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Kida Y, Taira J, Yamamoto T, Higashimoto Y, Kuwano K. EprS, an autotransporter protein of Pseudomonas aeruginosa, possessing serine protease activity induces inflammatory responses through protease-activated receptors. Cell Microbiol 2013; 15:1168-81. [PMID: 23311922 DOI: 10.1111/cmi.12106] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 12/18/2012] [Accepted: 01/02/2013] [Indexed: 11/29/2022]
Abstract
PA3535 (EprS), an autotransporter (AT) protein of Pseudomonas aeruginosa, is predicted to contain a serine protease motif. The eprS encodes a 104.5 kDa protein with a 30-amino-acid-long signal peptide, a 51.2 kDa amino-terminal secreted passenger domain and a 50.1 kDa carboxyl-terminal outer membrane channel formed translocator. Although the majority of AT proteins have been reported to be virulence factors, little is known about the functions of EprS in the pathogenicity of P. aeruginosa. In this study, we performed functional analyses of recombinant EprS secreted by Escherichia coli. The proteolytic activity of EprS was markedly decreased by changing Ser to Ala at position 308 or by serine protease inhibitors. EprS preferred to cleave substrates that terminated with arginine or lysine residues. Thus, these results indicate that EprS, a serine protease, displays the substrate specificity, cleaving after basic residues. We demonstrated that EprS activates NF-κB-driven promoters through protease-activated receptor (PAR)-1, -2 or -4 and induces IL-8 production through PAR-2 in a human bronchiole epithelial cell line. Moreover, EprS cleaved the peptides corresponding to the tethered ligand region of PAR-1, -2 and -4 at a specific site with exposure oftheir tethered ligands. Collectively, these results suggest that EprS activates host inflammatory responses through PARs.
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Affiliation(s)
- Yutaka Kida
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan
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System specificity of the TpsB transporters of coexpressed two-partner secretion systems of Neisseria meningitidis. J Bacteriol 2012; 195:788-97. [PMID: 23222722 DOI: 10.1128/jb.01355-12] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The two-partner secretion (TPS) systems of Gram-negative bacteria consist of a large secreted exoprotein (TpsA) and a transporter protein (TpsB) located in the outer membrane. TpsA targets TpsB for transport across the membrane via its ∼30-kDa TPS domain located at its N terminus, and this domain is also the minimal secretory unit. Neisseria meningitidis genomes encode up to five TpsAs and two TpsBs. Sequence alignments of TPS domains suggested that these are organized into three systems, while there are two TpsBs, which raised questions on their system specificity. We show here that the TpsB2 transporter of Neisseria meningitidis is able to secrete all types of TPS domains encoded in N. meningitidis and the related species Neisseria lactamica but not domains of Haemophilus influenzae and Pseudomonas aeruginosa. In contrast, the TpsB1 transporter seemed to be specific for its cognate N. meningitidis system and did not secrete the TPS domains of other meningococcal systems. However, TpsB1 did secrete the TPS2b domain of N. lactamica, which is related to the meningococcal TPS2 domains. Apparently, the secretion depends on specific sequences within the TPS domain rather than the overall TPS domain structure.
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53
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Pieretti I, Royer M, Barbe V, Carrere S, Koebnik R, Couloux A, Darrasse A, Gouzy J, Jacques MA, Lauber E, Manceau C, Mangenot S, Poussier S, Segurens B, Szurek B, Verdier V, Arlat M, Gabriel DW, Rott P, Cociancich S. Genomic insights into strategies used by Xanthomonas albilineans with its reduced artillery to spread within sugarcane xylem vessels. BMC Genomics 2012; 13:658. [PMID: 23171051 PMCID: PMC3542200 DOI: 10.1186/1471-2164-13-658] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 11/18/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy compared to other species of Xanthomonas. For example, this species produces a potent DNA gyrase inhibitor called albicidin that is largely responsible for inducing disease symptoms; its habitat is limited to xylem; and the species exhibits large variability. A first manuscript on the complete genome sequence of the highly pathogenic X. albilineans strain GPE PC73 focused exclusively on distinctive genomic features shared with Xylella fastidiosa-another xylem-limited Xanthomonadaceae. The present manuscript on the same genome sequence aims to describe all other pathogenicity-related genomic features of X. albilineans, and to compare, using suppression subtractive hybridization (SSH), genomic features of two strains differing in pathogenicity. RESULTS Comparative genomic analyses showed that most of the known pathogenicity factors from other Xanthomonas species are conserved in X. albilineans, with the notable absence of two major determinants of the "artillery" of other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis gene cluster, and the type III secretion system Hrp (hypersensitive response and pathogenicity). Genomic features specific to X. albilineans that may contribute to specific adaptation of this pathogen to sugarcane xylem vessels were also revealed. SSH experiments led to the identification of 20 genes common to three highly pathogenic strains but missing in a less pathogenic strain. These 20 genes, which include four ABC transporter genes, a methyl-accepting chemotaxis protein gene and an oxidoreductase gene, could play a key role in pathogenicity. With the exception of hypothetical proteins revealed by our comparative genomic analyses and SSH experiments, no genes potentially involved in any offensive or counter-defensive mechanism specific to X. albilineans were identified, supposing that X. albilineans has a reduced artillery compared to other pathogenic Xanthomonas species. Particular attention has therefore been given to genomic features specific to X. albilineans making it more capable of evading sugarcane surveillance systems or resisting sugarcane defense systems. CONCLUSIONS This study confirms that X. albilineans is a highly distinctive species within the genus Xanthomonas, and opens new perpectives towards a greater understanding of the pathogenicity of this destructive sugarcane pathogen.
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Affiliation(s)
| | - Monique Royer
- CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France
| | - Valérie Barbe
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | | | - Ralf Koebnik
- IRD, UMR RPB, F-34394 Montpellier Cedex 5, France
| | - Arnaud Couloux
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | | | - Jérôme Gouzy
- INRA, UMR LIPM, F-31326 Castanet-Tolosan Cedex France
| | | | | | | | - Sophie Mangenot
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | - Stéphane Poussier
- Université de la Réunion, UMR PVBMT, F-97715 Saint-Denis La Réunion, France
| | - Béatrice Segurens
- CEA/DSV/IG/Génoscope, Centre National de Séquençage, F-91057 Evry Cedex France
| | - Boris Szurek
- IRD, UMR RPB, F-34394 Montpellier Cedex 5, France
| | | | - Matthieu Arlat
- Université Paul Sabatier, UMR LIPM, F-31326 Castanet-Tolosan Cedex France
| | - Dean W Gabriel
- University of Florida, Plant Pathology Department, Gainesville FL 32605 USA
| | - Philippe Rott
- CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France
| | - Stéphane Cociancich
- CIRAD, UMR BGPI, F-34398 Montpellier Cedex 5, France
- UMR BGPI, Campus International de Baillarguet, TA A-54/K, F-34398 Montpellier Cedex 5, France
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54
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Dalbey RE, Kuhn A. Protein Traffic in Gram-negative bacteria – how exported and secreted proteins find their way. FEMS Microbiol Rev 2012; 36:1023-45. [DOI: 10.1111/j.1574-6976.2012.00327.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 01/04/2012] [Indexed: 11/27/2022] Open
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Mendez JA, Soares NC, Mateos J, Gayoso C, Rumbo C, Aranda J, Tomas M, Bou G. Extracellular Proteome of a Highly Invasive Multidrug-resistant Clinical Strain of Acinetobacter baumannii. J Proteome Res 2012; 11:5678-94. [DOI: 10.1021/pr300496c] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Jose Antonio Mendez
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Nelson C. Soares
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Jesús Mateos
- Unidad de Proteómica, INIBIC, As Xubias s/n, La Coruña, Spain
| | - Carmen Gayoso
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Carlos Rumbo
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Jesús Aranda
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Maria Tomas
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
| | - Germán Bou
- Laboratório de Microbiología,
Instituto de Investigación Biomédica de A Coruña
(INIBIC), Servicio de Microbiología, Complejo Hospitalario Universitario A Coruña (CHUAC),
As Xubias s/n, La Coruña, Spain
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Oberhettinger P, Schütz M, Leo JC, Heinz N, Berger J, Autenrieth IB, Linke D. Intimin and invasin export their C-terminus to the bacterial cell surface using an inverse mechanism compared to classical autotransport. PLoS One 2012; 7:e47069. [PMID: 23056583 PMCID: PMC3467248 DOI: 10.1371/journal.pone.0047069] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 09/07/2012] [Indexed: 11/19/2022] Open
Abstract
Invasin and intimin are major virulence factors of enteropathogenic Yersiniae and Escherichia coli, mediating invasion into and intimate adherence to host cells, respectively. Several studies have hinted that extracellular portion of these homologous proteins might be exported via an autotransport mechanism, but rigorous experimental proof has been lacking. Here, we present a topology model for invasin and intimin, consistent with the hypothesis that the N-terminal β-barrel domain acts as a translocation pore to secrete the C-terminal passenger domain. We confirmed this topology model by inserting epitope tags into the loops of the β-barrel. We further show that obstructing the pore of β-barrel hinders the export of the passenger domain. As for classical autotransport, the biogenesis of invasin and intimin is dependent on the Bam complex and the periplasmic chaperone SurA, whereas the chaperone/protease DegP is involved in quality control. However, compared to classical autotransporters (Type Va secretion), the domain structure of intimin and invasin is inverted. We conclude that proteins of the intimin and invasin family constitute a novel group of autotransported proteins, and propose that this class of autotransporters be termed Type Ve secretion.
