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Author

Sérgio P. Fernandes da Costa

Other affiliations: University of Tübingen
Bio: Sérgio P. Fernandes da Costa is an academic researcher from University of Exeter. The author has contributed to research in topics: Clostridium perfringens & Toxin. The author has an hindex of 8, co-authored 8 publications receiving 359 citations. Previous affiliations of Sérgio P. Fernandes da Costa include University of Tübingen.

Papers
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Journal ArticleDOI
TL;DR: The exquisite specificity of the toxin for specific cell types suggests that it binds to a receptor found only on these cells, and the crystal structure of ε‐toxin reveals similarity to aerolysin from Aeromonas’hydrophila, parasporin‐2 from Bacillus’thuringiensis and a lectin from Laetiporus’sulphureus.
Abstract: Clostridium perfringens e-toxin is produced by toxinotypes B and D strains. The toxin is the aetiological agent of dysentery in newborn lambs but is also associated with enteritis and enterotoxaemia in goats, calves and foals. It is considered to be a potential biowarfare or bioterrorism agent by the US Government Centers for Disease Control and Prevention. The relatively inactive 32.9 kDa prototoxin is converted to active mature toxin by proteolytic cleavage, either by digestive proteases of the host, such as trypsin and chymotrypsin, or by C. perfringens λ-protease. In vivo, the toxin appears to target the brain and kidneys, but relatively few cell lines are susceptible to the toxin, and most work has been carried out using Madin-Darby canine kidney (MDCK) cells. The binding of e-toxin to MDCK cells and rat synaptosomal membranes is associated with the formation of a stable, high molecular weight complex. The crystal structure of e-toxin reveals similarity to aerolysin from Aeromonas hydrophila, parasporin-2 from Bacillus thuringiensis and a lectin from Laetiporus sulphureus. Like these toxins, e-toxin appears to form heptameric pores in target cell membranes. The exquisite specificity of the toxin for specific cell types suggests that it binds to a receptor found only on these cells.

111 citations

Journal ArticleDOI
TL;DR: The crystal structure of the pore form of NetB is presented, showing that NetB does not bind phosphocholine efficiently but instead interacts directly with cholesterol leading to enhanced oligomerization and pore formation and providing potential new tools to the field of bionanotechnology.

97 citations

Journal ArticleDOI
20 Aug 2013-Vaccine
TL;DR: Vaccination with a NetB genetic or formaldehyde toxoid protects chicken in an in vivo disease model and could form the bases of an efficient vaccine against necrotic enteritis.

48 citations

Journal ArticleDOI
TL;DR: Experiments with several antimicrobials support the hypothesis that the full activity of Lys44 requires sudden ion-nonspecific dissipation of the proton motive force, an event undertaken by the fOg44 holin in the phage infection context.
Abstract: The intrinsic resistance of Oenococcus oeni cells to the secreted endolysin from oenophage fOg44 (Lys44) was investigated. Experiments with several antimicrobials support the hypothesis that the full activity of Lys44 requires sudden ion-nonspecific dissipation of the proton motive force, an event undertaken by the fOg44 holin in the phage infection context.

43 citations

Journal ArticleDOI
TL;DR: The role of surface exposed tyrosine residues in domain I of E tx in binding to MDCK cells and the suitability of Etx‐H149A for further receptor binding studies are confirmed and have important implications for developing strategies designed to neutralise toxin activity.
Abstract: Clostridium perfringens epsilon toxin (Etx) is a pore-forming toxin responsible for a severe and rapidly fatal enterotoxemia of ruminants. The toxin is classified as a category B bioterrorism agent by the U.S. Government Centres for Disease Control and Prevention (CDC), making work with recombinant toxin difficult. To reduce the hazard posed by work with recombinant Etx, we have used a variant of Etx that contains a H149A mutation (Etx-H149A), previously reported to have reduced, but not abolished, toxicity. The three-dimensional structure of H149A prototoxin shows that the H149A mutation in domain III does not affect organisation of the putative receptor binding loops in domain I of the toxin. Surface exposed tyrosine residues in domain I of Etx-H149A (Y16, Y20, Y29, Y30, Y36 and Y196) were mutated to alanine and mutants Y30A and Y196A showed significantly reduced binding to MDCK.2 cells relative to Etx-H149A that correlated with their reduced cytotoxic activity. Thus, our study confirms the role of surface exposed tyrosine residues in domain I of Etx in binding to MDCK cells and the suitability of Etx-H149A for further receptor binding studies. In contrast, binding of all of the tyrosine mutants to ACHN cells was similar to that of Etx-H149A, suggesting that Etx can recognise different cell surface receptors. In support of this, the crystal structure of Etx-H149A identified a glycan (β-octyl-glucoside) binding site in domain III of Etx-H149A, which may be a second receptor binding site. These findings have important implications for developing strategies designed to neutralise toxin activity.

41 citations


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Journal ArticleDOI
TL;DR: The diverse pore architectures and membrane insertion mechanisms that have been revealed by structural studies of PFTs are discussed, and how these features contribute to binding specificity for different membrane targets are considered.
Abstract: Pore-forming toxins (PFTs) are virulence factors produced by many pathogenic bacteria and have long fascinated structural biologists, microbiologists and immunologists. Interestingly, pore-forming proteins with remarkably similar structures to PFTs are found in vertebrates and constitute part of their immune system. Recently, structural studies of several PFTs have provided important mechanistic insights into the metamorphosis of PFTs from soluble inactive monomers to cytolytic transmembrane assemblies. In this Review, we discuss the diverse pore architectures and membrane insertion mechanisms that have been revealed by these studies, and we consider how these features contribute to binding specificity for different membrane targets. Finally, we explore the potential of these structural insights to enable the development of novel therapeutic strategies that would prevent both the establishment of bacterial resistance and an excessive immune response.

