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Meng W, Chen S, Huang L, Yang J, Zhang W, Zhong Z, Zhou Z, Liu H, Fu H, He T, Peng G. Isolation, characterization, and pathogenicity assessment of Corynebacterium pseudotuberculosis biovar equi strains from alpacas ( Vicugna pacos) in China. Front Microbiol 2023; 14:1206187. [PMID: 37465023 PMCID: PMC10350510 DOI: 10.3389/fmicb.2023.1206187] [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: 04/15/2023] [Accepted: 06/15/2023] [Indexed: 07/20/2023] Open
Abstract
Corynebacterium pseudotuberculosis is a zoonotic pathogen that causes lymphadenitis in humans, livestock, and wildlife. In this study, C. pseudotuberculosis biovar equi strains were isolated from three alpacas. Antibiotic susceptibility tests and pathogenicity tests were also conducted. Moreover, one strain was sequenced using DNBSEQ and Oxford Nanopore technology. The three strains exhibited resistance to aztreonam, fosfomycin, and nitrofurantoin. The median lethal doses (LD50) of strains G1, S2 and BA3 in experimentally infected mice was 1.66 × 105 CFU, 3.78 × 105 CFU and 3.78 × 105 CFU, respectively. The sequencing of strain G1 resulted in the assembly of a chromosomal scaffold comprising 2,379,166 bp with a G + C content of 52.06%. Genome analysis of strain G1 revealed the presence of 48 virulence genes and 5 antibiotic resistance genes (ARGs). Comparative genomic analysis demonstrates a high degree of genetic similarity among C. pseudotuberculosis strains, in contrast to other Corynebacterium species, with a clear delineation between strains belonging to the two biovars (ovis and equi). The data of the present study contribute to a better understanding of the properties of C. pseudotuberculosis biovar equi strains and the potential risk they pose to alpacas and other livestock, as well as the necessity of ongoing surveillance and monitoring of infectious diseases in animals.
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Affiliation(s)
- Wanyu Meng
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Shanyu Chen
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Lin Huang
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Jinpeng Yang
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Wenqing Zhang
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Zhijun Zhong
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Ziyao Zhou
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Haifeng Liu
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Hualin Fu
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Tingmei He
- Sichuan Wolong National Natural Reserve Administration, Wenchuan, Sichuan, China
| | - Guangneng Peng
- The Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
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Enhanced Hemolytic Activity of Mesophilic Aeromonas salmonicida SRW-OG1 Is Brought about by Elevated Temperatures. Microorganisms 2022; 10:microorganisms10102033. [PMID: 36296309 PMCID: PMC9609485 DOI: 10.3390/microorganisms10102033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 10/04/2022] [Accepted: 10/12/2022] [Indexed: 11/17/2022] Open
Abstract
Aeromonas salmonicida is a well-known cold-water pathogenic bacterium. Previously, we reported the first isolation of pathogenic A. salmonicida from diseased Epinephelus coioides, a kind of warm-water fish, and it was proved to be a putative mesophilic strain with potent pathogenicity to humans. In order to investigate the mechanisms underlying mesophilic growth ability and virulence, the transcriptome of A. salmonicida SRW-OG1 at 18, 28, and 37 °C was analyzed. The transcriptome of A. salmonicida SRW-OG1 at different temperatures showed a clear separation boundary, which might provide valuable information for the temperature adaptation and virulence regulation of A. salmonicida SRW-OG1. Interestingly, aerA and hlyA, the hemolytic genes encoding aerolysin and hemolysin, were found to be significantly up-regulated at 28 and 37 °C. Since aerolysin and hemolysin are the most well-known and -characterized virulence factors of pathogenic Aeromonas strains, the induction of aerA and hlyA was associated with the mesophilic virulence. Further study proved that the extracellular products (ECPs) purchased from A. salmonicida SRW-OG1 cultured at 28 and 37 °C showed elevated hemolytic activity and virulence than those at 18 °C. Moreover, the silence of aerA and hlyA led to significantly decreased hemolysis and virulence. Taken together, our results revealed that the mesophilic virulence of A. salmonicida SRW-OG1 might be due to the enhanced expression of aerA and hlyA induced by elevated temperatures.
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Streptococcus suis TrpX is part of a tryptophan uptake system, and its expression is regulated by a T-box regulatory element. Sci Rep 2022; 12:13920. [PMID: 35978073 PMCID: PMC9382623 DOI: 10.1038/s41598-022-18227-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 08/08/2022] [Indexed: 11/25/2022] Open
Abstract
Streptococcus suis, a common member of the porcine respiratory microbiota, can cause life-threatening diseases in pigs as well as humans. A previous study identified the gene trpX as conditionally essential for in vivo survival by intrathecal infection of pigs with a transposon library of S. suis strain 10. Here, we characterized trpX, encoding a putative tryptophan/tyrosine transport system substrate-binding protein, in more detail. We compared growth capacities of the isogenic trpX-deficient mutant derivative strain 10∆trpX with its parent. Growth experiments in chemically defined media (CDM) revealed that growth of 10∆trpX depended on tryptophan concentration, suggesting TrpX involvement in tryptophan uptake. We demonstrated that trpX is part of an operon structure and co-transcribed with two additional genes encoding a putative permease and ATPase, respectively. Bioinformatics analysis identified a putative tryptophan T-box riboswitch in the 5′ untranslated region of this operon. Finally, qRT-PCR and a reporter activation assay revealed trpX mRNA induction under tryptophan-limited conditions. In conclusion, our study showed that TrpX is part of a putative tryptophan ABC transporter system regulated by a T-box riboswitch probably functioning as a substrate-binding protein. Due to the tryptophan auxotrophy of S. suis, TrpX plays a crucial role for metabolic adaptation and growth during infection.
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Pellegrini A, Lentini G, Famà A, Bonacorsi A, Scoffone VC, Buroni S, Trespidi G, Postiglione U, Sassera D, Manai F, Pietrocola G, Firon A, Biondo C, Teti G, Beninati C, Barbieri G. CodY Is a Global Transcriptional Regulator Required for Virulence in Group B Streptococcus. Front Microbiol 2022; 13:881549. [PMID: 35572655 PMCID: PMC9096947 DOI: 10.3389/fmicb.2022.881549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 03/21/2022] [Indexed: 12/03/2022] Open
Abstract
Group B Streptococcus (GBS) is a Gram-positive bacterium able to switch from a harmless commensal of healthy adults to a pathogen responsible for invasive infections in neonates. The signals and regulatory mechanisms governing this transition are still largely unknown. CodY is a highly conserved global transcriptional regulator that links nutrient availability to the regulation of major metabolic and virulence pathways in low-G+C Gram-positive bacteria. In this work, we investigated the role of CodY in BM110, a GBS strain representative of a hypervirulent lineage associated with the majority of neonatal meningitis. Deletion of codY resulted in a reduced ability of the mutant strain to cause infections in neonatal and adult animal models. The observed decreased in vivo lethality was associated with an impaired ability of the mutant to persist in the blood, spread to distant organs, and cross the blood-brain barrier. Notably, the codY null mutant showed reduced adhesion to monolayers of human epithelial cells in vitro and an increased ability to form biofilms, a phenotype associated with strains able to asymptomatically colonize the host. RNA-seq analysis showed that CodY controls about 13% of the genome of GBS, acting mainly as a repressor of genes involved in amino acid transport and metabolism and encoding surface anchored proteins, including the virulence factor Srr2. CodY activity was shown to be dependent on the availability of branched-chain amino acids, which are the universal cofactors of this regulator. These results highlight a key role for CodY in the control of GBS virulence.
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Affiliation(s)
- Angelica Pellegrini
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Germana Lentini
- Department of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Agata Famà
- Department of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Andrea Bonacorsi
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Viola Camilla Scoffone
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Silvia Buroni
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Gabriele Trespidi
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Umberto Postiglione
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Davide Sassera
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | - Federico Manai
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
| | | | - Arnaud Firon
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Unité Biologie des Bactéries Pathogènes à Gram-positif, Paris, France
| | - Carmelo Biondo
- Department of Human Pathology and Medicine, University of Messina, Messina, Italy
| | | | - Concetta Beninati
- Department of Human Pathology and Medicine, University of Messina, Messina, Italy
| | - Giulia Barbieri
- Department of Biology and Biotechnology "Lazzaro Spallanzani," University of Pavia, Pavia, Italy
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The Copper Resistome of Group B Streptococcus Reveals Insight into the Genetic Basis of Cellular Survival during Metal Ion Stress. J Bacteriol 2022; 204:e0006822. [PMID: 35404113 DOI: 10.1128/jb.00068-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In bacteria, copper (Cu) can support metabolic processes as an enzymatic cofactor but can also cause cell damage if present in excess, leading to intoxication. In group B Streptococcus (GBS), a system for control of Cu efflux based on the prototypical cop operon supports survival during Cu stress. In some other bacteria, genetic systems additional to the cop operon are engaged during Cu stress and also contribute to the management of cellular Cu homeostasis. Here, we examined genetic systems beyond the cop operon in GBS for regions that contribute to survival of GBS in Cu stress using a forward genetic screen and probe of the entire bacterial genome. A high-density mutant library, generated using pGh9-ISS1, was used to expose GBS to Cu stress and compare it to nonexposed controls en masse. Eight genes were identified as essential for GBS survival in Cu stress, whereas five genes constrained GBS growth in Cu stress. The genes encode varied factors including enzymes for metabolism, cell wall synthesis, transporters, and cell signaling factors. Targeted mutation of the genes validated their roles in GBS resistance to Cu stress. Excepting copA, the genes identified are new to the area of bacterial metal ion intoxication. We conclude that a discrete and limited suite of genes beyond the cop operon in GBS contributes to a repertoire of mechanisms used to survive Cu stress in vitro and achieve cellular homeostasis. IMPORTANCE Genetic systems for copper (Cu) homeostasis in bacteria, including streptococci, are vital to survive metal ion stress. Genetic systems that underpin survival of GBS during Cu stress, beyond the archetypal cop operon for Cu management, are undefined. We show that Streptococcus resists Cu intoxication by utilizing a discrete and limited suite of genes beyond the cop operon, including several genes that are new to the area of bacterial cell metal ion homeostasis. The Cu resistome of GBS defined here enhances our understanding of metal ion homeostasis in GBS.
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Fernando DM, Gee CT, Griffith EC, Meyer CJ, Wilt LA, Tangallapally R, Wallace MJ, Miller DJ, Lee RE. Biophysical analysis of the Mycobacteria tuberculosis peptide binding protein DppA reveals a stringent peptide binding pocket. Tuberculosis (Edinb) 2022; 132:102157. [PMID: 34894561 PMCID: PMC8818035 DOI: 10.1016/j.tube.2021.102157] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 11/21/2021] [Accepted: 11/26/2021] [Indexed: 01/03/2023]
Abstract
The peptide binding protein DppA is an ABC transporter found in prokaryotes that has the potential to be used as drug delivery tool for hybrid antibiotic compounds. Understanding the motifs and structures that bind to DppA is critical to the development of these bivalent compounds. This study focused on the biophysical analysis of the MtDppA from M. tuberculosis. Analysis of the crystal structure revealed a SVA tripeptide was co-crystallized with the protein. Further peptide analysis demonstrated MtDppA shows very little affinity for dipeptides but rather preferentially binds to peptides that are 3-4 amino acids in length. The structure-activity relationships (SAR) between MtDppA and tripeptides with varied amino acid substitutions were evaluated using thermal shift, SPR, and molecular dynamics simulations. Efforts to identify novel ligands for use as alternative scaffolds through the thermal shift screening of 35,000 compounds against MtDppA were unsuccessful, indicating that the MtDppA binding pocket is highly specialized for uptake of peptides. Future development of compounds that seek to utilize MtDppA as a drug delivery mechanism, will likely require a tri- or tetrapeptide component with a hydrophobic -non-acidic peptide sequence.