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Affiliation(s)
- Philipp Oberhettinger
- Institut für Medizinische Mikrobiologie und Hygiene, Universität Tübingen, Tübingen, Germany
| | - Monika Schütz
- Institut für Medizinische Mikrobiologie und Hygiene, Universität Tübingen, Tübingen, Germany
| | - Jack C. Leo
- Abteilung 1, Max Planck Institut für Entwicklungsbiologie, Tübingen, Germany
| | - Nadja Heinz
- Abteilung 1, Max Planck Institut für Entwicklungsbiologie, Tübingen, Germany
| | - Jürgen Berger
- Abteilung 1, Max Planck Institut für Entwicklungsbiologie, Tübingen, Germany
| | - Ingo B. Autenrieth
- Institut für Medizinische Mikrobiologie und Hygiene, Universität Tübingen, Tübingen, Germany
| | - Dirk Linke
- Abteilung 1, Max Planck Institut für Entwicklungsbiologie, Tübingen, Germany
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57
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Type II-dependent secretion of a Pseudomonas aeruginosa DING protein. Res Microbiol 2012; 163:457-69. [PMID: 22835944 DOI: 10.1016/j.resmic.2012.07.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 07/16/2012] [Indexed: 11/24/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen that uses a wide range of protein secretion systems to interact with its host. Genes encoding the PAO1 Hxc type II secretion system are linked to genes encoding phosphatases (LapA/LapB). Microarray genotyping suggested that Pseudomonas aeruginosa clinical isolates, including urinary tract (JJ692) and blood (X13273) isolates, lacked the lapA/lapB genes. Instead, we show that they carry a gene encoding a protein of the PstS family. This protein, which we call LapC, also has significant similarities with LapA/LapB. LapC belongs to the family of DING proteins and displays the canonical DINGGG motif within its N terminus. DING proteins are members of a prokaryotic phosphate binding protein superfamily. We show that LapC is secreted in an Hxc-dependent manner and is under the control of the PhoB response regulator. The genetic organization hxc-lapC found in JJ692 and X13273 is similar to PA14, which is the most frequent P. aeruginosa genotype. While the role of LapA, LapB and LapC proteins remains unclear in P. aeruginosa pathogenesis, they are likely to be part of a phosphate scavenging or sensing system needed to survive and thrive when low phosphate environments are encountered within the host.
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58
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Leo JC, Grin I, Linke D. Type V secretion: mechanism(s) of autotransport through the bacterial outer membrane. Philos Trans R Soc Lond B Biol Sci 2012; 367:1088-101. [PMID: 22411980 PMCID: PMC3297439 DOI: 10.1098/rstb.2011.0208] [Citation(s) in RCA: 172] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Autotransport in Gram-negative bacteria denotes the ability of surface-localized proteins to cross the outer membrane (OM) autonomously. Autotransporters perform this task with the help of a β-barrel transmembrane domain localized in the OM. Different classes of autotransporters have been investigated in detail in recent years; classical monomeric but also trimeric autotransporters comprise many important bacterial virulence factors. So do the two-partner secretion systems, which are a special case as the transported protein resides on a different polypeptide chain than the transporter. Despite the great interest in these proteins, the exact mechanism of the transport process remains elusive. Moreover, different periplasmic and OM factors have been identified that play a role in the translocation, making the term ‘autotransport’ debatable. In this review, we compile the wealth of details known on the mechanism of single autotransporters from different classes and organisms, and put them into a bigger perspective. We also discuss recently discovered or rediscovered classes of autotransporters.
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Affiliation(s)
- Jack C Leo
- Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
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59
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Kim KH, Aulakh S, Paetzel M. The bacterial outer membrane β-barrel assembly machinery. Protein Sci 2012; 21:751-68. [PMID: 22549918 DOI: 10.1002/pro.2069] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Accepted: 03/20/2012] [Indexed: 12/31/2022]
Abstract
β-Barrel proteins found in the outer membrane of Gram-negative bacteria serve a variety of cellular functions. Proper folding and assembly of these proteins are essential for the viability of bacteria and can also play an important role in virulence. The β-barrel assembly machinery (BAM) complex, which is responsible for the proper assembly of β-barrels into the outer membrane of Gram-negative bacteria, has been the focus of many recent studies. This review summarizes the significant progress that has been made toward understanding the structure and function of the bacterial BAM complex.
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Affiliation(s)
- Kelly H Kim
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
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60
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Abstract
Bartonella spp. are facultative intracellular pathogens that employ a unique stealth infection strategy comprising immune evasion and modulation, intimate interaction with nucleated cells, and intraerythrocytic persistence. Infections with Bartonella are ubiquitous among mammals, and many species can infect humans either as their natural host or incidentally as zoonotic pathogens. Upon inoculation into a naive host, the bartonellae first colonize a primary niche that is widely accepted to involve the manipulation of nucleated host cells, e.g., in the microvasculature. Consistently, in vitro research showed that Bartonella harbors an ample arsenal of virulence factors to modulate the response of such cells, gain entrance, and establish an intracellular niche. Subsequently, the bacteria are seeded into the bloodstream where they invade erythrocytes and give rise to a typically asymptomatic intraerythrocytic bacteremia. While this course of infection is characteristic for natural hosts, zoonotic infections or the infection of immunocompromised patients may alter the path of Bartonella and result in considerable morbidity. In this review we compile current knowledge on the molecular processes underlying both the infection strategy and pathogenesis of Bartonella and discuss their connection to the clinical presentation of human patients, which ranges from minor complaints to life-threatening disease.
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Affiliation(s)
- Alexander Harms
- Focal Area Infection Biology, Biozentrum, University of Basel, Switzerland
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61
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Serra DO, Conover MS, Arnal L, Sloan GP, Rodriguez ME, Yantorno OM, Deora R. FHA-mediated cell-substrate and cell-cell adhesions are critical for Bordetella pertussis biofilm formation on abiotic surfaces and in the mouse nose and the trachea. PLoS One 2011; 6:e28811. [PMID: 22216115 PMCID: PMC3245231 DOI: 10.1371/journal.pone.0028811] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 11/15/2011] [Indexed: 01/17/2023] Open
Abstract
Bordetella spp. form biofilms in the mouse nasopharynx, thereby providing a potential mechanism for establishing chronic infections in humans and animals. Filamentous hemagglutinin (FHA) is a major virulence factor of B. pertussis, the causative agent of the highly transmissible and infectious disease, pertussis. In this study, we dissected the role of FHA in the distinct biofilm developmental stages of B. pertussis on abiotic substrates and in the respiratory tract by employing a murine model of respiratory biofilms. Our results show that the lack of FHA reduced attachment and decreased accumulation of biofilm biomass on artificial surfaces. FHA contributes to biofilm development by promoting the formation of microcolonies. Absence of FHA from B. pertussis or antibody-mediated blockade of surface-associated FHA impaired the attachment of bacteria to the biofilm community. Exogenous addition of FHA resulted in a dose-dependent inhibitory effect on bacterial association with the biofilms. Furthermore, we show that FHA is important for the structural integrity of biofilms formed on the mouse nose and trachea. Together, these results strongly support the hypothesis that FHA promotes the formation and maintenance of biofilms by mediating cell-substrate and inter-bacterial adhesions. These discoveries highlight FHA as a key factor in establishing structured biofilm communities in the respiratory tract.
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Affiliation(s)
- Diego O. Serra
- Facultad de Ciencias Exactas, Centro de Investigación y Desarrollo en Fermentaciones Industriales (CINDEFI), CONICET-CCT-La Plata, Universidad Nacional de La Plata, La Plata, Argentina
| | - Matt S. Conover
- Program in Molecular Genetics, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America
| | - Laura Arnal
- Facultad de Ciencias Exactas, Centro de Investigación y Desarrollo en Fermentaciones Industriales (CINDEFI), CONICET-CCT-La Plata, Universidad Nacional de La Plata, La Plata, Argentina
| | - Gina Parise Sloan
- Department of Microbiology and Immunology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America
| | - María E. Rodriguez
- Facultad de Ciencias Exactas, Centro de Investigación y Desarrollo en Fermentaciones Industriales (CINDEFI), CONICET-CCT-La Plata, Universidad Nacional de La Plata, La Plata, Argentina
| | - Osvaldo M. Yantorno
- Facultad de Ciencias Exactas, Centro de Investigación y Desarrollo en Fermentaciones Industriales (CINDEFI), CONICET-CCT-La Plata, Universidad Nacional de La Plata, La Plata, Argentina
- * E-mail: (RD); (OMY)
| | - Rajendar Deora
- Program in Molecular Genetics, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America
- Department of Microbiology and Immunology, Wake Forest University Health Sciences, Winston-Salem, North Carolina, United States of America
- * E-mail: (RD); (OMY)
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62
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Siddaramappa S, Challacombe JF, Duncan AJ, Gillaspy AF, Carson M, Gipson J, Orvis J, Zaitshik J, Barnes G, Bruce D, Chertkov O, Detter JC, Han CS, Tapia R, Thompson LS, Dyer DW, Inzana TJ. Horizontal gene transfer in Histophilus somni and its role in the evolution of pathogenic strain 2336, as determined by comparative genomic analyses. BMC Genomics 2011; 12:570. [PMID: 22111657 PMCID: PMC3339403 DOI: 10.1186/1471-2164-12-570] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 11/23/2011] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Pneumonia and myocarditis are the most commonly reported diseases due to Histophilus somni, an opportunistic pathogen of the reproductive and respiratory tracts of cattle. Thus far only a few genes involved in metabolic and virulence functions have been identified and characterized in H. somni using traditional methods. Analyses of the genome sequences of several Pasteurellaceae species have provided insights into their biology and evolution. In view of the economic and ecological importance of H. somni, the genome sequence of pneumonia strain 2336 has been determined and compared to that of commensal strain 129Pt and other members of the Pasteurellaceae. RESULTS The chromosome of strain 2336 (2,263,857 bp) contained 1,980 protein coding genes, whereas the chromosome of strain 129Pt (2,007,700 bp) contained only 1,792 protein coding genes. Although the chromosomes of the two strains differ in size, their average GC content, gene density (total number of genes predicted on the chromosome), and percentage of sequence (number of genes) that encodes proteins were similar. The chromosomes of these strains also contained a number of discrete prophage regions and genomic islands. One of the genomic islands in strain 2336 contained genes putatively involved in copper, zinc, and tetracycline resistance. Using the genome sequence data and comparative analyses with other members of the Pasteurellaceae, several H. somni genes that may encode proteins involved in virulence (e.g., filamentous haemaggutinins, adhesins, and polysaccharide biosynthesis/modification enzymes) were identified. The two strains contained a total of 17 ORFs that encode putative glycosyltransferases and some of these ORFs had characteristic simple sequence repeats within them. Most of the genes/loci common to both the strains were located in different regions of the two chromosomes and occurred in opposite orientations, indicating genome rearrangement since their divergence from a common ancestor. CONCLUSIONS Since the genome of strain 129Pt was ~256,000 bp smaller than that of strain 2336, these genomes provide yet another paradigm for studying evolutionary gene loss and/or gain in regard to virulence repertoire and pathogenic ability. Analyses of the complete genome sequences revealed that bacteriophage- and transposon-mediated horizontal gene transfer had occurred at several loci in the chromosomes of strains 2336 and 129Pt. It appears that these mobile genetic elements have played a major role in creating genomic diversity and phenotypic variability among the two H. somni strains.
