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Role of HSPGs in Systemic Bacterial Infections. Methods Mol Biol 2021. [PMID: 34626410 DOI: 10.1007/978-1-0716-1398-6_46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Heparan sulfate proteoglycans (HSPGs) are at the forefront of host-microbe interactions. Cell surface HSPGs are thought to promote infection as attachment and internalization receptors for many bacterial pathogens and as soluble inhibitors of host immunity when released from the cell surface by ectodomain shedding. However, the importance of HSPG-pathogen interactions in vivo has yet to be clearly established. Here we describe several representative methods to study the role of HSPGs in systemic bacterial infections, such as bacteremia and sepsis. The overall experimental strategy is to use mouse models to establish the physiological significance of HSPGs, to determine the identity of HSPGs that specifically promote infection, and to define key structural features of HSPGs that enhance bacterial virulence in systemic infections.
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Immune Inhibitor A Metalloproteases Contribute to Virulence in Bacillus Endophthalmitis. Infect Immun 2021; 89:e0020121. [PMID: 34097460 DOI: 10.1128/iai.00201-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Endophthalmitis is a devastating infection that can cause blindness. Over half of Bacillus endophthalmitis cases result in significant loss of useful vision. Bacillus produces many virulence factors that may contribute to retinal damage and robust inflammation. We analyzed Bacillus immune inhibitor A (InhA) metalloproteases in the context of this disease, hypothesizing that InhAs contribute to Bacillus intraocular virulence and inflammation. We analyzed phenotypes and infectivity of wild type (WT), InhA1-deficient (ΔinhA1), InhA2-deficient (ΔinhA2), or InhA1, A2, and A3-deficient (ΔinhA1-3) Bacillus thuringiensis. In vitro analysis of growth, proteolysis, and cytotoxicity were compared. WT and InhA mutants were similarly cytotoxic to retinal cells. Mutants ΔinhA1 and ΔinhA2 entered log phase growth earlier than WT. Proteolysis by the ΔinhA1-3 mutant was decreased, but this strain grew similar to WT in vitro. Experimental endophthalmitis was initiated by intravitreally infecting C57BL/6J mice with 200 CFU of B. thuringiensis WT or InhA mutants. Eyes were analyzed for intraocular Bacillus and myeloperoxidase concentrations, retinal function loss, and gross histological changes. Eyes infected with ΔinhA1 or ΔinhA2 strains contained greater numbers of bacteria than eyes infected with WT throughout the infection course. Eyes infected with single mutants had inflammation and retinal function loss similar to eyes infected with WT strain. Eyes infected with ΔinhA1-3 cleared the infection. RT-PCR results suggested that there may be compensatory expression of the other InhAs in the single InhA mutant. These results indicate that together, the InhA metalloproteases contribute to the severity of infection and inflammation in Bacillus endophthalmitis.
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Shikov AE, Malovichko YV, Lobov AA, Belousova ME, Nizhnikov AA, Antonets KS. The Distribution of Several Genomic Virulence Determinants Does Not Corroborate the Established Serotyping Classification of Bacillus thuringiensis. Int J Mol Sci 2021; 22:2244. [PMID: 33668147 PMCID: PMC7956386 DOI: 10.3390/ijms22052244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/02/2021] [Accepted: 02/18/2021] [Indexed: 02/06/2023] Open
Abstract
Bacillus thuringiensis, commonly referred to as Bt, is an object of the lasting interest of microbiologists due to its highly effective insecticidal properties, which make Bt a prominent source of biologicals. To categorize the exuberance of Bt strains discovered, serotyping assays are utilized in which flagellin serves as a primary seroreactive molecule. Despite its convenience, this approach is not indicative of Bt strains' phenotypes, neither it reflects actual phylogenetic relationships within the species. In this respect, comparative genomic and proteomic techniques appear more informative, but their use in Bt strain classification remains limited. In the present work, we used a bottom-up proteomic approach based on fluorescent two-dimensional difference gel electrophoresis (2D-DIGE) coupled with liquid chromatography/tandem mass spectrometry(LC-MS/MS) protein identification to assess which stage of Bt culture, vegetative or spore, would be more informative for strain characterization. To this end, the proteomic differences for the israelensis-attributed strains were assessed to compare sporulating cultures of the virulent derivative to the avirulent one as well as to the vegetative stage virulent bacteria. Using the same approach, virulent spores of the israelensis strain were also compared to the spores of strains belonging to two other major Bt serovars, namely darmstadiensis and thuringiensis. The identified proteins were analyzed regarding the presence of the respective genes in the 104 Bt genome assemblies available at open access with serovar attributions specified. Of 21 proteins identified, 15 were found to be encoded in all the present assemblies at 67% identity threshold, including several virulence factors. Notable, individual phylogenies of these core genes conferred neither the serotyping nor the flagellin-based phylogeny but corroborated the reconstruction based on phylogenomics approaches in terms of tree topology similarity. In its turn, the distribution of accessory protein genes was not confined to the existing serovars. The obtained results indicate that neither gene presence nor the core gene sequence may serve as distinctive bases for the serovar attribution, undermining the notion that the serotyping system reflects strains' phenotypic or genetic similarity. We also provide a set of loci, which fit in with the phylogenomics data plausibly and thus may serve for draft phylogeny estimation of the novel strains.
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Affiliation(s)
- Anton E. Shikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
| | - Yury V. Malovichko
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
| | - Arseniy A. Lobov
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
- Laboratory of Regenerative Biomedicine, Institute of Cytology of the Russian Academy of Science, 194064 St. Petersburg, Russia
| | - Maria E. Belousova
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
| | - Anton A. Nizhnikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
| | - Kirill S. Antonets
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
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Wang Y, Jiang N, Wang B, Tao H, Zhang X, Guan Q, Liu C. Integrated Transcriptomic and Proteomic Analyses Reveal the Role of NprR in Bacillus anthracis Extracellular Protease Expression Regulation and Oxidative Stress Responses. Front Microbiol 2020; 11:590851. [PMID: 33362738 PMCID: PMC7756075 DOI: 10.3389/fmicb.2020.590851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 11/18/2020] [Indexed: 12/18/2022] Open
Abstract
NprR is a protein of Bacillus anthracis that exhibits moonlighting functions as either a phosphatase or a neutral protease regulator that belongs to the RNPP family. We previously observed that the extracellular protease activity of an nprR deletion mutant significantly decreased within in vitro cultures. To identify the genes within the regulatory network of nprR that contribute to its protease activity, integrated transcriptomic and proteomic analyses were conducted here by comparing the nprR deletion mutant and parent strains. A total of 366 differentially expressed genes (DEGs) between the strains were observed via RNA-seq analysis. In addition, label-free LC-MS/MS analysis revealed 503 differentially expressed proteins (DEPs) within the intracellular protein fraction and 213 extracellular DEPs with significant expressional differences between the strains. The majority of DEGs and DEPs were involved in environmental information processing and metabolism. Integrated transcriptomic and proteomic analyses indicated that oxidation-reduction-related GO terms for intracellular DEPs and endopeptidase-related GO terms for extracellular DEPs were significantly enriched in the mutant strain. Notably, many genes involved in protease activity were largely downregulated in the nprR deletion mutant cultures. Moreover, western blot analysis revealed that the major extracellular neutral protease Npr599 was barely expressed in the nprR deletion mutant strain. The mutant also exhibited impaired degradation of protective antigen, which is a major B. anthracis toxin component, thereby resulting in higher protein yields. Concomitantly, another global transcriptional regulator, SpxA1, was also dramatically downregulated in the nprR deletion mutant, resulting in higher sensitivity to oxidative and disulfide stress. These data consequently indicate that NprR is a transcriptional regulator that controls genes whose products function as extracellular proteases and also is involved in oxidative stress responses. This study thus contributes to a more comprehensive understanding of the biological function of NprR, and especially in the middle growth stages of B. anthracis.
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Affiliation(s)
- Yanchun Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
| | - Na Jiang
- Beijing Fisheries Research Institute, Beijing, China
| | - Bowen Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
| | - Haoxia Tao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
| | - Xin Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
| | - Qing Guan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
| | - Chunjie Liu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China
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Bacillus cereus Decreases NHE and CLO Exotoxin Synthesis to Maintain Appropriate Proteome Dynamics During Growth at Low Temperature. Toxins (Basel) 2020; 12:toxins12100645. [PMID: 33036317 PMCID: PMC7601483 DOI: 10.3390/toxins12100645] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/17/2020] [Accepted: 09/23/2020] [Indexed: 12/02/2022] Open
Abstract
Cellular proteomes and exoproteomes are dynamic, allowing pathogens to respond to environmental conditions to sustain growth and virulence. Bacillus cereus is an important food-borne pathogen causing intoxication via emetic toxin and/or multiple protein exotoxins. Here, we compared the dynamics of the cellular proteome and exoproteome of emetic B. cereus cells grown at low (16 °C) and high (30 °C) temperature. Tandem mass spectrometry (MS/MS)-based shotgun proteomics analysis identified 2063 cellular proteins and 900 extracellular proteins. Hierarchical clustering following principal component analysis indicated that in B. cereus the abundance of a subset of these proteins—including cold-stress responders, and exotoxins non-hemolytic enterotoxin (NHE) and hemolysin I (cereolysin O (CLO))—decreased at low temperature, and that this subset governs the dynamics of the cellular proteome. NHE, and to a lesser extent CLO, also contributed significantly to exoproteome dynamics; with decreased abundances in the low-temperature exoproteome, especially in late growth stages. Our data therefore indicate that B. cereus may reduce its production of secreted protein toxins to maintain appropriate proteome dynamics, perhaps using catabolite repression to conserve energy for growth in cold-stress conditions, at the expense of virulence.