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Affiliation(s)
- Dinesh M. Fernando
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Clifford T. Gee
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Elizabeth C. Griffith
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Christopher J. Meyer
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Laura A. Wilt
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Rajendra Tangallapally
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Miranda J. Wallace
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Darcie J. Miller
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Richard E. Lee
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN 38105,Corresponding Author:
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Zhang H, Liu Y, Wu G, Dong X, Xiong Q, Chen L, Xu Z, Feng H, Zhang R. Bacillus velezensis tolerance to the induced oxidative stress in root colonization contributed by the two-component regulatory system sensor ResE. PLANT, CELL & ENVIRONMENT 2021; 44:3094-3102. [PMID: 33864643 DOI: 10.1111/pce.14068] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 04/08/2021] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
Efficient root colonization of plant growth-promoting rhizobacteria is critical for their plant-beneficial functions. However, the strategy to overcome plant immunity during root colonization is not well understood. In particular, how Bacillus strains cope with plant-derived reactive oxygen species (ROS), which function as the first barrier of plant defence, is not clear. In the present study, we found that the homolog of flg22 in Bacillus velezensis SQR9 (flg22SQR9 ) has 78.95% identity to the typical flg22 (flg22P.s. ) and induces a significant oxidative burst in cucumber and Arabidopsis. In contrast to pathogenic or beneficial Pseudomonas, live B. velezensis SQR9 also induced an oxidative burst in cucumber. We further found that B. velezensis SQR9 tolerated higher H2 O2 levels than Pst DC3000, the pathogen that harbours the typical flg22, and that it possesses the ability to suppress the flg22-induced oxidative burst, indicating that B. velezensis SQR9 may exploit a more efficient ROS tolerance system than DC3000. Further experimentation with mutagenesis of bacteria and Arabidopsis showed that the two-component regulatory system, ResDE, in B. velezensis SQR9 is involved in tolerance to plant-derived oxidative stress, thus contributing to root colonization. This study supports a further investigation of the interaction between beneficial rhizobacteria and plant immunity.
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Affiliation(s)
- Huihui Zhang
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Yunpeng Liu
- Key Laboratory of Agricultural Microbial Resources Collection and Preservation, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Gengwei Wu
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Xiaoyan Dong
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Qin Xiong
- Key Laboratory of Agricultural Microbial Resources Collection and Preservation, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Lin Chen
- Experimental Center of Forestry in North China, Chinese Academy of Forestry, Beijing, China
| | - Zhihui Xu
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Haichao Feng
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
| | - Ruifu Zhang
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China
- Key Laboratory of Agricultural Microbial Resources Collection and Preservation, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
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Xu X, Chen J, Huang X, Feng S, Zhang X, She F, Wen Y. The Role of a Dipeptide Transporter in the Virulence of Human Pathogen, Helicobacter pylori. Front Microbiol 2021; 12:633166. [PMID: 33732225 PMCID: PMC7959749 DOI: 10.3389/fmicb.2021.633166] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 02/05/2021] [Indexed: 12/16/2022] Open
Abstract
Helicobacter pylori harbors a dipeptide (Dpp) transporter consisting of a substrate-binding protein (DppA), two permeases (DppB and C), and two ATPases (DppD and F). The Dpp transporter is responsible for the transportation of dipeptides and short peptides. We found that its expression is important for the growth of H. pylori. To understand the role of the Dpp transporter in the pathogenesis of H. pylori, the expression of virulence factors and H. pylori-induced IL-8 production were investigated in H. pylori wild-type and isogenic H. pylori Dpp transporter mutants. We found that expression of CagA was downregulated, while expression of type 4 secretion system (T4SS) components was upregulated in Dpp transporter mutants. The DppA mutant strain expressed higher levels of outer membrane proteins (OMPs), including BabA, HopZ, OipA, and SabA, and showed a higher adhesion level to gastric epithelial AGS cells compared with the H. pylori 26695 wild-type strain. After infection of AGS cells, H. pylori ΔdppA induced a higher level of NF-κB activation and IL-8 production compared with wild-type. These results suggested that in addition to supporting the growth of H. pylori, the Dpp transporter causes bacteria to alter the expression of virulence factors and reduces H. pylori-induced NF-κB activation and IL-8 production in gastric epithelial cells.
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Affiliation(s)
- Xiaohong Xu
- Key Laboratory of Gastrointestinal Cancer (Fujian Medical University), Ministry of Education, Fuzhou, China.,Fujian Key Laboratory of Tumor Microbiology, Department of Medical Microbiology, Fujian Medical University, Fuzhou, China.,Fujian Medical University Union Hospital, Fuzhou, China
| | - Junwei Chen
- Key Laboratory of Gastrointestinal Cancer (Fujian Medical University), Ministry of Education, Fuzhou, China.,Fujian Key Laboratory of Tumor Microbiology, Department of Medical Microbiology, Fujian Medical University, Fuzhou, China
| | - Xiaoxing Huang
- Key Laboratory of Gastrointestinal Cancer (Fujian Medical University), Ministry of Education, Fuzhou, China.,Fujian Key Laboratory of Tumor Microbiology, Department of Medical Microbiology, Fujian Medical University, Fuzhou, China
| | - Shunhang Feng
- Key Laboratory of Gastrointestinal Cancer (Fujian Medical University), Ministry of Education, Fuzhou, China.,Fujian Key Laboratory of Tumor Microbiology, Department of Medical Microbiology, Fujian Medical University, Fuzhou, China
| | - Xiaoyan Zhang
- Key Laboratory of Gastrointestinal Cancer (Fujian Medical University), Ministry of Education, Fuzhou, China.,Fujian Key Laboratory of Tumor Microbiology, Department of Medical Microbiology, Fujian Medical University, Fuzhou, China
| | - Feifei She
- Key Laboratory of Gastrointestinal Cancer (Fujian Medical University), Ministry of Education, Fuzhou, China.,Fujian Key Laboratory of Tumor Microbiology, Department of Medical Microbiology, Fujian Medical University, Fuzhou, China
| | - Yancheng Wen
- Key Laboratory of Gastrointestinal Cancer (Fujian Medical University), Ministry of Education, Fuzhou, China.,Fujian Key Laboratory of Tumor Microbiology, Department of Medical Microbiology, Fujian Medical University, Fuzhou, China
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Molecular Basis of Unexpected Specificity of ABC Transporter-Associated Substrate-Binding Protein DppA from Helicobacter pylori. J Bacteriol 2019; 201:JB.00400-19. [PMID: 31358613 DOI: 10.1128/jb.00400-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 07/22/2019] [Indexed: 12/16/2022] Open
Abstract
The gastric pathogen Helicobacter pylori has limited ability to use carbohydrates as a carbon source, relying instead on exogenous amino acids and peptides. Uptake of certain peptides by H. pylori requires an ATP binding cassette (ABC) transporter annotated dipeptide permease (Dpp). The transporter specificity is determined by its cognate substrate-binding protein DppA, which captures ligands in the periplasm and delivers them to the permease. Here, we show that, unlike previously characterized DppA proteins, H. pylori DppA binds, with micromolar affinity, peptides of diverse amino acid sequences ranging between two and eight residues in length. We present analysis of the 1.45-Å-resolution crystal structure of its complex with the tetrapeptide STSA, which provides a structural rationale for the observed broad specificity. Analysis of the molecular surface revealed a ligand-binding pocket that is large enough to accommodate peptides of up to nine residues in length. The structure suggests that H. pylori DppA is able to recognize a wide range of peptide sequences by forming interactions primarily with the peptide main chain atoms. The loop that terminates the peptide-binding pocket in DppAs from other bacteria is significantly shorter in the H. pylori protein, providing an explanation for its ability to bind longer peptides. The subsites accommodating the two N-terminal residues of the peptide ligand make the greatest contribution to the protein-ligand binding energy, in agreement with the observation that dipeptides bind with affinity close to that of longer peptides.IMPORTANCE The World Health Organization listed Helicobacter pylori as a high-priority pathogen for antibiotic development. The potential of using peptide transporters in drug design is well recognized. We discovered that the substrate-binding protein of the ABC transporter for peptides, termed dipeptide permease, is an unusual member of its family in that it directly binds peptides of diverse amino acid sequences, ranging between two and eight residues in length. We also provided a structural rationale for the observed broad specificity. Since the ability to import peptides as a source of carbon is critical for H. pylori, our findings will inform drug design strategies based on inhibition or fusion of membrane-impermeant antimicrobials with peptides.
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10
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Zhang JS, Corredig M, Morales-Rayas R, Hassan A, Griffiths MW, LaPointe G. Downregulation of Salmonella Virulence Gene Expression During Invasion of Epithelial Cells Treated with Lactococcus lactis subsp. cremoris JFR1 Requires OppA. Probiotics Antimicrob Proteins 2019; 12:577-588. [PMID: 31377945 DOI: 10.1007/s12602-019-09574-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Invasion of Salmonella into host intestinal epithelial cells requires the expression of virulence genes. In this study, cell culture models of human intestinal cells (mucus-producing HT29-MTX cells, absorptive Caco-2 cells, and combined cocultures of the two) were used to determine the effects of Lactococcus lactis subsp. cremoris treatments (exopolysaccharide producing and nonproducing strains) on the virulence gene expression of Salmonella Typhimurium and its mutant lacking the oligopeptide permease subunit A (ΔoppA). During the course of epithelial cell (HT29-MTX, Caco-2, and combined) infection by Salmonella Typhimurium DT104, improved barrier function was reflected by increased transepithelial electrical resistance in cells treated with both strains of L. lactis subsp. cremoris. In addition, virulence gene expression was downregulated, accompanied with lower numbers of invasive bacteria into epithelial cells in the presence of L. lactis subsp. cremoris treatments. Similarly, virulence gene expression of Salmonella was also suppressed when coincubated with overnight cultures of both L. lactis subsp. cremoris strains in the absence of epithelial cells. However, in medium or in the presence of cell cultures, Salmonella lacking the OppA permease function remained virulent. HT29-MTX cells and combined cultures stimulated by Salmonella Typhimurium DT104 showed significantly lower secretion levels of pro-inflammatory cytokine IL-8 after treatment with L. lactis subsp. cremoris cell suspensions. Contrarily, these responses were not observed during infection with S. Typhimurium ΔoppA. Both the exopolysaccharide producing and nonproducing strains of L. lactis subsp. cremoris JFR1 exhibited an antivirulence effect against S. Typhimurium DT104 although no significant difference between the two strains was observed. Our results show that an intact peptide transporter is essential for the suppression of Salmonella virulence genes which leads to the protection of the barrier function in the cell culture models studied.
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Affiliation(s)
- J S Zhang
- Canadian Research Institute for Food Safety, Department of Food Science, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - M Corredig
- Department of Food Science, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - R Morales-Rayas
- Canadian Research Institute for Food Safety, Department of Food Science, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - A Hassan
- Daisy Brand, Dallas, TX, 75251, USA
| | - M W Griffiths
- Canadian Research Institute for Food Safety, Department of Food Science, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Gisèle LaPointe
- Canadian Research Institute for Food Safety, Department of Food Science, University of Guelph, Guelph, ON, N1G 2W1, Canada.