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Affiliation(s)
- Shivakumara Siddaramappa
- Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
- DOE Joint Genome Institute, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Jean F Challacombe
- DOE Joint Genome Institute, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Alison J Duncan
- Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
| | - Allison F Gillaspy
- Laboratory for Genomics and Bioinformatics, and Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 731042, USA
| | - Matthew Carson
- Laboratory for Genomics and Bioinformatics, and Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 731042, USA
| | - Jenny Gipson
- Laboratory for Genomics and Bioinformatics, and Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 731042, USA
| | - Joshua Orvis
- Laboratory for Genomics and Bioinformatics, and Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 731042, USA
| | - Jeremy Zaitshik
- Laboratory for Genomics and Bioinformatics, and Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 731042, USA
| | - Gentry Barnes
- Laboratory for Genomics and Bioinformatics, and Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 731042, USA
| | - David Bruce
- DOE Joint Genome Institute, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Olga Chertkov
- DOE Joint Genome Institute, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J Chris Detter
- DOE Joint Genome Institute, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Cliff S Han
- DOE Joint Genome Institute, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Roxanne Tapia
- DOE Joint Genome Institute, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Linda S Thompson
- DOE Joint Genome Institute, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - David W Dyer
- Laboratory for Genomics and Bioinformatics, and Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 731042, USA
| | - Thomas J Inzana
- Center for Molecular Medicine and Infectious Diseases, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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63
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Protein domain of unknown function 3233 is a translocation domain of autotransporter secretory mechanism in gamma proteobacteria. PLoS One 2011; 6:e25570. [PMID: 22073138 PMCID: PMC3206015 DOI: 10.1371/journal.pone.0025570] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 09/07/2011] [Indexed: 11/25/2022] Open
Abstract
Vibrio cholerae, the enteropathogenic gram negative bacteria is one of the main causative agents of waterborne diseases like cholera. About 1/3rd of the organism's genome is uncharacterised with many protein coding genes lacking structure and functional information. These proteins form significant fraction of the genome and are crucial in understanding the organism's complete functional makeup. In this study we report the general structure and function of a family of hypothetical proteins, Domain of Unknown Function 3233 (DUF3233), which are conserved across gram negative gammaproteobacteria (especially in Vibrio sp. and similar bacteria). Profile and HMM based sequence search methods were used to screen homologues of DUF3233. The I-TASSER fold recognition method was used to build a three dimensional structural model of the domain. The structure resembles the transmembrane beta-barrel with an axial N-terminal helix and twelve antiparallel beta-strands. Using a combination of amphipathy and discrimination analysis we analysed the potential transmembrane beta-barrel forming properties of DUF3233. Sequence, structure and phylogenetic analysis of DUF3233 indicates that this gram negative bacterial hypothetical protein resembles the beta-barrel translocation unit of autotransporter Va secretory mechanism with a gene organisation that differs from the conventional Va system.
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The extended signal peptide of the trimeric autotransporter EmaA of Aggregatibacter actinomycetemcomitans modulates secretion. J Bacteriol 2011; 193:6983-94. [PMID: 22001514 DOI: 10.1128/jb.05813-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The extracellular matrix protein adhesin A (EmaA) of the Gram-negative bacterium Aggregatibacter actinomycetemcomitans is a fibrillar collagen adhesin belonging to the family of trimeric autotransporters. The protein forms antenna-like structures on the bacterial surface required for collagen adhesion. The 202-kDa protein monomers are proposed to be targeted and translocated across the inner membrane by a long signal peptide composed of 56 amino acids. The predicted signal peptide was functionally active in Escherichia coli and A. actinomycetemcomitans using truncated PhoA and Aae chimeric proteins, respectively. Mutations in the signal peptide were generated and characterized for PhoA activity in E. coli. A. actinomycetemcomitans strains expressing EmaA with the identical mutant signal peptides were assessed for cellular localization, surface expression, and collagen binding activity. All of the mutants impaired some aspect of EmaA structure or function. A signal peptide mutant that promoted alkaline phosphatase secretion did not allow any cell surface presentation of EmaA. A second mutant allowed for cell surface exposure but abolished protein function. A third mutant allowed for the normal localization and function of EmaA at 37°C but impaired localization at elevated temperatures. Likewise, replacement of the long EmaA signal peptide with a typical signal peptide also impaired localization above 37°C. The data suggest that the residues of the EmaA signal peptide are required for protein folding or assembly of this collagen adhesin.
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Kawai F, Grass S, Kim Y, Choi KJ, St Geme JW, Yeo HJ. Structural insights into the glycosyltransferase activity of the Actinobacillus pleuropneumoniae HMW1C-like protein. J Biol Chem 2011; 286:38546-38557. [PMID: 21908603 DOI: 10.1074/jbc.m111.237602] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Glycosylation of proteins is a fundamental process that influences protein function. The Haemophilus influenzae HMW1 adhesin is an N-linked glycoprotein that mediates adherence to respiratory epithelium, an essential early step in the pathogenesis of H. influenzae disease. HMW1 is glycosylated by HMW1C, a novel glycosyltransferase in the GT41 family that creates N-glycosidic linkages with glucose and galactose at asparagine residues and di-glucose linkages at sites of glucose modification. Here we report the crystal structure of Actinobacillus pleuropneumoniae HMW1C (ApHMW1C), a functional homolog of HMW1C. The structure of ApHMW1C contains an N-terminal all α-domain (AAD) fold and a C-terminal GT-B fold with two Rossmann-like domains and lacks the tetratricopeptide repeat fold characteristic of the GT41 family. The GT-B fold harbors the binding site for UDP-hexose, and the interface of the AAD fold and the GT-B fold forms a unique groove with potential to accommodate the acceptor protein. Structure-based functional analyses demonstrated that the HMW1C protein shares the same structure as ApHMW1C and provided insights into the unique bi-functional activity of HMW1C and ApHMW1C, suggesting an explanation for the similarities and differences of the HMW1C-like proteins compared with other GT41 family members.
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Affiliation(s)
- Fumihiro Kawai
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204
| | - Susan Grass
- Departments of Pediatrics and Molecular Genetics & Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Youngchang Kim
- Structural Biology Center, Argonne National Laboratory, Argonne, Illinois 60439
| | - Kyoung-Jae Choi
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204
| | - Joseph W St Geme
- Departments of Pediatrics and Molecular Genetics & Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Hye-Jeong Yeo
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204.
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Filloux A. Protein Secretion Systems in Pseudomonas aeruginosa: An Essay on Diversity, Evolution, and Function. Front Microbiol 2011; 2:155. [PMID: 21811488 PMCID: PMC3140646 DOI: 10.3389/fmicb.2011.00155] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 07/01/2011] [Indexed: 12/25/2022] Open
Abstract
Protein secretion systems are molecular nanomachines used by Gram-negative bacteria to thrive within their environment. They are used to release enzymes that hydrolyze complex carbon sources into usable compounds, or to release proteins that capture essential ions such as iron. They are also used to colonize and survive within eukaryotic hosts, causing acute or chronic infections, subverting the host cell response and escaping the immune system. In this article, the opportunistic human pathogen Pseudomonas aeruginosa is used as a model to review the diversity of secretion systems that bacteria have evolved to achieve these goals. This diversity may result from a progressive transformation of cell envelope complexes that initially may not have been dedicated to secretion. The striking similarities between secretion systems and type IV pili, flagella, bacteriophage tail, or efflux pumps is a nice illustration of this evolution. Differences are also needed since various secretion configurations call for diversity. For example, some proteins are released in the extracellular medium while others are directly injected into the cytosol of eukaryotic cells. Some proteins are folded before being released and transit into the periplasm. Other proteins cross the whole cell envelope at once in an unfolded state. However, the secretion system requires conserved basic elements or features. For example, there is a need for an energy source or for an outer membrane channel. The structure of this review is thus quite unconventional. Instead of listing secretion types one after each other, it presents a melting pot of concepts indicating that secretion types are in constant evolution and use basic principles. In other words, emergence of new secretion systems could be predicted the way Mendeleïev had anticipated characteristics of yet unknown elements.