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Dissecting capture and twisting of aureolysin and pseudolysin: functional amino acids of the Dispase autolysis-inducing protein. Biochem J 2020; 477:2595-2606. [PMID: 32602533 DOI: 10.1042/bcj20200407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/26/2020] [Accepted: 06/30/2020] [Indexed: 11/17/2022]
Abstract
The Dispase autolysis-inducing protein (DAIP) from Streptomyces mobaraensis attracts M4 metalloproteases, which results in inhibition and autolysis of bacillolysin (BL) and thermolysin (TL). The present study shows that aureolysin (AL) from Staphylococcus aureus and pseudolysin (LasB) from Pseudomonas aeruginosa are likewise impaired by DAIP. Complete inhibition occurred when DAIP significantly exceeded the amount of the target protease. At low DAIP concentrations, AL and BL performed autolysis, while LasB and TL degradation required reductants or detergents that break intramolecular disulfide bonds or change the protein structure. Site directed mutagenesis of DAIP and removal of an exposed protein loop either influenced binding or inhibition of AL and TL but had no effect on LasB and BL. The Y170A and Δ239-248 variants had completely lost affinity for TL and AL. The exchange of Asn-275 also impaired the interaction of DAIP with AL. In contrast, DAIP Phe-297 substitution abolished inhibition and autolysis of both target proteases but still allowed complex formation. Our results give rise to the conclusion that other, yet unknown DAIP amino acids inactivate LasB and BL. Obviously, various bacteria in the same habitat caused Streptomyces mobaraensis to continuously optimize DAIP in inactivating the tackling metalloproteases.
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Coburn PS, Miller FC, Enty MA, Land C, LaGrow AL, Mursalin MH, Callegan MC. Expression of Bacillus cereus Virulence-Related Genes in an Ocular Infection-Related Environment. Microorganisms 2020; 8:microorganisms8040607. [PMID: 32331252 PMCID: PMC7232466 DOI: 10.3390/microorganisms8040607] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 04/21/2020] [Indexed: 12/03/2022] Open
Abstract
Bacillus cereus produces many factors linked to pathogenesis and is recognized for causing gastrointestinal toxemia and infections. B. cereus also causes a fulminant and often blinding intraocular infection called endophthalmitis. We reported that the PlcR/PapR system regulates intraocular virulence, but the specific factors that contribute to B. cereus virulence in the eye remain elusive. Here, we compared gene expression in ex vivo vitreous humor with expression in Luria Bertani (LB) and Brain Heart Infusion (BHI) broth by RNA-Seq. The expression of several cytolytic toxins in vitreous was less than or similar to levels observed in BHI or LB. Regulators of virulence genes, including PlcR/PapR, were expressed in vitreous. PlcR/PapR was expressed at low levels, though we reported that PlcR-deficient B. cereus was attenuated in the eye. Chemotaxis and motility genes were expressed at similar levels in LB and BHI, but at low to undetectable levels in vitreous, although motility is an important phenotype for B. cereus in the eye. Superoxide dismutase, a potential inhibitor of neutrophil activity in the eye during infection, was the most highly expressed gene in vitreous. Genes previously reported to be important to intraocular virulence were expressed at low levels in vitreous under these conditions, possibly because in vivo cues are required for higher level expression. Genes expressed in vitreous may contribute to the unique virulence of B. cereus endophthalmitis, and future analysis of the B. cereus virulome in the eye will identify those expressed in vivo, which could potentially be targeted to arrest virulence.
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Affiliation(s)
- Phillip S. Coburn
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (M.A.E.); (C.L.); (A.L.L.); (M.C.C.)
- Correspondence:
| | - Frederick C. Miller
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA;
- Department of Family and Preventive Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Morgan A. Enty
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (M.A.E.); (C.L.); (A.L.L.); (M.C.C.)
| | - Craig Land
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (M.A.E.); (C.L.); (A.L.L.); (M.C.C.)
| | - Austin L. LaGrow
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (M.A.E.); (C.L.); (A.L.L.); (M.C.C.)
| | - Md Huzzatul Mursalin
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA;
| | - Michelle C. Callegan
- Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (M.A.E.); (C.L.); (A.L.L.); (M.C.C.)
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA;
- Dean McGee Eye Institute, Oklahoma City, OK 73104, USA
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Barbosa AS, Isaac L. Strategies used by Leptospira spirochetes to evade the host complement system. FEBS Lett 2020; 594:2633-2644. [PMID: 32153015 DOI: 10.1002/1873-3468.13768] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/27/2020] [Accepted: 02/28/2020] [Indexed: 12/19/2022]
Abstract
Leptospires are highly invasive spirochetes equipped with efficient strategies for dissemination in the host. The Leptospira genus currently comprises 64 species divided into two major clades: the saprophytes composed of nonpathogenic, free-living organisms, and the pathogens encompassing all the species that cause mild or severe infections in humans and animals. While saprophytes are highly susceptible to the lytic action of the complement system, pathogenic (virulent) strains have evolved virulence strategies that allow efficient colonization of a variety of hosts and target organs, including mechanisms to circumvent hosts' innate and acquired immune responses. Pathogenic Leptospira avoid complement-mediated killing by recruiting host complement regulatory proteins and by targeting complement proteins using own and host-expressed proteases. This review outlines the role of complement in eradicating saprophytic Leptospira and the stratagems adopted by pathogenic Leptospira to maneuver the host complement system for their benefit.
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Affiliation(s)
| | - Lourdes Isaac
- Laboratory of Complement, Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, Brazil
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Abstract
The Bacillus cereus group includes several Bacillus species with closely related phylogeny. The most well-studied members of the group, B. anthracis, B. cereus, and B. thuringiensis, are known for their pathogenic potential. Here, we present the historical rationale for speciation and discuss shared and unique features of these bacteria. Aspects of cell morphology and physiology, and genome sequence similarity and gene synteny support close evolutionary relationships for these three species. For many strains, distinct differences in virulence factor synthesis provide facile means for species assignment. B. anthracis is the causative agent of anthrax. Some B. cereus strains are commonly recognized as food poisoning agents, but strains can also cause localized wound and eye infections as well as systemic disease. Certain B. thuringiensis strains are entomopathogens and have been commercialized for use as biopesticides, while some strains have been reported to cause infection in immunocompromised individuals. In this article we compare and contrast B. anthracis, B. cereus, and B. thuringiensis, including ecology, cell structure and development, virulence attributes, gene regulation and genetic exchange systems, and experimental models of disease.
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Jessberger N, Kranzler M, Da Riol C, Schwenk V, Buchacher T, Dietrich R, Ehling-Schulz M, Märtlbauer E. Assessing the toxic potential of enteropathogenic Bacillus cereus. Food Microbiol 2019; 84:103276. [PMID: 31421762 DOI: 10.1016/j.fm.2019.103276] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/18/2019] [Accepted: 07/20/2019] [Indexed: 12/17/2022]
Abstract
The diarrheal type of food poisoning caused by enteropathogenic Bacillus cereus has been linked to various exotoxins. Best described are the non-hemolytic enterotoxin (Nhe), hemolysin BL (Hbl), and cytotoxin K (CytK). Due to the ubiquitous prevalence of B. cereus in soil and crops and its ability to form highly resistant endospores, contaminations during food production and processing cannot be completely avoided. Although phylogenetically closely related, enteropathogenic B. cereus strains show a high versatility of their toxic potential. Thus, functional tools for evaluating the pathogenic potential are urgently needed in order to predict hazardous food contaminations. As the diarrheal syndrome is the result of a toxico-infection with enterotoxin production in the intestine, the entire passage of the bacteria within the host, from spore survival in the stomach, spore germination, host cell adherence, and motility, to enterotoxin production under simulated intestinal conditions was compared in a panel of 20 strains, including high pathogenic as well as apathogenic ones. This approach resulted in an overarching virulence analysis scheme. In parallel, we searched for potential toxico-specific secreted markers to discriminate low and high pathogenic strains. To this end, we targeted known exotoxins using an easy to implement immunoblotting approach as well as a caseinolytic exoprotease activity assay. Overall, Nhe component B, sphingomyelinase, and exoproteases showed good correlation with the complex virulence analysis scheme and can serve as a template for future fast and easy risk assessment tools to be implemented in routine diagnostic procedures and HACCP studies.
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Affiliation(s)
- Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany.
| | - Markus Kranzler
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210, Vienna, Austria
| | - Claudia Da Riol
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany
| | - Valerie Schwenk
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany
| | - Tanja Buchacher
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210, Vienna, Austria
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany
| | - Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210, Vienna, Austria
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764, Oberschleißheim, Germany
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Repertoire of the Bacillus thuringiensis Virulence Factors Unrelated to Major Classes of Protein Toxins and Its Role in Specificity of Host-Pathogen Interactions. Toxins (Basel) 2019; 11:toxins11060347. [PMID: 31212976 PMCID: PMC6628457 DOI: 10.3390/toxins11060347] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/21/2019] [Accepted: 06/10/2019] [Indexed: 12/28/2022] Open
Abstract
Bacillus thuringiensis (Bt) is a Gram-positive soil bacteria that infects invertebrates, predominantly of Arthropoda phylum. Due to its immense host range Bt has become a leading producer of biopesticides applied both in biotechnology and agriculture. Cytotoxic effect of Bt, as well as its host specificity, are commonly attributed either to proteinaceous crystal parasporal toxins (Cry and Cyt) produced by bacteria in a stationary phase or to soluble toxins of Vip and Sip families secreted by vegetative cells. At the same time, numerous non-toxin virulence factors of Bt have been discovered, including metalloproteases, chitinases, aminopolyol antibiotics and nucleotide-mimicking moieties. These agents act at each stage of the B. thuringiensis invasion and contribute to cytotoxic properties of Bt strains enhancing toxin activity, ensuring host immune response evasion and participating in extracellular matrix degeneration. In this review we attempt to classify Bt virulence factors unrelated to major groups of protein toxins and discuss their putative role in the establishment of Bt specificity to various groups of insects.