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11
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Zhu L, Shahid MA, Markham J, Browning GF, Noormohammadi AH, Marenda MS. Comparative genomic analyses of Mycoplasma synoviae vaccine strain MS-H and its wild-type parent strain 86079/7NS: implications for the identification of virulence factors and applications in diagnosis of M. synoviae. Avian Pathol 2019; 48:537-548. [PMID: 31244324 DOI: 10.1080/03079457.2019.1637514] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mycoplasma synoviae is an economically important avian pathogen worldwide, causing respiratory disease, infectious synovitis, airsacculitis and eggshell apex abnormalities in commercial chickens. Despite the widespread use of MS-H as a live attenuated vaccine over the past two decades, the precise molecular basis for loss of virulence in this vaccine is not yet fully understood. To address this, the whole genome sequence of the vaccine parent strain, 86079/7NS, was obtained and compared to that of the MS-H vaccine. Except for the vlhA expressed region, both genomes were nearly identical. Thirty-two single nucleotide polymorphisms (SNPs) were identified in MS-H, including 11 non-synonymous mutations that were predicted, by bioinformatics analysis, to have changed the secondary structure of the deduced proteins. One of these mutations caused truncation of the oppF-1 gene, which encodes the ATP-binding protein of an oligopeptide permease transporter. Overall, the attenuation of MS-H strain may be caused by the cumulative and complex effects of several mutations. The SNPs identified in MS-H were further analyzed by comparing the MS-H and 86079/7NS sequences with the strains WVU-1853 and MS53. In the genomic regions conserved between all strains, 30 SNPs were found to be unique to MS-H lineage. These results have provided a foundation for developing novel biomarkers for the detection of virulence in M. synoviae and also for designing new genotyping assays for discrimination of MS-H from field strains.
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Affiliation(s)
- Ling Zhu
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, the University of Melbourne , Werribee , Australia
| | - Muhammad A Shahid
- Department of Pathobiology, Faculty of Veterinary Sciences, Bahauddin Zakariya University , Multan , Pakistan
| | - John Markham
- Department of Electrical and Electronic Engineering, the University of Melbourne , Parkville , Australia
| | - Glenn F Browning
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, the University of Melbourne , Parkville , Australia
| | - Amir H Noormohammadi
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, the University of Melbourne , Werribee , Australia
| | - Marc S Marenda
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, the University of Melbourne , Werribee , Australia
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12
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Zwe YH, Goh ZHE, Chau ML, Aung KT, Yuk HG. Survival of an emerging foodborne pathogen: Group B Streptococcus (GBS) serotype III sequence type (ST) 283-under simulated partial cooking and gastric fluid conditions. Food Sci Biotechnol 2018; 28:939-944. [PMID: 31093453 DOI: 10.1007/s10068-018-0525-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/19/2018] [Accepted: 11/27/2018] [Indexed: 01/13/2023] Open
Abstract
Group B Streptococcus (GBS) was previously not known to be transmitted through food, but an outbreak investigation in Singapore in 2015 documented for the first time an association between GBS Type III Sequence Type 283 infection and consumption of raw fish dishes. As very little is known about the survival of GBS during heat treatment and the stomach transit, its survival under simulated conditions was studied, in comparison with that of Escherichia coli O157:H7 and Listeria monocytogenes. The mean D-values of four GBS strains ranging from 0.72 to 0.88 min in neutral pH tryptone soy broth at 56.4 °C and 0.44-1.43 min at pH 2.35 at 37 °C in simulated gastric fluid, were significantly lower (p < 0.05) than those of E. coli O157:H7 and L. monocytogenes. This study suggests possible factors other than acid or heat resistance of GBS to be instrumental to its pathogenicity.
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Affiliation(s)
- Ye Htut Zwe
- 1Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 2, Singapore, 117543 Singapore
| | - Zhu Hui Esther Goh
- 1Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 2, Singapore, 117543 Singapore
| | - Man Ling Chau
- 2Environmental Health Institute, National Environment Agency, 11 Biopolis Way, Singapore, 138667 Singapore
| | - Kyaw Thu Aung
- 2Environmental Health Institute, National Environment Agency, 11 Biopolis Way, Singapore, 138667 Singapore.,3School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, Singapore, 637459 Singapore
| | - Hyun-Gyun Yuk
- 4Department of Food Science and Technology, Korea National University of Transportation, 61 Daehak-ro, Jeungpyeong-gun, Cheongju, Chungbuk 27909 Republic of Korea
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13
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Tavares GC, Carvalho AF, Pereira FL, Rezende CP, Azevedo VAC, Leal CAG, Figueiredo HCP. Transcriptome and Proteome of Fish-Pathogenic Streptococcus agalactiae Are Modulated by Temperature. Front Microbiol 2018; 9:2639. [PMID: 30450092 PMCID: PMC6224512 DOI: 10.3389/fmicb.2018.02639] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 10/16/2018] [Indexed: 12/23/2022] Open
Abstract
Streptococcus agalactiae is one of the most important pathogens associated with streptococcosis outbreaks in Nile tilapia farms worldwide. High water temperature (above 27°C) has been described as a predisposing factor for the disease in fish. At low temperatures (below 25°C), fish mortalities are not usually observed in farms. Temperature variation can modulate the expression of genes and proteins involved in metabolism, adaptation, and bacterial pathogenicity, thus increasing or decreasing the ability to infect the host. This study aimed to evaluate the transcriptome and proteome of a fish-pathogenic S. agalactiae strain SA53 subjected to in vitro growth at different temperatures using a microarray and label-free shotgun LC-HDMSE approach. Biological triplicates of isolates were cultured in BHIT broth at 22 or 32°C for RNA and protein isolation and submitted for transcriptomic and proteomic analyses. In total, 1,730 transcripts were identified in SA53, with 107 genes being differentially expressed between the temperatures evaluated. A higher number of genes related to metabolism, mainly from the phosphotransferase system (PTS) and ATP-binding cassette (ABC) transport system, were upregulated at 32°C. In the proteome analysis, 1,046 proteins were identified in SA53, of which 81 were differentially regulated between 22 and 32°C. Proteins involved in defense mechanisms, lipid transport and metabolism, and nucleotide transport and metabolism were upregulated at 32°C. A higher number of interactions were observed in proteins involved in nucleotide transport and metabolism. We observed a low correlation between the transcriptome and proteome datasets. Our study indicates that the transcriptome and proteome of a fish-adapted S. agalactiae strain are modulated by temperature, particularly showing differential expression of genes/proteins involved in metabolism, virulence factors, and adaptation.
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Affiliation(s)
- Guilherme C Tavares
- AQUACEN-National Reference Laboratory of Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Alex F Carvalho
- AQUACEN-National Reference Laboratory of Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Felipe L Pereira
- AQUACEN-National Reference Laboratory of Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Cristiana P Rezende
- AQUACEN-National Reference Laboratory of Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Vasco A C Azevedo
- LGCM-Laboratory of Cellular and Molecular Genetics, Biological Science Institute, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Carlos A G Leal
- AQUACEN-National Reference Laboratory of Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Henrique C P Figueiredo
- AQUACEN-National Reference Laboratory of Aquatic Animal Diseases, Ministry of Agriculture, Livestock and Food Supply, Veterinary School, Federal University of Minas Gerais, Belo Horizonte, Brazil
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14
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Masukagami Y, Nijagal B, Tseng CW, Dayalan S, Tivendale KA, Markham PF, Browning GF, Sansom FM. Metabolite profiling of Mycoplasma gallisepticum mutants, combined with bioinformatic analysis, can reveal the likely functions of virulence-associated genes. Vet Microbiol 2018; 223:160-167. [PMID: 30173742 DOI: 10.1016/j.vetmic.2018.08.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 08/01/2018] [Accepted: 08/01/2018] [Indexed: 11/18/2022]
Abstract
Mycoplasma gallisepticum is an economically important pathogen of commercial poultry. An improved understanding of M. gallisepticum pathogenesis is required to develop better control methods. We recently identified a number of M. gallisepticum mutants with defects in colonization and persistence in chickens using signature-tagged transposon mutagenesis. Loss of virulence was associated with mutations in a putative oligopeptide/dipeptide (opp/dpp) ATP-binding cassette (ABC) transporter (where the transposon was inserted into the MGA_0220 (oppD1) gene and two hypothetical proteins (encoded by MGA_1102 and MGA_0588), one of which (MGA_1102) contains a putative peptidase motif. To further characterise the function of these proteins, we compared the metabolome of each transposon mutant with that of wild type bacteria. Two independent LC/MS analyses revealed consistent significant decreases in the abundances of several amino acids and the dipeptide alanyl-glycine (Ala-Gly) in the MGA_0220 mutant, consistent with this protein being a peptide transporter. Similarly, lysine and Ala-Gly were significantly decreased in the MGA_1102 mutant, consistent with our bioinformatic analysis suggesting that MGA_1102 encodes a membrane-located peptidase. Few differences were observed in metabolite levels in the MGA_0588 mutant, suggesting that the disrupted protein has a non-metabolic role. Overall, this study indicates that metabolomics is a useful tool in the functional analysis of mutants.
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Affiliation(s)
- Yumiko Masukagami
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Brunda Nijagal
- Metabolomics Australia, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, Victoria, Australia
| | - Chi-Wen Tseng
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Saravanan Dayalan
- Metabolomics Australia, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, Victoria, Australia
| | - Kelly A Tivendale
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Philip F Markham
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Glenn F Browning
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia
| | - Fiona M Sansom
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Victoria, Australia.
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15
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Devaux L, Sleiman D, Mazzuoli MV, Gominet M, Lanotte P, Trieu-Cuot P, Kaminski PA, Firon A. Cyclic di-AMP regulation of osmotic homeostasis is essential in Group B Streptococcus. PLoS Genet 2018; 14:e1007342. [PMID: 29659565 PMCID: PMC5919688 DOI: 10.1371/journal.pgen.1007342] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 04/26/2018] [Accepted: 03/28/2018] [Indexed: 02/03/2023] Open
Abstract
Cyclic nucleotides are universally used as secondary messengers to control cellular physiology. Among these signalling molecules, cyclic di-adenosine monophosphate (c-di-AMP) is a specific bacterial second messenger recognized by host cells during infections and its synthesis is assumed to be necessary for bacterial growth by controlling a conserved and essential cellular function. In this study, we sought to identify the main c-di-AMP dependent pathway in Streptococcus agalactiae, the etiological agent of neonatal septicaemia and meningitis. By conditionally inactivating dacA, the only diadenyate cyclase gene, we confirm that c-di-AMP synthesis is essential in standard growth conditions. However, c-di-AMP synthesis becomes rapidly dispensable due to the accumulation of compensatory mutations. We identified several mutations restoring the viability of a ΔdacA mutant, in particular a loss-of-function mutation in the osmoprotectant transporter BusAB. Identification of c-di-AMP binding proteins revealed a conserved set of potassium and osmolyte transporters, as well as the BusR transcriptional factor. We showed that BusR negatively regulates busAB transcription by direct binding to the busAB promoter. Loss of BusR repression leads to a toxic busAB expression in absence of c-di-AMP if osmoprotectants, such as glycine betaine, are present in the medium. In contrast, deletion of the gdpP c-di-AMP phosphodiesterase leads to hyperosmotic susceptibility, a phenotype dependent on a functional BusR. Taken together, we demonstrate that c-di-AMP is essential for osmotic homeostasis and that the predominant mechanism is dependent on the c-di-AMP binding transcriptional factor BusR. The regulation of osmotic homeostasis is likely the conserved and essential function of c-di-AMP, but each species has evolved specific c-di-AMP mechanisms of osmoregulation to adapt to its environment. Nucleotide-based second messengers play central functions in bacterial physiology and host-pathogen interactions. Among these signalling nucleotides, cyclic-di-AMP (c-di-AMP) synthesis was originally assumed to be essential for bacterial growth. In this study, we confirmed that the only di-adenylate cyclase enzyme in the opportunistic pathogen Streptococcus agalactiae is essential in standard growth conditions. However, c-di-AMP synthesis becomes rapidly dispensable by accumulating spontaneous mutations in genes involved in osmotic regulation. We identified that c-di-AMP binds directly to four proteins necessary to maintain osmotic homeostasis, including three osmolyte transporters and the BusR transcriptional factor. We demonstrated that BusR negatively controls the expression of the busAB operon and that it is the main component leading to growth inhibition in the absence of c-di-AMP synthesis if osmoprotectants are present in the environment. Overall, c-di-AMP is essential to maintain osmotic homeostasis by coordinating osmolyte uptake and thus bacteria have developed specific mechanisms to keep c-di-AMP as the central regulator of osmotic homeostasis.
