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Abstract
Type III secretion systems (T3SSs) are utilized by Gram-negative pathogens to enhance their pathogenesis. This secretion system is associated with the delivery of effectors through a needle-like structure from the bacterial cytosol directly into a target eukaryotic cell. These effector proteins then manipulate specific eukaryotic cell functions to benefit pathogen survival within the host. The obligate intracellular pathogens of the family Chlamydiaceae have a highly evolutionarily conserved nonflagellar T3SS that is an absolute requirement for their survival and propagation within the host with about one-seventh of the genome dedicated to genes associated with the T3SS apparatus, chaperones, and effectors. Chlamydiae also have a unique biphasic developmental cycle where the organism alternates between an infectious elementary body (EB) and replicative reticulate body (RB). T3SS structures have been visualized on both EBs and RBs. And there are effector proteins that function at each stage of the chlamydial developmental cycle, including entry and egress. This review will discuss the history of the discovery of chlamydial T3SS and the biochemical characterization of components of the T3SS apparatus and associated chaperones in the absence of chlamydial genetic tools. These data will be contextualized into how the T3SS apparatus functions throughout the chlamydial developmental cycle and the utility of heterologous/surrogate models to study chlamydial T3SS. Finally, there will be a targeted discussion on the history of chlamydial effectors and recent advances in the field.
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Affiliation(s)
- Elizabeth A. Rucks
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Durham Research Center II, Omaha, Nebraska, USA
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2
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Collingro A, Köstlbacher S, Siegl A, Toenshoff ER, Schulz F, Mitchell SO, Weinmaier T, Rattei T, Colquhoun DJ, Horn M. The Fish Pathogen "Candidatus Clavichlamydia salmonicola"-A Missing Link in the Evolution of Chlamydial Pathogens of Humans. Genome Biol Evol 2023; 15:evad147. [PMID: 37615694 PMCID: PMC10448858 DOI: 10.1093/gbe/evad147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/22/2023] [Indexed: 08/25/2023] Open
Abstract
Chlamydiae like Chlamydia trachomatis and Chlamydia psittaci are well-known human and animal pathogens. Yet, the chlamydiae are a much larger group of evolutionary ancient obligate intracellular bacteria that includes predominantly symbionts of protists and diverse animals. This makes them ideal model organisms to study evolutionary transitions from symbionts in microbial eukaryotes to pathogens of humans. To this end, comparative genome analysis has served as an important tool. Genome sequence data for many chlamydial lineages are, however, still lacking, hampering our understanding of their evolutionary history. Here, we determined the first high-quality draft genome sequence of the fish pathogen "Candidatus Clavichlamydia salmonicola", representing a separate genus within the human and animal pathogenic Chlamydiaceae. The "Ca. Clavichlamydia salmonicola" genome harbors genes that so far have been exclusively found in Chlamydia species suggesting that basic mechanisms important for the interaction with chordate hosts have evolved stepwise in the history of chlamydiae. Thus, the genome sequence of "Ca. Clavichlamydia salmonicola" allows to constrain candidate genes to further understand the evolution of chlamydial virulence mechanisms required to infect mammals.
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Affiliation(s)
- Astrid Collingro
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Stephan Köstlbacher
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
- Doctoral School in Microbiology and Environmental Science, University of Vienna, Vienna, Austria
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Alexander Siegl
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Elena R Toenshoff
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zürich (ETH), Zürich, Switzerland
| | - Frederik Schulz
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
- DOE Joint Genome Institute, Berkeley, California, USA
| | | | - Thomas Weinmaier
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Thomas Rattei
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | | | - Matthias Horn
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
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Rudra B, Duncan L, Shah AJ, Shah HN, Gupta RS. Phylogenomic and comparative genomic studies robustly demarcate two distinct clades of Pseudomonas aeruginosa strains: proposal to transfer the strains from an outlier clade to a novel species Pseudomonas paraeruginosa sp. nov. Int J Syst Evol Microbiol 2022; 72. [PMID: 36355412 DOI: 10.1099/ijsem.0.005542] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The strains of
Pseudomonas aeruginosa
exhibit considerable differences in their genotypic and pathogenic properties. To clarify their evolutionary/taxonomic relationships, comprehensive phylogenomic and comparative genomic studies were conducted on the genome sequences of 212
P
.
aeruginosa
strains covering their genetic diversity. In a phylogenomic tree based on 118 conserved proteins, the analysed strains formed two distinct clades. One of these clades, Clade-1, encompassing >70 % of the strains including the type strain DSM 50071T, represents the species P. aeruginosa sensu stricto. Clade-2, referred to in earlier work as the outlier group, with NCTC 13628T as its type strain, constitutes a novel species level lineage. The average nucleotide identity, average amino acid identity and digital DNA–DNA hybridization values between the strains from Clade-1 and Clade-2 are in the range of 93.4–93.7, 95.1–95.3 and 52–53 %, respectively. The 16S rRNA gene of
P. aeruginosa
DSM 50071T also shows 98.3 % similarity to that of NCTC 13628T. These values are lower than the suggested cut-off values for species distinction, indicating that the Clade-2 strains (NCTC 13628T) constitute a new species. We also report the identification of 12 conserved signature indels in different proteins and 24 conserved signature proteins that are exclusively found in either Clade-1 or Clade-2, providing a reliable means for distinguishing these clades. Additionally, in contrast to swimming motility, twitching motility is only present in Clade-1 strains. Based on earlier work, the strains from these two clades also differ in their pathogenic mechanisms (presence/absence of Type III secretion system), production of biosurfactants, phenazines and siderophores, and several other genomic characteristics. Based on the evidence from different studies, we propose that the Clade-2 strains constitute a novel species for which the name Pseudomonas paraeruginosa is proposed. The type strain is NCTC 13628T (=PA7T=ATCC 9027T). The description of
Pseudomonas aeruginosa
is also emended to include information for different molecular markers specific for this species.