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Disruption of SpoIIID decreases sporulation, increases extracellular proteolytic activity and virulence in Bacillus anthracis. Biochem Biophys Res Commun 2019; 513:651-656. [PMID: 30982579 DOI: 10.1016/j.bbrc.2019.04.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 04/08/2019] [Indexed: 11/20/2022]
Abstract
Endospores are important for maintenance of the B. anthracis lifecycle and necessary for its effective spread between hosts. Our experiments with B. anthracis showed that disruption of SpoIIID results in a spore formation defect, as determined by heat resistance assays and microscopic assessment. We further found complete engulfment by the ΔspoIIID mutant strain by membrane morphology staining but no synthesis of the clarity coat and exosporium by transmission electron microscopy. Reduced transcription and expression of small acid-soluble spore protein(sasP-2) and the spore development associated genes (σK, gerE and cotE) in the mother cell were found in the ΔspoIIID strain, suggesting that the spore formation defect in B. anthracis A16R is related to decreased transcription and expression of these genes. Extracellular protease and virulence enhancement in the ΔspoIIID strain may be related to the elevation of metalloproteinases (TasA and Camelysin) levels. Our findings pave the way for further research on the regulation network of sporulation, survival and virulence in these two morphological forms of B. anthracis.
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Porcine Gastric Mucin Triggers Toxin Production of Enteropathogenic Bacillus cereus. Infect Immun 2019; 87:IAI.00765-18. [PMID: 30745328 DOI: 10.1128/iai.00765-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/21/2019] [Indexed: 02/01/2023] Open
Abstract
Enteropathogenic Bacillus cereus causes foodborne infections due to the production of pore-forming enterotoxins in the intestine. Before that, spores have to be ingested, survive the stomach passage, and germinate. Thus, before reaching epithelial cells, B. cereus comes in contact with the intestinal mucus layer. In the present study, different aspects of this interaction were analyzed. Total RNA sequencing revealed major transcriptional changes of B. cereus strain F837/76 upon incubation with porcine gastric mucin (PGM), comprising genes encoding enterotoxins and further putative virulence factors, as well as proteins involved in adhesion to and degradation of mucin. Indeed, PGM was partially degraded by B. cereus via secreted, EDTA-sensitive proteases. The amount of enterotoxins detectable in culture media supplemented with PGM was also clearly increased. Tests of further strains revealed that enhancement of enterotoxin production upon contact with PGM is broadly distributed among B. cereus strains. Interestingly, evidence was found that PGM can also strain-specifically trigger germination of B. cereus spores and that vegetative cells actively move toward mucin. Overall, our data suggest that B. cereus is well adapted to the host environment due to massive transcriptome changes upon contact with PGM, attributing mucin an important and, thus far, neglected role in pathogenesis.
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Genes under positive selection in the core genome of pathogenic Bacillus cereus group members. INFECTION GENETICS AND EVOLUTION 2018; 65:55-64. [PMID: 30006047 DOI: 10.1016/j.meegid.2018.07.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 07/06/2018] [Accepted: 07/07/2018] [Indexed: 11/24/2022]
Abstract
In this comparative genomics study our aim was to unravel genes under positive selection in the core genome of the Bacillus cereus group. Indeed, the members of this group share close genetic relationships but display a rather large phenotypic and ecological diversity, providing a unique opportunity for studying how genomic changes reflect ecological adaptation during the divergence of a bacterial group. For this purpose, we screened ten completely sequenced genomes of four pathogenic Bacillus species, finding that 254 out of 3093 genes have codon sites with dN/dS (ω) values above one. These results remained unchanged after having disentangled the confounding effects of recombination and selection signature in a Bayesian framework. The presumably adaptive nucleotide polymorphisms are distributed over a wide range of biological functions, such as antibiotic resistance, DNA repair, nutrient uptake, metabolism, cell wall assembly and spore structure. Our results indicate that adaptation to animal hosts, whether as pathogens, saprophytes or symbionts, is the major driving force in the evolution of the Bacillus cereus group. Future work should seek to understand the evolutionary dynamics of both core and accessory genes in an integrative framework to ultimately unravel the key networks involved in host adaptation.
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Chura-Chambi RM, Fraga TR, da Silva LB, Yamamoto BB, Isaac L, Barbosa AS, Morganti L. Leptospira interrogans thermolysin refolded at high pressure and alkaline pH displays proteolytic activity against complement C3. ACTA ACUST UNITED AC 2018; 19:e00266. [PMID: 29992100 PMCID: PMC6036645 DOI: 10.1016/j.btre.2018.e00266] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/23/2018] [Accepted: 06/16/2018] [Indexed: 11/30/2022]
Abstract
Enzymes from the thermolysin family are crucial factors in the pathogenesis of several diseases caused by bacteria and are potential targets for therapeutic interventions. Thermolysin encoded by the gene LIC13322 of the causative agent of leptospirosis, Leptospira interrogans, was shown to cleave proteins from the Complement System. However, the production of this recombinant protein using traditional refolding processes with high levels of denaturing reagents for thermolysin inclusion bodies (TL-IBs) solubilization results in poor recovery and low proteolytic activity probably due to improper refolding of the protein. Based on the assumption that leptospiral proteases play a crucial role during infection, the aim of this work was to obtain a functional recombinant thermolysin for future studies on the role of these metalloproteases on leptospiral infection. The association of high hydrostatic pressure (HHP) and alkaline pH was utilized for thermolysin refolding. Incubation of a suspension of TL-IBs at HHP and a pH of 11.0 is non-denaturing but effective for thermolysin solubilization. Soluble protein does not reaggregate by dialysis to pH 8.0. A volumetric yield of 46 mg thermolysin/L of bacterial culture and a yield of near 100% in relation to the total thermolysin present in TL-IBs were obtained. SEC-purified thermolysin suffers fragmentation, likely due to autoproteolysis and presents proteolytic activity against complement C3 α-chain, possibly by a generation of a C3b-like molecule. The proteolytic activity of thermolysin against C3 was time and dose-dependent. The experience gained in this study shall help to establish efficient HHP-based processes for refolding of bioactive proteins from IBs.
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Affiliation(s)
- Rosa Maria Chura-Chambi
- Instituto de Pesquisas Energéticas e Nucleares IPEN-CNEN/SP, Centro de Biotecnologia, Av. Prof. Lineu Prestes, 2242, CEP 05508-000, São Paulo, SP, Brazil
| | - Tatiana Rodrigues Fraga
- Instituto de Ciências Biomédicas, Universidade de São Paulo, Departamento de Imunologia, Av. Prof. Lineu Prestes, 1374, CEP 05508-900, São Paulo, SP, Brazil
| | - Ludmila Bezerra da Silva
- Instituto Butantan, Laboratório de Bacteriologia, Av. Vital Brasil, 1500, CEP 05503-900, São Paulo, SP, Brazil
| | - Bruno Bernardi Yamamoto
- Instituto Butantan, Laboratório de Bacteriologia, Av. Vital Brasil, 1500, CEP 05503-900, São Paulo, SP, Brazil
| | - Lourdes Isaac
- Instituto de Ciências Biomédicas, Universidade de São Paulo, Departamento de Imunologia, Av. Prof. Lineu Prestes, 1374, CEP 05508-900, São Paulo, SP, Brazil
| | - Angela Silva Barbosa
- Instituto Butantan, Laboratório de Bacteriologia, Av. Vital Brasil, 1500, CEP 05503-900, São Paulo, SP, Brazil
| | - Ligia Morganti
- Instituto de Pesquisas Energéticas e Nucleares IPEN-CNEN/SP, Centro de Biotecnologia, Av. Prof. Lineu Prestes, 2242, CEP 05508-000, São Paulo, SP, Brazil
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Haydar A, Tran SL, Guillemet E, Darrigo C, Perchat S, Lereclus D, Coquet L, Jouenne T, Ramarao N. InhA1-Mediated Cleavage of the Metalloprotease NprA Allows Bacillus cereus to Escape From Macrophages. Front Microbiol 2018; 9:1063. [PMID: 29875760 PMCID: PMC5974196 DOI: 10.3389/fmicb.2018.01063] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/04/2018] [Indexed: 12/20/2022] Open
Abstract
Bacillus cereus is a Gram-positive spore-forming bacterium causing food poisoning and serious opportunistic infections. These infections are characterized by bacterial accumulation in the host despite the induction of inflammation. To circumvent inflammation, bacteria must resist the bactericidal activity of professional phagocytes, which constitute a first line of host defense against pathogens. Interactions between phagocytic cells and B. cereus are still poorly characterized and the mechanism of resistance to the host immune system is not known yet. We have previously shown that the spores are phagocytosed by macrophages but survive and escape from these cells. The metalloprotease InhA1 is a key effector involved in these processes. inhA1-deficient spores are retained intracellularly, in contrast to the wild type strain spores. NprA is also a B. cereus metalloprotease able to cleave tissue components such as fibronectin, laminin, and collagen. Here, we show that NprA, concomitantly secreted with InhA1 in the B. cereus secretome, is essential to promote bacterial escape from macrophages. We show that InhA1 cleaves NprA at specific sites. This cleavage allows liberation of the mature form of the NprA protein in the supernatant of the wild type strain. This mature form of NprA is actually the principal effector allowing bacterial escape from host macrophages.
