13 results on '"Stebbins, C. Erec"'
Search Results
2. Context-dependent protein folding of a virulence peptide in the bacterial and host environments: structure of an SycH-YopH chaperone-effector complex.
- Author
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Vujanac M and Stebbins CE
- Subjects
- Bacterial Proteins metabolism, Crystallography, X-Ray, Peptides metabolism, Protein Folding, Virulence Factors metabolism, Yersinia pestis chemistry, Bacterial Outer Membrane Proteins chemistry, Bacterial Proteins chemistry, Host-Pathogen Interactions, Molecular Chaperones chemistry, Peptides chemistry, Protein Tyrosine Phosphatases chemistry, Virulence Factors chemistry
- Abstract
Yersinia pestis injects numerous bacterial proteins into host cells through an organic nanomachine called the type 3 secretion system. One such substrate is the tyrosine phosphatase YopH, which requires an interaction with a cognate chaperone in order to be effectively injected. Here, the first crystal structure of a SycH-YopH complex is reported, determined to 1.9 Å resolution. The structure reveals the presence of (i) a nonglobular polypeptide in YopH, (ii) a so-called β-motif in YopH and (iii) a conserved hydrophobic patch in SycH that recognizes the β-motif. Biochemical studies establish that the β-motif is critical to the stability of this complex. Finally, since previous work has shown that the N-terminal portion of YopH adopts a globular fold that is functional in the host cell, aspects of how this polypeptide adopts radically different folds in the host and in the bacterial environments are analysed.
- Published
- 2013
- Full Text
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3. Structure of the HopA1(21-102)-ShcA chaperone-effector complex of Pseudomonas syringae reveals conservation of a virulence factor binding motif from animal to plant pathogens.
- Author
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Janjusevic R, Quezada CM, Small J, and Stebbins CE
- Subjects
- Amino Acid Motifs, Amino Acid Sequence, Animals, Bacterial Proteins genetics, Models, Molecular, Molecular Chaperones genetics, Mutation, Plants microbiology, Protein Binding, Protein Conformation, Pseudomonas syringae genetics, Pseudomonas syringae pathogenicity, Virulence Factors genetics, Bacterial Proteins metabolism, Gene Expression Regulation, Bacterial physiology, Molecular Chaperones metabolism, Pseudomonas syringae metabolism, Virulence Factors metabolism
- Abstract
Pseudomonas syringae injects numerous bacterial proteins into host plant cells through a type 3 secretion system (T3SS). One of the first such bacterial effectors discovered, HopA1, is a protein that has unknown functions in the host cell but possesses close homologs that trigger the plant hypersensitive response in resistant strains. Like the virulence factors in many bacterial pathogens of animals, HopA1 depends upon a cognate chaperone in order to be effectively translocated by the P. syringae T3SS. Herein, we report the crystal structure of a complex of HopA1(21-102) with its chaperone, ShcA, determined to 1.56-Å resolution. The structure reveals that three key features of the chaperone-effector interactions found in animal pathogens are preserved in the Gram-negative pathogens of plants, namely, (i) the interaction of the chaperone with a nonglobular polypeptide of the effector, (ii) an interaction centered on the so-called β-motif, and (iii) the presence of a conserved hydrophobic patch in the chaperone that recognizes the β-motif. Structure-based mutagenesis and biochemical studies have established that the β-motif is critical for the stability of this complex. Overall, these results show that the β-motif interactions are broadly conserved in bacterial pathogens utilizing T3SSs, spanning an interkingdom host range.
- Published
- 2013
- Full Text
- View/download PDF
4. Structure of the catalytic domain of the Salmonella virulence factor SseI.
- Author
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Bhaskaran SS and Stebbins CE
- Subjects
- Amino Acid Sequence, Catalytic Domain, Cloning, Molecular, Crystallization, Models, Molecular, Molecular Sequence Data, Protein Conformation, Proteolysis, Salmonella pathogenicity, Virulence Factors chemistry, Virulence Factors genetics, Virulence Factors isolation & purification, Salmonella metabolism, Virulence, Virulence Factors metabolism
- Abstract
SseI is secreted into host cells by Salmonella and contributes to the establishment of systemic infections. The crystal structure of the C-terminal domain of SseI has been solved to 1.70 Å resolution, revealing it to be a member of the cysteine protease superfamily with a catalytic triad consisting of Cys178, His216 and Asp231 that is critical to its virulence activities. Structure-based analysis revealed that SseI is likely to possess either acyl hydrolase or acyltransferase activity, placing this virulence factor in the rapidly growing class of enzymes of this family utilized by bacterial pathogens inside eukaryotic cells.