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Affiliation(s)
- Laura Devaux
- Institut Pasteur, Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS ERL 6002, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Dona Sleiman
- Institut Pasteur, Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS ERL 6002, Paris, France
| | - Maria-Vittoria Mazzuoli
- Institut Pasteur, Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS ERL 6002, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Myriam Gominet
- Institut Pasteur, Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS ERL 6002, Paris, France
| | - Philippe Lanotte
- Université de Tours, Infectiologie et Santé Publique, Bactéries et Risque Materno-Fœtal, INRA UMR1282, Tours France
- Hôpital Bretonneau, Centre Hospitalier Régional et Universitaire de Tours, Service de Bactériologie-Virologie, Tours France
| | - Patrick Trieu-Cuot
- Institut Pasteur, Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS ERL 6002, Paris, France
| | - Pierre-Alexandre Kaminski
- Institut Pasteur, Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS ERL 6002, Paris, France
| | - Arnaud Firon
- Institut Pasteur, Unité Biologie des Bactéries Pathogènes à Gram-positif, CNRS ERL 6002, Paris, France
- * E-mail:
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16
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Shabayek S, Spellerberg B. Acid Stress Response Mechanisms of Group B Streptococci. Front Cell Infect Microbiol 2017; 7:395. [PMID: 28936424 PMCID: PMC5594096 DOI: 10.3389/fcimb.2017.00395] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Accepted: 08/23/2017] [Indexed: 12/20/2022] Open
Abstract
Group B streptococcus (GBS) is a leading cause of neonatal mortality and morbidity in the United States and Europe. It is part of the vaginal microbiota in up to 30% of pregnant women and can be passed on to the newborn through perinatal transmission. GBS has the ability to survive in multiple different host niches. The pathophysiology of this bacterium reveals an outstanding ability to withstand varying pH fluctuations of the surrounding environments inside the human host. GBS host pathogen interations include colonization of the acidic vaginal mucosa, invasion of the neutral human blood or amniotic fluid, breaching of the blood brain barrier as well as survival within the acidic phagolysosomal compartment of macrophages. However, investigations on GBS responses to acid stress are limited. Technologies, such as whole genome sequencing, genome-wide transcription and proteome mapping facilitate large scale identification of genes and proteins. Mechanisms enabling GBS to cope with acid stress have mainly been studied through these techniques and are summarized in the current review
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Affiliation(s)
- Sarah Shabayek
- Institute of Medical Microbiology and Hygiene, University of UlmUlm, Germany.,Department of Microbiology and Immunology, Faculty of Pharmacy, Suez Canal UniversityIsmailia, Egypt
| | - Barbara Spellerberg
- Institute of Medical Microbiology and Hygiene, University of UlmUlm, Germany
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17
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Liu W, Huang L, Su Y, Qin Y, Zhao L, Yan Q. Contributions of the oligopeptide permeases in multistep of Vibrio alginolyticus pathogenesis. Microbiologyopen 2017; 6. [PMID: 28714216 PMCID: PMC5635161 DOI: 10.1002/mbo3.511] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 05/25/2017] [Accepted: 05/30/2017] [Indexed: 01/14/2023] Open
Abstract
Vibrio alginolyticus has been associated with several diseases of cultivated marine animals, and has led to considerable economic losses. The oligopeptide permease (Opp) has been proven to play a variety of important roles in nutrition and virulence in several bacteria. In our previous research, the opp gene cluster was identified in Vibrio alginolyticus with transcriptome sequence, which also indicated that the Opp system might play roles in the regulation of adhesion. In this study, the relationship between V. alginolyticus virulence and the opp gene cluster was determined using gene silencing followed by RT‐qPCR, in vitro adhesion assay, growth curves detection in the presence of glutathione (GSH) as a toxic substrate, hemolysis assay, biofilm assay, and artificial infection. Silencing these genes led to deficiencies in adhesion, peptide internalization, biofilm production, hemolytic activity, and virulence. The expression levels of hapr, hapa, tlh, and hlya, which are important genes closely related to the hemolytic activity of Vibrio, were significantly downregulated in all of the RNAi groups. Furthermore, the expression of oppA, oppB, oppC, oppD, and oppF was significantly influenced by temperature, starvation, and pH. These results indicate that (1) oppABCDF contributed in multistep of V. alginolyticus pathogenesis, including adhesion, biofilm production, and hemolytic activity; (2) oppABCDF was sensitive to different temperatures, changes in pH, and increased starvation time.
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Affiliation(s)
- Wenjia Liu
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Lixing Huang
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Yongquan Su
- State Key Laboratory of Large Yellow Croaker Breeding, Ningde, China.,College of Ocean & Earth Sciences, Xiamen University, Xiamen, China
| | - Yingxue Qin
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Lingmin Zhao
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Qingpi Yan
- Key Laboratory of Healthy Mariculture for the East China Sea, Fisheries College, Ministry of Agriculture, Jimei University, Xiamen, China.,State Key Laboratory of Large Yellow Croaker Breeding, Ningde, China
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18
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Garai P, Chandra K, Chakravortty D. Bacterial peptide transporters: Messengers of nutrition to virulence. Virulence 2016; 8:297-309. [PMID: 27589415 DOI: 10.1080/21505594.2016.1221025] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Bacteria possess numerous peptide transporters for importing peptides as nutrients. However, these peptide transporters are now consistently reported to play a role in the virulence of various bacterial pathogens. Their ability to transport peptides has implications in antibacterial therapy as well. Therefore, it would be instrumental to have complete knowledge about the role of peptide transporters in mediating this cross connection between metabolism and pathogenesis. Studies on various peptide transporters in bacterial pathogens have improved our understanding of this field. In this review, we have given an overview of the functioning of bacterial peptide transporters and their contribution in virulence of major bacterial pathogens.
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Affiliation(s)
- Preeti Garai
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
| | - Kasturi Chandra
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
| | - Dipshikha Chakravortty
- a Department of Microbiology and Cell Biology , Indian Institute of Science , Bangalore , India
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19
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Sharma N, Aduri NG, Iqbal A, Prabhala BK, Mirza O. Peptide Selectivity of the Proton-Coupled Oligopeptide Transporter from Neisseria meningitidis. J Mol Microbiol Biotechnol 2016; 26:312-9. [DOI: 10.1159/000447129] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 05/26/2016] [Indexed: 11/19/2022] Open
Abstract
Peptide transport in living organisms is facilitated by either primary transport, hydrolysis of ATP, or secondary transport, cotransport of protons. In this study, we focused on investigating the ligand specificity of the <i>Neisseria meningitidis</i> proton-coupled oligopeptide transporter (NmPOT). It has been shown that the gene encoding this transporter is upregulated during infection. NmPOT conformed to the typical chain length preference as observed in prototypical transporters of this family. In contrast to prototypical transporters, it was unable to accommodate a positively charged peptide residue at the C-terminus position of the substrate peptide. Sequence analysis of the active site of NmPOT displayed a distinctive aromatic patch, which has not been observed in any other transporters from this family. This aromatic patch may be involved in providing NmPOT with its atypical preferences. This study provides important novel information towards understanding how these transporters recognize their substrates.
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20
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Pietrocola G, Rindi S, Rosini R, Buccato S, Speziale P, Margarit I. The Group B Streptococcus-Secreted Protein CIP Interacts with C4, Preventing C3b Deposition via the Lectin and Classical Complement Pathways. THE JOURNAL OF IMMUNOLOGY 2015; 196:385-94. [PMID: 26608922 DOI: 10.4049/jimmunol.1501954] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/30/2015] [Indexed: 02/06/2023]
Abstract
The group B Streptococcus (GBS) is a leading cause of neonatal invasive disease. GBS bacteria are surrounded by a thick capsular polysaccharide that is a potent inhibitor of complement deposition via the alternative pathway. Several of its surface molecules can however activate the classical and lectin complement pathways, rendering this species still vulnerable to phagocytic killing. In this study we have identified a novel secreted protein named complement interfering protein (CIP) that downregulates complement activation via the classical and lectin pathways, but not the alternative pathway. The CIP protein showed high affinity toward C4b and inhibited its interaction with C2, presumably preventing the formation of the C4bC2a convertase. Addition of recombinant CIP to GBS cip-negative bacteria resulted in decreased deposition of C3b on their surface and in diminished phagocytic killing in a whole-blood assay. Our data reveal a novel strategy exploited by GBS to counteract innate immunity and could be valuable for the development of anti-infective agents against this important pathogen.
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Affiliation(s)
- Giampiero Pietrocola
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia, 27100 Pavia, Italy; and
| | - Simonetta Rindi
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia, 27100 Pavia, Italy; and
| | | | | | - Pietro Speziale
- Department of Molecular Medicine, Unit of Biochemistry, University of Pavia, 27100 Pavia, Italy; and
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21
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Garai P, Lahiri A, Ghosh D, Chatterjee J, Chakravortty D. Peptide utilizing carbon starvation gene yjiY is required for flagella mediated infection caused by Salmonella. MICROBIOLOGY-SGM 2015; 162:100-116. [PMID: 26497384 DOI: 10.1099/mic.0.000204] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Peptide metabolism forms an important part of the metabolic network of Salmonella and to acquire these peptides the pathogen possesses a number of peptide transporters. While various peptide transporters known in Salmonella are well studied, very little is known about the carbon starvation (cst) genes, cstA and yjiY, which are also predicted to be involved in peptide metabolism. We investigated the role of these genes in the metabolism and pathogenesis of Salmonella and demonstrated for the first time that cst genes actually participate in transport of specific peptides in Salmonella. Further, we established that the carbon starvation gene yjiY affects the expression of flagella leading to poor adhesion of the bacterium to host cells. In contrast with the previously reported role of the gene cstA in virulence of Salmonella in C. elegans, we showed that yjiY is required for successful colonization of Salmonella in the mouse gut. Thus, cst genes not only contribute to the metabolism of Salmonella but also influence its virulence.
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Affiliation(s)
- Preeti Garai
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Amit Lahiri
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Dipan Ghosh
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Jayanta Chatterjee
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
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22
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RovS and its associated signaling peptide form a cell-to-cell communication system required for Streptococcus agalactiae pathogenesis. mBio 2015; 6:mBio.02306-14. [PMID: 25604789 PMCID: PMC4324310 DOI: 10.1128/mbio.02306-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Bacteria can communicate with each other to coordinate their biological functions at the population level. In a previous study, we described a cell-to-cell communication system in streptococci that involves a transcriptional regulator belonging to the Rgg family and short hydrophobic peptides (SHPs) that act as signaling molecules. Streptococcus agalactiae, an opportunistic pathogenic bacterium responsible for fatal infections in neonates and immunocompromised adults, has one copy of the shp/rgg locus. The SHP-associated Rgg is called RovS in S. agalactiae. In this study, we found that the SHP/RovS cell-to-cell communication system is active in the strain NEM316 of S. agalactiae, and we identified different partners that are involved in this system, such as the Eep peptidase, the PptAB, and the OppA1-F oligopeptide transporters. We also identified a new target gene controlled by this system and reexamined the regulation of a previously proposed target gene, fbsA, in the context of the SHP-associated RovS system. Furthermore, our results are the first to indicate the SHP/RovS system specificity to host liver and spleen using a murine model, which demonstrates its implication in streptococci virulence. Finally, we observed that SHP/RovS regulation influences S. agalactiae's ability to adhere to and invade HepG2 hepatic cells. Hence, the SHP/RovS cell-to-cell communication system appears to be an essential mechanism that regulates pathogenicity in S. agalactiae and represents an attractive target for the development of new therapeutic strategies. IMPORTANCE Rgg regulators and their cognate pheromones, called small hydrophobic peptides (SHPs), are present in nearly all streptococcal species. The general pathways of the cell-to-cell communication system in which Rgg and SHP take part are well understood. However, many other players remain unidentified, and the direct targets of the system, as well as its link to virulence, remain unclear. Here, we identified the different players involved in the SHP/Rgg system in S. agalactiae, which is the leading agent of severe infections in human newborns. We have identified a direct target of the Rgg regulator in S. agalactiae (called RovS) and examined a previously proposed target, all in the context of associated SHP. For the first time, we have also demonstrated the implication of the SHP/RovS mechanism in virulence, as well as its host organ specificity. Thus, this cell-to-cell communication system may represent a future target for S. agalactiae disease treatment.