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Affiliation(s)
- Abbass Haydar
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Seav-Ly Tran
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Elisabeth Guillemet
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Claire Darrigo
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Stéphane Perchat
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Didier Lereclus
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Laurent Coquet
- CNRS, UMR 6270, Normandy University, UNIROUEN, Plate-forme PISSARO, Mont-Saint-Aignan, France
| | - Thierry Jouenne
- CNRS, UMR 6270, Normandy University, UNIROUEN, Plate-forme PISSARO, Mont-Saint-Aignan, France
| | - Nalini Ramarao
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
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Abstract
Syndecan-1 (Sdc1) is a major cell surface heparan sulfate (HS) proteoglycan of epithelial cells, a cell type targeted by many bacterial pathogens early in their pathogenesis. Loss of Sdc1 in mice is a gain-of-function mutation that significantly decreases the susceptibility to several bacterial infections, suggesting that subversion of Sdc1 is an important virulence strategy. HS glycosaminoglycan (GAG) chains of cell surface Sdc1 promote bacterial pathogenesis by facilitating the attachment of bacteria to host cells. Engagement of cell surface Sdc1 HS chains by bacterial adhesins transmits signal through the highly conserved Sdc1 cytoplasmic domain, which can lead to uptake of intracellular bacterial pathogens. On the other hand, several bacteria that do not require Sdc1 for their attachment and invasion stimulate Sdc1 shedding and exploit the capacity of Sdc1 ectodomain HS GAGs to disarm innate defense mechanisms to evade immune clearance. Recent data suggest that select HS sulfate motifs, and not the overall charge of HS, are important in the inhibition of innate immune mechanisms. Here, we discuss several examples of Sdc1 subversion in bacterial infections.
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Rahman MT, Karim MM. Metallothionein: a Potential Link in the Regulation of Zinc in Nutritional Immunity. Biol Trace Elem Res 2018; 182:1-13. [PMID: 28585004 DOI: 10.1007/s12011-017-1061-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 05/22/2017] [Indexed: 01/03/2023]
Abstract
Nutritional immunity describes mechanisms for withholding essential transition metals as well as directing the toxicity of these metals against infectious agents. Zinc is one of these transition elements that are essential for both humans and microbial pathogens. At the same time, Zn can be toxic both for man and microbes if its concentration is higher than the tolerance limit. Therefore a "delicate" balance of Zn must be maintained to keep the immune cells surveilling while making the level of Zn either to starve or to intoxicate the pathogens. On the other hand, the invading pathogens will exploit the host Zn pool for its survival and replication. Apparently, different sets of protein in human and bacteria are involved to maintain their Zn need. Metallothionein (MT)-a group of low molecular weight proteins, is well known for its Zn-binding ability and is expected to play an important role in that Zn balance at the time of active infection. However, the differences in structural, functional, and molecular control of biosynthesis between human and bacterial MT might play an important role to determine the proper use of Zn and the winning side. The current review explains the possible involvement of human and bacterial MT at the time of infection to control and exploit Zn for their need.
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Gupta V, Chaudhary N, Aggarwal S, Adlakha N, Gulati P, Bhatnagar R. Functional analysis of BAS2108-2109 two component system: Evidence for protease regulation in Bacillus anthracis. Int J Biochem Cell Biol 2017; 89:71-84. [PMID: 28602714 DOI: 10.1016/j.biocel.2017.06.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/01/2017] [Accepted: 06/03/2017] [Indexed: 01/18/2023]
Abstract
BACKGROUND Bacillus anthracis (BA) is a major bioterrorism concern which has evolved complex regulatory mechanisms for its virulence factors. Secreted proteases play an imperative role in the pathogenesis of BA, however their regulation remains elusive. Two component systems (TCS) are often employed by bacteria to sense and adapt to the environmental perturbations. In several pathogens, TCS are commonly associated with the regulation of virulence factors including proteases. The genome of BA encodes 41 TCS pairs, however, the role of any TCS in regulation of its proteases is not known. PRINCIPAL FINDINGS The study established BAS2108-2109 as a prototypical TCS where BAS2108 functions as a histidine kinase and BAS2109 as the response regulator. The expression of BAS2109 was found to be elevated under host simulated conditions and in pellicle forming cells. Electrophoretic mobility shift assay (EMSA) and lacZ reporter assay revealed positive autoregulation of the BAS2108-2109 operon by BAS2109. Collective analysis of ANS assay and EMSA demonstrated Lys167, Thr179 and Thr182 residues are crucial for the DNA binding activity of BAS2109. EMSA analysis further highlighted BAS2109 as the transcriptional regulator for different genes of BA, particularly proteases. Upregulation of proteases in BA overexpressing BAS2109 further strengthen its role in protease regulation. SIGNIFICANCE This is the first report to identify a TCS pair for its role in the regulation of proteases of BA. Importance of proteases in the pathogenesis of BA is well documented, therefore, studying the regulatory networks governing their expression will help in identification of new drug targets.
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Affiliation(s)
- Vatika Gupta
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India; Medical Microbiology and Bioprocess Technology Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, India
| | - Neha Chaudhary
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India
| | - Somya Aggarwal
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India
| | - Nidhi Adlakha
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India
| | - Pooja Gulati
- Medical Microbiology and Bioprocess Technology Laboratory, Department of Microbiology, Maharshi Dayanand University, Rohtak, Haryana, India
| | - Rakesh Bhatnagar
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, India.
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Arolas JL, Goulas T, Pomerantsev AP, Leppla SH, Gomis-Rüth FX. Structural Basis for Latency and Function of Immune Inhibitor A Metallopeptidase, a Modulator of the Bacillus anthracis Secretome. Structure 2016; 24:25-36. [PMID: 26745529 DOI: 10.1016/j.str.2015.10.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Revised: 10/15/2015] [Accepted: 10/15/2015] [Indexed: 01/07/2023]
Abstract
Immune inhibitor A(InhA)-type metallopeptidases are potential virulence factors secreted by members of the Bacillus cereus group. Two paralogs from anthrax-causing Bacillus anthracis (BaInhA1 and BaInhA2) were shown to degrade host tissue proteins with broad substrate specificity. Analysis of their activation mechanism and the crystal structure of a zymogenic BaInhA2 variant revealed a ∼750-residue four-domain structure featuring a pro-peptide, a catalytic domain, a domain reminiscent of viral envelope glycoproteins, and a MAM domain grafted into the latter. This domain, previously found only in eukaryotes, is required for proper protein expression in B. anthracis and evinces certain flexibility. Latency is uniquely modulated by the N-terminal segment of the pro-peptide, which binds the catalytic zinc through its α-amino group and occupies the primed side of the active-site cleft. The present results further our understanding of the modus operandi of an anthrax secretome regulator.
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Affiliation(s)
- Joan L Arolas
- Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac, 15-21, 08028 Barcelona, Spain
| | - Theodoros Goulas
- Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac, 15-21, 08028 Barcelona, Spain
| | - Andrei P Pomerantsev
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - F Xavier Gomis-Rüth
- Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac, 15-21, 08028 Barcelona, Spain.
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Abstract
Ancient bacteria originated from metal-rich environments. Billions of years of evolution directed these tiny single cell creatures to exploit the versatile properties of metals in catalyzing chemical reactions and biological responses. The result is an entire metallome of proteins that use metal co-factors to facilitate key cellular process that range from the production of energy to the replication of DNA. Two key metals in this regard are iron and zinc, both abundant on Earth but not readily accessible in a human host. Instead, pathogenic bacteria must employ clever ways to acquire these metals. In this review we describe the many elegant ways these bacteria mine, regulate, and craft the use of two key metals (iron and zinc) to build a virulence arsenal that challenges even the most sophisticated immune response.
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Affiliation(s)
- Li Ma
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77459, USA.
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Acyl carrier protein is a bacterial cytoplasmic target of cationic antimicrobial peptide LL-37. Biochem J 2015; 470:243-53. [PMID: 26188040 DOI: 10.1042/bj20150432] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/16/2015] [Indexed: 11/17/2022]
Abstract
In addition to membrane disruption, the cathelicidin antimicrobial peptide (AMP) LL-37 translocates through the bacterial inner membrane to target intracellular molecules. The present study aims to identify an alternate mechanism and a cytoplasmic target of LL-37 in Francisella. LL-37 binding proteins from Francisella novicida U112 bacterial lysates were precipitated by using biotinylated LL-37 (B-LL-37) and NeutrAvidin-agarose beads. Bound proteins were identified by LC-MS/MS, validated and characterized by bead pull-down assays and differential scanning fluorimetry (DSF). The cationic AMP (CAMP) LL-37 was able to interact with Francisella cytoplasmic acyl carrier protein (AcpP; FTN1340/FTT1376). Further study confirmed that LL-37 peptide could bind to AcpP and that the sheep cathelicidin SMAP-29 (Sheep Myeloid Antimicrobial Peptide 29) further increased LL-37 binding to AcpP, suggesting a synergistic effect of SMAP-29 on the binding. LL-37 could also bind to both AcpP of Escherichia coli and Bacillus anthracis, implying a mechanism of broad action of LL-37-AcpP binding. Overexpression of the acpP gene in F. novicida led to an increase in LL-37 susceptibility. LL-37 binding to AcpP changed the fatty acid composition profiles. Taken together, we identified a novel cytoplasmic target of LL-37 in Francisella, suggesting a mechanism of action of this peptide beyond membrane permeabilization. Our findings highlight a novel mechanism of antimicrobial activity of this peptide and document a previously unexplored target of α-helical CAMPs.