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Affiliation(s)
- Bashudev Rudra
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton L8N 3Z5, Canada
| | - Louise Duncan
- School of Cancer and Pharmaceutical Sciences, King's College London, London SE1 9NH, UK
| | - Ajit J Shah
- Department of Natural Sciences, Middlesex University, London NW4 4BT, UK
| | - Haroun N Shah
- Department of Natural Sciences, Middlesex University, London NW4 4BT, UK
| | - Radhey S Gupta
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton L8N 3Z5, Canada
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Maddy J, Staker BL, Subramanian S, Abendroth J, Edwards TE, Myler PJ, Hybiske K, Asojo OA. Crystal structure of an inorganic pyrophosphatase from Chlamydia trachomatis D/UW-3/Cx. Acta Crystallogr F Struct Biol Commun 2022; 78:135-142. [PMID: 35234139 PMCID: PMC8900733 DOI: 10.1107/s2053230x22002138] [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: 01/04/2022] [Accepted: 02/23/2022] [Indexed: 11/11/2022] Open
Abstract
Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections globally and is one of the most commonly reported infections in the United States. There is a need to develop new therapeutics due to drug resistance and the failure of current treatments to clear persistent infections. Structures of potential C. trachomatis rational drug-discovery targets, including C. trachomatis inorganic pyrophosphatase (CtPPase), have been determined by the Seattle Structural Genomics Center for Infectious Disease. Inorganic pyrophosphatase hydrolyzes inorganic pyrophosphate during metabolism. Furthermore, bacterial inorganic pyrophosphatases have shown promise for therapeutic discovery. Here, a 2.2 Å resolution X-ray structure of CtPPase is reported. The crystal structure of CtPPase reveals shared structural features that may facilitate the repurposing of inhibitors identified for bacterial inorganic pyrophosphatases as starting points for new therapeutics for C. trachomatis.
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Jensen JL, Yamini S, Rietsch A, Spiller BW. "The structure of the Type III secretion system export gate with CdsO, an ATPase lever arm". PLoS Pathog 2020; 16:e1008923. [PMID: 33048983 PMCID: PMC7584215 DOI: 10.1371/journal.ppat.1008923] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 10/23/2020] [Accepted: 08/24/2020] [Indexed: 01/10/2023] Open
Abstract
Type III protein secretion systems (T3SS) deliver effector proteins from the Gram-negative bacterial cytoplasm into a eukaryotic host cell through a syringe-like, multi-protein nanomachine. Cytosolic components of T3SS include a portion of the export apparatus, which traverses the inner membrane and features the opening of the secretion channel, and the sorting complex for substrate recognition and for providing the energetics required for protein secretion. Two components critical for efficient effector export are the export gate protein and the ATPase, which are proposed to be linked by the central stalk protein of the ATPase. We present the structure of the soluble export gate homo-nonamer, CdsV, in complex with the central stalk protein, CdsO, of its cognate ATPase, both derived from Chlamydia pneumoniae. This structure defines the interface between these essential T3S proteins and reveals that CdsO engages the periphery of the export gate that may allow the ATPase to catalyze an opening between export gate subunits to allow cargo to enter the export apparatus. We also demonstrate through structure-based mutagenesis of the homologous export gate in Pseudomonas aeruginosa that mutation of this interface disrupts effector secretion. These results provide novel insights into the molecular mechanisms governing active substrate recognition and translocation through a T3SS. Many pathogenic Gram-negative bacteria utilize T3SS to export virulence factors in a well-regulated manner. Most component proteins of the T3SS are highly structurally conserved, capable of recognizing and secreting diverse effectors, which are recruited to the cytoplasmic sorting complex by chaperones. This work describes the molecular architecture of two essential components of a T3SS, identifies the interface between the components, and establishes the necessity of this interaction for effector secretion.
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Affiliation(s)
- Jaime L. Jensen
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Shavait Yamini
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States of America
| | - Arne Rietsch
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH, United States of America
| | - Benjamin W. Spiller
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, TN, United States of America
- * E-mail:
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Gitsels A, Van Lent S, Sanders N, Vanrompay D. Chlamydia: what is on the outside does matter. Crit Rev Microbiol 2020; 46:100-119. [PMID: 32093536 DOI: 10.1080/1040841x.2020.1730300] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This review summarises major highlights on the structural biology of the chlamydial envelope. Chlamydiae are obligate intracellular bacteria, characterised by a unique biphasic developmental cycle. Depending on the stage of their lifecycle, they appear in the form of elementary or reticulate bodies. Since these particles have distinctive functions, it is not surprising that their envelope differs in lipid as well as in protein content. Vice versa, by identifying surface proteins, specific characteristics of the particles such as rigidity or immunogenicity may be deduced. Detailed information on the bacterial membranes will increase our understanding on the host-pathogen interactions chlamydiae employ to survive and grow and might lead to new strategies to battle chlamydial infections.