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Affiliation(s)
- Alain Filloux
- Division of Cell and Molecular Biology, Centre for Molecular Microbiology and Infection, Imperial College London London, UK
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Delattre A, Saint N, Clantin B, Willery E, Lippens G, Locht C, Villeret V, Jacob‐Dubuisson F. Substrate recognition by the POTRA domains of TpsB transporter FhaC. Mol Microbiol 2011; 81:99-112. [DOI: 10.1111/j.1365-2958.2011.07680.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Anne‐Sophie Delattre
- Inserm U1019, Center for Infection and Immunity of Lille, F‐59019 Lille, France
- Institut Pasteur de Lille, F‐59019 Lille, France
- Univ Lille Nord de France, F‐59000 Lille, France
- CNRS UMR8204, F‐59021 Lille, France
| | - Nathalie Saint
- INSERM U1046, Université de Montpellier 1 et 2, F‐34090 Montpellier cedex, France
| | - Bernard Clantin
- CNRS USR3078, Institut de Recherche Interdisciplinaire – Université de Lille 1 – Université de Lille 2, F‐59658 Villeneuve d'Ascq, France
| | - Eve Willery
- Inserm U1019, Center for Infection and Immunity of Lille, F‐59019 Lille, France
- Institut Pasteur de Lille, F‐59019 Lille, France
- Univ Lille Nord de France, F‐59000 Lille, France
- CNRS UMR8204, F‐59021 Lille, France
| | - Guy Lippens
- CNRS UMR 8576 – Université de Lille I, F‐59655 Villeneuve d'Ascq – France
| | - Camille Locht
- Inserm U1019, Center for Infection and Immunity of Lille, F‐59019 Lille, France
- Institut Pasteur de Lille, F‐59019 Lille, France
- Univ Lille Nord de France, F‐59000 Lille, France
- CNRS UMR8204, F‐59021 Lille, France
| | - Vincent Villeret
- CNRS USR3078, Institut de Recherche Interdisciplinaire – Université de Lille 1 – Université de Lille 2, F‐59658 Villeneuve d'Ascq, France
| | - Françoise Jacob‐Dubuisson
- Inserm U1019, Center for Infection and Immunity of Lille, F‐59019 Lille, France
- Institut Pasteur de Lille, F‐59019 Lille, France
- Univ Lille Nord de France, F‐59000 Lille, France
- CNRS UMR8204, F‐59021 Lille, France
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Baud C, Gutsche I, Willery E, de Paepe D, Drobecq H, Gilleron M, Locht C, Jamin M, Jacob-Dubuisson F. Membrane-associated DegP in Bordetella chaperones a repeat-rich secretory protein. Mol Microbiol 2011; 80:1625-36. [DOI: 10.1111/j.1365-2958.2011.07672.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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69
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Characterization of putative virulence genes on the related RepFIB plasmids harbored by Cronobacter spp. Appl Environ Microbiol 2011; 77:3255-67. [PMID: 21421789 DOI: 10.1128/aem.03023-10] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cronobacter spp. are emerging neonatal pathogens that cause meningitis, sepsis, and necrotizing enterocolitis. The genus Chronobacter consists of six species: C. sakazakii, C. malonaticus, C. muytjensii, C. turicensis, C. dublinensis, and Cronobacter genomospecies group 1. Whole-genome sequencing of C. sakazakii BAA-894 and C. turicensis z3032 revealed that they harbor similarly sized plasmids identified as pESA3 (131 kb) and pCTU1 (138 kb), respectively. In silico analysis showed that both plasmids encode a single RepFIB-like origin of replication gene, repA, as well as two iron acquisition systems (eitCBAD and iucABCD/iutA). In a chrome azurol S agar diffusion assay, it was demonstrated that siderophore activity was associated with the presence of pESA3 or pCTU1. Additionally, pESA3 contains a cpa (Cronobacter plasminogen activator) gene and a 17-kb type 6 secretion system (T6SS) locus, while pCTU1 contains a 27-kb region encoding a filamentous hemagglutinin gene (fhaB), its specifc transporter gene (fhaC), and associated putative adhesins (FHA locus), suggesting that these are virulence plasmids. In a repA-targeted PCR assay, 97% of 229 Cronobacter species isolates were found to possess a homologous RepFIB plasmid. All repA PCR-positive strains were also positive for the eitCBAD and iucABCD/iutA iron acquisition systems. However, the presence of cpa, T6SS, and FHA loci depended on species, demonstrating a strong correlation with the presence of virulence traits, plasmid type, and species. These results support the hypothesis that these plasmids have evolved from a single archetypical plasmid backbone through the cointegration, or deletion, of specific virulence traits in each species.
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Zhang D, Iyer LM, Aravind L. A novel immunity system for bacterial nucleic acid degrading toxins and its recruitment in various eukaryotic and DNA viral systems. Nucleic Acids Res 2011; 39:4532-52. [PMID: 21306995 PMCID: PMC3113570 DOI: 10.1093/nar/gkr036] [Citation(s) in RCA: 150] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The use of nucleases as toxins for defense, offense or addiction of selfish elements is widely encountered across all life forms. Using sensitive sequence profile analysis methods, we characterize a novel superfamily (the SUKH superfamily) that unites a diverse group of proteins including Smi1/Knr4, PGs2, FBXO3, SKIP16, Syd, herpesviral US22, IRS1 and TRS1, and their bacterial homologs. Using contextual analysis we present evidence that the bacterial members of this superfamily are potential immunity proteins for a variety of toxin systems that also include the recently characterized contact-dependent inhibition (CDI) systems of proteobacteria. By analyzing the toxin proteins encoded in the neighborhood of the SUKH superfamily we predict that they possess domains belonging to diverse nuclease and nucleic acid deaminase families. These include at least eight distinct types of DNases belonging to HNH/EndoVII- and restriction endonuclease-fold, and RNases of the EndoU-like and colicin E3-like cytotoxic RNases-folds. The N-terminal domains of these toxins indicate that they are extruded by several distinct secretory mechanisms such as the two-partner system (shared with the CDI systems) in proteobacteria, ESAT-6/WXG-like ATP-dependent secretory systems in Gram-positive bacteria and the conventional Sec-dependent system in several bacterial lineages. The hedgehog-intein domain might also release a subset of toxic nuclease domains through auto-proteolytic action. Unlike classical colicin-like nuclease toxins, the overwhelming majority of toxin systems with the SUKH superfamily is chromosomally encoded and appears to have diversified through a recombination process combining different C-terminal nuclease domains to N-terminal secretion-related domains. Across the bacterial superkingdom these systems might participate in discriminating `self’ or kin from `non-self’ or non-kin strains. Using structural analysis we demonstrate that the SUKH domain possesses a versatile scaffold that can be used to bind a wide range of protein partners. In eukaryotes it appears to have been recruited as an adaptor to regulate modification of proteins by ubiquitination or polyglutamylation. Similarly, another widespread immunity protein from these toxin systems, namely the suppressor of fused (SuFu) superfamily has been recruited for comparable roles in eukaryotes. In animal DNA viruses, such as herpesviruses, poxviruses, iridoviruses and adenoviruses, the ability of the SUKH domain to bind diverse targets has been deployed to counter diverse anti-viral responses by interacting with specific host proteins.
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Affiliation(s)
- Dapeng Zhang
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
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71
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Abstract
Staphylococcus aureus encodes the Sec-independent Ess secretion pathway, an ortholog of mycobacterial T7 secretion systems which is required for the virulence of this Gram-positive microbe. The Ess (ESX secretion) pathway was previously defined as a genomic cluster of eight genes, esxA, esaA, essA, essB, esaB, essC, esaC, and esxB. essABC encode membrane proteins involved in the stable expression of esxA, esxB, and esaC, genes specifying three secreted polypeptide substrates. esaB, which encodes a small cytoplasmic protein, represses the synthesis of EsaC but not that of EsxA and EsxB. Here we investigated a hitherto uncharacterized gene, esaD, located downstream of esxB. Expression of esaD is activated by mutations in esaB and essB. EsaD, the 617-amino-acid product of esaD, is positioned in the membrane and is also accessible to EsaD-specific antibodies on the bacterial surface. S. aureus mutants lacking esaD are defective in the secretion of EsxA. Following intravenous inoculation of mice, S. aureus esaD mutants generate fewer abscesses with a reduced bacterial load compared to wild-type parent strain Newman. The chromosomes of Listeria and Bacillus species with Ess pathways also harbor esaD homologues downstream of esxB, suggesting that the contributory role of EsaD in Ess secretion may be shared among Gram-positive pathogens.
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Cooperation between LepA and PlcH contributes to the in vivo virulence and growth of Pseudomonas aeruginosa in mice. Infect Immun 2010; 79:211-9. [PMID: 21041488 DOI: 10.1128/iai.01053-10] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Pseudomonas aeruginosa-derived large extracellular protease (LepA) and hemolytic phospholipase C (PlcH) are considered to play an important role in the pathogenicity of this organism. Although bacterial growth appears to be closely related to virulence, little is known about whether LepA and PlcH participate in the growth and virulence of P. aeruginosa. In this study, we investigated whether LepA and PlcH contribute to the virulence and growth of P. aeruginosa using a wild-type strain and mutants. The growth rate of the isogenic lepA single mutant was lower than that of the wild-type strain in a minimal medium containing serum albumin or hemoglobin as the sole carbon and nitrogen source. Furthermore, the growth rate of the lepA plcH double mutant decreased greatly compared with that of the wild-type strain in a minimal medium containing erythrocytes as a sole nutrient source for growth. Thus, these results indicate that cooperation between LepA and PlcH would contribute to the utilization of erythrocytes as a sole nutrient source for the growth of P. aeruginosa. In addition, mouse infection experiments demonstrated that the virulence of the lepA and plcH single mutants was attenuated, and the numbers of the mutants were lower than the numbers of the wild-type strain in peritoneal lavage fluid and whole-blood specimens. In particular, the virulence and growth rate of the lepA plcH double mutant were markedly lower than those of the wild-type strain. Collectively, these results suggest that LepA and PlcH contribute to the in vivo virulence and growth of P. aeruginosa.
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73
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Delattre AS, Clantin B, Saint N, Locht C, Villeret V, Jacob-Dubuisson F. Functional importance of a conserved sequence motif in FhaC, a prototypic member of the TpsB/Omp85 superfamily. FEBS J 2010; 277:4755-65. [PMID: 20955520 DOI: 10.1111/j.1742-4658.2010.07881.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In Gram-negative bacteria, the two-partner secretion pathway mediates the secretion of TpsA proteins with various functions. TpsB transporters specifically recognize their TpsA partners in the periplasm and mediate their transport through a hydrophilic channel. The filamentous haemagglutinin adhesin (FHA)/FhaC pair represents a model two-partner secretion system, with the structure of the TpsB transporter FhaC providing the bases to decipher the mechanism of action of these proteins. FhaC is composed of a β-barrel preceded by two periplasmic polypeptide-transport-associated (POTRA) domains in tandem. The barrel is occluded by an N-terminal helix and an extracellular loop, L6, folded back into the FhaC channel. In this article, we describe a functionally important motif of FhaC. The VRGY tetrad is highly conserved in the TpsB family and, in FhaC, it is located at the tip of L6 reaching the periplasm. Replacement by Ala of the invariant Arg dramatically affects the secretion efficiency, although the structure of FhaC and its channel properties remain unaffected. This substitution affects the secretion mechanism at a step beyond the initial TpsA-TpsB interaction. Replacement of the conserved Tyr affects the channel properties, but not the secretion activity, suggesting that this residue stabilizes the loop in the resting conformation of FhaC. Thus, the conserved motif at the tip of L6 represents an important piece of two-partner secretion machinery. This motif is conserved in a predicted loop between two β-barrel strands in more distant relatives of FhaC involved in protein transport across or assembly into the outer membranes of bacteria and organelles, suggesting a conserved function in the molecular mechanism of transport.