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Ruan L, Crickmore N, Peng D, Sun M. Are nematodes a missing link in the confounded ecology of the entomopathogen Bacillus thuringiensis? Trends Microbiol 2015; 23:341-6. [DOI: 10.1016/j.tim.2015.02.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Revised: 01/29/2015] [Accepted: 02/25/2015] [Indexed: 01/23/2023]
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Bacillus anthracis Overcomes an Amino Acid Auxotrophy by Cleaving Host Serum Proteins. J Bacteriol 2015; 197:2400-11. [PMID: 25962917 DOI: 10.1128/jb.00073-15] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/21/2015] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Bacteria sustain an infection by acquiring nutrients from the host to support replication. The host sequesters these nutrients as a growth-restricting strategy, a concept termed "nutritional immunity." Historically, the study of nutritional immunity has centered on iron uptake because many bacteria target hemoglobin, an abundant circulating protein, as an iron source. Left unresolved are the mechanisms that bacteria use to attain other nutrients from host sources, including amino acids. We employed a novel medium designed to mimic the chemical composition of human serum, and we show here that Bacillus anthracis, the causative agent of anthrax disease, proteolyzes human hemoglobin to liberate essential amino acids which enhance its growth. This property can be traced to the actions of InhA1, a secreted metalloprotease, and extends to at least three other serum proteins, including serum albumin. The results suggest that we must also consider proteolysis of key host proteins to be a way for bacterial pathogens to attain essential nutrients, and we provide an experimental framework to determine the host and bacterial factors involved in this process. IMPORTANCE The mechanisms by which bacterial pathogens acquire nutrients during infection are poorly understood. Here we used a novel defined medium that approximates the chemical composition of human blood serum, blood serum mimic (BSM), to better model the nutritional environment that pathogens encounter during bacteremia. Removing essential amino acids from BSM revealed that two of the most abundant proteins in blood-hemoglobin and serum albumin-can satiate the amino acid requirement for Bacillus anthracis, the causative agent of anthrax. We further demonstrate that hemoglobin is proteolyzed by the secreted protease InhA1. These studies highlight that common blood proteins can be a nutrient source for bacteria. They also challenge the historical view that hemoglobin is solely an iron source for bacterial pathogens.
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Kong L, Lu A, Guan J, Yang B, Li M, Hillyer JF, Ramarao N, Söderhäll K, Liu C, Ling E. Thermolysin damages animal life through degradation of plasma proteins enhanced by rapid cleavage of serpins and activation of proteases. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2015; 88:64-84. [PMID: 25042057 DOI: 10.1002/arch.21178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Thermolysin, a metallopeptidase secreted by pathogenic microbes, is concluded as an important virulence factor due to cleaving purified host proteins in vitro. Using the silkworm Bombyx mori as a model system, we found that thermolysin injection into larvae induces the destruction of the coagulation response and the activation of hemolymph melanization, which results in larval death. Thermolysin triggers the rapid degradation of insect and mammalian plasma proteins at a level that is considerably greater than expected in vitro and/or in vivo. To more specifically explore the mechanism, thermolysin-induced changes to key proteins belonging to the insect melanization pathway were assessed as a window for observing plasma protein cleavage. The application of thermolysin induced the rapid cleavage of the melanization negative regulator serpin-3, but did not directly activate the melanization rate-limiting enzyme prophenoloxidase (PPO) or the terminal serine proteases responsible for PPO activation. Terminal serine proteases of melanization are activated indirectly after thermolysin exposure. We hypothesize that thermolysin induces the rapid degradation of serpins and the activation of proteases directly or indirectly, boosting uncontrolled plasma protein degradation in insects and mammalians.
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Affiliation(s)
- Lulu Kong
- College of Life Science, Anhui Agricultural University, Changjiang, People's Republic of China; College of Agriculture and Biology, Shanghai Jiaotong University, Dongchuan, Shanghai, People's Republic of China; Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China
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Whole proteome analysis of mouse lymph nodes in cutaneous anthrax. PLoS One 2014; 9:e110873. [PMID: 25329596 PMCID: PMC4203832 DOI: 10.1371/journal.pone.0110873] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 09/25/2014] [Indexed: 12/16/2022] Open
Abstract
This study aimed to characterize a soluble proteome of popliteal lymph nodes during lymphadenitis induced by intradermal injection of Bacillus anthracis Sterne spores in mice using tandem LC-MS/MS and reverse-phase protein microarray with antibodies specific to epitopes of phosphorylated proteins. More than 380 proteins were detected in the normal intra-nodal lymph, while the infectious process resulted in the profound changes in the protein abundances and appearance of 297 unique proteins. These proteins belong to an array of processes reflecting response to wounding, inflammation and perturbations of hemostasis, innate immune response, coagulation and fibrinolysis, regulation of body fluid levels and vascular disturbance among others. Comparison of lymph and serum revealed 83 common proteins. Also, using 71 antibodies specific to total and phosphorylated forms of proteins we carried initial characterization of circulating lymph phosphoproteome which brought additional information regarding signaling pathways operating in the lymphatics. The results demonstrate that the proteome of intra-nodal lymph serves as a sensitive sentinel of the processes occurring within the lymph nodes during infection. The acute innate response of the lymph nodes to anthrax is accompanied by cellular damage and inflammation with a large number of up- and down-regulated proteins many of which are distinct from those detected in serum. MS data are available via ProteomeXchange with identifier PXD001342.
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Tsuboi S, Yamamura S, Imai A, Satou T, Iwasaki K. Linking temporal changes in bacterial community structures with the detection and phylogenetic analysis of neutral metalloprotease genes in the sediments of a hypereutrophic lake. Microbes Environ 2014; 29:314-21. [PMID: 25130992 PMCID: PMC4159043 DOI: 10.1264/jsme2.me14064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We investigated spatial and temporal variations in bacterial community structures as well as the presence of three functional proteolytic enzyme genes in the sediments of a hypereutrophic freshwater lake in order to acquire an insight into dynamic links between bacterial community structures and proteolytic functions. Bacterial communities determined from 16S rRNA gene clone libraries markedly changed bimonthly, rather than vertically in the sediment cores. The phylum Firmicutes dominated in the 4–6 cm deep sediment layer sample after August in 2007, and this correlated with increases in interstitial ammonium concentrations (p < 0.01). The Firmicutes clones were mostly composed of the genus Bacillus. npr genes encoding neutral metalloprotease, an extracellular protease gene, were detected after the phylum Firmicutes became dominant. The deduced Npr protein sequences from the retrieved npr genes also showed that most of the Npr sequences used in this study were closely related to those of the genus Bacillus, with similarities ranging from 61% to 100%. Synchronous temporal occurrences of the 16S rRNA gene and Npr sequences, both from the genus Bacillus, were positively associated with increases in interstitial ammonium concentrations, which may imply that proteolysis by Npr from the genus Bacillus may contribute to the marked increases observed in ammonium concentrations in the sediments. Our results suggest that sedimentary bacteria may play an important role in the biogeochemical nitrogen cycle of freshwater lakes.
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Affiliation(s)
- Shun Tsuboi
- National Institute for Environmental Studies (NIES)
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28
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Selvaraj C, Bharathi Priya R, Singh SK. Communication of γ Phage Lysin plyG Enzymes Binding toward SrtA for Inhibition ofBacillus Anthracis: Protein–Protein Interaction and Molecular Dynamics Study. ACTA ACUST UNITED AC 2014; 21:257-65. [DOI: 10.3109/15419061.2014.927444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Fevre C, Bestebroer J, Mebius MM, de Haas CJC, van Strijp JAG, Fitzgerald JR, Haas PJA. Staphylococcus aureus proteins SSL6 and SElX interact with neutrophil receptors as identified using secretome phage display. Cell Microbiol 2014; 16:1646-65. [PMID: 24840181 DOI: 10.1111/cmi.12313] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/02/2014] [Accepted: 05/05/2014] [Indexed: 12/20/2022]
Abstract
In order to cause colonization and invasive disease, pathogenic bacteria secrete proteins that modulate host immune defences. Identification and characterization of these proteins leads to a better understanding of the pathological processes underlying infectious and inflammatory diseases and is essential in the development of new strategies for their prevention and treatment. Current techniques to functionally characterize these proteins are laborious and inefficient. Here we describe a high-throughput functional selection strategy using phage display in order to identify immune evasion proteins. Using this technique we identified two previously uncharacterized proteins secreted by Staphylococcus aureus, SElX and SSL6 that bind to neutrophil surface receptors. SElX binds PSGL-1 on neutrophils and thereby inhibits the interaction between PSGL-1 and P-selectin, a crucial step in the recruitment of neutrophils to the site of infection. SSL6 is the first bacterial protein identified that binds CD47, a widely expressed cell surface protein recently described as an interesting target in anti-cancer therapy. Our findings provide new insights into the pathogenesis of S. aureus infections and support phage display as an efficient method to identify bacterial secretome proteins interacting with humoral or cellular immune components.
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Affiliation(s)
- Cindy Fevre
- Department of Medical Microbiology, University Medical Center Utrecht, PO G04.614, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands
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Kim SK, Park MK, Kim SH, Oh KG, Jung KH, Hong CH, Yoon JW, Chai YG. Identification of stringent response-related and potential serological proteins released from Bacillus anthracis overexpressing the RelA/SpoT homolog, Rsh Bant. Curr Microbiol 2014; 69:436-44. [PMID: 24838666 DOI: 10.1007/s00284-014-0606-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Accepted: 03/20/2014] [Indexed: 11/28/2022]
Abstract
RelA and SpoT synthesize ppGpp, a key effector molecule that facilitates the adaptation of bacteria to nutrient starvation and other stresses, known as the stringent response. To investigate the role of Rsh Bant , a putative RelA/SpoT homolog (encoded by BAS4302) in Bacillus anthracis, we examined the alteration of the secretome profiles after the overexpression of a functional His-Rsh Bant protein in the B. anthracis strain Sterne at the stationary growth phase. In the ppGpp-deficient E. coli mutant strain CF1693, overexpression of Rsh Bant restored a ppGpp-dependent growth defect on minimal glucose media. The secretome profiles obtained using a two-dimensional electrophoresis (2-DE) analysis were altered by overexpression of Rsh Bant in B. anthracis. Among the 66 protein spots differentially expressed >1.5-fold, the 29 proteins were abundant for further identification using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Functional categorization of those proteins implicated their involvement in various biological activities. Taken together, our results imply that overexpression of a functional His-Rsh Bant can lead to the increased levels of intracellular ppGpp in B. anthracis, resulting in the significant changes in its secretome profiling. The stringent response-controlled proteins identified are likely useful as potential targets for serodiagnostic applications.