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Affiliation(s)
- Arlieke Gitsels
- Laboratory of Immunology and Animal Biotechnology, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Sarah Van Lent
- Laboratory of Immunology and Animal Biotechnology, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Niek Sanders
- Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Daisy Vanrompay
- Laboratory of Immunology and Animal Biotechnology, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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Bugalhão JN, Mota LJ. The multiple functions of the numerous Chlamydia trachomatis secreted proteins: the tip of the iceberg. MICROBIAL CELL 2019; 6:414-449. [PMID: 31528632 PMCID: PMC6717882 DOI: 10.15698/mic2019.09.691] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Chlamydia trachomatis serovars are obligate intracellular bacterial pathogens mainly causing ocular and urogenital infections that affect millions of people worldwide and which can lead to blindness or sterility. They reside and multiply intracellularly within a membrane-bound vacuolar compartment, known as inclusion, and are characterized by a developmental cycle involving two morphologically and physiologically distinct chlamydial forms. Completion of the developmental cycle involves the secretion of > 70 C. trachomatis proteins that function in the host cell cytoplasm and nucleus, in the inclusion membrane and lumen, and in the extracellular milieu. These proteins can, for example, interfere with the host cell cytoskeleton, vesicular and non-vesicular transport, metabolism, and immune signalling. Generally, this promotes C. trachomatis invasion into, and escape from, host cells, the acquisition of nutrients by the chlamydiae, and evasion of cell-autonomous, humoral and cellular innate immunity. Here, we present an in-depth review on the current knowledge and outstanding questions about these C. trachomatis secreted proteins.
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Affiliation(s)
- Joana N Bugalhão
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Luís Jaime Mota
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
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Cryo-EM structure of the homohexameric T3SS ATPase-central stalk complex reveals rotary ATPase-like asymmetry. Nat Commun 2019; 10:626. [PMID: 30733444 PMCID: PMC6367419 DOI: 10.1038/s41467-019-08477-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 01/11/2019] [Indexed: 12/31/2022] Open
Abstract
Many Gram-negative bacteria, including causative agents of dysentery, plague, and typhoid fever, rely on a type III secretion system - a multi-membrane spanning syringe-like apparatus - for their pathogenicity. The cytosolic ATPase complex of this injectisome is proposed to play an important role in energizing secretion events and substrate recognition. We present the 3.3 Å resolution cryo-EM structure of the enteropathogenic Escherichia coli ATPase EscN in complex with its central stalk EscO. The structure shows an asymmetric pore with different functional states captured in its six catalytic sites, details directly supporting a rotary catalytic mechanism analogous to that of the heterohexameric F1/V1-ATPases despite its homohexameric nature. Situated at the C-terminal opening of the EscN pore is one molecule of EscO, with primary interaction mediated through an electrostatic interface. The EscN-EscO structure provides significant atomic insights into how the ATPase contributes to type III secretion, including torque generation and binding of chaperone/substrate complexes.
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9
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Gao X, Mu Z, Yu X, Qin B, Wojdyla J, Wang M, Cui S. Structural Insight Into Conformational Changes Induced by ATP Binding in a Type III Secretion-Associated ATPase From Shigella flexneri. Front Microbiol 2018; 9:1468. [PMID: 30013545 PMCID: PMC6036117 DOI: 10.3389/fmicb.2018.01468] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 06/12/2018] [Indexed: 11/13/2022] Open
Abstract
Gram-negative bacteria utilize the type III secretion system (T3SS) to inject effector proteins into the host cell cytoplasm, where they subvert cellular functions and assist pathogen invasion. The conserved type III-associated ATPase is critical for the separation of chaperones from effector proteins, the unfolding of effector proteins and translocating them through the narrow channel of the secretion apparatus. However, how ATP hydrolysis is coupled to the mechanical work of the enzyme remains elusive. Herein, we present a complete description of nucleoside triphosphate binding by surface presentation antigens 47 (Spa47) from Shigella flexneri, based on crystal structures containing ATPγS, a catalytic magnesium ion and an ordered water molecule. Combining the crystal structures of Spa47-ATPγS and unliganded Spa47, we propose conformational changes in Spa47 associated with ATP binding, the binding of ATP induces a conformational change of a highly conserved luminal loop, facilitating ATP hydrolysis by the Spa47 ATPase. Additionally, we identified a specific hydrogen bond critical for ATP recognition and demonstrated that, while ATPγS is an ideal analog for probing ATP binding, AMPPNP is a poor ATP mimic. Our findings provide structural insight pertinent for inhibitor design.