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Woolery AR, Luong P, Broberg CA, Orth K. AMPylation: Something Old is New Again. Front Microbiol 2010; 1:113. [PMID: 21607083 PMCID: PMC3095399 DOI: 10.3389/fmicb.2010.00113] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2010] [Accepted: 09/22/2010] [Indexed: 01/21/2023] Open
Abstract
The post-translational modification AMPylation is emerging as a significant regulatory mechanism in both prokaryotic and eukaryotic biology. This process involves the covalent addition of an adenosine monophosphate to a protein resulting in a modified protein with altered activity. Proteins capable of catalyzing AMPylation, termed AMPylators, are comparable to kinases in that they both hydrolyze ATP and reversibly transfer a part of this primary metabolite to a hydroxyl side chain of the protein substrate. To date, only four AMPylators have been characterized, though many more potential candidates have been identified through amino acid sequence analysis and preliminary in vitro studies. This modification was first discovered over 40 years ago by Earl Stadtman and colleagues through the modification of glutamine synthetase by adenylyl transferase; however research into this mechanism has only just been reenergized by the studies on bacterial effectors. New AMPylators were revealed due to the discovery that a bacterial effector having a conserved Fic domain transfers an AMP group to protein substrates. Current research focuses on identifying and characterizing various types of AMPylators homologous to Fic domains and adenylyl transferase domains and their respective substrates. While all AMPylators characterized thus far are bacterial proteins, the conservation of the Fic domain in eukaryotic organisms suggests that AMPylation is omnipresent in various forms of life and has significant impact on a wide range of regulatory processes.
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Affiliation(s)
- Andrew R Woolery
- Department of Molecular Biology, University of Texas Southwestern Medical Center Dallas, TX, USA
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Arnold T, Zeth K, Linke D. Omp85 from the thermophilic cyanobacterium Thermosynechococcus elongatus differs from proteobacterial Omp85 in structure and domain composition. J Biol Chem 2010; 285:18003-15. [PMID: 20351097 PMCID: PMC2878562 DOI: 10.1074/jbc.m110.112516] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/26/2010] [Indexed: 12/03/2022] Open
Abstract
Omp85 proteins are essential proteins located in the bacterial outer membrane. They are involved in outer membrane biogenesis and assist outer membrane protein insertion and folding by an unknown mechanism. Homologous proteins exist in eukaryotes, where they mediate outer membrane assembly in organelles of endosymbiotic origin, the mitochondria and chloroplasts. We set out to explore the homologous relationship between cyanobacteria and chloroplasts, studying the Omp85 protein from the thermophilic cyanobacterium Thermosynechococcus elongatus. Using state-of-the art sequence analysis and clustering methods, we show how this protein is more closely related to its chloroplast homologue Toc75 than to proteobacterial Omp85, a finding supported by single channel conductance measurements. We have solved the structure of the periplasmic part of the protein to 1.97 A resolution, and we demonstrate that in contrast to Omp85 from Escherichia coli the protein has only three, not five, polypeptide transport-associated (POTRA) domains, which recognize substrates and generally interact with other proteins in bigger complexes. We model how these POTRA domains are attached to the outer membrane, based on the relationship of Omp85 to two-partner secretion system proteins, which we show and analyze. Finally, we discuss how Omp85 proteins with different numbers of POTRA domains evolved, and evolve to this day, to accomplish an increasing number of interactions with substrates and helper proteins.
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Affiliation(s)
- Thomas Arnold
- From Department I, Protein Evolution, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Kornelius Zeth
- From Department I, Protein Evolution, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
| | - Dirk Linke
- From Department I, Protein Evolution, Max Planck Institute for Developmental Biology, Spemannstrasse 35, 72076 Tübingen, Germany
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The Haemophilus influenzae HMW1C protein is a glycosyltransferase that transfers hexose residues to asparagine sites in the HMW1 adhesin. PLoS Pathog 2010; 6:e1000919. [PMID: 20523900 PMCID: PMC2877744 DOI: 10.1371/journal.ppat.1000919] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 04/23/2010] [Indexed: 01/27/2023] Open
Abstract
The Haemophilus influenzae HMW1 adhesin is a high-molecular weight protein that is secreted by the bacterial two-partner secretion pathway and mediates adherence to respiratory epithelium, an essential early step in the pathogenesis of H. influenzae disease. In recent work, we discovered that HMW1 is a glycoprotein and undergoes N-linked glycosylation at multiple asparagine residues with simple hexose units rather than N-acetylated hexose units, revealing an unusual N-glycosidic linkage and suggesting a new glycosyltransferase activity. Glycosylation protects HMW1 against premature degradation during the process of secretion and facilitates HMW1 tethering to the bacterial surface, a prerequisite for HMW1-mediated adherence. In the current study, we establish that the enzyme responsible for glycosylation of HMW1 is a protein called HMW1C, which is encoded by the hmw1 gene cluster and shares homology with a group of bacterial proteins that are generally associated with two-partner secretion systems. In addition, we demonstrate that HMW1C is capable of transferring glucose and galactose to HMW1 and is also able to generate hexose-hexose bonds. Our results define a new family of bacterial glycosyltransferases. Decoration of proteins with carbohydrates has an important impact on protein function throughout biology and has been recognized increasingly in pathogenic bacteria. Haemophilus influenzae is a common cause of both bacterial respiratory tract disease and bacterial invasive disease and initiates infection by colonizing the upper respiratory tract. The Haemophilus HMW1 adhesin is a large protein that resides on the bacterial surface and mediates bacterial attachment to respiratory epithelial cells, an essential step in the process of colonization. In recent work, we discovered that HMW1 is decorated at multiple sites with short carbohydrate units that serve to prevent degradation and to stabilize association with the bacterial surface. In the current study we identify the enzyme responsible for adding carbohydrate units at specific sites of HMW1. In addition, we demonstrate that this enzyme is capable of creating both carbohydrate-protein and carbohydrate-carbohydrate bonds. The amino acid sequence of this enzyme is similar to the sequences of proteins in several other bacteria, suggesting a new family of bacterial enzymes capable of creating carbohydrate-protein and carbohydrate-carbohydrate bonds.
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77
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Schielke S, Frosch M, Kurzai O. Virulence determinants involved in differential host niche adaptation of Neisseria meningitidis and Neisseria gonorrhoeae. Med Microbiol Immunol 2010; 199:185-96. [PMID: 20379743 DOI: 10.1007/s00430-010-0150-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Indexed: 11/28/2022]
Abstract
Neisseria meningitidis and Neisseria gonorrhoeae are the only pathogenic species of the genus Neisseria. Although these two species are closely related, they specialized on survival in completely different environments within the human host-the nasopharynx in the case of N. meningitidis versus the urogenital tract in the case of N. gonorrhoeae. The genetic background of these differences has not yet been determined. Here, we present a comparison of all characterized transcriptional regulators in these species, delineating analogous functions and disclosing differential functional developments of these DNA-binding proteins with a special focus on the recently characterized regulator FarR and its contribution to divergent host niche adaptation in the two Neisseria spp. Furthermore, we summarize the present knowledge on two-partner secretion systems in meningococci, highlighting their overall expression among meningococcal strains in contrast to the complete absence in gonococci. Concluding, the decisive role of these two entirely different factors in host niche adaptation of the two human pathogenic Neisseria species is depicted, illuminating another piece of the puzzle to locate the molecular basis of their differences in preferred colonization sites and pathogenicity.
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Affiliation(s)
- Stephanie Schielke
- Institute of Hygiene and Microbiology, University of Würzburg, Würzburg, Germany
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Voegel TM, Warren JG, Matsumoto A, Igo MM, Kirkpatrick BC. Localization and characterization of Xylella fastidiosa haemagglutinin adhesins. MICROBIOLOGY-SGM 2010; 156:2172-2179. [PMID: 20378647 DOI: 10.1099/mic.0.037564-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Xylella fastidiosa is a gram-negative, xylem-inhabiting, plant-pathogenic bacterium responsible for several important diseases including Pierce's disease (PD) of grapevines. The bacteria form biofilms in grapevine xylem that contribute to the occlusion of the xylem vessels. X. fastidiosa haemagglutinin (HA) proteins are large afimbrial adhesins that have been shown to be crucial for biofilm formation. Little is known about the mechanism of X. fastidiosa HA-mediated cell-cell aggregation or the localization of the adhesins on the cell. We generated anti-HA antibodies and show that X. fastidiosa HAs are present in the outer membrane and secreted both as soluble proteins and in membrane vesicles. Furthermore, the HA pre-proteins are processed from the predicted molecular mass of 360 kDa to a mature 220 kDa protein. Based on this information, we are evaluating a novel form of potential resistance against PD by generating HA-expressing transgenic grapevines.