- Published
- 2012
- Full Text
- View/download PDF
5. A family of Salmonella virulence factors functions as a distinct class of autoregulated E3 ubiquitin ligases.
- Author
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Quezada CM, Hicks SW, Galán JE, and Stebbins CE
- Subjects
- Bacterial Proteins chemistry, Catalytic Domain, Crystallography, X-Ray, Enzyme Activation, HeLa Cells, Humans, Models, Molecular, Protein Structure, Secondary, Protein Structure, Tertiary, Protein Transport, Ubiquitin-Protein Ligases chemistry, Ubiquitination, Bacterial Proteins metabolism, Salmonella typhimurium enzymology, Salmonella typhimurium pathogenicity, Ubiquitin-Protein Ligases metabolism, Virulence Factors metabolism
- Abstract
Processes as diverse as receptor binding and signaling, cytoskeletal dynamics, and programmed cell death are manipulated by mimics of host proteins encoded by pathogenic bacteria. We show here that the Salmonella virulence factor SspH2 belongs to a growing class of bacterial effector proteins that harness and subvert the eukaryotic ubiquitination pathway. This virulence protein possesses ubiquitination activity that depends on a conserved cysteine residue. A crystal structure of SspH2 reveals a canonical leucine-rich repeat (LRR) domain that interacts with a unique E3 ligase [which we have termed NEL for Novel E3 Ligase] C-terminal fold unrelated to previously observed HECT or RING-finger E3 ligases. Moreover, the LRR domain sequesters the catalytic cysteine residue contained in the NEL domain, and we suggest a mechanism for activation of the ligase requiring a substantial conformational change to release the catalytic domain for function. We also show that the N-terminal domain targets SspH2 to the apical plasma membrane of polarized epithelial cells and propose a model whereby binding of the LRR to proteins at the target site releases the ligase domain for site-specific function.
- Published
- 2009
- Full Text
- View/download PDF
6. Targeting plague virulence factors: a combined machine learning method and multiple conformational virtual screening for the discovery of Yersinia protein kinase A inhibitors.
- Author
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Hu X, Prehna G, and Stebbins CE
- Subjects
- Amino Acid Sequence, Anthraquinones chemistry, Artificial Intelligence, Bacterial Proteins antagonists & inhibitors, Indoles chemistry, Mitogen-Activated Protein Kinases chemistry, Models, Molecular, Molecular Conformation, Molecular Sequence Data, Protein Kinase C chemistry, Protein Serine-Threonine Kinases antagonists & inhibitors, Pyrimidines chemistry, Quantitative Structure-Activity Relationship, Sequence Homology, Amino Acid, Virulence Factors antagonists & inhibitors, Anti-Bacterial Agents chemistry, Bacterial Proteins chemistry, Plague microbiology, Protein Kinase Inhibitors chemistry, Protein Serine-Threonine Kinases chemistry, Virulence Factors chemistry, Yersinia enzymology
- Abstract
Yersinia spp. is currently an antibiotic resistance concern and a re-emerging disease. The essential virulence factor Yersinia protein kinase A (YpkA) contains a Ser/Thr kinase domain whose activity modulates pathogenicity. Here, we present an approach integrating a machine learning method, homology modeling, and multiple conformational high-throughput docking for the discovery of YpkA inhibitors. These first reported inhibitors of YpkA may facilitate studies of the pathogenic mechanism of YpkA and serve as a starting point for development of anti-plague drugs.