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Affiliation(s)
- Xiaopan Gao
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Zhixia Mu
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Xia Yu
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Bo Qin
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Justyna Wojdyla
- Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
| | - Meitian Wang
- Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
| | - Sheng Cui
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
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Novel Sequence Features of DNA Repair Genes/Proteins from Deinococcus Species Implicated in Protection from Oxidatively Generated Damage. Genes (Basel) 2018. [PMID: 29518000 PMCID: PMC5867870 DOI: 10.3390/genes9030149] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Deinococcus species display a high degree of resistance to radiation and desiccation due to their ability to protect critical proteome from oxidatively generated damage; however, the underlying mechanisms are not understood. Comparative analysis of DNA repair proteins reported here has identified 22 conserved signature indels (CSIs) in the proteins UvrA1, UvrC, UvrD, UvsE, MutY, MutM, Nth, RecA, RecD, RecG, RecQ, RecR, RuvC, RadA, PolA, DnaE, LigA, GyrA and GyrB, that are uniquely shared by all/most Deinococcus homologs. Of these CSIs, a 30 amino acid surface-exposed insert in the Deinococcus UvrA1, which distinguishes it from all other UvrA homologs, is of much interest. The uvrA1 gene in Deinococcus also exhibits specific genetic linkage (predicted operonic arrangement) to genes for three other proteins including a novel Deinococcus-specific transmembrane protein (designated dCSP-1) and the proteins DsbA and DsbB, playing central roles in protein disulfide bond formation by oxidation-reduction of CXXC (C represents cysteine, X any other amino acid) motifs. The CXXC motifs provide important targets for oxidation damage and they are present in many DNA repair proteins including five in UvrA, which are part of Zinc-finger elements. A conserved insert specific for Deinococcus is also present in the DsbA protein. Additionally, the uvsE gene in Deinococcus also shows specific linkage to the gene for a membrane-associated protein. To account for these novel observations, a model is proposed where specific interaction of the Deinococcus UvrA1 protein with membrane-bound dCSP-1 enables the UvrA1 to receive electrons from DsbA-DsbB oxido-reductase machinery to ameliorate oxidation damage in the UvrA1 protein.
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11
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Barbour AG, Adeolu M, Gupta RS. Division of the genus Borrelia into two genera (corresponding to Lyme disease and relapsing fever groups) reflects their genetic and phenotypic distinctiveness and will lead to a better understanding of these two groups of microbes (Margos et al. (2016) There is inadequate evidence to support the division of the genus Borrelia. Int. J. Syst. Evol. Microbiol. doi: 10.1099/ijsem.0.001717). Int J Syst Evol Microbiol 2017; 67:2058-2067. [PMID: 28141502 DOI: 10.1099/ijsem.0.001815] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Alan G Barbour
- Departments of Medicine, Microbiology & Molecular Genetics, and Ecology & Evolutionary Biology, University of California, Irvine, California, USA
| | - Mobolaji Adeolu
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Radhey S Gupta
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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12
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Abstract
Type III secretion systems (T3SSs) afford Gram-negative bacteria an intimate means of altering the biology of their eukaryotic hosts--the direct delivery of effector proteins from the bacterial cytoplasm to that of the eukaryote. This incredible biophysical feat is accomplished by nanosyringe "injectisomes," which form a conduit across the three plasma membranes, peptidoglycan layer, and extracellular space that form a barrier to the direct delivery of proteins from bacterium to host. The focus of this chapter is T3SS function at the structural level; we will summarize the core findings that have shaped our understanding of the structure and function of these systems and highlight recent developments in the field. In turn, we describe the T3SS secretory apparatus, consider its engagement with secretion substrates, and discuss the posttranslational regulation of secretory function. Lastly, we close with a discussion of the future prospects for the interrogation of structure-function relationships in the T3SS.
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13
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Gupta RS. Impact of genomics on the understanding of microbial evolution and classification: the importance of Darwin's views on classification. FEMS Microbiol Rev 2016; 40:520-53. [PMID: 27279642 DOI: 10.1093/femsre/fuw011] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2016] [Indexed: 12/24/2022] Open
Abstract
Analyses of genome sequences, by some approaches, suggest that the widespread occurrence of horizontal gene transfers (HGTs) in prokaryotes disguises their evolutionary relationships and have led to questioning of the Darwinian model of evolution for prokaryotes. These inferences are critically examined in the light of comparative genome analysis, characteristic synapomorphies, phylogenetic trees and Darwin's views on examining evolutionary relationships. Genome sequences are enabling discovery of numerous molecular markers (synapomorphies) such as conserved signature indels (CSIs) and conserved signature proteins (CSPs), which are distinctive characteristics of different prokaryotic taxa. Based on these molecular markers, exhibiting high degree of specificity and predictive ability, numerous prokaryotic taxa of different ranks, currently identified based on the 16S rRNA gene trees, can now be reliably demarcated in molecular terms. Within all studied groups, multiple CSIs and CSPs have been identified for successive nested clades providing reliable information regarding their hierarchical relationships and these inferences are not affected by HGTs. These results strongly support Darwin's views on evolution and classification and supplement the current phylogenetic framework based on 16S rRNA in important respects. The identified molecular markers provide important means for developing novel diagnostics, therapeutics and for functional studies providing important insights regarding prokaryotic taxa.
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Affiliation(s)
- Radhey S Gupta
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
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14
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Ferrell JC, Fields KA. A working model for the type III secretion mechanism in Chlamydia. Microbes Infect 2015; 18:84-92. [PMID: 26515030 DOI: 10.1016/j.micinf.2015.10.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 10/19/2015] [Accepted: 10/19/2015] [Indexed: 01/09/2023]
Abstract
It has been appreciated for almost 20 years that members of the Chlamydiales possess a virulence-associated type III secretion mechanism. Given the obligate intracellular nature of these bacteria, defining exactly how type III secretion functions to promote pathogenesis has been challenging. We present a working model herein that is based on current evidence.