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Characterization of the Opp peptide transporter of Corynebacterium pseudotuberculosis and its role in virulence and pathogenicity. BIOMED RESEARCH INTERNATIONAL 2014; 2014:489782. [PMID: 24895581 PMCID: PMC4034477 DOI: 10.1155/2014/489782] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 04/16/2014] [Indexed: 11/17/2022]
Abstract
Despite the economic importance of caseous lymphadenitis (CLA), a chronic disease caused by Corynebacterium pseudotuberculosis, few genes related to the virulence of its etiologic agent have been characterized. The oligopeptide permease (Opp) transporters are located in the plasma membrane and have functions generally related to the uptake of peptides from the extracellular environment. These peptide transporters, in addition to having an important role in cell nutrition, also participate in the regulation of various processes involving intercellular signaling, including the control of the expression of virulence genes in pathogenic bacteria. To study the role of Opp in C. pseudotuberculosis, an OppD deficient strain was constructed via simple crossover with a nonreplicative plasmid carrying part of the oppD gene sequence. As occurred to the wild-type, the ΔoppD strain showed impaired growth when exposed to the toxic glutathione peptide (GSH), indicating two possible scenarios: (i) that this component can be internalized by the bacterium through an Opp-independent pathway or (ii) that there is toxicity while the peptide is extracellular. Additionally, the ΔoppD mutant presented a reduced ability to adhere to and infect macrophages compared to the wild-type, although both strains exhibit the same potential to colonize spleens and cause injury and death to infected mice.
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Adaptive response of Group B streptococcus to high glucose conditions: new insights on the CovRS regulation network. PLoS One 2013; 8:e61294. [PMID: 23585887 PMCID: PMC3621830 DOI: 10.1371/journal.pone.0061294] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 03/10/2013] [Indexed: 11/23/2022] Open
Abstract
Although the contribution of carbohydrate catabolism to bacterial colonization and infection is well recognized, the transcriptional changes during these processes are still unknown. In this study, we have performed comparative global gene expression analysis of GBS in sugar-free versus high glucose milieu. The analysis revealed a differential expression of genes involved in metabolism, transport and host-pathogen interaction. Many of them appeared to be among the genes previously reported to be controlled by the CovRS two-component system. Indeed, the transcription profile of a ΔcovRS strain grown in high-glucose conditions was profoundly affected. In particular, of the total genes described to be regulated by glucose, ∼27% were under CovRS control with a functional role in protein synthesis, transport, energy metabolism and regulation. Among the CovRS dependent genes, we found bibA, a recently characterized adhesin involved in bacterial serum resistance and here reported to be down-regulated by glucose. ChIP analysis revealed that in the presence of glucose, CovR binds bibA promoter in vivo, suggesting that CovR may act as a negative regulator or a repressor. We also demonstrated that, as for other target promoters, chemical phosphorylation of CovR in aspartic acid increases its affinity for the bibA promoter region. The data reported in this study contribute to the understanding of the molecular mechanisms modulating the adaptation of GBS to glucose.
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Plasmid content of a clinically relevant Klebsiella pneumoniae clone from the Czech Republic producing CTX-M-15 and QnrB1. Antimicrob Agents Chemother 2012; 57:1073-6. [PMID: 23229477 DOI: 10.1128/aac.01886-12] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The entire plasmid content of a multidrug-resistant, CTX-M-15-producing Klebsiella pneumoniae ST416 clone was investigated. Two FII(K) plasmids, pKDO1 (127 kb) and pKPN-CZ (207 kb), were identified and found to carry a formidable set of genes conferring resistance to toxic compounds, metals, and antimicrobial drugs and exhibiting novel features putatively associated with adaptation and fitness of the bacterium in the human host.
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Chimalapati S, Cohen JM, Camberlein E, MacDonald N, Durmort C, Vernet T, Hermans PWM, Mitchell T, Brown JS. Effects of deletion of the Streptococcus pneumoniae lipoprotein diacylglyceryl transferase gene lgt on ABC transporter function and on growth in vivo. PLoS One 2012; 7:e41393. [PMID: 22911788 PMCID: PMC3404074 DOI: 10.1371/journal.pone.0041393] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 06/21/2012] [Indexed: 12/14/2022] Open
Abstract
Lipoproteins are an important class of surface associated proteins that have diverse roles and frequently are involved in the virulence of bacterial pathogens. As prolipoproteins are attached to the cell membrane by a single enzyme, prolipoprotein diacylglyceryl transferase (Lgt), deletion of the corresponding gene potentially allows the characterisation of the overall importance of lipoproteins for specific bacterial functions. We have used a Δlgt mutant strain of Streptococcus pneumoniae to investigate the effects of loss of lipoprotein attachment on cation acquisition, growth in media containing specific carbon sources, and virulence in different infection models. Immunoblots of triton X-114 extracts, flow cytometry and immuno-fluorescence microscopy confirmed the Δlgt mutant had markedly reduced lipoprotein expression on the cell surface. The Δlgt mutant had reduced growth in cation depleted medium, increased sensitivity to oxidative stress, reduced zinc uptake, and reduced intracellular levels of several cations. Doubling time of the Δlgt mutant was also increased slightly when grown in medium with glucose, raffinose and maltotriose as sole carbon sources. These multiple defects in cation and sugar ABC transporter function for the Δlgt mutant were associated with only slightly delayed growth in complete medium. However the Δlgt mutant had significantly reduced growth in blood or bronchoalveolar lavage fluid and a marked impairment in virulence in mouse models of nasopharyngeal colonisation, sepsis and pneumonia. These data suggest that for S. pneumoniae loss of surface localisation of lipoproteins has widespread effects on ABC transporter functions that collectively prevent the Δlgt mutant from establishing invasive infection.
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Affiliation(s)
- Suneeta Chimalapati
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Jonathan M. Cohen
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
- Infectious Diseases & Microbiology Unit, UCL Institute of Child Health, London, United Kingdom
| | - Emilie Camberlein
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Nathanael MacDonald
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
| | - Claire Durmort
- CEA, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- CNRS, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- Université Joseph Fourier – Grenoble 1, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
| | - Thierry Vernet
- CEA, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- CNRS, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
- Université Joseph Fourier – Grenoble 1, Institut de Biologie Structurale Jean-Pierre Ebel, Grenoble, France
| | - Peter W. M. Hermans
- Laboratory of Pediatric Infectious Diseases, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Timothy Mitchell
- Division of Infection and Immunity, IBLS, University of Glasgow, Glasgow, United Kingdom
| | - Jeremy S. Brown
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London, United Kingdom
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Senn BM, Visram Z, Meinke AL, Neubauer C, Gelbmann D, Sinzinger J, Hanner M, Lundberg U, Boisvert H, Reinscheid D, von Gabain A, Nagy E. Monoclonal antibodies targeting different cell wall antigens of group B streptococcus mediate protection in both Fc-dependent and independent manner. Vaccine 2011; 29:4116-24. [DOI: 10.1016/j.vaccine.2011.03.100] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Revised: 03/20/2011] [Accepted: 03/28/2011] [Indexed: 10/18/2022]
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Bamford CV, Francescutti T, Cameron CE, Jenkinson HF, Dymock D. Characterization of a novel family of fibronectin-binding proteins with M23 peptidase domains from Treponema denticola. Mol Oral Microbiol 2011; 25:369-83. [PMID: 21040511 DOI: 10.1111/j.2041-1014.2010.00584.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Interactions with fibronectin are important in the virulence strategies of a range of disease-related bacteria. The periodontitis-associated oral spirochaete Treponema denticola expresses at least two fibronectin-binding proteins, designated Msp (major surface protein) and OppA (oligopeptide-binding protein homologue). To identify other T. denticola outer membrane fibronectin-binding proteins, the amino acid sequence of the Treponema pallidum fibronectin-binding protein Tp0155 was used to survey the T. denticola genome. Seven T. denticola genes encoding orthologous proteins were identified. All but two were expressed in Escherichia coli and purified recombinant proteins bound fibronectin. Using antibodies to the N-terminal region of Tp0155, it was demonstrated that T. denticola TDE2318, with highest homology to Tp0155, was cell surface localized. Like Tp0155, the seven T. denticola proteins contained an M23 peptidase domain and four (TDE2318, TDE2753, TDE1738, TDE1297) contained one or two LysM domains. M23 peptidases can degrade peptidoglycan whereas LysM domains recognize carbohydrate polymers. In addition, TDE1738 may act as a bacteriocin based on homology with other bacterial lysins and the presence of an adjacent gene encoding a putative immunity factor. Collectively, these results suggest that T. denticola expresses fibronectin-binding proteins associated with the cell surface that may also have cell wall modifying or lytic functions.
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Affiliation(s)
- C V Bamford
- Oral Microbiology Unit, Department of Oral and Dental Science, University of Bristol, Bristol, UK.
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Samen U, Heinz B, Boisvert H, Eikmanns BJ, Reinscheid DJ, Borges F. Rga is a regulator of adherence and pilus formation in Streptococcus agalactiae. MICROBIOLOGY-SGM 2011; 157:2319-2327. [PMID: 21330442 DOI: 10.1099/mic.0.044933-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Streptococcus agalactiae is the leading cause of bacterial sepsis and meningitis in neonates and is also the causative agent of several serious infections in immunocompromised adults. S. agalactiae encounters multiple niches during an infection, suggesting that regulatory mechanisms control the expression of specific virulence factors in this bacterium. The present study describes the functional characterization of a gene from S. agalactiae, designated rga, which encodes a protein with significant similarity to members of the RofA-like protein (RALP) family of transcriptional regulators. After deletion of the rga gene in the genome of S. agalactiae, the mutant strain exhibited significantly reduced expression of the genes srr-1 and pilA, which encode a serine-rich repeat surface glycoprotein and a pilus protein, respectively, and moderately increased expression of the fbsA gene, which encodes a fibrinogen-binding protein. Electrophoretic mobility shift assays demonstrated specific DNA binding of purified Rga to the promoter regions of pilA and fbsA, suggesting that Rga directly controls pilA and fbsA. Adherence assays revealed significantly reduced binding of the Δrga mutant to epithelial HEp-2 cells and to immobilized human keratin 4, respectively. In contrast, the adherence of the Δrga mutant to A549 cells and its binding to human fibrinogen was significantly increased. Immunoblot and immunoelectron microscopy revealed that the quantity of pilus structures was significantly reduced in the Δrga mutant compared with the parental strain. The wild-type phenotype could be restored by plasmid-mediated expression of rga, demonstrating that the mutant phenotypes resulted from a loss of Rga function.