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Affiliation(s)
- Se Kye Kim
- Department of Molecular and Life Sciences, Hanyang University, 1271, Ansan, 426-791, Gyeonggi-do, Republic of Korea
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Modulation of the Bacillus anthracis secretome by the immune inhibitor A1 protease. J Bacteriol 2013; 196:424-35. [PMID: 24214942 DOI: 10.1128/jb.00690-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Bacillus anthracis secretome includes protective antigen, lethal factor, and edema factor, which are the components of anthrax toxin, and other proteins with known or potential roles in anthrax disease. Immune inhibitor A1 (InhA1) is a secreted metalloprotease that is unique to pathogenic members of the Bacillus genus and has been associated with cleavage of host proteins during infection. Here, we report the effect of InhA1 on the B. anthracis secretome. Differential in-gel electrophoresis of proteins present in culture supernatants from a parent strain and an isogenic inhA1-null mutant revealed multiple differences. Of the 1,340 protein spots observed, approximately one-third were less abundant and one-third were more abundant in the inhA1 secretome than in the parent strain secretome. Proteases were strongly represented among those proteins exhibiting a 9-fold or greater change. InhA1 purified from a B. anthracis culture supernatant directly cleaved each of the anthrax toxin proteins as well as an additional secreted protease, Npr599. The conserved zinc binding motif HEXXH of InhA1 (HEYGH) was critical for its proteolytic activity. Our data reveal that InhA1 directly and indirectly modulates the form and/or abundance of over half of all the secreted proteins of B. anthracis. The proteolytic activity of InhA1 on established secreted virulence factors, additional proteases, and other secreted proteins suggests that this major protease plays an important role in virulence not only by cleaving mammalian substrates but also by modulating the B. anthracis secretome itself.
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Fraga TR, Courrol DDS, Castiblanco-Valencia MM, Hirata IY, Vasconcellos SA, Juliano L, Barbosa AS, Isaac L. Immune evasion by pathogenic Leptospira strains: the secretion of proteases that directly cleave complement proteins. J Infect Dis 2013; 209:876-86. [PMID: 24163418 DOI: 10.1093/infdis/jit569] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Leptospirosis is an infectious disease of public health importance. To successfully colonize the host, pathogens have evolved multiple strategies to escape the complement system. Here we demonstrate that the culture supernatant of pathogenic but not saprophytic Leptospira inhibit the three complement pathways. We showed that the proteolytic activity in the supernatants of pathogenic strains targets the central complement molecule C3 and specific proteins from each pathway, such as factor B, C2, and C4b. The proteases cleaved α and β chains of C3 and work in synergy with host regulators to inactivate C3b. Proteolytic activity was inhibited by 1,10-phenanthroline, suggesting the participation of metalloproteases. A recombinant leptospiral metalloprotease from the thermolysin family cleaved C3 in serum and could be one of the proteases responsible for the supernatant activity. We conclude that pathogenic leptospiral proteases can deactivate immune effector molecules and represent potential targets to the development of new therapies in leptospirosis.
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Edwin A, Rompikuntal P, Björn E, Stier G, Wai SN, Sauer-Eriksson AE. Calcium binding by the PKD1 domain regulates interdomain flexibility in Vibrio cholerae metalloprotease PrtV. FEBS Open Bio 2013; 3:263-70. [PMID: 23905008 PMCID: PMC3722578 DOI: 10.1016/j.fob.2013.06.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 06/20/2013] [Accepted: 06/21/2013] [Indexed: 01/06/2023] Open
Abstract
Vibrio cholerae, the causative agent of cholera, releases several virulence factors including secreted proteases when it infects its host. These factors attack host cell proteins and break down tissue barriers and cellular matrix components such as collagen, laminin, fibronectin, keratin, elastin, and they induce necrotic tissue damage. The secreted protease PrtV constitutes one virulence factors of V. cholerae. It is a metalloprotease belonging to the M6 peptidase family. The protein is expressed as an inactive, multidomain, 102 kDa pre-pro-protein that undergoes several N- and C-terminal modifications after which it is secreted as an intermediate variant of 81 kDa. After secretion from the bacteria, additional proteolytic steps occur to produce the 55 kDa active M6 metalloprotease. The domain arrangement of PrtV is likely to play an important role in these maturation steps, which are known to be regulated by calcium. However, the molecular mechanism by which calcium controls proteolysis is unknown. In this study, we report the atomic resolution crystal structure of the PKD1 domain from V. cholera PrtV (residues 755–838) determined at 1.1 Å. The structure reveals a previously uncharacterized Ca2+-binding site located near linker regions between domains. Conformational changes in the Ca2+-free and Ca2+-bound forms suggest that Ca2+-binding at the PKD1 domain controls domain linker flexibility, and plays an important structural role, providing stability to the PrtV protein. The PKD1 domain was expressed in E. coli and purified to homogeneity. Purified PKD1 domains are not toxic for human HTC8 cells. The atomic 1.1 Å crystal structure of the PKD1 domain revealed a Ca2+-binding site. Ca2+ binding causes large conformational changes in the N-terminal half of the PKD1 domain. Ca2+ stabilizes the 81 kDa pro-protein outside the bacterial cell, preventing its degradation.
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Affiliation(s)
- Aaron Edwin
- Department of Chemistry, Umeå University, Umeå SE-901 87, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå SE-901 87, Sweden
| | - Pramod Rompikuntal
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå SE-901 87, Sweden
- Department of Molecular Biology, Umeå University, Umeå SE-901 87, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå SE-901 87, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, Umeå SE-901 87, Sweden
| | - Gunter Stier
- Department of Chemistry, Umeå University, Umeå SE-901 87, Sweden
| | - Sun N. Wai
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå SE-901 87, Sweden
- Department of Molecular Biology, Umeå University, Umeå SE-901 87, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå SE-901 87, Sweden
| | - A. Elisabeth Sauer-Eriksson
- Department of Chemistry, Umeå University, Umeå SE-901 87, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå SE-901 87, Sweden
- Corresponding author at: Department of Chemistry, Umeå University, Umeå SE-901 87, Sweden. Tel.: +46 90 7865923; fax: +46 90 7865944.
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Potempa M, Potempa J. Protease-dependent mechanisms of complement evasion by bacterial pathogens. Biol Chem 2013; 393:873-88. [PMID: 22944688 DOI: 10.1515/hsz-2012-0174] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 05/06/2012] [Indexed: 12/11/2022]
Abstract
The human immune system has evolved a variety of mechanisms for the primary task of neutralizing and eliminating microbial intruders. As the first line of defense, the complement system is responsible for rapid recognition and opsonization of bacteria, presentation to phagocytes and bacterial cell killing by direct lysis. All successful human pathogens have mechanisms of circumventing the antibacterial activity of the complement system and escaping this stage of the immune response. One of the ways in which pathogens achieve this is the deployment of proteases. Based on the increasing number of recent publications in this area, it appears that proteolytic inactivation of the antibacterial activities of the complement system is a common strategy of avoiding targeting by this arm of host innate immune defense. In this review, we focus on those bacteria that deploy proteases capable of degrading complement system components into non-functional fragments, thus impairing complement-dependent antibacterial activity and facilitating pathogen survival inside the host.
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Affiliation(s)
- Michal Potempa
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
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Chung MC, Narayanan A, Popova TG, Kashanchi F, Bailey CL, Popov SG. Bacillus anthracis-derived nitric oxide induces protein S-nitrosylation contributing to macrophage death. Biochem Biophys Res Commun 2013. [DOI: 10.1016/j.bbrc.2012.11.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Kau JH, Shih YL, Lien TS, Lee CC, Huang HH, Lin HC, Sun DS, Chang HH. Activated protein C ameliorates Bacillus anthracis lethal toxin-induced lethal pathogenesis in rats. J Biomed Sci 2012; 19:98. [PMID: 23170801 PMCID: PMC3536616 DOI: 10.1186/1423-0127-19-98] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 10/18/2012] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Lethal toxin (LT) is a major virulence factor of Bacillus anthracis. Sprague Dawley rats manifest pronounced lung edema and shock after LT treatments, resulting in high mortality. The heart failure that is induced by LT has been suggested to be a principal mechanism of lung edema and mortality in rodents. Since LT-induced death occurs more rapidly in rats than in mice, suggesting that other mechanisms in addition to the heart dysfunction may be contributed to the fast progression of LT-induced pathogenesis in rats. Coagulopathy may contribute to circulatory failure and lung injury. However, the effect of LT on coagulation-induced lung dysfunction is unclear. METHODS To investigate the involvement of coagulopathy in LT-mediated pathogenesis, the mortality, lung histology and coagulant levels of LT-treated rats were examined. The effects of activated protein C (aPC) on LT-mediated pathogenesis were also evaluated. RESULTS Fibrin depositions were detected in the lungs of LT-treated rats, indicating that coagulation was activated. Increased levels of plasma D-dimer and thrombomodulin, and the ameliorative effect of aPC further suggested that the activation of coagulation-fibrinolysis pathways plays a role in LT-mediated pathogenesis in rats. Reduced mortality was associated with decreased plasma levels of D-dimer and thrombomodulin following aPC treatments in rats with LT-mediated pathogenesis. CONCLUSIONS These findings suggest that the activation of coagulation in lung tissue contributes to mortality in LT-mediated pathogenesis in rats. In addition, anticoagulant aPC may help to develop a feasible therapeutic strategy.