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Affiliation(s)
- Joshua C Ferrell
- Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Kenneth A Fields
- Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
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15
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Banerjee A, Dey S, Chakraborty A, Datta A, Basu A, Chakrabarti S, Datta S. Binding mode analysis of a major T3SS translocator protein PopB with its chaperone PcrH from Pseudomonas aeruginosa. Proteins 2014; 82:3273-85. [PMID: 25116453 DOI: 10.1002/prot.24666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 07/25/2014] [Accepted: 08/05/2014] [Indexed: 11/10/2022]
Abstract
Pseudomonas aeruginosa, a Gram-negative pathogen uses a specialized set of Type III secretion system (T3SS) translocator proteins to establish virulence in the host cell. An understanding of the factors that govern translocation by the translocator protein-chaperone complex is thus of immense importance. In this work, experimental and computational techniques were used to probe into the structure of the major translocator protein PopB from P. aeruginosa and to identify the important regions involved in functioning of the translocator protein. This study reveals that the binding sites of the common chaperone PcrH, needed for maintenance of the translocator PopB within the bacterial cytoplasm, which are primarily localized within the N-terminal domain. However, disordered and flexible residues located both at the N- and C-terminal domains are also observed to be involved in association with the chaperone. This intrinsic disorderliness of the terminal domains is conserved for all the major T3SS translocator proteins and is functionally important to maintain the intrinsically disordered state of the translocators. Our experimental and computational analyses suggest that a "disorder-to-order" transition of PopB protein might take place upon PcrH binding. The long helical coiled-coil part of PopB protein perhaps helps in pore formation while the flexible apical region is involved in chaperone interaction. Thus, our computational model of translocator protein PopB and its binding analyses provide crucial functional insights into the T3SS translocation mechanism.
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Affiliation(s)
- Anindyajit Banerjee
- Division of Structural Biology and Bioinformatics, Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, Kolkata, 700 032, West Bengal, India
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EscO, a functional and structural analog of the flagellar FliJ protein, is a positive regulator of EscN ATPase activity of the enteropathogenic Escherichia coli injectisome. J Bacteriol 2014; 196:2227-41. [PMID: 24706741 DOI: 10.1128/jb.01551-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Type III secretion systems (T3SSs) are multiprotein molecular devices used by many Gram-negative bacterial pathogens to translocate effector proteins into eukaryotic cells. A T3SS is also used for protein export in flagellar assembly, which promotes bacterial motility. The two systems are evolutionarily related, possessing highly conserved components in their export apparatuses. Enteropathogenic Escherichia coli (EPEC) employs a T3SS, encoded by genes in the locus of enterocyte effacement (LEE) pathogenicity island, to colonize the human intestine and cause diarrheal disease. In the present work, we investigated the role of the LEE-encoded EscO protein (previously Orf15 or EscA) in T3SS biogenesis. We show that EscO shares similar properties with the flagellar FliJ and the Yersinia YscO protein families. Our findings demonstrate that EscO is essential for secretion of all categories of T3SS substrates. Consistent with its central role in protein secretion, it was found to interact with the ATPase EscN and its negative regulator, EscL, of the export apparatus. Moreover, we show that EscO stimulates EscN enzymatic activity; however, it is unable to upregulate ATP hydrolysis in the presence of EscL. Remarkably, EscO partially restored the swimming defect of a Salmonella flagellar fliJ mutant and was able to stimulate the ATPase activity of FliI. Overall, our data indicate that EscO is the virulence counterpart of the flagellar FliJ protein.
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Abrusci P, McDowell MA, Lea SM, Johnson S. Building a secreting nanomachine: a structural overview of the T3SS. Curr Opin Struct Biol 2014; 25:111-7. [PMID: 24704748 PMCID: PMC4045390 DOI: 10.1016/j.sbi.2013.11.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 11/05/2013] [Accepted: 11/06/2013] [Indexed: 12/21/2022]
Abstract
To fulfill complex biological tasks, such as locomotion and protein translocation, bacteria assemble macromolecular nanomachines. One such nanodevice, the type III secretion system (T3SS), has evolved to provide a means of transporting proteins from the bacterial cytoplasm across the periplasmic and extracellular spaces. T3SS can be broadly classified into two highly homologous families: the flagellar T3SS which drive cell motility, and the non-flagellar T3SS (NF-T3SS) that inject effector proteins into eukaryotic host cells, a trait frequently associated with virulence. Although the structures and symmetries of ancillary components of the T3SS have diversified to match requirements of different species adapted to different niches, recent genetic, molecular and structural studies demonstrate that these systems are built by arranging homologous modular protein assemblies.