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Affiliation(s)
- Ulrike Samen
- Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
| | - Beate Heinz
- Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
| | - Heike Boisvert
- Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
| | - Bernhard J Eikmanns
- Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
| | - Dieter J Reinscheid
- University of Applied Sciences Bonn-Rhein-Sieg, 53359 Rheinbach, Germany.,Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
| | - Frédéric Borges
- Laboratoire d'Ingénierie des Biomolécules, Nancy Université, ENSAIA - INPL, 54505 Vandoeuvre-lès-Nancy, France.,Institute of Microbiology and Biotechnology, University of Ulm, 89069 Ulm, Germany
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Le Maréchal C, Jardin J, Jan G, Even S, Pulido C, Guibert JM, Hernandez D, François P, Schrenzel J, Demon D, Meyer E, Berkova N, Thiéry R, Vautor E, Le Loir Y. Staphylococcus aureus seroproteomes discriminate ruminant isolates causing mild or severe mastitis. Vet Res 2011; 42:35. [PMID: 21324116 PMCID: PMC3052181 DOI: 10.1186/1297-9716-42-35] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Accepted: 02/15/2011] [Indexed: 11/24/2022] Open
Abstract
Staphylococcus aureus is a major cause of mastitis in ruminants. In ewe mastitis, symptoms range from subclinical to gangrenous mastitis. S. aureus factors or host-factors contributing to the different outcomes are not completely elucidated. In this study, experimental mastitis was induced on primiparous ewes using two S. aureus strains, isolated from gangrenous (strain O11) or subclinical (strain O46) mastitis. Strains induced drastically distinct clinical symptoms when tested in ewe and mice experimental mastitis. Notably, they reproduced mild (O46) or severe (O11) mastitis in ewes. Ewe sera were used to identify staphylococcal immunoreactive proteins commonly or differentially produced during infections of variable severity and to define core and accessory seroproteomes. Such SERological Proteome Analysis (SERPA) allowed the identification of 89 immunoreactive proteins, of which only 52 (58.4%) were previously identified as immunogenic proteins in other staphylococcal infections. Among the 89 proteins identified, 74 appear to constitute the core seroproteome. Among the 15 remaining proteins defining the accessory seroproteome, 12 were specific for strain O11, 3 were specific for O46. Distribution of one protein specific for each mastitis severity was investigated in ten other strains isolated from subclinical or clinical mastitis. We report here for the first time the identification of staphylococcal immunogenic proteins common or specific to S. aureus strains responsible for mild or severe mastitis. These findings open avenues in S. aureus mastitis studies as some of these proteins, expressed in vivo, are likely to account for the success of S. aureus as a pathogen of the ruminant mammary gland.
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Affiliation(s)
- Caroline Le Maréchal
- INRA, UMR1253 Science et Technologie du Lait et de l'Œuf, F-35042 Rennes, France.
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31
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Meinke AL, Senn BM, Visram Z, Henics TZ, Minh DB, Schüler W, Neubauer C, Gelbmann D, Noiges B, Sinzinger J, Hanner M, Dewasthaly S, Lundberg U, Hordnes K, Masoud H, Sevelda P, von Gabain A, Nagy E. Immunological fingerprinting of group B streptococci: From circulating human antibodies to protective antigens. Vaccine 2010; 28:6997-7008. [DOI: 10.1016/j.vaccine.2010.08.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 08/03/2010] [Accepted: 08/06/2010] [Indexed: 11/25/2022]
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Flores-Valdez MA, Morris RP, Laval F, Daffé M, Schoolnik GK. Mycobacterium tuberculosis modulates its cell surface via an oligopeptide permease (Opp) transport system. FASEB J 2009; 23:4091-104. [PMID: 19671666 DOI: 10.1096/fj.09-132407] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bacterial species utilize a vast repertoire of surface structures to interact with their surroundings and employ a number of strategies to reconfigure the cellular envelope according to specific stimuli. Gram-positive bacteria, exemplified by Streptomyces and Bacillus species, control production of some exposed molecules by importing oligopeptide signals via permeases (Opp). Such oligopeptides modulate intracellular signaling pathways. In this work, we functionally characterized an Opp of the human pathogen Mycobacterium tuberculosis (Mtb) and propose its reannotation. Using genome-wide transcriptional profiling, we found that Opp was required to modulate (fold-change ranging from -3.5 to 2.0) the expression of several genes, most of them encoding surface-exposed molecules. These included the virulence-associated lipids mycolic acids and phthiocerol dimycocerosates (PDIMs) as well as PE-family proteins. By thin-layer chromatography and MALDI-TOF-MS we confirmed changes in the lipid profile, including an altered accumulation of triacylglycerides and an affected ratio of mycolic acids to PDIMs. An Opp loss of function mutant showed no in vitro growth defect, but had diminished burden during chronic infection and produced a slightly delayed time to death of animals when compared to WT Mtb infection.
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Affiliation(s)
- Mario Alberto Flores-Valdez
- Centro de Investigación y Asistencia en Tecnología y diseño del Estado de Jalisco A.C., Normalistas 800, Colinas de la Normal, 44270 Guadalajara, Jalisco, México.
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Sitkiewicz I, Green NM, Guo N, Bongiovanni AM, Witkin SS, Musser JM. Transcriptome adaptation of group B Streptococcus to growth in human amniotic fluid. PLoS One 2009; 4:e6114. [PMID: 19568429 PMCID: PMC2700258 DOI: 10.1371/journal.pone.0006114] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 05/25/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Streptococcus agalactiae (group B Streptococcus) is a bacterial pathogen that causes severe intrauterine infections leading to fetal morbidity and mortality. The pathogenesis of GBS infection in this environment is poorly understood, in part because we lack a detailed understanding of the adaptation of this pathogen to growth in amniotic fluid. To address this knowledge deficit, we characterized the transcriptome of GBS grown in human amniotic fluid (AF) and compared it with the transcriptome in rich laboratory medium. METHODS GBS was grown in Todd Hewitt-yeast extract medium and human AF. Bacteria were collected at mid-logarithmic, late-logarithmic and stationary growth phase. We performed global expression microarray analysis using a custom-made Affymetrix GeneChip. The normalized hybridization values derived from three biological replicates at each growth point were obtained. AF/THY transcript ratios representing greater than a 2-fold change and P-value exceeding 0.05 were considered to be statistically significant. PRINCIPAL FINDINGS We have discovered that GBS significantly remodels its transcriptome in response to exposure to human amniotic fluid. GBS grew rapidly in human AF and did not exhibit a global stress response. The majority of changes in GBS transcripts in AF compared to THY medium were related to genes mediating metabolism of amino acids, carbohydrates, and nucleotides. The majority of the observed changes in transcripts affects genes involved in basic bacterial metabolism and is connected to AF composition and nutritional requirements of the bacterium. Importantly, the response to growth in human AF included significant changes in transcripts of multiple virulence genes such as adhesins, capsule, and hemolysin and IL-8 proteinase what might have consequences for the outcome of host-pathogen interactions. CONCLUSIONS/SIGNIFICANCE Our work provides extensive new information about how the transcriptome of GBS responds to growth in AF, and thus new leads for pathogenesis research.
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Affiliation(s)
- Izabela Sitkiewicz
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, and Department of Pathology, The Methodist Hospital, Houston, Texas, United States of America
| | - Nicole M. Green
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, and Department of Pathology, The Methodist Hospital, Houston, Texas, United States of America
| | - Nina Guo
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, and Department of Pathology, The Methodist Hospital, Houston, Texas, United States of America
| | - Ann Marie Bongiovanni
- Weill Medical College of Cornell University, New York, New York, United States of America
| | - Steven S. Witkin
- Weill Medical College of Cornell University, New York, New York, United States of America
| | - James M. Musser
- Center for Molecular and Translational Human Infectious Diseases Research, The Methodist Hospital Research Institute, and Department of Pathology, The Methodist Hospital, Houston, Texas, United States of America
- Weill Medical College of Cornell University, New York, New York, United States of America
- * E-mail:
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CsrRS regulates group B Streptococcus virulence gene expression in response to environmental pH: a new perspective on vaccine development. J Bacteriol 2009; 191:5387-97. [PMID: 19542277 DOI: 10.1128/jb.00370-09] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To identify factors involved in the response of group B streptococci (GBS) to environmental pH, we performed a comparative global gene expression analysis of GBS at acidic and neutral pHs. We found that the transcription of 317 genes was increased at pH 5.5 relative to that at pH 7.0, while 61 genes were downregulated. The global response to acid stress included the differential expression of genes involved in transport, metabolism, stress response, and virulence. Known vaccine candidates, such as BibA and pilus components, were also regulated by pH. We observed that many of the genes involved in the GBS response to pH are known to be controlled by the CsrRS two-component system. Comparison of the regulon of wild-type strain 2603 V/R with that of a csrRS deletion mutant strain revealed that the pH-dependent regulation of 90% of the downregulated genes and 59.3% of the up-regulated genes in strain 2603 V/R was CsrRS dependent and that many virulence factors were overexpressed at high pH. Beta-hemolysin regulation was abrogated by selective inactivation of csrS, suggesting the implication of the CsrS protein in pH sensing. These results imply that the translocation of GBS from the acidic milieu of the vagina to the neutral pH of the neonatal lung signals the up-regulation of GBS virulence factors and conversion from a colonizing to an invasive phenotype. In addition, the fact that increased exposure of BibA on the bacterial surface at pH 7.0 induced opsonophagocytic killing of GBS in immune serum highlights the importance of pH regulation in the protective efficacy of specific antibodies to surface-exposed GBS proteins.
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Kazmierczak KM, Wayne KJ, Rechtsteiner A, Winkler ME. Roles of rel(Spn) in stringent response, global regulation and virulence of serotype 2 Streptococcus pneumoniae D39. Mol Microbiol 2009; 72:590-611. [PMID: 19426208 PMCID: PMC2739083 DOI: 10.1111/j.1365-2958.2009.06669.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
RelA/SpoT homologue (RSH) proteins have (p)ppGpp synthetase and hydrolase activities that mediate major global responses to nutrient limitation and other stresses. RSH proteins are conserved in most bacteria and play diverse roles in bacterial pathogenesis. We report here that the RSH protein of Streptococcus pneumoniae, Rel(Spn), can be deleted and is the primary source of (p)ppGpp synthesis in virulent strain D39 under some conditions. A D39 Deltarel(Spn) mutant grew well in complex medium, but did not grow in chemically defined medium unless supplemented with the metals copper and manganese. Transcriptome analysis of D39 rel(+)(Spn) and Deltarel(Spn) strains treated with mupirocin revealed rel(Spn)-independent (translation stress), rel(Spn)-dependent (stringent response) and Deltarel(Spn)-dependent changes, suggesting that rel(Spn) and (p)ppGpp amount play wide-ranging homeostatic roles in pneumococcal physiology, besides adjusting macromolecular synthesis and transport in response to nutrient availability. Notably, the rel(Spn)-dependent response included significant upregulation of the ply operon encoding pneumolysin toxin, whereas the Deltarel(Spn)-dependent response affected expression linked to the VicRK and CiaRH two-component systems. Finally, a D39 Deltarel(Spn) mutant was severely attenuated and displayed a significantly altered course of disease progression in a mouse model of infection, which was restored to normal by an ectopic copy of rel(+)(Spn).
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Affiliation(s)
| | - Kyle J. Wayne
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana 47405 U.S.A
| | - Andreas Rechtsteiner
- Center for Genomics and Bioinformatics, Indiana University Bloomington, Bloomington, Indiana 47405 U.S.A
| | - Malcolm E. Winkler
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana 47405 U.S.A
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Wu Z, Zhang W, Lu C. Immunoproteomic assay of surface proteins ofStreptococcus suisserotype 9. ACTA ACUST UNITED AC 2008; 53:52-9. [DOI: 10.1111/j.1574-695x.2008.00401.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Bolotin S, Fuller JD, Bast DJ, de Azavedo JCS. The two-component system sivS/R regulates virulence in Streptococcus iniae. ACTA ACUST UNITED AC 2008; 51:547-54. [PMID: 17991014 DOI: 10.1111/j.1574-695x.2007.00334.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Streptococcus iniae causes invasive disease and death in fish, and to a lesser extent, sporadic cases of soft-tissue infections in humans. A two-component system termed sivS/R, which regulates capsule expression, was previously identified and characterized. In this study, it is shown that a sivS/R deletion-insertion mutant, termed 9117Deltasiv, causes transient bacteremia and reduced virulence compared with the parent strain when tested in a murine model of bacteremic infection. Furthermore, real-time PCR studies indicated that SivS/R regulates the expression levels of the streptolysin S structural gene, sagA, as well as the CAMP factor gene, cfi. Sodium dodecyl sulphate polyacrylamide gel electrophoresis of S. iniae spheroplasts revealed downregulation of three surface proteins in the mutant strain compared with the parent strain. These proteins were identified by MS to be a putative lipoprotein, a hyaluronate-associated protein and a pyruvate kinase. This study demonstrates that SivS/R regulates virulence in vivo, and controls the expression of a number of genes in S. iniae.