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Affiliation(s)
- Tanja M Voegel
- Department of Plant Pathology, University of California, Davis, CA 951616, USA
- Center for Applied Biosciences, University of Freiburg, Germany
| | - Jeremy G Warren
- Department of Plant Pathology, University of California, Davis, CA 951616, USA
| | - Ayumi Matsumoto
- Department of Microbiology, University of California, Davis, CA 951616, USA
| | - Michele M Igo
- Department of Microbiology, University of California, Davis, CA 951616, USA
| | - Bruce C Kirkpatrick
- Department of Plant Pathology, University of California, Davis, CA 951616, USA
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79
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Histophilus somni IbpA DR2/Fic in virulence and immunoprotection at the natural host alveolar epithelial barrier. Infect Immun 2010; 78:1850-8. [PMID: 20176790 DOI: 10.1128/iai.01277-09] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Newly recognized Fic family virulence proteins may be important in many bacterial pathogens. To relate cellular mechanisms to pathogenesis and immune protection, we studied the cytotoxicity of the Histophilus somni immunoglobulin-binding protein A (IbpA) direct repeat 2 Fic domain (DR2/Fic) for natural host target cells. Live virulent IbpA-producing H. somni strain 2336, a cell-free culture supernatant (CCS) of this strain, or recombinant DR2/Fic (rDR2/Fic) caused dramatic retraction and rounding of bovine alveolar type 2 (BAT2) epithelial cells. IbpA-deficient H. somni strain 129Pt and a Fic motif His(298)Ala mutant rDR2/Fic protein were not cytotoxic. The cellular mechanism of DR2/Fic cytotoxicity was demonstrated by incubation of BAT2 cell lysates with strain 2336 CCS or rDR2/Fic in the presence of [alpha-(32)P]ATP, which resulted in adenylylation of Rho GTPases and cytoskeletal disruption. Since IbpA is not secreted by type III or type IV secretion systems, we determined whether DR2/Fic entered the host cytoplasm to access its Rho GTPase targets. Although H. somni did not invade BAT2 cells, DR2/Fic was internalized by cells treated with H. somni, CCS, or the rDR2/Fic protein, as shown by confocal immunomicroscopy. Transwell bacterial migration assays showed that large numbers of strain 2336 bacteria migrated between retracted BAT2 cells, but IbpA-deficient strain 129Pt did not cross a monolayer unless the monolayer was pretreated with strain 2336 CCS or rDR2/Fic protein. Antibody to rDR2/Fic or passively protective convalescent-phase serum blocked IbpA-mediated cytotoxicity and inhibited H. somni transmigration across BAT2 monolayers, confirming the role of DR2/Fic in pathogenesis and corresponding to the results for in vivo protection in previous animal studies.
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80
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A genomic window into the virulence of Histophilus somni. Trends Microbiol 2010; 18:90-9. [DOI: 10.1016/j.tim.2009.11.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2008] [Revised: 11/10/2009] [Accepted: 11/27/2009] [Indexed: 11/17/2022]
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81
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Choi PS, Bernstein HD. Sequential translocation of an Escherchia coli two-partner secretion pathway exoprotein across the inner and outer membranes. Mol Microbiol 2010; 75:440-51. [PMID: 19968793 PMCID: PMC3107007 DOI: 10.1111/j.1365-2958.2009.06993.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In Gram-negative bacteria, a variety of high molecular weight 'exoproteins' are translocated across the outer membrane (OM) via the two-partner secretion (TPS) pathway by interacting with a dedicated transporter. It is unclear, however, whether the translocation of exoproteins across the OM is coupled to their translocation across the inner membrane (IM). To address this question, we separated the production of an Escherichia coli O157:H7 exoprotein (OtpA) and its transporter (OtpB) temporally by placing otpA and otpB under the control of distinct regulatable promoters. We found that when both full-length and truncated forms of OtpA were expressed prior to OtpB, a significant fraction of the exoprotein was secreted. The results indicate that OtpA can be translocated into the periplasm and briefly remain secretion-competent. Furthermore, by engineering cysteine residues into OtpA and using disulphide bond formation as a reporter of periplasmic localization, we obtained additional evidence that the C-terminus of OtpA enters the periplasm before the N-terminus is translocated across the OM even when OtpA and OtpB are expressed simultaneously. Taken together, our results demonstrate that the translocation of a TPS exoprotein across the OM can occur independently from its translocation across the IM.
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Affiliation(s)
- Peter S. Choi
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0538, USA
| | - Harris D. Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0538, USA
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82
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Abstract
Bacterial toxins damage the host at the site of bacterial infection or distant from the site. Bacterial toxins can be single proteins or oligomeric protein complexes that are organized with distinct AB structure-function properties. The A domain encodes a catalytic activity. ADP ribosylation of host proteins is the earliest post-translational modification determined to be performed by bacterial toxins; other modifications include glucosylation and proteolysis. Bacterial toxins also catalyze the non-covalent modification of host protein function or can modify host cell properties through direct protein-protein interactions. The B domain includes two functional domains: a receptor-binding domain, which defines the tropism of a toxin for a cell and a translocation domain that delivers the A domain across a lipid bilayer, either on the plasma membrane or the endosome. Bacterial toxins are often characterized based upon the secretion mechanism that delivers the toxin out of the bacterium, termed types I-VII. This review summarizes the major families of bacterial toxins and also describes the specific structure-function properties of the botulinum neurotoxins.
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Affiliation(s)
- James S Henkel
- Medical College of Wisconsin, Department of Microbiology and Molecular Genetics, Milwaukee, WI 53151, USA.
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83
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Abstract
Bacterial autotransporters represent a diverse family of proteins that autonomously translocate across the inner membrane of Gram-negative bacteria via the Sec complex and across the outer bacterial membrane. They often possess exceptionally long N-terminal signal sequences. We analyzed 90 long signal sequences of bacterial autotransporters and members of the two-partner secretion pathway in silico and describe common domain organization found in 79 of these sequences. The domains are in agreement with previously published experimental data. Our algorithmic approach allows for the systematic identification of functionally different domains in long signal sequences.
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Affiliation(s)
- Jan A Hiss
- Johann Wolfgang Goethe-University, Chair for Chem- and Bioinformatics, Centre for Membrane Proteomics, Siesmayerstr. 70, D-60323 Frankfurt am Main, Germany.
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84
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Barret M, Frey-Klett P, Guillerm-Erckelboudt AY, Boutin M, Guernec G, Sarniguet A. Effect of wheat roots infected with the pathogenic fungus Gaeumannomyces graminis var. tritici on gene expression of the biocontrol bacterium Pseudomonas fluorescens Pf29Arp. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:1611-1623. [PMID: 19888826 DOI: 10.1094/mpmi-22-12-1611] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Traits contributing to the competence of biocontrol bacteria to colonize plant roots are often induced in the rhizosphere in response to plant components. These interactions have been studied using the two partners in gnotobiotic systems. However, in nature, beneficial or pathogenic fungi often colonize roots. Influence of these plant-fungus interactions on bacterial behavior remains to be investigated. Here, we have examined the influence of colonization of wheat roots by the take-all fungus Gaeumannomyces graminis var. tritici on gene expression of the biocontrol bacterium Pseudomonas fluorescens Pf29Arp. Bacteria were inoculated onto healthy, early G. graminis var. tritici-colonized and necrotic roots and transcriptomes were compared by shotgun DNA microarray. Pf29Arp decreased disease severity when inoculated before the onset of necrosis. Necrotic roots exerted a broader effect on gene expression compared with early G. graminis var. tritici-colonized and healthy roots. A gene encoding a putative type VI secretion system effector was only induced in necrotic conditions. A common pool of Pf29Arp genes differentially expressed on G. graminis var. tritici-colonized roots was related to carbon metabolism and oxidative stress, with a highest fold-change with necrosis. Overall, the data showed that the association of the pathogenic fungus with the roots strongly altered Pf29Arp adaptation with differences between early and late G. graminis var. tritici infection steps.
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Affiliation(s)
- Matthieu Barret
- Institut National de la Recherche Agronomique, Agrocampus Rennes-Université Rennes 1, UMR 1099 Biologie des Organismes et des Populations appliquée à la Protection des Plantes, Le Rheu, France
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85
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Arya G, Niven DF. Production of haemolysins by strains of the Actinobacillus minor/"porcitonsillarum" complex. Vet Microbiol 2009; 141:332-41. [PMID: 19819087 DOI: 10.1016/j.vetmic.2009.09.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 09/18/2009] [Accepted: 09/22/2009] [Indexed: 11/29/2022]
Abstract
Actinobacillus minor and "Actinobacillus porcitonsillarum" are distinguished by their haemolytic activities, the latter organism being haemolytic and the former, non-haemolytic. Analysis of a whole genome shotgun sequence, however, revealed that A. minor strain 202, like "A. porcitonsillarum", possesses a haemolysin-encoding apxII operon. The purpose of this study was therefore to investigate haemolysin production by this organism and also by three additional members of the A. minor/"porcitonsillarum" complex, strains 33PN and 7ATS and A. minor strain NM305(T). Primers based on sequences within the apxII genes of strain 202 allowed the amplification of appropriately sized fragments from DNA from strain 33PN suggesting that this organism also possesses an apxII operon. Analysis of a whole genome shotgun sequence failed to reveal any trace of an apxII operon in strain NM305(T) and attempts to amplify apxII genes from DNA from strain 7ATS also failed. Strains 202 and 33PN, and surprisingly, the type strain of A. minor and strain 7ATS, were all found to be haemolysin-positive as growth media from cultures of these organisms could promote the lysis of erythrocytes in suspension. The erythrocyte specificities of the haemolysins produced by strains 202 and 33PN indicated that the haemolytic activities exhibited by these organisms were due to ApxII. In keeping with the apparent lack of apxII genes in strains NM305(T) and 7ATS, the haemolysins produced by these organisms were not erythrocyte-specific and with both organisms, haemolytic activity appeared to be due to a combination of heat-stable and heat-labile components. The identities of these components, however, remain unknown.