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Affiliation(s)
- Patrizia Abrusci
- Sir William Dunn School of Pathology, Oxford University, South Parks Road, Oxford OX1 3RE, United Kingdom
| | - Melanie A McDowell
- Sir William Dunn School of Pathology, Oxford University, South Parks Road, Oxford OX1 3RE, United Kingdom
| | - Susan M Lea
- Sir William Dunn School of Pathology, Oxford University, South Parks Road, Oxford OX1 3RE, United Kingdom.
| | - Steven Johnson
- Sir William Dunn School of Pathology, Oxford University, South Parks Road, Oxford OX1 3RE, United Kingdom
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18
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Burkinshaw BJ, Strynadka NCJ. Assembly and structure of the T3SS. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1649-63. [PMID: 24512838 DOI: 10.1016/j.bbamcr.2014.01.035] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/27/2014] [Accepted: 01/29/2014] [Indexed: 02/06/2023]
Abstract
The Type III Secretion System (T3SS) is a multi-mega Dalton apparatus assembled from more than twenty components and is found in many species of animal and plant bacterial pathogens. The T3SS creates a contiguous channel through the bacterial and host membranes, allowing injection of specialized bacterial effector proteins directly to the host cell. In this review, we discuss our current understanding of T3SS assembly and structure, as well as highlight structurally characterized Salmonella effectors. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Brianne J Burkinshaw
- Department of Biochemistry and Molecular Biology, Center for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology, Center for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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19
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Naushad HS, Lee B, Gupta RS. Conserved signature indels and signature proteins as novel tools for understanding microbial phylogeny and systematics: identification of molecular signatures that are specific for the phytopathogenic genera Dickeya, Pectobacterium and Brenneria. Int J Syst Evol Microbiol 2014; 64:366-383. [DOI: 10.1099/ijs.0.054213-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genome sequences are enabling applications of different approaches to more clearly understand microbial phylogeny and systematics. Two of these approaches involve identification of conserved signature indels (CSIs) and conserved signature proteins (CSPs) that are specific for different lineages. These molecular markers provide novel and more definitive means for demarcation of prokaryotic taxa and for identification of species from these groups. Genome sequences are also enabling determination of phylogenetic relationships among species based upon sequences for multiple proteins. In this work, we have used all of these approaches for studying the phytopathogenic bacteria belonging to the genera
Dickeya
,
Pectobacterium
and
Brenneria
. Members of these genera, which cause numerous diseases in important food crops and ornamental plants, are presently distinguished mainly on the basis of their branching in phylogenetic trees. No biochemical or molecular characteristic is known that is uniquely shared by species from these genera. Hence, detailed studies using the above approaches were carried out on proteins from the genomes of these bacteria to identify molecular markers that are specific for them. In phylogenetic trees based upon concatenated sequences for 23 conserved proteins, members of the genera
Dickeya
,
Pectobacterium
and
Brenneria
formed a strongly supported clade within the other
Enterobacteriales
. Comparative analysis of protein sequences from the
Dickeya
,
Pectobacterium
and
Brenneria
genomes has identified 10 CSIs and five CSPs that are either uniquely or largely found in all genome-sequenced species from these genera, but not present in any other bacteria in the database. In addition, our analyses have identified 10 CSIs and 17 CSPs that are specifically present in either all or most sequenced
Dickeya
species/strains, and six CSIs and 19 CSPs that are uniquely found in the sequenced
Pectobacterium
genomes. Finally, our analysis also identified three CSIs and one CSP that are specifically shared by members of the genera
Pectobacterium
and
Brenneria
, but absent in species of the genus
Dickeya
, indicating that the former two genera shared a common ancestor exclusive of
Dickeya
. The identified CSIs and CSPs provide novel tools for identification of members of the genera
Dickeya
and
Pectobacterium
and for delimiting these taxa in molecular terms. Descriptions of the genera
Dickeya
and
Pectobacterium
have been revised to provide information for these molecular markers. Biochemical studies on these CSIs and CSPs, which are specific for these genera, may lead to discovery of novel properties that are unique to these bacteria and which could be targeted to develop antibacterial agents that are specific for these plant-pathogenic bacteria.
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Affiliation(s)
- Hafiz Sohail Naushad
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
| | - Brian Lee
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
| | - Radhey S. Gupta
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada L8N 3Z5
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20
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Cherradi Y, Hachani A, Allaoui A. Spa13 of Shigella flexneri has a dual role: chaperone escort and export gate-activator switch of the type III secretion system. Microbiology (Reading) 2014; 160:130-141. [DOI: 10.1099/mic.0.071712-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The type III secretion apparatus (T3SA) is used by numerous Gram-negative pathogens to inject virulence factors into eukaryotic cells. The Shigella flexneri T3SA spans the bacterial envelope and its assembly requires the products of ~20 mxi and spa genes. Despite progress made in understanding how the T3SA is assembled, the role of several predicted soluble components, such as Spa13, remains elusive. Here, we show that the secretion defect of the spa13 mutant is associated with lack of T3SA assembly which is partly due to the instability of the needle component MxiH. In contrast to its Yersinia counterpart, Spa13 is not a secreted protein. We identified a network of interactions between Spa13 and the ATPase Spa47, the C-ring protein Spa33, and the inner-membrane protein Spa40. Moreover, we revealed a Spa13 interaction with the inner-membrane MxiA and showed that overexpression of the large cytoplasmic domain of MxiA in the WT background shuts off secretion. Lastly, we demonstrated that Spa13 interacts with the cleaved form of Spa40 and with the translocator chaperone IpgC, suggesting that Spa13 intervenes during the secretion hierarchy switch process. Collectively, our results support a dual role of Spa13 as a chaperone escort and as an export gate-activator switch.