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Affiliation(s)
- Shelly Bolotin
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
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Variation in the group B Streptococcus CsrRS regulon and effects on pathogenicity. J Bacteriol 2008; 190:1956-65. [PMID: 18203834 DOI: 10.1128/jb.01677-07] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CsrRS (or CovRS) is a two-component regulatory system that controls expression of multiple virulence factors in the important human pathogen group B Streptococcus (GBS). We now report global gene expression studies in GBS strains 2603V/R and 515 and their isogenic csrR and csrS mutants. Together with data reported previously for strain NEM316, the results reveal a conserved 39-gene CsrRS regulon. In vitro phosphorylation-dependent binding of recombinant CsrR to promoter regions of both positively and negatively regulated genes suggests that direct binding of CsrR can mediate activation as well as repression of target gene expression. Distinct patterns of gene regulation in csrR versus csrS mutants in strain 2603V/R compared to 515 were associated with different hierarchies of relative virulence of wild-type, csrR, and csrS mutants in murine models of systemic infection and septic arthritis. We conclude that CsrRS regulates a core group of genes including important virulence factors in diverse strains of GBS but also displays marked variability in the repertoire of regulated genes and in the relative effects of CsrS signaling on CsrR-mediated gene regulation. Such variation is likely to play an important role in strain-specific adaptation of GBS to particular host environments and pathogenic potential in susceptible hosts.
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Khandavilli S, Homer KA, Yuste J, Basavanna S, Mitchell T, Brown JS. Maturation of Streptococcus pneumoniae lipoproteins by a type II signal peptidase is required for ABC transporter function and full virulence. Mol Microbiol 2007; 67:541-57. [PMID: 18086214 PMCID: PMC2228790 DOI: 10.1111/j.1365-2958.2007.06065.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cell surface lipoproteins are important for the full virulence of several bacterial pathogens, including Streptococcus pneumoniae. Processing of prolipoproteins seems to be conserved among different bacterial species, and requires type II signal peptidase (Lsp) mediated cleavage of the N-terminal signal peptide to form the mature lipoprotein. Lsp has been suggested as a target for new antibiotic therapies, but at present there are only limited data on the function of Lsp for Gram-positive bacterial pathogens. We have investigated the function and role during disease pathogenesis of the S. pneumoniae Lsp, which, blast searches suggest, is encoded by the gene Sp0928. Expression of Sp0928 protected Escherichia coli against the Lsp antagonist globomycin, and proteomics and immunoblot analysis demonstrated that deletion of Sp0928 prevented processing of S. pneumoniae prolipoproteins to mature lipoproteins. These data strongly suggest that Sp0928 encodes the S. pneumoniae Lsp. However, immunoblots of membrane-associated proteins, immunoelectron microscopy and flow cytometry assays all confirmed that in the absence of Lsp, immature lipoproteins were still attached to the cell surface. Despite preservation of lipoprotein attachment to the cell membrane, loss of S. pneumoniae Lsp resulted in several phenotypes associated with impaired lipoprotein function and reduced S. pneumoniae replication in animal models of infection.
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Affiliation(s)
- Suneeta Khandavilli
- Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London WC1E 6JJ, UK
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Ritt JF, Guilloux-Benatier M, Guzzo J, Alexandre H, Remize F. Oligopeptide assimilation and transport by Oenococcus oeni. J Appl Microbiol 2007; 104:573-80. [PMID: 17927746 DOI: 10.1111/j.1365-2672.2007.03585.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS Oenococcus oeni is a slow-growing wine bacterium with a low growth yield. It thrives better on complex nitrogen sources than on free amino-acid medium. We aimed to characterize the oligopeptide use of this micro-organism. METHODS AND RESULTS Several peptides of two to eight amino-acid residues were able to provide essential amino acids. The disappearance of various peptides from extracellular medium was assessed with whole cells. Initial rates of utilization varied with the peptide, and free amino acids were released into the medium. CONCLUSIONS Oenococcus oeni was able to transport the oligopeptides with two to five amino-acid residues tested and to hydrolyse them further. SIGNIFICANCE AND IMPACT OF THE STUDY This study has clear implications for the relationship between wine nitrogen composition and the ability of O. oeni to cope with its environment.
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Affiliation(s)
- J-F Ritt
- Laboratoire Recherche En Vigne et Vin, Université de Bourgogne, Dijon, France
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Control of the transcription of a short gene encoding a cyclic peptide in Streptococcus thermophilus: a new quorum-sensing system? J Bacteriol 2007; 189:8844-54. [PMID: 17921293 DOI: 10.1128/jb.01057-07] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gram-positive bacteria secrete a variety of peptides that are often subjected to posttranslational modifications and that are either antimicrobials or pheromones involved in bacterial communication. Our objective was to identify peptides secreted by Streptococcus thermophilus, a nonpathogenic bacterium widely used in dairy technology in association with other bacteria, and to understand their potential roles in cell-cell communication. Using reverse-phase liquid chromatography, mass spectrometry, and Edman sequencing, we analyzed the culture supernatants of three S. thermophilus strains (CNRZ1066, LMG18311, and LMD-9) grown in a medium containing no peptides. We identified several peptides in the culture supernatants, some of them found with the three strains while others were specific to the LMD-9 strain. We focused our study on a new modified peptide secreted by S. thermophilus LMD-9 and designated Pep1357C. This peptide contains 9 amino acids and lost 2 Da in a posttranslational modification, most probably a dehydrogenation, leading to a linkage between the Lys2 and Trp6 residues. Production of Pep1357C and transcription of its encoding gene depend on both the medium composition and the growth phase. Furthermore, we demonstrated that transcription of the gene coding for Pep1357C is drastically decreased in mutants inactivated for the synthesis of a short hydrophobic peptide, a transcriptional regulator, or the oligopeptide transport system. Taken together, our results led us to deduce that the transcription of the Pep1357C-encoding gene is controlled by a new quorum-sensing system.
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Nepomuceno RSL, Tavares MB, Lemos JA, Griswold AR, Ribeiro JL, Balan A, Guimarães KS, Cai S, Burne RA, Ferreira LCS, Ferreira RCC. The oligopeptide (opp) gene cluster of Streptococcus mutans: identification, prevalence, and characterization. ACTA ACUST UNITED AC 2007; 22:277-84. [PMID: 17600541 DOI: 10.1111/j.1399-302x.2007.00368.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
INTRODUCTION The Opp system is an ATP-binding cassette-type transporter formed by membrane-associated proteins required for the uptake of oligopeptides in bacteria. In gram-positive bacteria, the Opp system, and particularly the oligopeptide-binding protein (OppA), has been shown to be involved in different aspects of cell physiology, including intercellular communication and binding to host proteins. METHODS In the present study we began to investigate the Opp system of Streptococcus mutans, the main etiological agent of dental caries. RESULTS Five opp genes (oppABCDF) organized in a single operon were identified in the genome of the S. mutans UA159 strain. Amino acid sequence analyses showed that the S. mutans OppA is closely related to an ortholog found in Streptococcus agalactiae. Incubation of S. mutans UA159 cells with an anti-OppA-specific serum did not inhibit biofilm formation on polystyrene plates. Moreover, S. mutans UA159 derivatives carrying deletions on the oppA or oppB genes did not show significant growth impairment, increased sensitivity to aminopterin, or defective capacity to form biofilms on polystyrene wells in the presence or not of saliva. Remarkably, only two out of three laboratory strains and one out of seven clinical strains recovered from tooth decay processes harbored a copy of the oppA gene and expressed the OppA protein. CONCLUSION Collectively, these results indicate that, in contrast to other Streptococcus species, the S. mutans Opp system, and particularly the OppA protein, does not represent an important trait required for growth and colonization.
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Affiliation(s)
- R S L Nepomuceno
- Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, Cidade Universitária, SP, Brazil
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Samen U, Eikmanns BJ, Reinscheid DJ, Borges F. The surface protein Srr-1 of Streptococcus agalactiae binds human keratin 4 and promotes adherence to epithelial HEp-2 cells. Infect Immun 2007; 75:5405-14. [PMID: 17709412 PMCID: PMC2168289 DOI: 10.1128/iai.00717-07] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Streptococcus agalactiae is frequently the cause of bacterial sepsis and meningitis in neonates. In addition, it is a commensal bacterium that colonizes the mammalian gastrointestinal tract. During its commensal and pathogenic lifestyles, S. agalactiae colonizes and invades a number of host compartments, thereby interacting with different host proteins. In the present study, the serine-rich repeat protein Srr-1 from S. agalactiae was functionally investigated. Immunofluorescence microscopy showed that Srr-1 was localized on the surface of streptococcal cells. The Srr-1 protein was shown to interact with a 62-kDa protein in human saliva, which was identified by matrix-assisted laser desorption ionization-time-of-flight analysis as human keratin 4 (K4). Immunoblot and enzyme-linked immunosorbent assay experiments allowed us to narrow down the K4 binding domain in Srr-1 to a region of 157 amino acids (aa). Furthermore, the Srr-1 binding domain of K4 was identified in the C-terminal 255 aa of human K4. Deletion of the srr-1 gene in the genome of S. agalactiae revealed that this gene plays a role in bacterial binding to human K4 and that it is involved in adherence to epithelial HEp-2 cells. Binding to immobilized K4 and adherence to HEp-2 cells were restored by introducing the srr-1 gene on a shuttle plasmid into the srr-1 mutant. Furthermore, incubation of HEp-2 cells with the K4 binding domain of Srr-1 blocked S. agalactiae adherence to epithelial cells in a dose-dependent fashion. This is the first report describing the interaction of a bacterial protein with human K4.
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Affiliation(s)
- Ulrike Samen
- Division of Gene Therapy, University of Ulm, 89081 Ulm, Germany.
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Hiron A, Borezée-Durant E, Piard JC, Juillard V. Only one of four oligopeptide transport systems mediates nitrogen nutrition in Staphylococcus aureus. J Bacteriol 2007; 189:5119-29. [PMID: 17496096 PMCID: PMC1951871 DOI: 10.1128/jb.00274-07] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Oligopeptides internalized by oligopeptide permease (Opp) transporters play key roles in bacterial nutrition, signaling, and virulence. To date, two opp operons, opp-1 and opp-2, have been identified in Staphylococcus aureus. Systematic in silico analysis of 11 different S. aureus genomes revealed the existence of two new opp operons, opp-3 and opp-4, plus an opp-5A gene encoding a putative peptide-binding protein. With the exception of opp-4, the opp operons were present in all S. aureus strains. Within a single strain, the different opp operons displayed little sequence similarity and distinct genetic organization. Transcriptional studies showed that opp-1, opp-2, opp-3, and opp-4 operons were polycistronic and that opp-5A is monocistronic. We designed a minimal chemically defined medium for S. aureus RN6390 and showed that all opp genes were expressed but at different levels. Where tested, OppA protein production paralleled transcriptional profiles. opp-3, which encodes proteins most similar to known peptide transport proteins, displayed the highest expression level and was the only transporter to be regulated by specific amino acids, tyrosine and phenylalanine. Defined deletion mutants in one or several peptide permeases were constructed and tested for their capacity to grow in peptide-containing medium. Among the four putative Opp systems, Opp-3 was the only system able to provide oligopeptides for growth, ranging in length from 3 to 8 amino acids. Dipeptides were imported exclusively by DtpT, a proton-driven di- and tripeptide permease. These data provide a first complete inventory of the peptide transport systems opp and dtpT of S. aureus. Among them, the newly identified Opp-3 appears to be the main Opp system supplying the cell with peptides as nutritional sources.