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Affiliation(s)
- Jyh-Hwa Kau
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan, ROC
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Bacillus thuringiensis metalloproteinase Bmp1 functions as a nematicidal virulence factor. Appl Environ Microbiol 2012; 79:460-8. [PMID: 23124228 DOI: 10.1128/aem.02551-12] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Some Bacillus thuringiensis strains have high toxicity to nematodes. Nematicidal activity has been found in several families of crystal proteins, such as Cry5, Cry6, and Cry55. The B. thuringiensis strain YBT-1518 has three cry genes that have high nematicidal activity. The whole genome sequence of this strain contains multiple potential virulence factors. To evaluate the pathogenic potential of virulence factors, we focused on a metalloproteinase called Bmp1. It encompasses a consecutive N-terminal signal peptide, an FTP superfamily domain, an M4 neutral protease GluZincin superfamily, two Big-3 superfamily motifs, and a Gram-positive anchor superfamily motif as a C-terminal domain. Here, we showed that purified Bmp1 protein showed metalloproteinase activity and toxicity against Caenorhabditis elegans (the 50% lethal concentration is 610 ± 9.37 μg/ml). In addition, mixing Cry5Ba with Bmp1 protein enhanced the toxicity 7.9-fold (the expected toxicity of the two proteins calculated from their separate toxicities) against C. elegans. Confocal microscopic observation revealed that Bmp1 protein was detected from around the mouth and esophagus to the intestine. Striking microscopic images revealed that Bmp1 degrades intestine tissues, and the Cry5Ba causes intestinal shrinkage from the body wall. Thus, the B. thuringiensis Bmp1 metalloproteinase is a nematicidal virulence factor. These findings give a new insight into the relationship between B. thuringiensis and its host nematodes.
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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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Nielsen-LeRoux C, Gaudriault S, Ramarao N, Lereclus D, Givaudan A. How the insect pathogen bacteria Bacillus thuringiensis and Xenorhabdus/Photorhabdus occupy their hosts. Curr Opin Microbiol 2012; 15:220-31. [PMID: 22633889 DOI: 10.1016/j.mib.2012.04.006] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/26/2012] [Accepted: 04/27/2012] [Indexed: 10/28/2022]
Abstract
Insects are the largest group of animals on earth. Like mammals, virus, fungi, bacteria and parasites infect them. Several tissue barriers and defense mechanisms are common for vertebrates and invertebrates. Therefore some insects, notably the fly Drosophila and the caterpillar Galleria mellonella, have been used as models to study host-pathogen interactions for several insect and mammal pathogens. They are excellent tools to identify pathogen determinants and host tissue cell responses. We focus here on the comparison of effectors used by two different groups of bacterial insect pathogens to accomplish the infection process in their lepidopteran larval host: Bacillus thuringiensis and the nematode-associated bacteria, Photorhabdus and Xenorhabdus. The comparison reveals similarities in function and expression profiles for some genes, which suggest that such factors are conserved during evolution in order to attack the tissue encountered during the infection process.
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Affiliation(s)
- Christina Nielsen-LeRoux
- INRA, UMR1319, Micalis, Génétique microbienne et Environnement, La Minière, F-78280 Guyancourt, France.
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Proteomic analysis of Bacillus thuringiensis at different growth phases by using an automated online two-dimensional liquid chromatography-tandem mass spectrometry strategy. Appl Environ Microbiol 2012; 78:5270-9. [PMID: 22636013 DOI: 10.1128/aem.00424-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The proteome of a new Bacillus thuringiensis subsp. kurstaki strain, 4.0718, from the middle vegetative (T(1)), early sporulation (T(2)), and late sporulation (T(3)) phases was analyzed using an integrated liquid chromatography (LC)-based protein identification system. The system comprised two-dimensional (2D) LC coupled with nanoscale electrospray ionization (ESI) tandem mass spectrometry (MS/MS) on a high-resolution hybrid mass spectrometer with an automated data analysis system. After deletion of redundant proteins from the different batches and B. thuringiensis subspecies, 918, 703, and 778 proteins were identified in the respective three phases. Their molecular masses ranged from 4.6 Da to 477.4 Da, and their isoelectric points ranged from 4.01 to 11.84. Function clustering revealed that most of the proteins in the three phases were functional metabolic proteins, followed by proteins participating in cell processes. Small molecular and macromolecular metabolic proteins were further classified according to the Kyoto Encyclopedia of Genes and Genome and BioCyc metabolic pathway database. Three protoxins (Cry2Aa, Cry1Aa, and Cry1Ac) as well as a series of potential intracellular active factors were detected. Many significant proteins related to spore and crystal formation, including sporulation proteins, help proteins, chaperones, and so on, were identified. The expression patterns of two identified proteins, CotJc and glutamine synthetase, were validated by Western blot analysis, which further confirmed the MS results. This study is the first to use shotgun technology to research the proteome of B. thuringiensis. Valuable experimental data are provided regarding the methodology of analyzing the B. thuringiensis proteome (which can be used to produce insecticidal crystal proteins) and have been added to the related protein database.
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Tonry JH, McNichol BA, Ramarao N, Chertow DS, Kim KS, Stibitz S, Schneewind O, Kashanchi F, Bailey CL, Popov S, Chung MC. Bacillus anthracis protease InhA regulates BslA-mediated adhesion in human endothelial cells. Cell Microbiol 2012; 14:1219-30. [PMID: 22452315 DOI: 10.1111/j.1462-5822.2012.01791.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
To achieve widespread dissemination in the host, Bacillus anthracis cells regulate their attachment to host endothelium during infection. Previous studies identified BslA (Bacillus anthracis S-layer Protein A), a virulence factor of B. anthracis, as necessary and sufficient for adhesion of vegetative cells to human endothelial cells. While some factors have been identified, bacteria-specific contributions to BslA mediated adhesion remain unclear. Using the attenuated vaccine Sterne 7702 strain of B. anthracis, we tested the hypothesis that InhA (immune inhibitor A), a B. anthracis protease, regulates BslA levels affecting the bacteria's ability to bind to endothelium. To test this, a combination of inhA mutant and complementation analysis in adhesion and invasion assays, Western blot and InhA inhibitor assays were employed. Results show InhA downregulates BslA activity reducing B. anthracis adhesion and invasion in human brain endothelial cells. BslA protein levels in ΔinhA bacteria were significantly higher than wild-type and complemented strains showing InhA levels and BslA expression are inversely related. BslA was sensitive to purified InhA degradation in a concentration- and time-dependent manner. Taken together these data support the role of InhA regulation of BslA-mediated vegetative cell adhesion and invasion.
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Affiliation(s)
- Jessica H Tonry
- Department of Biosciences and Biomedical Research Laboratory, George Mason University, 10650 Pyramid Place, Manassas, Virginia 20110, USA
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Necrotrophism is a quorum-sensing-regulated lifestyle in Bacillus thuringiensis. PLoS Pathog 2012; 8:e1002629. [PMID: 22511867 PMCID: PMC3325205 DOI: 10.1371/journal.ppat.1002629] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 02/22/2012] [Indexed: 11/19/2022] Open
Abstract
How pathogenic bacteria infect and kill their host is currently widely investigated. In comparison, the fate of pathogens after the death of their host receives less attention. We studied Bacillus thuringiensis (Bt) infection of an insect host, and show that NprR, a quorum sensor, is active after death of the insect and allows Bt to survive in the cadavers as vegetative cells. Transcriptomic analysis revealed that NprR regulates at least 41 genes, including many encoding degradative enzymes or proteins involved in the synthesis of a nonribosomal peptide named kurstakin. These degradative enzymes are essential in vitro to degrade several substrates and are specifically expressed after host death suggesting that Bt has an active necrotrophic lifestyle in the cadaver. We show that kurstakin is essential for Bt survival during necrotrophic development. It is required for swarming mobility and biofilm formation, presumably through a pore forming activity. A nprR deficient mutant does not develop necrotrophically and does not sporulate efficiently in the cadaver. We report that necrotrophism is a highly regulated mechanism essential for the Bt infectious cycle, contributing to spore spreading.
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Updating perspectives on the initiation of Bacillus anthracis growth and dissemination through its host. Infect Immun 2012; 80:1626-33. [PMID: 22354031 DOI: 10.1128/iai.06061-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Since 1957, it has been proposed that the dissemination of inhalational anthrax required spores to be transported from the lumena of the lungs into the lymphatic system. In 2002, this idea was expanded to state that alveolar macrophages act as a "Trojan horse" capable of transporting spores across the lung epithelium into draining mediastinal lymph nodes. Since then, the Trojan horse model of dissemination has become the most widely cited model of inhalational infection as well as the focus of the majority of studies aiming to understand events initiating inhalational anthrax infections. However, recent observations derived from animal models of Bacillus anthracis infection are inconsistent with aspects of the Trojan horse model and imply that bacterial dissemination patterns during inhalational infection may be more similar to the cutaneous and gastrointestinal forms than previously thought. In light of these studies, it is of significant importance to reassess the mechanisms of inhalational anthrax dissemination, since it is this form of anthrax that is most lethal and of greatest concern when B. anthracis is weaponized. Here we propose a new "jailbreak" model of B. anthracis dissemination which applies to the dissemination of all common manifestations of the disease anthrax. The proposed model impacts the field by deemphasizing the role of host cells as conduits for dissemination and increasing the role of phagocytes as central players in innate defenses, while moving the focus toward interactions between B. anthracis and lymphoid and epithelial tissues.