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Affiliation(s)
- Youness Cherradi
- Laboratoire de Bactériologie Moléculaire, Faculté de Médecine, Université Libre de Bruxelles, Route de Lennik, 808, 1070 Bruxelles, Belgium
| | - Abderrahman Hachani
- Laboratoire de Bactériologie Moléculaire, Faculté de Médecine, Université Libre de Bruxelles, Route de Lennik, 808, 1070 Bruxelles, Belgium
| | - Abdelmounaaïm Allaoui
- Laboratoire de Bactériologie Moléculaire, Faculté de Médecine, Université Libre de Bruxelles, Route de Lennik, 808, 1070 Bruxelles, Belgium
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21
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Functionally essential interaction between Yersinia YscO and the T3S4 domain of YscP. J Bacteriol 2013; 195:4631-8. [PMID: 23935040 DOI: 10.1128/jb.00876-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The type III secretion (T3S) system is essential to the virulence of a large number of Gram-negative bacterial pathogens, including Yersinia. YscO is required for T3S in Yersinia and is known to interact with several other T3S proteins, including the chaperone SycD and the needle length regulator YscP. To define which interactions of YscO are required for T3S, we pursued model-guided mutagenesis: three conserved and surface-exposed regions of modeled YscO were targeted for multiple alanine substitutions. Most of the mutations abrogated T3S and did so in a recessive manner, consistent with a loss of function. Both functional and nonfunctional YscO mutant proteins interacted with SycD, indicating that the mutations had not affected protein stability. Likewise, both functional and nonfunctional versions of YscO were exclusively intrabacterial. Functional and nonfunctional versions of YscO were, however, distinguishable with respect to interaction with YscP. This interaction was observed only for wild-type YscO and a T3S-proficient mutant of YscO but not for the several T3S-deficient mutants of YscO. Evidence is presented that the YscO-YscP interaction is direct and that the type III secretion substrate specificity switch (T3S4) domain of YscP is sufficient for this interaction. These results provide evidence that the interaction of YscO with YscP, and in particular the T3S4 domain of YscP, is essential to type III secretion.
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22
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Kishikawa JI, Ibuki T, Nakamura S, Nakanishi A, Minamino T, Miyata T, Namba K, Konno H, Ueno H, Imada K, Yokoyama K. Common evolutionary origin for the rotor domain of rotary ATPases and flagellar protein export apparatus. PLoS One 2013; 8:e64695. [PMID: 23724081 PMCID: PMC3665681 DOI: 10.1371/journal.pone.0064695] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 04/17/2013] [Indexed: 02/02/2023] Open
Abstract
The V1- and F1- rotary ATPases contain a rotor that rotates against a catalytic A3B3 or α3β3 stator. The rotor F1-γ or V1-DF is composed of both anti-parallel coiled coil and globular-loop parts. The bacterial flagellar type III export apparatus contains a V1/F1-like ATPase ring structure composed of FliI6 homo-hexamer and FliJ which adopts an anti-parallel coiled coil structure without the globular-loop part. Here we report that FliJ of Salmonella enterica serovar Typhimurium shows a rotor like function in Thermus thermophilus A3B3 based on both biochemical and structural analysis. Single molecular analysis indicates that an anti-parallel coiled-coil structure protein (FliJ structure protein) functions as a rotor in A3B3. A rotary ATPase possessing an F1-γ-like protein generated by fusion of the D and F subunits of V1 rotates, suggesting F1-γ could be the result of a fusion of the genes encoding two separate rotor subunits. Together with sequence comparison among the globular part proteins, the data strongly suggest that the rotor domains of the rotary ATPases and the flagellar export apparatus share a common evolutionary origin.
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Affiliation(s)
- Jun-ichi Kishikawa
- Department of Molecular Biosciences, Kyoto Sangyo University, Motoyama Kamigamo, Kita-ku, Kyoto, Japan
| | - Tatsuya Ibuki
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Shuichi Nakamura
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
- Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai, Miyagi, Japan
| | - Astuko Nakanishi
- Department of Molecular Biosciences, Kyoto Sangyo University, Motoyama Kamigamo, Kita-ku, Kyoto, Japan
| | - Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Tomoko Miyata
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
- Riken Quantitative Biology Center, Osaka, Japan
| | - Hiroki Konno
- Imaging Research Division, Bio-AFM Frontier Research Center, Kanazawa University, Kanazawa, Ishikawa, Japan
| | - Hiroshi Ueno
- Department of Physics, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan
| | - Katsumi Imada
- Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
- * E-mail: (KI); (KY)
| | - Ken Yokoyama
- Department of Molecular Biosciences, Kyoto Sangyo University, Motoyama Kamigamo, Kita-ku, Kyoto, Japan
- * E-mail: (KI); (KY)
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23
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Weiling H, Xiaowen Y, Chunmei L, Jianping X. Function and evolution of ubiquitous bacterial signaling adapter phosphopeptide recognition domain FHA. Cell Signal 2013. [DOI: 10.1016/j.cellsig.2012.11.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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24
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Ab initio structural modeling of and experimental validation for Chlamydia trachomatis protein CT296 reveal structural similarity to Fe(II) 2-oxoglutarate-dependent enzymes. J Bacteriol 2011; 193:6517-28. [PMID: 21965559 DOI: 10.1128/jb.05488-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Chlamydia trachomatis is a medically important pathogen that encodes a relatively high percentage of proteins with unknown function. The three-dimensional structure of a protein can be very informative regarding the protein's functional characteristics; however, determining protein structures experimentally can be very challenging. Computational methods that model protein structures with sufficient accuracy to facilitate functional studies have had notable successes. To evaluate the accuracy and potential impact of computational protein structure modeling of hypothetical proteins encoded by Chlamydia, a successful computational method termed I-TASSER was utilized to model the three-dimensional structure of a hypothetical protein encoded by open reading frame (ORF) CT296. CT296 has been reported to exhibit functional properties of a divalent cation transcription repressor (DcrA), with similarity to the Escherichia coli iron-responsive transcriptional repressor, Fur. Unexpectedly, the I-TASSER model of CT296 exhibited no structural similarity to any DNA-interacting proteins or motifs. To validate the I-TASSER-generated model, the structure of CT296 was solved experimentally using X-ray crystallography. Impressively, the ab initio I-TASSER-generated model closely matched (2.72-Å C(α) root mean square deviation [RMSD]) the high-resolution (1.8-Å) crystal structure of CT296. Modeled and experimentally determined structures of CT296 share structural characteristics of non-heme Fe(II) 2-oxoglutarate-dependent enzymes, although key enzymatic residues are not conserved, suggesting a unique biochemical process is likely associated with CT296 function. Additionally, functional analyses did not support prior reports that CT296 has properties shared with divalent cation repressors such as Fur.