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Affiliation(s)
- Aurelia Hiron
- Unité Bactéries Lactiques et pathogènes Opportunistes, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas cedex, France
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Weinberg MV, Maier RJ. Peptide transport in Helicobacter pylori: roles of dpp and opp systems and evidence for additional peptide transporters. J Bacteriol 2007; 189:3392-402. [PMID: 17322309 PMCID: PMC1855898 DOI: 10.1128/jb.01636-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Despite research into the nutritional requirements of Helicobacter pylori, little is known regarding its use of complex substrates, such as peptides. Analysis of genome sequences revealed putative ABC-type transporter genes for dipeptide (dppABCDF) and oligopeptide (oppABCD) transport. Genes from each system were PCR amplified, cloned, and disrupted by cassette insertion either individually (dppA, dppB, dppC, oppA, oppB, and oppC) or to create double mutants (dppA oppA, dppB oppB, dppB dppC, and oppB oppC). Peptide-utilizing abilities of the strains were assessed by monitoring growth in a chemically defined medium where the only source of the essential amino acid isoleucine was from peptides of various lengths (two to nine amino acids long). The dipeptide system mutants lacked the ability to use certain dipeptides, hexapeptides, and nonapeptides. However, these mutants retained some ability to grow with other dipeptides, tripeptides, and tetrapeptides. Of the oligopeptide mutants, only the oppB strain differed significantly from the wild type. This strain showed a wild-type phenotype for growth with longer peptides (hexa- and nonapeptides) while having a decreased ability to utilize di-, tri-, and tetrapeptides. The dppA oppA and dppB oppB mutants showed similar phenotypes to those of the dppA and dppB mutants, respectively. Peptide digestion by metalloproteases was ruled out as the cause for residual peptide transport by growing mutant strains in the presence of either EDTA or EGTA. Degradation products associated with a fluorescein isothiocyanate-labeled hexapeptide (plus cells) were minimal. An as yet unidentified peptide transport system(s) in H. pylori is proposed to be responsible for the residual transport.
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Affiliation(s)
- Michael V Weinberg
- Department of Microbiology, Biological Sciences Building, University of Georgia, Athens, GA 30602, USA
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Samen UM, Eikmanns BJ, Reinscheid DJ. The transcriptional regulator RovS controls the attachment of Streptococcus agalactiae to human epithelial cells and the expression of virulence genes. Infect Immun 2006; 74:5625-35. [PMID: 16988238 PMCID: PMC1594887 DOI: 10.1128/iai.00667-06] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus agalactiae is part of the normal flora of the human gastrointestinal tract and also the leading cause of bacterial infections in human newborns and immunocompromised adults. The colonization and infection of different regions within the human host require a regulatory network in S. agalactiae that senses environmental stimuli and controls the formation of specific virulence factors. In the present study, we characterized an Rgg-like transcriptional regulator, designated RovS (regulator of virulence in Streptococcus agalactiae). Deletion of the rovS gene in the genome of S. agalactiae resulted in strain 6313 DeltarovS, which exhibited an increased attachment to immobilized fibrinogen and a significant increase in adherence to the eukaryotic lung epithelial cell line A549. Quantification of expression levels of known and putative S. agalactiae virulence genes by real-time PCR revealed that RovS influences the expression of fbsA, gbs0230, sodA, rogB, and the cyl operon. The altered gene expression in mutant 6313 DeltarovS was restored by plasmid-mediated expression of rovS, confirming the RovS deficiency as the cause for the observed changes in virulence gene expression in S. agalactiae. DNA electrophoretic mobility shift assays showed that RovS specifically binds to the promoter regions of fbsA, gbs0230, sodA, and the cyl operon, indicating that RovS directly regulates their expression. Deletion and mutation studies in the promoter region of fbsA, encoding the main fibrinogen receptor in S. agalactiae, identified a RovS DNA motif. Similar motifs were also found in the promoter regions of gbs0230, sodA, and the cyl operon, and alignments allowed us to propose a consensus sequence for the DNA-binding site of RovS.
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Affiliation(s)
- Ulrike M Samen
- Department of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, D-89069 Ulm, Germany.
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Domelier AS, van der Mee-Marquet N, Grandet A, Mereghetti L, Rosenau A, Quentin R. Loss of catabolic function in Streptococcus agalactiae strains and its association with neonatal meningitis. J Clin Microbiol 2006; 44:3245-50. [PMID: 16954255 PMCID: PMC1594740 DOI: 10.1128/jcm.02550-05] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The abilities of 151 Streptococcus agalactiae strains to oxidize 95 carbon sources were studied using the Biolog system. Two populations were constituted: one with a high risk of causing meningitis (HR group; 63 strains), and the other with a lower risk of causing meningitis (LR group; 46 strains). Strains belonging to the HR group were significantly less able to use four carbon sources, i.e., alpha-D-glucose-1-phosphate, D-ribose, beta-methyl-D-glucoside, and D,L-alpha-glycerol phosphate, than strains from the LR group (P <or= 0.004). Moreover, strains in the HR group significantly more frequently possessed one of several mobile genetic elements or genome deletions previously shown to be associated with strains responsible for neonatal meningitis than strains in the LR group (P < 0.001). These findings suggest that genetic disruption might have occurred in virulent clones of S. agalactiae. Fifteen biotypes (B1 to B15) were identified from the results of oxidation of the four carbon sources, of which six (B1 to B6) included 92% of the isolates belonging to the HR group. Strains of biotypes B1 to B6 are thus 13 times more likely to be able to invade the central nervous system of neonates than strains of biotypes B7 to B15. In addition, 86% of strains recently associated with neonatal meningitis (42 strains studied) were identified as being of biotypes B1 to B6. Identification of particular S. agalactiae biotypes may therefore be one of the criteria to assist clinicians in assessing the level of risk of neonatal meningitis when a mother and/or her neonate is colonized with S. agalactiae.
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Affiliation(s)
- Anne-Sophie Domelier
- Equipe d'Accueil 3854, Institut Fédératif de Recherche 136, Bactéries et risque maternofoetal, UFR Médecine, Université François-Rabelais de Tours, 2 bis Boulevard Tonnellé, 37032 Tours Cedex, France
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Rajagopal L, Vo A, Silvestroni A, Rubens CE. Regulation of purine biosynthesis by a eukaryotic-type kinase in Streptococcus agalactiae. Mol Microbiol 2005; 56:1329-46. [PMID: 15882424 PMCID: PMC2366208 DOI: 10.1111/j.1365-2958.2005.04620.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Group B streptococci (GBS) are the principal causal agents of human neonatal pneumonia, sepsis and meningitis. We had previously described the existence of a eukaryotic-type serine/threonine kinase (Stk1) and phosphatase (Stp1) in GBS that regulate growth and virulence of the pathogen. Our previous results also demonstrated that these enzymes reversibly phosphorylated an inorganic pyrophosphatase. To understand the role of these eukaryotic-type enzymes on growth of GBS, we assessed the stk1-mutants for auxotrophic requirements. In this report, we describe that in the absence of the kinase (Stk1), GBS are attenuated for de novo purine biosynthesis and are consequently growth arrested. During growth in media lacking purines, the intracellular G nucleotide pools (GTP, GDP and GMP) are significantly reduced in the Stk1-deficient strains, while levels of A nucleotides (ATP, ADP and AMP) are marginally increased when compared with the isogenic wild-type strain. We provide evidence that the reduced pools of G nucleotides result from altered activity of the IMP utilizing enzymes, adenylosuccinate synthetase (PurA) and IMP dehydrogenase (GuaB) in these strains. We also demonstrate that Stk1 and Stp1 reversibly phosphorylate and consequently regulate PurA activity in GBS. Collectively, these data indicate the novel role of eukaryotic-type kinases in regulation of metabolic processes such as purine biosynthesis.
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Affiliation(s)
- Lakshmi Rajagopal
- Division of Infectious Disease and Department of Pediatrics, Children's Hospital and Regional Medical Center and University of Washington, Suite 300, Mail Stop CW, 307 Westlake Ave. North, Seattle, WA 98109, USA.
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Kreikemeyer B, Nakata M, Oehmcke S, Gschwendtner C, Normann J, Podbielski A. Streptococcus pyogenes collagen type I-binding Cpa surface protein. Expression profile, binding characteristics, biological functions, and potential clinical impact. J Biol Chem 2005; 280:33228-39. [PMID: 16040603 DOI: 10.1074/jbc.m502896200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Streptococcus pyogenes collagen type I-binding protein Cpa (collagen-binding protein of group A streptococci) expressed by 28 serotypes of group A streptococci has been extensively characterized at the gene and protein levels. Evidence for three distinct families of cpa genes was found, all of which shared a common sequence encoding a 60-amino acid domain that accounted for selective binding to type I collagen. Surface plasmon resonance-based affinity measurements and functional studies indicated that the expression of Cpa was consistent with an attachment role for bacteria to tissue containing collagen type I. A cpa mutant displayed a significantly decreased internalization rate when incubated with HEp-2 cells but had no effect on the host cell viability. By utilizing serum from patients with a positive titer for streptolysin/DNase antibody, an increased anti-Cpa antibody titer was noted for patients with a clinical history of arthritis or osteomyelitis. Taken together, these results suggest Cpa may be a relevant matrix adhesin contributing to the pathogenesis of S. pyogenes infection of bones and joints.
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Affiliation(s)
- Bernd Kreikemeyer
- Department of Medical Microbiology and Hospital Hygiene, Hospital of Rostock University, Schillingallee 70, D-18057 Rostock, Germany
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Tenenbaum T, Bloier C, Adam R, Reinscheid DJ, Schroten H. Adherence to and invasion of human brain microvascular endothelial cells are promoted by fibrinogen-binding protein FbsA of Streptococcus agalactiae. Infect Immun 2005; 73:4404-9. [PMID: 15972538 PMCID: PMC1168575 DOI: 10.1128/iai.73.7.4404-4409.2005] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus agalactiae is a frequent cause of bacterial sepsis and meningitis in neonates. During the course of infection, S. agalactiae colonizes and invades a number of host compartments, thereby interacting with different host tissues. Deletion of the fbsA gene, encoding the fibrinogen protein FbsA, significantly impaired the adherence and invasion of human brain microvascular endothelial cells (HBMEC) by S. agalactiae. The adherence and invasiveness of an fbsA deletion mutant were restored by reintroducing the fbsA gene on an expression vector. Heterologous expression of fbsA in Lactococcus lactis enabled this bacterium to adhere to but not to invade HBMEC, suggesting that FbsA is a streptococcal adhesin. Finally, host cell adherence and invasion were significantly blocked in competition experiments with either purified FbsA fusion protein or a monoclonal antibody directed against the fibrinogen-binding epitope of FbsA. The S. agalactiae fbsA mutant induced a release of the neutrophil chemoattractant interleukin-8 (IL-8) equal to that induced by the wild type. Taken together, our studies demonstrate that FbsA promotes the adherence of S. agalactiae to HBMEC but that FbsA neither mediates the bacterial invasion into host cells nor plays a role in IL-8 release for HBMEC.
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Affiliation(s)
- Tobias Tenenbaum
- Pädiatrische Infektiologie, Klinik für Allgemeine Pädiatrie, Heinrich Heine Universität Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany
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