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Rodney K. Tweten

Bio: Rodney K. Tweten is an academic researcher from University of Oklahoma Health Sciences Center. The author has contributed to research in topics: Cholesterol-dependent cytolysin & MACPF. The author has an hindex of 52, co-authored 111 publications receiving 8056 citations. Previous affiliations of Rodney K. Tweten include University of California, Los Angeles & University of Pennsylvania.


Papers
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Journal ArticleDOI
TL;DR: The cholesterol-dependent cytolysins are a large family of pore-forming toxins that are produced by more than 20 species from the genera Clostridium, Streptococcus, Listeria, Bacillus, and Arcanobacterium.
Abstract: The cholesterol-dependent cytolysins (CDCs) are a large family of pore-forming toxins that are produced by more than 20 species from the genera Clostridium , Streptococcus , Listeria , Bacillus , and Arcanobacterium . The pore-forming mechanism of these toxins exhibits two hallmark characteristics:

465 citations

Journal ArticleDOI
30 May 1997-Cell
TL;DR: The first crystal structure of a thiol-activated cytolysin, perfringolysin O, a member of a large family of toxins that kill eukaryotic cells by punching holes in their membranes is presented.

461 citations

Journal ArticleDOI
29 Oct 1999-Cell
TL;DR: The insertion of two transmembrane hairpins per toxin monomer and the major change in secondary structure are striking and define a novel paradigm for the mechanism of membrane insertion by a cytolytic toxin.

355 citations

Journal ArticleDOI
TL;DR: Evidence is presented of a significant difference in the height by which the prepore and pore protrude from the membrane surface; this results in combination with those of spectrofluorimetric analyses indicate that the monomers remain in a perpendicular orientation to the bilayer plane during this transition.
Abstract: Perfringolysin O (PFO) is a prototype of the large family of pore-forming cholesterol-dependent cytolysins (CDCs). A central enigma of the cytolytic mechanism of the CDCs is that their membrane-spanning β-hairpins (the transmembrane amphipathic β-hairpins (TMHs)) appear to be ∼40 A too far above the membrane surface to cross the bilayer and form the pore. We now present evidence, using atomic force microscopy (AFM), of a significant difference in the height by which the prepore and pore protrude from the membrane surface: 113±5 A for the prepore but only 73±5 A for the pore. Time-lapse AFM micrographs show this change in height in real time. Moreover, the monomers in both complexes exhibit nearly identical surface features and these results in combination with those of spectrofluorimetric analyses indicate that the monomers remain in a perpendicular orientation to the bilayer plane during this transition. Therefore, the PFO undergoes a vertical collapse that brings its TMHs to the membrane surface so that they can extend across the bilayer to form the β-barrel pore.

239 citations

Journal ArticleDOI
TL;DR: It is shown that ILY, via its domain 4 structure, binds to the glycosyl-phosphatidylinositol–linked membrane protein human CD59 (huCD59), an inhibitor of the membrane attack complex of human complement.
Abstract: Cholesterol is believed to serve as the common receptor for the cholesterol-dependent cytolysins (CDCs). One member of this toxin family, Streptococcus intermedius intermedilysin (ILY), exhibits a narrow spectrum of cellular specificity that is seemingly inconsistent with this premise. We show here that ILY, via its domain 4 structure, binds to the glycosyl-phosphatidylinositol-linked membrane protein human CD59 (huCD59). CD59 is an inhibitor of the membrane attack complex of human complement. ILY specifically binds to huCD59 via residues that are the binding site for the C8alpha and C9 complement proteins. These studies provide a new model for the mechanism of cellular recognition by a CDC.

230 citations


Cited by
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Journal ArticleDOI
TL;DR: The molecular determinants of Listeria virulence and their mechanism of action are described and the current knowledge on the pathophysiology of listeriosis and the cell biology and host cell responses to Listersia infection is summarized.
Abstract: The gram-positive bacterium Listeria monocytogenes is the causative agent of listeriosis, a highly fatal opportunistic foodborne infection. Pregnant women, neonates, the elderly, and debilitated or immunocompromised patients in general are predominantly affected, although the disease can also develop in normal individuals. Clinical manifestations of invasive listeriosis are usually severe and include abortion, sepsis, and meningoencephalitis. Listeriosis can also manifest as a febrile gastroenteritis syndrome. In addition to humans, L. monocytogenes affects many vertebrate species, including birds. Listeria ivanovii, a second pathogenic species of the genus, is specific for ruminants. Our current view of the pathophysiology of listeriosis derives largely from studies with the mouse infection model. Pathogenic listeriae enter the host primarily through the intestine. The liver is thought to be their first target organ after intestinal translocation. In the liver, listeriae actively multiply until the infection is controlled by a cell-mediated immune response. This initial, subclinical step of listeriosis is thought to be common due to the frequent presence of pathogenic L. monocytogenes in food. In normal indivuals, the continual exposure to listerial antigens probably contributes to the maintenance of anti-Listeria memory T cells. However, in debilitated and immunocompromised patients, the unrestricted proliferation of listeriae in the liver may result in prolonged low-level bacteremia, leading to invasion of the preferred secondary target organs (the brain and the gravid uterus) and to overt clinical disease. L. monocytogenes and L. ivanovii are facultative intracellular parasites able to survive in macrophages and to invade a variety of normally nonphagocytic cells, such as epithelial cells, hepatocytes, and endothelial cells. In all these cell types, pathogenic listeriae go through an intracellular life cycle involving early escape from the phagocytic vacuole, rapid intracytoplasmic multiplication, bacterially induced actin-based motility, and direct spread to neighboring cells, in which they reinitiate the cycle. In this way, listeriae disseminate in host tissues sheltered from the humoral arm of the immune system. Over the last 15 years, a number of virulence factors involved in key steps of this intracellular life cycle have been identified. This review describes in detail the molecular determinants of Listeria virulence and their mechanism of action and summarizes the current knowledge on the pathophysiology of listeriosis and the cell biology and host cell responses to Listeria infection. This article provides an updated perspective of the development of our understanding of Listeria pathogenesis from the first molecular genetic analyses of virulence mechanisms reported in 1985 until the start of the genomic era of Listeria research.