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25
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Osborne SE, Coombes BK. Expression and secretion hierarchy in the nonflagellar type III secretion system. Future Microbiol 2011; 6:193-202. [PMID: 21366419 DOI: 10.2217/fmb.10.172] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Type III secretion systems that deliver bacterial proteins into eukaryotic cells are the basis for both symbiotic and pathogenic relationships between many Gram-negative bacteria and their hosts. Exploration of the structure, function and assembly of this secretion system has greatly enhanced our knowledge of bacterial ecology in the context of infectious disease and has spawned new avenues in anti-infective research with a view towards inhibiting virulence functions. We outline advances in understanding type III secretion system function with specific focus on how assembly is hierarchically coordinated at the level of expression and how the type III secretion system mediates transitions in substrate specificity.
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Affiliation(s)
- Suzanne E Osborne
- Michael G DeGroote Institute for Infectious Disease Research & Department of Biochemistry & Biomedical Sciences, HSC-4H17, McMaster University, Hamilton, ON, Canada
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26
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Ibuki T, Imada K, Minamino T, Kato T, Miyata T, Namba K. Common architecture of the flagellar type III protein export apparatus and F- and V-type ATPases. Nat Struct Mol Biol 2011; 18:277-82. [PMID: 21278755 DOI: 10.1038/nsmb.1977] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 11/17/2010] [Indexed: 01/06/2023]
Abstract
The proteins that form the bacterial flagellum are translocated to its distal end through the central channel of the growing flagellum by the flagellar-specific protein export apparatus, a family of the type III protein secretion system. FliI and FliJ are soluble components of this apparatus. FliI is an ATPase that has extensive structural similarity to the α and β subunits of F(o)F(1)-ATP synthase. FliJ is essential for export, but its function remains obscure. Here we show that the structure of FliJ derived from Salmonella enterica serovar Typhimurium is remarkably similar to that of the two-stranded α-helical coiled-coil part of the γ subunit of F(o)F(1)-ATP synthase and that FliJ promotes the formation of FliI hexamer rings by binding to the center of the ring. These results suggest that the type III protein export system and F- and V-type ATPases share a similar mechanism and an evolutionary relationship.
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27
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Uversky VN. Multitude of binding modes attainable by intrinsically disordered proteins: a portrait gallery of disorder-based complexes. Chem Soc Rev 2011; 40:1623-34. [DOI: 10.1039/c0cs00057d] [Citation(s) in RCA: 209] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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28
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Betts-Hampikian HJ, Fields KA. The Chlamydial Type III Secretion Mechanism: Revealing Cracks in a Tough Nut. Front Microbiol 2010; 1:114. [PMID: 21738522 PMCID: PMC3125583 DOI: 10.3389/fmicb.2010.00114] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 09/22/2010] [Indexed: 12/22/2022] Open
Abstract
Present-day members of the Chlamydiaceae contain parasitic bacteria that have been co-evolving with their eukaryotic hosts over hundreds of millions of years. Likewise, a type III secretion system encoded within all genomes has been refined to complement the unique obligate intracellular niche colonized so successfully by Chlamydia spp. All this adaptation has occurred in the apparent absence of the horizontal gene transfer responsible for creating the wide range of diversity in other Gram-negative, type III-expressing bacteria. The result is a system that is, in many ways, uniquely chlamydial. A critical mass of information has been amassed that sheds significant light on how the chlamydial secretion system functions and contributes to an obligate intracellular lifestyle. Although the overall mechanism is certainly similar to homologous systems, an image has emerged where the chlamydial secretion system is essential for both survival and virulence. Numerous apparent differences, some subtle and some profound, differentiate chlamydial type III secretion from others. Herein, we provide a comprehensive review of the current state of knowledge regarding the Chlamydia type III secretion mechanism. We focus on the aspects that are distinctly chlamydial and comment on how this important system influences chlamydial pathogenesis. Gaining a grasp on this fascinating system has been challenging in the absence of a tractable genetic system. However, the surface of this tough nut has been scored and the future promises to be fruitful and revealing.
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