- Published
- 2007
- Full Text
- View/download PDF
7. Yersinia virulence depends on mimicry of host Rho-family nucleotide dissociation inhibitors.
- Author
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Prehna G, Ivanov MI, Bliska JB, and Stebbins CE
- Subjects
- Amino Acid Sequence, Animals, Bacterial Proteins chemistry, Bacterial Proteins genetics, Cell Line, Crystallography, Cytoskeleton metabolism, Guanine Nucleotide Dissociation Inhibitors chemistry, Humans, Intestinal Mucosa metabolism, Mice, Models, Molecular, Molecular Sequence Data, Mutation, Protein Serine-Threonine Kinases chemistry, Protein Serine-Threonine Kinases genetics, Transfection, Virulence Factors chemistry, Virulence Factors genetics, Yersinia pseudotuberculosis enzymology, Yersinia pseudotuberculosis metabolism, cdc42 GTP-Binding Protein chemistry, cdc42 GTP-Binding Protein metabolism, rac1 GTP-Binding Protein chemistry, rho-Specific Guanine Nucleotide Dissociation Inhibitors, rhoA GTP-Binding Protein chemistry, rhoA GTP-Binding Protein metabolism, Bacterial Proteins metabolism, Guanine Nucleotide Dissociation Inhibitors metabolism, Molecular Mimicry, Protein Serine-Threonine Kinases metabolism, Virulence Factors metabolism, Yersinia pseudotuberculosis pathogenicity, rac1 GTP-Binding Protein metabolism
- Abstract
Yersinia spp. cause gastroenteritis and the plague, representing historically devastating pathogens that are currently an important biodefense and antibiotic resistance concern. A critical virulence determinant is the Yersinia protein kinase A, or YpkA, a multidomain protein that disrupts the eukaryotic actin cytoskeleton. Here we solve the crystal structure of a YpkA-Rac1 complex and find that YpkA possesses a Rac1 binding domain that mimics host guanidine nucleotide dissociation inhibitors (GDIs) of the Rho GTPases. YpkA inhibits nucleotide exchange in Rac1 and RhoA, and mutations that disrupt the YpkA-GTPase interface abolish this activity in vitro and impair in vivo YpkA-induced cytoskeletal disruption. In cell culture experiments, the kinase and the GDI domains of YpkA act synergistically to promote cytoskeletal disruption, and a Y. pseudotuberculosis mutant lacking YpkA GDI activity shows attenuated virulence in a mouse infection assay. We conclude that virulence in Yersinia depends strongly upon mimicry of host GDI proteins by YpkA.
- Published
- 2006
- Full Text
- View/download PDF
8. A steric antagonism of actin polymerization by a salmonella virulence protein.
- Author
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Margarit SM, Davidson W, Frego L, and Stebbins CE
- Subjects
- ADP Ribose Transferases genetics, ADP Ribose Transferases metabolism, Actins genetics, Amino Acid Sequence, Crystallography, X-Ray, Mass Spectrometry, Molecular Sequence Data, Protein Conformation, Virulence Factors genetics, Virulence Factors metabolism, ADP Ribose Transferases chemistry, Actins chemistry, Actins metabolism, Models, Molecular, Salmonella chemistry, Virulence Factors chemistry
- Abstract
Salmonella spp. require the ADP-ribosyltransferase activity of the SpvB protein for intracellular growth and systemic virulence. SpvB covalently modifies actin, causing cytoskeletal disruption and apoptosis. We report here the crystal structure of the catalytic domain of SpvB, and we show by mass spectrometric analysis that SpvB modifies actin at Arg177, inhibiting its ATPase activity. We also describe two crystal structures of SpvB-modified, polymerization-deficient actin. These structures reveal that ADP-ribosylation does not lead to dramatic conformational changes in actin, suggesting a model in which this large family of toxins inhibits actin polymerization primarily through steric disruption of intrafilament contacts.
- Published
- 2006
- Full Text
- View/download PDF
9. A common structural motif in the binding of virulence factors to bacterial secretion chaperones.
- Author
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Lilic M, Vujanac M, and Stebbins CE
- Subjects
- Amino Acid Motifs physiology, Amino Acid Sequence, Bacterial Proteins metabolism, Bacterial Proteins physiology, Crystallography, X-Ray, Gene Targeting, Microfilament Proteins physiology, Molecular Sequence Data, Protein Binding physiology, Protein Structure, Tertiary, Salmonella typhimurium chemistry, Salmonella typhimurium physiology, Bacterial Proteins chemistry, Microfilament Proteins chemistry, Molecular Chaperones metabolism, Virulence Factors chemistry, Virulence Factors metabolism
- Abstract
Salmonella invasion protein A (SipA) is translocated into host cells by a type III secretion system (T3SS) and comprises two regions: one domain binds its cognate type III secretion chaperone, InvB, in the bacterium to facilitate translocation, while a second domain functions in the host cell, contributing to bacterial uptake by polymerizing actin. We present here the crystal structures of the SipA chaperone binding domain (CBD) alone and in complex with InvB. The SipA CBD is found to consist of a nonglobular polypeptide as well as a large globular domain, both of which are necessary for binding to InvB. We also identify a structural motif that may direct virulence factors to their cognate chaperones in a diverse range of pathogenic bacteria. Disruption of this structural motif leads to a destabilization of several chaperone-substrate complexes from different species, as well as an impairment of secretion in Salmonella.