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Affiliation(s)
- Gitanjali Arya
- Department of Natural Resource Sciences, Macdonald Campus, McGill University, 21111 Lakeshore Road, Ste. Anne de Bellevue, Que., Canada H9X 3V9
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86
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Llamas MA, van der Sar A, Chu BCH, Sparrius M, Vogel HJ, Bitter W. A Novel extracytoplasmic function (ECF) sigma factor regulates virulence in Pseudomonas aeruginosa. PLoS Pathog 2009; 5:e1000572. [PMID: 19730690 PMCID: PMC2729926 DOI: 10.1371/journal.ppat.1000572] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Accepted: 08/10/2009] [Indexed: 11/28/2022] Open
Abstract
Next to the two-component and quorum sensing systems, cell-surface signaling (CSS) has been recently identified as an important regulatory system in Pseudomonas aeruginosa. CSS systems sense signals from outside the cell and transmit them into the cytoplasm. They generally consist of a TonB-dependent outer membrane receptor, a sigma factor regulator (or anti-sigma factor) in the cytoplasmic membrane, and an extracytoplasmic function (ECF) sigma factor. Upon perception of the extracellular signal by the receptor the ECF sigma factor is activated and promotes the transcription of a specific set of gene(s). Although most P. aeruginosa CSS systems are involved in the regulation of iron uptake, we have identified a novel system involved in the regulation of virulence. This CSS system, which has been designated PUMA3, has a number of unusual characteristics. The most obvious difference is the receptor component which is considerably smaller than that of other CSS outer membrane receptors and lacks a β-barrel domain. Homology modeling of PA0674 shows that this receptor is predicted to be a bilobal protein, with an N-terminal domain that resembles the N-terminal periplasmic signaling domain of CSS receptors, and a C-terminal domain that resembles the periplasmic C-terminal domains of the TolA/TonB proteins. Furthermore, the sigma factor regulator both inhibits the function of the ECF sigma factor and is required for its activity. By microarray analysis we show that PUMA3 regulates the expression of a number of genes encoding potential virulence factors, including a two-partner secretion (TPS) system. Using zebrafish (Danio rerio) embryos as a host we have demonstrated that the P. aeruginosa PUMA3-induced strain is more virulent than the wild-type. PUMA3 represents the first CSS system dedicated to the transcriptional activation of virulence functions in a human pathogen. Pseudomonas aeruginosa is a versatile pathogen; these bacteria are able to cause an infection in humans and other mammals, zebrafish, insects, nematodes and even plants. P. aeruginosa evolved an impressive amount of gene regulation systems to be able to express the right virulence genes under the right circumstances. The best studied examples of these are the two-component systems and the autoinducers. In addition, P. aeruginosa is also able to regulate virulence genes using the pyoverdine cell-surface signaling system (CSS). Genome analysis shows that there are multiple putative CSS systems in P. aeruginosa. In this paper we have studied a novel CSS system with a number of remarkable characteristics and show that this system is involved in the regulation of several putative virulence factors. Induction of this system leads to increased virulence in our zebrafish embryo infection model. Our study provides new insights into the regulation of virulence by P. aeruginosa.
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Affiliation(s)
- María A Llamas
- Department of Medical Microbiology, VU University Medical Center, Amsterdam, The Netherlands.
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87
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EtpB is a pore-forming outer membrane protein showing TpsB protein features involved in the two-partner secretion system. J Membr Biol 2009; 230:143-54. [PMID: 19711123 DOI: 10.1007/s00232-009-9195-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 07/28/2009] [Indexed: 10/20/2022]
Abstract
Attachment to host tissues is a critical step in the pathogenesis of most bacterial infections. Enterotoxigenic Escherichia coli (ETEC) remains one of the principal causes of infectious diarrhea in humans. The recent identification of additional ETEC surface molecules suggests that new targets may be exploited in vaccine development. The EtpA protein identified in ETEC H10407 is a large glycosylated adhesin secreted via the two-partner secretion system. EtpA requires its putative partner EtpB for translocation across the outer membrane (OM). We investigated the biochemical and electrophysiological properties of purified EtpB. We showed that EtpB is 65-kDa heat-modifiable protein localized to the OM. Electrophysiological experiments indicated that EtpB is able to form pores in planar lipid bilayer membranes with an asymmetric current, suggesting its functional asymmetry. The pore of EtpB frequently assumes an opened conformation and fluctuates between three well-defined conductance states. In silico analysis of the EtpB amino acid sequence and molecular modeling suggest that EtpB is similar to the well-known TpsB protein FhaC from Bordetella pertussis and has a C-terminal transmembrane beta-barrel domain that is occluded by an N-terminal alpha-helix, an extracellular loop, and two periplasmic polypeptide-transport-associated (POTRA) domains. Together, these data confirm that EtpB is a pore-forming protein mainly folded into a beta-barrel conformation and indicate that EtpB presents typical features of the OM TpsB proteins.
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88
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Baud C, Hodak H, Willery E, Drobecq H, Locht C, Jamin M, Jacob-Dubuisson F. Role of DegP for two-partner secretion in Bordetella. Mol Microbiol 2009; 74:315-29. [PMID: 19703106 DOI: 10.1111/j.1365-2958.2009.06860.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Sorting of proteins destined to the surface or the extracellular milieu is mediated by specific machineries, which guide the protein substrates towards the proper route of secretion and determine the compartment in which folding occurs. In gram-negative bacteria, the two-partner secretion (TPS) pathway is dedicated to the secretion of large proteins rich in beta-helical structure. The secretion of the filamentous haemagglutinin (FHA), a 230 kDa adhesin of Bordetella pertussis, represents a model TPS system. FHA is exported by the Sec machinery and transits through the periplasm in an extended conformation. From there it is translocated across the outer membrane by its dedicated transporter FhaC to finally fold into a long beta-helix at the cell surface in a progressive manner. In this work, we show that B. pertussis lacking the periplasmic chaperone/protease DegP has a strong growth defect at 37 degrees C, and the integrity of its outer membrane is compromised. While both phenotypes are significantly aggravated by the presence of FHA, the chaperone activity of DegP markedly alleviates the periplasmic stress. In vitro, DegP binds to non-native FHA with high affinity. We propose that DegP chaperones the extended FHA polypeptide in the periplasm and is thus involved in the TPS pathway.
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Affiliation(s)
- C Baud
- INSERM U629, Lille, France
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89
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A prototype two-partner secretion pathway: the Haemophilus influenzae HMW1 and HMW2 adhesin systems. Trends Microbiol 2009; 17:355-60. [PMID: 19660953 DOI: 10.1016/j.tim.2009.06.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Revised: 05/19/2009] [Accepted: 06/01/2009] [Indexed: 11/23/2022]
Abstract
Nontypable Haemophilus influenzae is a common cause of human disease and initiates infection by colonizing the upper respiratory tract. Adherence to respiratory epithelium is an important step in the process of colonization and is influenced by adhesive proteins called adhesins. In approximately 80% of nontypable H. influenzae isolates, the major adhesins are related proteins called HMW1 and HMW2. Here, we summarize recent advances in our understanding of HMW1 and HMW2 as prototype members of the bacterial two-partner secretion pathway and examples of the expanding number of bacterial glycoproteins, highlighting experimental approaches that might be useful in studies of other secreted proteins and glycoproteins.
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90
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Jacob-Dubuisson F, Villeret V, Clantin B, Delattre AS, Saint N. First structural insights into the TpsB/Omp85 superfamily. Biol Chem 2009; 390:675-84. [DOI: 10.1515/bc.2009.099] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Abstract
Proteins of the TpsB/Omp85 superfamily are involved in protein transport across, or assembly into, the outer membrane of Gram-negative bacteria, and their distant eukaryotic relatives exert similar functions in chloroplasts and mitochondria. The X-ray structure of one TpsB transporter, FhaC, provides the bases to decipher the mechanisms of action of these proteins. With two POTRA domains in the periplasm, a transmembrane β barrel and a large loop harboring a functionally important motif, FhaC epitomizes the conserved features of the super-family.
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91
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Fleckenstein JM, Roy K. Purification of recombinant high molecular weight two-partner secretion proteins from Escherichia coli. Nat Protoc 2009; 4:1083-92. [PMID: 19707189 DOI: 10.1038/nprot.2009.87] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This protocol describes the purification of a recombinant high molecular weight (HMW) two-partner secretion exoprotein (generically referred to as TpsA proteins) from Escherichia coli using methods developed recently to obtain highly purified flagellin-free recombinant EtpA (rEtpA) glycoprotein. The protocol addresses problems frequently encountered with the expression of these HMW proteins, namely plasmid instability and protein degradation, as well as a recently recognized issue of flagellin contamination. Briefly, the TpsA protein of interest is expressed with its outer membrane transporter (TpsB) protein in a flagellin-minus recombinant E. coli background. Culture supernatants are collected, concentrated through high molecular weight cutoff filters, followed by purification by size exclusion column chromatography. Details are included for the expression of HMW TpsA glycoproteins as polyhistidine-tagged molecules, which can be further purified by metal affinity chromatography (MAC). Using this protocol, it is possible to obtain highly purified microgram-milligram quantities of the TpsA protein of interest within 2-3 days.
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Affiliation(s)
- James M Fleckenstein
- Department of Veterans Affairs Medical Center Research (151), Memphis, Tennessee, USA.
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92
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Rocco F, De Gregorio E, Colonna B, Di Nocera PP. Stenotrophomonas maltophilia genomes: a start-up comparison. Int J Med Microbiol 2009; 299:535-46. [PMID: 19574092 DOI: 10.1016/j.ijmm.2009.05.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 05/06/2009] [Accepted: 05/21/2009] [Indexed: 10/20/2022] Open
Abstract
The whole DNA sequences of 2 Stenotrophomonas maltophilia strains isolated from the blood of a cancer patient (K279a) and the poplar Populus trichocarpa (R551-3) have been compared. The 2 chromosomes exhibit extensive synteny, but each is punctuated by about 40 genomic islands (GEIs), which vary in size from 3 to 70kb, and may encode up to about 50 proteins. A large set of smaller DNA sequences, encoding strain-specific 'solo' orfs, contributes to genetic heterogeneity in a significant manner. S. maltophilia GEIs potentially encode several proteins mediating interactions with the environment such as transmembrane proteins, haemagglutinins, components of type I and IV secretion systems, and efflux proteins having a role in metal and/or drug resistance. The presence of specific GEIs in the S. maltophilia population was monitored by PCR and slot-blot analyses. Data suggest that some islands are present at sites different from those identified in K279a and that alternative islands may be integrated at mapped sites.
