis strain expressing only the N-terminal domain of Esp fused to a heterologous protein anchor formed biofilms that were quantitatively similar to those formed by a strain expressing full-length Esp. This suggested that the minimal region contributing to Esp-mediated biofilm enhancement in E. faecalis was confined to the nonrepeat N-terminal domain. Expression of full-length E. faecalis Esp in heterologous host systems of esp-deficient Lactococcus lactis and Enterococcus faecium did not enhance biofilm formation as was observed for E. faecalis. These results suggest that Esp may require interaction with an additional E. faecalis-specific factor(s) to result in biofilm enhancement.
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Affiliation(s)
- Preeti M Tendolkar
- Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, P.O. Box 26901, Oklahoma City, OK 73190, USA
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Rincon MT, Cepeljnik T, Martin JC, Lamed R, Barak Y, Bayer EA, Flint HJ. Unconventional mode of attachment of the Ruminococcus flavefaciens cellulosome to the cell surface. J Bacteriol 2005; 187:7569-78. [PMID: 16267281 PMCID: PMC1280307 DOI: 10.1128/jb.187.22.7569-7578.2005] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Accepted: 08/24/2005] [Indexed: 11/20/2022] Open
Abstract
Sequence extension of the scaffoldin gene cluster from Ruminococcus flavefaciens revealed a new gene (scaE) that encodes a protein with an N-terminal cohesin domain and a C terminus with a typical gram-positive anchoring signal for sortase-mediated attachment to the bacterial cell wall. The recombinant cohesin of ScaE was recovered after expression in Escherichia coli and was shown to bind to the C-terminal domain of the cellulosomal structural protein ScaB, as well as to three unknown polypeptides derived from native cellulose-bound Ruminococcus flavefaciens protein extracts. The ScaB C terminus includes a cryptic dockerin domain that is unusual in its sequence, and considerably larger than conventional dockerins. The ScaB dockerin binds to ScaE, suggesting that this interaction occurs through a novel cohesin-dockerin pairing. The novel ScaB dockerin was expressed as a xylanase fusion protein, which was shown to bind tenaciously and selectively to a recombinant form of the ScaE cohesin. Thus, ScaE appears to play a role in anchoring the cellulosomal complex to the bacterial cell envelope via its interaction with ScaB. This sortase-mediated mechanism for covalent cell-wall anchoring of the cellulosome in R. flavefaciens differs from those reported thus far for any other cellulosome system.
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Affiliation(s)
- Marco T Rincon
- Microbial Ecology Group, Rowett Research Institute, Aberdeen, UK.
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