2,139 citations

Journal ArticleDOI
15 Feb 2013-Science
TL;DR: Cytosolic DNA induces type I interferons and other cytokines that are important for antimicrobial defense but can also result in autoimmunity, and cGAMP functions as an endogenous second messenger in metazoans and triggers interferon production in response to cytosolicDNA.
Abstract: Cytosolic DNA induces type I interferons and other cytokines that are important for antimicrobial defense but can also result in autoimmunity. This DNA signaling pathway requires the adaptor protein STING and the transcription factor IRF3, but the mechanism of DNA sensing is unclear. We found that mammalian cytosolic extracts synthesized cyclic guanosine monophosphate–adenosine monophosphate (cyclic GMP-AMP, or cGAMP) in vitro from adenosine triphosphate and guanosine triphosphate in the presence of DNA but not RNA. DNA transfection or DNA virus infection of mammalian cells also triggered cGAMP production. cGAMP bound to STING, leading to the activation of IRF3 and induction of interferon-β. Thus, cGAMP functions as an endogenous second messenger in metazoans and triggers interferon production in response to cytosolic DNA.

1,667 citations

Journal ArticleDOI
TL;DR: The 'new view' of these diseases suggests that other degenerative conditions could have similar underlying origins to those of the amyloidoses, and suggests some intriguing new factors that could be of great significance in the evolution of biological molecules and the mechanisms that regulate their behaviour.
Abstract: The deposition of proteins in the form of amyloid fibrils and plaques is the characteristic feature of more than 20 degenerative conditions affecting either the central nervous system or a variety of peripheral tissues. As these conditions include Alzheimer's, Parkinson's and the prion diseases, several forms of fatal systemic amyloidosis, and at least one condition associated with medical intervention (haemodialysis), they are of enormous importance in the context of present-day human health and welfare. Much remains to be learned about the mechanism by which the proteins associated with these diseases aggregate and form amyloid structures, and how the latter affect the functions of the organs with which they are associated. A great deal of information concerning these diseases has emerged, however, during the past 5 years, much of it causing a number of fundamental assumptions about the amyloid diseases to be re-examined. For example, it is now apparent that the ability to form amyloid structures is not an unusual feature of the small number of proteins associated with these diseases but is instead a general property of polypeptide chains. It has also been found recently that aggregates of proteins not associated with amyloid diseases can impair the ability of cells to function to a similar extent as aggregates of proteins linked with specific neurodegenerative conditions. Moreover, the mature amyloid fibrils or plaques appear to be substantially less toxic than the pre-fibrillar aggregates that are their precursors. The toxicity of these early aggregates appears to result from an intrinsic ability to impair fundamental cellular processes by interacting with cellular membranes, causing oxidative stress and increases in free Ca2+ that eventually lead to apoptotic or necrotic cell death. The 'new view' of these diseases also suggests that other degenerative conditions could have similar underlying origins to those of the amyloidoses. In addition, cellular protection mechanisms, such as molecular chaperones and the protein degradation machinery, appear to be crucial in the prevention of disease in normally functioning living organisms. It also suggests some intriguing new factors that could be of great significance in the evolution of biological molecules and the mechanisms that regulate their behaviour.

1,607 citations

Journal ArticleDOI
07 Jul 2016-Nature
TL;DR: It is demonstrated that the liposome-leakage and pore-forming activities of the gasdermin-N domain are required for pyroptosis and provide insights into the roles of theGasdermin family in necrosis, immunity and diseases.
Abstract: The N-terminal domains of gasdermin proteins cause pyroptotic cell death by oligomerizing to form membrane pores.

1,567 citations

Journal Article
TL;DR: The similarity of clinical response to invasive infection by Gram-positive and Gram-negative bacteria is due to bacterial recognition via similar TLRs, and a soluble preparation of peptidoglycan prepared from S. aureus was tested.
Abstract: Invasive infection with Gram-positive and Gram-negative bacteria often results in septic shock and death. The basis for the earliest steps in innate immune response to Gram-positive bacterial infection is poorly understood. The LPS component of the Gram-negative bacterial cell wall appears to activate cells via CD14 and Toll-like receptor (TLR) 2 and TLR4. We hypothesized that Gram-positive bacteria might also be recognized by TLRs. Heterologous expression of human TLR2, but not TLR4, in fibroblasts conferred responsiveness to Staphylococcus aureus and Streptococcus pneumoniae as evidenced by inducible translocation of NF-kappaB. CD14 coexpression synergistically enhanced TLR2-mediated activation. To determine which components of Gram-positive cell walls activate Toll proteins, we tested a soluble preparation of peptidoglycan prepared from S. aureus. Soluble peptidoglycan substituted for whole organisms. These data suggest that the similarity of clinical response to invasive infection by Gram-positive and Gram-negative bacteria is due to bacterial recognition via similar TLRs.

1,291 citations