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Affiliation(s)
- Francesco Rocco
- Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università Federico II, 80131 Napoli, Italy
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93
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The fic domain: regulation of cell signaling by adenylylation. Mol Cell 2009; 34:93-103. [PMID: 19362538 DOI: 10.1016/j.molcel.2009.03.008] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 02/12/2009] [Accepted: 03/20/2009] [Indexed: 11/22/2022]
Abstract
We show that the secreted antigen, IbpA, of the respiratory pathogen Histophilus somni induces cytotoxicity in mammalian cells via its Fic domains. Fic domains are defined by a core HPFxxGNGR motif and are conserved from bacteria to humans. We demonstrate that the Fic domains of IbpA catalyze a unique reversible adenylylation event that uses ATP to add an adenosine monophosphate (AMP) moiety to a conserved tyrosine residue in the switch I region of Rho GTPases. This modification requires the conserved histidine of the Fic core motif and renders Rho GTPases inactive. We further demonstrate that the only human protein containing a Fic domain, huntingtin yeast-interacting protein E (HYPE), also adenylylates Rho GTPases in vitro. Thus, we classify Fic domain-containing proteins as a class of enzymes that mediate bacterial pathogenesis as well as a previously unrecognized eukaryotic posttranslational modification that may regulate key signaling events.
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94
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Weaver TM, Hocking JM, Bailey LJ, Wawrzyn GT, Howard DR, Sikkink LA, Ramirez-Alvarado M, Thompson JR. Structural and functional studies of truncated hemolysin A from Proteus mirabilis. J Biol Chem 2009; 284:22297-22309. [PMID: 19494116 DOI: 10.1074/jbc.m109.014431] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In this study we analyzed the structure and function of a truncated form of hemolysin A (HpmA265) from Proteus mirabilis using a series of functional and structural studies. Hemolysin A belongs to the two-partner secretion pathway. The two-partner secretion pathway has been identified as the most common protein secretion pathway among Gram-negative bacteria. Currently, the mechanism of action for the two-partner hemolysin members is not fully understood. In this study, hemolysis experiments revealed a unidirectional, cooperative, biphasic activity profile after full-length, inactive hemolysin A was seeded with truncated hemolysin A. We also solved the first x-ray structure of a TpsA hemolysin. The truncated hemolysin A formed a right-handed parallel beta-helix with three adjoining segments of anti-parallel beta-sheet. A CXXC disulfide bond, four buried solvent molecules, and a carboxyamide ladder were all located at the third complete beta-helix coil. Replacement of the CXXC motif led to decreased activity and stability according to hemolysis and CD studies. Furthermore, the crystal structure revealed a sterically compatible, dry dimeric interface formed via anti-parallel beta-sheet interactions between neighboring beta-helix monomers. Laser scanning confocal microscopy further supported the unidirectional interconversion of full-length hemolysin A. From these results, a model has been proposed, where cooperative, beta-strand interactions between HpmA265 and neighboring full-length hemolysin A molecules, facilitated in part by the highly conserved CXXC pattern, account for the template-assisted hemolysis.
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Affiliation(s)
- Todd M Weaver
- Departments of Chemistry, La Crosse, Wisconsin 54601
| | | | | | | | - David R Howard
- Biology, University Wisconsin-La Crosse, La Crosse, Wisconsin 54601
| | - Laura A Sikkink
- the Departments of Biochemistry and Molecular Biology, Rochester, Minnesota 55905
| | | | - James R Thompson
- Physiology and Biomedical Imaging, College of Medicine, Mayo Clinic, Rochester, Minnesota 55905
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95
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Damron FH, Napper J, Teter MA, Yu HD. Lipotoxin F of Pseudomonas aeruginosa is an AlgU-dependent and alginate-independent outer membrane protein involved in resistance to oxidative stress and adhesion to A549 human lung epithelia. MICROBIOLOGY-SGM 2009; 155:1028-1038. [PMID: 19332805 DOI: 10.1099/mic.0.025833-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Chronic lung infection with P. aeruginosa and excessive neutrophil-associated inflammation are major causes of morbidity and mortality in patients with cystic fibrosis (CF). Overproduction of an exopolysaccharide known as alginate leads to the formation of mucoid biofilms that are resistant to antibiotics and host defences. Alginate overproduction or mucoidy is controlled by a stress-related ECF sigma factor AlgU/T. Mutation in the anti-sigma factor MucA is a known mechanism for conversion to mucoidy. Recently, we showed that inactivation of a kinase (KinB) in nonmucoid strain PAO1 results in overproduction of alginate. Here, we report the initial characterization of lipotoxin F (LptF, PA3692), an OmpA-like outer membrane protein that exhibited increased expression in the mucoid PAO1kinB mutant. The lipotoxin family of proteins has been previously shown to induce inflammation in lung epithelia, which may play a role in CF disease progression. Expression of LptF was observed to be AlgU-dependent and upregulated in CF isolates. Deletion of lptF from the kinB mutant had no effect on alginate production. Deletion of lptF from PAO1 caused a differential susceptibility to oxidants that can be generated by phagocytes. The lptF and algU mutants were more sensitive to hypochlorite than PAO1. However, the lptF mutant displayed increased resistance to hydrogen peroxide. LptF also contributed to adhesion to A549 human lung epithelial cells. Our data suggest that LptF is an outer membrane protein that may be important for P. aeruginosa survival in harsh environments, including lung colonization in CF.
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Affiliation(s)
- F Heath Damron
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25755-9320, USA
| | - Jennifer Napper
- Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25755-9320, USA
| | - M Allison Teter
- Department of Biology and Environmental Science, West Virginia Wesleyan College, Buckhannon, WV 26201, USA
| | - Hongwei D Yu
- Progenesis Technologies, LLC, Bldg 740, Rm 4136, Dow Technology Park, 3200 Kanawha Turnpike, South Charleston, WV 25303, USA.,Department of Pediatrics, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25701-3655, USA.,Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25755-9320, USA
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Hoshinoo K, Sasaki K, Tanaka A, Corbeil LB, Tagawa Y. Virulence attributes of Histophilus somni with a deletion mutation in the ibpA gene. Microb Pathog 2009; 46:273-82. [DOI: 10.1016/j.micpath.2009.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2008] [Revised: 02/23/2009] [Accepted: 02/25/2009] [Indexed: 01/22/2023]
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97
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Saier MH, Ma CH, Rodgers L, Tamang DG, Yen MR. Protein secretion and membrane insertion systems in bacteria and eukaryotic organelles. ADVANCES IN APPLIED MICROBIOLOGY 2009; 65:141-97. [PMID: 19026865 DOI: 10.1016/s0065-2164(08)00606-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Milton H Saier
- Division of Biological Sciences, University of California at San Diego, La Jolla, California 92093-0116, USA
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Gottig N, Garavaglia BS, Garofalo CG, Orellano EG, Ottado J. A filamentous hemagglutinin-like protein of Xanthomonas axonopodis pv. citri, the phytopathogen responsible for citrus canker, is involved in bacterial virulence. PLoS One 2009; 4:e4358. [PMID: 19194503 PMCID: PMC2632755 DOI: 10.1371/journal.pone.0004358] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Accepted: 12/29/2008] [Indexed: 11/19/2022] Open
Abstract
Xanthomonas axonopodis pv. citri, the phytopathogen responsible for citrus canker has a number of protein secretion systems and among them, at least one type V protein secretion system belonging to the two-partner secretion pathway. This system is mainly associated to the translocation of large proteins such as adhesins to the outer membrane of several pathogens. Xanthomonas axonopodis pv. citri possess a filamentous hemagglutinin-like protein in close vicinity to its putative transporter protein, XacFhaB and XacFhaC, respectively. Expression analysis indicated that XacFhaB was induced in planta during plant-pathogen interaction. By mutation analysis of XacFhaB and XacFhaC genes we determined that XacFhaB is involved in virulence both in epiphytic and wound inoculations, displaying more dispersed and fewer canker lesions. Unexpectedly, the XacFhaC mutant in the transporter protein produced an intermediate virulence phenotype resembling wild type infection, suggesting that XacFhaB could be secreted by another partner different from XacFhaC. Moreover, XacFhaB mutants showed a general lack of adhesion and were affected in leaf surface attachment and biofilm formation. In agreement with the in planta phenotype, adhesin lacking cells moved faster in swarming plates. Since no hyperflagellation phenotype was observed in this bacteria, the faster movement may be attributed to the lack of cell-to-cell aggregation. Moreover, XacFhaB mutants secreted more exopolysaccharide that in turn may facilitate its motility. Our results suggest that this hemagglutinin-like protein is required for tissue colonization being mainly involved in surface attachment and biofilm formation, and that plant tissue attachment and cell-to-cell aggregation are dependent on the coordinated action of adhesin molecules and exopolysaccharides.
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Affiliation(s)
- Natalia Gottig
- Molecular Biology Division, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Betiana S. Garavaglia
- Molecular Biology Division, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Cecilia G. Garofalo
- Molecular Biology Division, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Elena G. Orellano
- Molecular Biology Division, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Jorgelina Ottado
- Molecular Biology Division, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
- * E-mail:
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99
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Persson OP, Pinhassi J, Riemann L, Marklund BI, Rhen M, Normark S, González JM, Hagström A. High abundance of virulence gene homologues in marine bacteria. Environ Microbiol 2009; 11:1348-57. [PMID: 19207573 PMCID: PMC2702493 DOI: 10.1111/j.1462-2920.2008.01861.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Marine bacteria can cause harm to single-celled and multicellular eukaryotes. However, relatively little is known about the underlying genetic basis for marine bacterial interactions with higher organisms. We examined whole-genome sequences from a large number of marine bacteria for the prevalence of homologues to virulence genes and pathogenicity islands known from bacteria that are pathogenic to terrestrial animals and plants. As many as 60 out of 119 genomes of marine bacteria, with no known association to infectious disease, harboured genes of virulence-associated types III, IV, V and VI protein secretion systems. Type III secretion was relatively uncommon, while type IV was widespread among alphaproteobacteria (particularly among roseobacters) and type VI was primarily found among gammaproteobacteria. Other examples included homologues of the Yersinia murine toxin and a phage-related ‘antifeeding’ island. Analysis of the Global Ocean Sampling metagenomic data indicated that virulence genes were present in up to 8% of the planktonic bacteria, with highest values in productive waters. From a marine ecology perspective, expression of these widely distributed genes would indicate that some bacteria infect or even consume live cells, that is, generate a previously unrecognized flow of organic matter and nutrients directly from eukaryotes to bacteria.
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Affiliation(s)
- Olof P Persson
- Marine Microbiology, Department of Natural Sciences, University of Kalmar, Kalmar, Sweden
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