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Abstract
Membrane-bound proteoglycans function primarily as coreceptors for many glycosaminoglycan (GAG)-binding ligands at the cell surface. The majority of membrane-bound proteoglycans can also function as soluble autocrine or paracrine effectors as their extracellular domains, replete with all GAG chains, are enzymatically cleaved and released from the cell surface by ectodomain shedding. In particular, the ectodomain shedding of syndecans, a major family of cell surface heparan sulfate proteoglycans, is an important posttranslational mechanism that modulates diverse pathophysiological processes. Syndecan shedding is a tightly controlled process that regulates the onset, progression, and resolution of various infectious and noninfectious inflammatory diseases. This review describes methods to induce and measure the shedding of cell membrane-bound proteoglycans, focusing on syndecan shedding as a prototypic example.
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Affiliation(s)
- Eon Jeong Nam
- Division of Respiratory Diseases, Children's Hospital, Harvard Medical School, Boston, MA, USA
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45
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Genome sequence of Brevibacillus laterosporus LMG 15441, a pathogen of invertebrates. J Bacteriol 2011; 193:5535-6. [PMID: 21914864 DOI: 10.1128/jb.05696-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here we announce the genome sequence of the bacterium Brevibacillus laterosporus LMG 15441, which is a pathogen of invertebrates. The genome consists of one chromosome and two circular plasmids. Sequence analysis revealed a large potential to produce polyketides, nonribosomal peptides, and toxins.
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Teng YHF, Aquino RS, Park PW. Molecular functions of syndecan-1 in disease. Matrix Biol 2011; 31:3-16. [PMID: 22033227 DOI: 10.1016/j.matbio.2011.10.001] [Citation(s) in RCA: 254] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 09/30/2011] [Accepted: 10/03/2011] [Indexed: 12/25/2022]
Abstract
Syndecan-1 is a cell surface heparan sulfate proteoglycan that binds to many mediators of disease pathogenesis. Through these molecular interactions, syndecan-1 can modulate leukocyte recruitment, cancer cell proliferation and invasion, angiogenesis, microbial attachment and entry, host defense mechanisms, and matrix remodeling. The significance of syndecan-1 interactions in disease is underscored by the striking pathological phenotypes seen in the syndecan-1 null mice when they are challenged with disease-instigating agents or conditions. This review discusses the key molecular functions of syndecan-1 in modulating the onset, progression, and resolution of inflammatory diseases, cancer, and infection.
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Affiliation(s)
- Yvonne Hui-Fang Teng
- Department of Medicine, Children's Hospital, Harvard Medical School, Boston, MA 02115, United States
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Popova TG, Millis B, Bailey C, Popov SG. Platelets, inflammatory cells, von Willebrand factor, syndecan-1, fibrin, fibronectin, and bacteria co-localize in the liver thrombi of Bacillus anthracis-infected mice. Microb Pathog 2011; 52:1-9. [PMID: 22001909 DOI: 10.1016/j.micpath.2011.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 08/16/2011] [Accepted: 08/23/2011] [Indexed: 11/27/2022]
Abstract
UNLABELLED Vascular dysfunction and thrombosis have been described in association with anthrax infection in humans and animals but the mechanisms of these dysfunctions, as well as the components involved in thrombi formation are poorly understood. Immunofluorescent microscopy was used to define the composition of thrombi in the liver of mice challenged with the Bacillus anthracis Sterne spores. Lethal infection with the toxigenic Sterne strain, in contrast to the non-lethal, non-toxigenic delta-Sterne strain, demonstrated time-dependent increase in the number of vegetative bacteria inside the liver sinusoids and central vein. Massive appearance of thrombi typically occluding the lumen of the vessels coincided with the sudden death of infected animals. Bacterial chains in the thrombi were stained positive for syndecan-1 (SDC-1), fibronectin, and were surrounded by fibrin polymers, GPIIb-positive platelets, von Willebrand Factor (vWF), CD45-positive leukocytes, and massive amount of shed SDC-1. Experiments with human umbilical vein endothelial cells (HUVECs) demonstrated the active role of the host response to the secreted pathogenic factors of bacteria during the onset of the pro-thrombotic condition. The bacterial culture supernatants, as well as the isolated proteins (the pore-forming toxin anthrolysin O and phospholipase C) induced release of vWF, while anthrolysin O, sphingomyelinase and edema toxin induced release of thrombin from HUVECs and polymerization of fibrin in the presence of human plasma. CONCLUSION Our findings suggest that activation of endothelium in response to infection can contribute to the formation of occlusive thrombi consisting of aggregated bacteria, vWF, shed SDC-1, fibrin, activated platelets, fibronectin and leukocytes.
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Affiliation(s)
- Taissia G Popova
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA 20110, USA.
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Perchat S, Dubois T, Zouhir S, Gominet M, Poncet S, Lemy C, Aumont-Nicaise M, Deutscher J, Gohar M, Nessler S, Lereclus D. A cell-cell communication system regulates protease production during sporulation in bacteria of the Bacillus cereus group. Mol Microbiol 2011; 82:619-33. [PMID: 21958299 DOI: 10.1111/j.1365-2958.2011.07839.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
In sporulating Bacillus, major processes like virulence gene expression and sporulation are regulated by communication systems involving signalling peptides and regulators of the RNPP family. We investigated the role of one such regulator, NprR, in bacteria of the Bacillus cereus group. We show that NprR is a transcriptional regulator whose activity depends on the NprX signalling peptide. In association with NprX, NprR activates the transcription of an extracellular protease gene (nprA) during the first stage of the sporulation process. The transcription start site of the nprA gene has been identified and the minimal region necessary for full activation has been characterized by promoter mutagenesis. We demonstrate that the NprX peptide is secreted, processed and then reimported within the bacterial cell. Once inside the cell, the mature form of NprX, presumably the SKPDIVG heptapeptide, directly binds to NprR allowing nprA transcription. Alignment of available NprR sequences from different species of the B. cereus group defines seven NprR clusters associated with seven NprX heptapeptide classes. This cell-cell communication system was found to be strain-specific with a possible cross-talk between some pherotypes. The phylogenic relationship between NprR and NprX suggests a coevolution of the regulatory protein and its signalling peptide.
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Guichard A, Nizet V, Bier E. New insights into the biological effects of anthrax toxins: linking cellular to organismal responses. Microbes Infect 2011; 14:97-118. [PMID: 21930233 DOI: 10.1016/j.micinf.2011.08.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/30/2011] [Accepted: 08/30/2011] [Indexed: 12/15/2022]
Abstract
The anthrax toxins lethal toxin (LT) and edema toxin (ET) are essential virulence factors produced by Bacillus anthracis. These toxins act during two distinct phases of anthrax infection. During the first, prodromal phase, which is often asymptomatic, anthrax toxins act on cells of the immune system to help the pathogen establish infection. Then, during the rapidly progressing (or fulminant) stage of the disease bacteria disseminate via a hematological route to various target tissues and organs, which are typically highly vascularized. As bacteria proliferate in the bloodstream, LT and ET begin to accumulate rapidly reaching a critical threshold level that will cause death even when the bacterial proliferation is curtailed by antibiotics. During this final phase of infection the toxins cause an increase in vascular permeability and a decrease in function of target organs including the heart, spleen, kidney, adrenal gland, and brain. In this review, we examine the various biological effects of anthrax toxins, focusing on the fulminant stage of the disease and on mechanisms by which the two toxins may collaborate to cause cardiovascular collapse. We discuss normal mechanisms involved in maintaining vascular integrity and based on recent studies indicating that LT and ET cooperatively inhibit membrane trafficking to cell-cell junctions we explore several potential mechanisms by which the toxins may achieve their lethal effects. We also summarize the effects of other potential virulence factors secreted by B. anthracis and consider the role of toxic factors in the evolutionarily recent emergence of this devastating disease.
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Affiliation(s)
- Annabel Guichard
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0349, USA
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A Bacillus anthracis strain deleted for six proteases serves as an effective host for production of recombinant proteins. Protein Expr Purif 2011; 80:80-90. [PMID: 21827967 DOI: 10.1016/j.pep.2011.05.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 05/23/2011] [Indexed: 12/25/2022]
Abstract
Bacillus anthracis produces a number of extracellular proteases that impact the integrity and yield of other proteins in the B. anthracis secretome. In this study we show that anthrolysin O (ALO) and the three anthrax toxin proteins, protective antigen (PA), lethal factor (LF), and edema factor (EF), produced from the B. anthracis Ames 35 strain (pXO1⁺, pXO2⁻), are completely degraded at the onset of stationary phase due to the action of proteases. An improved Cre-loxP gene knockout system was used to sequentially delete the genes encoding six proteases (InhA1, InhA2, camelysin, TasA, NprB, and MmpZ). The role of each protease in degradation of the B. anthracis toxin components and ALO was demonstrated. Levels of the anthrax toxin components and ALO in the supernatant of the sporulation defective, pXO1⁺ A35HMS mutant strain deleted for the six proteases were significantly increased and remained stable over 24 h. A pXO1-free variant of this six-protease mutant strain, designated BH460, provides an improved host strain for the preparation of recombinant proteins. As an example, BH460 was used to produce recombinant EF, which previously has been difficult to obtain from B. anthracis. The EF protein produced from BH460 had the highest in vivo potency of any EF previously purified from B. anthracis or Escherichia coli hosts. BH460 is recommended as an effective host strain for recombinant protein production, typically yielding greater than 10mg pure protein per liter of culture.
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