- Published
- 2006
- Full Text
- View/download PDF
10. Structural microbiology at the pathogen-host interface.
- Author
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Stebbins CE
- Subjects
- Animals, Bacterial Adhesion physiology, Bacterial Proteins chemistry, Cadherins metabolism, Models, Molecular, Molecular Chaperones chemistry, Protein Binding, Protein Conformation, Virulence Factors chemistry, Bacterial Physiological Phenomena, Bacterial Proteins metabolism, Bacterial Toxins metabolism, Molecular Chaperones metabolism, Virulence Factors metabolism
- Abstract
Bacterial pathogens achieve the internalization of a multitude of virulence factors into eukaryotic cells. Some secrete extracellular toxins which bring about their own entry, usually by hijacking cell surface receptors and endocytic pathways. Others possess specialized secretion and translocation systems to directly inject bacterial proteins into the host cytosol. Recent advances in the structural biology of these virulence factors has begun to reveal at the molecular level how these bacterial proteins are delivered and modulate host activities ranging from cytoskeletal structure to cell cycle progression.
- Published
- 2005
- Full Text
- View/download PDF
11. Computational analysis of tyrosine phosphatase inhibitor selectivity for the virulence factors YopH and SptP.
- Author
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Hu X, Vujanac M, and Stebbins CE
- Subjects
- Bacterial Outer Membrane Proteins chemistry, Binding Sites, Drug Design, Enzyme Inhibitors chemistry, Models, Molecular, Molecular Structure, Protein Conformation, Protein Tyrosine Phosphatase, Non-Receptor Type 1, Protein Tyrosine Phosphatases chemistry, Salmonella enzymology, Salmonella pathogenicity, Thermodynamics, Virulence Factors chemistry, Yersinia enzymology, Yersinia pathogenicity, Bacterial Outer Membrane Proteins antagonists & inhibitors, Enzyme Inhibitors pharmacology, Protein Tyrosine Phosphatases antagonists & inhibitors, Virulence Factors antagonists & inhibitors
- Abstract
Bacterial pathogens such as Yersinia and Salmonella represent an important medical concern, causing human diseases ranging from gastrointestinal disease to the plague. The development of novel treatments of these bacterial infections has gained high priority recently due to the emergence of antibiotic resistance in these pathogens and the threat of the use of microbial agents as biological weapons. YopH of Yersinia and SptP of Salmonella are virulence factors that belong to the family of protein tyrosine phosphatases (PTPs). A great challenge remains in the design of selective PTPs inhibitors due to their highly conserved active site. In this paper, we present a comparative docking study to probe the selective inhibition of YopH and SptP with PTP1B in order to better understand their binding interactions with the bacterial tyrosine phosphates. Characterized binding sites in PTP1B were compared with YopH and SptP. Molecular dynamics simulations were used to incorporate ligand-induced conformational changes in the binding sites. These results, together with those binding modes and binding affinities distinguished in individual PTPs, provide insight into the structure-based design of inhibitors for YopH and SptP.
- Published
- 2004
- Full Text
- View/download PDF
12. Priming virulence factors for delivery into the host.
- Author
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Stebbins CE and Galán JE
- Subjects
- Animals, Humans, Gram-Negative Bacteria pathogenicity, Molecular Chaperones metabolism, Virulence Factors metabolism
- Abstract
Several medically important Gram-negative bacterial pathogens inject virulence factors into host cells through a type III secretion system and specialized bacterial chaperones are required for their effective delivery. Recent structural work shows that these chaperones maintain virulence factors in a partially non-globular conformation that is primed for unfolding and translocation through the 'injectisome'.
- Published
- 2003
- Full Text
- View/download PDF
13. Type 3 Secretion Systems Shape Up as They Ship Out
- Author
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Marlovits, Thomas C. and Stebbins, C. Erec
- Subjects
Protein Folding ,Bacterial Proteins ,Models, Chemical ,Macromolecular Substances ,Virulence Factors ,Membrane Transport Proteins ,Models, Biological ,Article ,Protein Binding - Abstract
Virulence associated protein type III secretion systems (T3SSs) are intricately structured organic nanosyringes that achieve the translocation of bacterial proteins from the prokaryotic cytoplasm across three membranes into the host cytosol. The substrates for these systems number in the hundreds, with remarkably diverse biological activities, modulating host cell biology for the benefit of the pathogen. Although there has been tremendous progress on the structure and function of the T3SS substrates, there has been comparatively little progress on the much more highly conserved secretion apparatus itself. This review summarizes recent advances in the field of structural microbiology that have begun to address this shortcoming, finally bringing to bear the power of structural biology to this central virulence system of Gram-negative bacterial pathogens.
- Published
- 2009
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