571 citations

Journal ArticleDOI
TL;DR: It is established that C. perfringens uses chromosomally encoded alpha toxin and perfringolysin O (a pore-forming toxin) during histotoxic infections and this bacterium causes intestinal disease by employing toxins encoded by mobile genetic elements.
Abstract: Clostridium perfringens uses its arsenal of >16 toxins to cause histotoxic and intestinal infections in humans and animals. It has been unclear why this bacterium produces so many different toxins, especially since many target the plasma membrane of host cells. However, it is now established that C. perfringens uses chromosomally encoded alpha toxin (a phospholipase C) and perfringolysin O (a pore-forming toxin) during histotoxic infections. In contrast, this bacterium causes intestinal disease by employing toxins encoded by mobile genetic elements, including C. perfringens enterotoxin, necrotic enteritis toxin B-like, epsilon toxin and beta toxin. Like perfringolysin O, the toxins with established roles in intestinal disease form membrane pores. However, the intestinal disease-associated toxins vary in their target specificity, when they are produced (sporulation vs vegetative growth), and in their sensitivity to intestinal proteases. Producing many toxins with diverse characteristics likely imparts virulence flexibility to C. perfringens so it can cause an array of diseases.

299 citations

Book ChapterDOI
TL;DR: The remarkable progress made in the past 20 years in discovering novel Cry toxins and in elucidating complex mechanisms of Cry and Cyt toxin action are reviewed; subjects relevant to the long-term control of insects that damage crops and vector human disease.
Abstract: Parasporal crystals produced by Bacillus thuringiensis (Bt) bacteria are the main virulence factors underlying Bt toxicity to insects. Parasporal crystals are composed primarily of Cry and Cyt proteins that act on the midgut of susceptible insects. Cry proteins are an important component of Bt biopesticides and are vital tools for insect control via expression in transgenic crop plants. Some members of the Cry group are more distantly related including ETX/MTX and binary type toxins. Cry toxin structure and action involves critical steps in toxin activation, binding to receptors such as cadherin and then aminopeptidase or alkaline phosphatase probably in a ‘sequential binding’ manner. Specific Cry toxin–receptor interactions are a focus of this review. Recently, the importance of midgut ATP-binding cassette proteins to Cry intoxication of insects has been demonstrated. Mechanistic details involved in ‘sequential binding’ and ‘pore formation’ models are examined. The Cyt toxin of Bt subspecies israelensis is an important and interesting component in Cry–midgut interactions in mosquitoes. For some Cry toxins, Cyt serves as a receptor for docking to midgut membrane. Recent engineering work has demonstrated that Cyt can be re-targeted generating novel toxins for insect control. Overall, we review the remarkable progress made in the past 20 years in discovering novel Cry toxins and in elucidating complex mechanisms of Cry and Cyt toxin action; subjects relevant to the long-term control of insects that damage crops and vector human disease.

253 citations

Journal ArticleDOI
TL;DR: A review of the major characteristics of bacteriophages and phage-encoded proteins affecting their usefulness as antimicrobial agents and several issues such as mode of action, pharmacodynamics, pharmacokinetics, resistance and manufacturing aspects are discussed.
Abstract: The emergence of bacteria resistance to most of the currently available antibiotics has become a critical therapeutic problem. The bacteria causing both hospital and community-acquired infections are most often multidrug resistant. In view of the alarming level of antibiotic resistance between bacterial species and difficulties with treatment, alternative or supportive antibacterial cure has to be developed. The presented review focuses on the major characteristics of bacteriophages and phage-encoded proteins affecting their usefulness as antimicrobial agents. We discuss several issues such as mode of action, pharmacodynamics, pharmacokinetics, resistance and manufacturing aspects of bacteriophages and phage-encoded proteins application.

207 citations

Journal ArticleDOI
TL;DR: The presence of toxin genes on conjugative plasmids, particularly in association with insertion sequences that may mobilize these toxin genes, likely provides C. perfringens with considerable virulence plasticity and adaptability when it causes diseases originating in the gastrointestinal tract.
Abstract: In both humans and animals, Clostridium perfringens is an important cause of histotoxic infections and diseases originating in the intestines, such as enteritis and enterotoxemia. The virulence of this Gram-positive, anaerobic bacterium is heavily dependent upon its prolific toxin-producing ability. Many of the ∼16 toxins produced by C. perfringens are encoded by large plasmids that range in size from ∼45 kb to ∼140 kb. These plasmid-encoded toxins are often closely associated with mobile elements. A C. perfringens strain can carry up to three different toxin plasmids, with a single plasmid carrying up to three distinct toxin genes. Molecular Koch's postulate analyses have established the importance of several plasmid-encoded toxins when C. perfringens disease strains cause enteritis or enterotoxemias. Many toxin plasmids are closely related, suggesting a common evolutionary origin. In particular, most toxin plasmids and some antibiotic resistance plasmids of C. perfringens share an ∼35-kb region containing a Tn916-related conjugation locus named tcp (transfer of clostridial plasmids). This tcp locus can mediate highly efficient conjugative transfer of these toxin or resistance plasmids. For example, conjugative transfer of a toxin plasmid from an infecting strain to C. perfringens normal intestinal flora strains may help to amplify and prolong an infection. Therefore, the presence of toxin genes on conjugative plasmids, particularly in association with insertion sequences that may mobilize these toxin genes, likely provides C. perfringens with considerable virulence plasticity and adaptability when it causes diseases originating in the gastrointestinal tract.

206 citations