scholarly journals Directionality of substrate translocation of the hemolysin A Type I secretion system

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Michael H. H. Lenders ◽  
Stefanie Weidtkamp-Peters ◽  
Diana Kleinschrodt ◽  
Karl-Erich Jaeger ◽  
Sander H. J. Smits ◽  
...  
Keyword(s):  
Type I ◽  
Bacterial Cells ◽  
Secretion Systems ◽  
Membrane Protein Complex ◽  
E Coli ◽  
C Terminus ◽  
One Step ◽  
C And N ◽  
Vectorial Transport

Abstract Type 1 secretion systems (T1SS) of Gram-negative bacteria are responsible for the secretion of various proteases, lipases, S-layer proteins or toxins into the extracellular space. The paradigm of these systems is the hemolysin A (HlyA) T1SS of Escherichia coli. This multiple membrane protein complex is able to secrete the toxin HlyA in one step across both E. coli membranes. Common to all secreted T1SS substrates is a C-terminal secretion sequence being necessary as well as sufficient for secretion. However, it is not known whether transport occurs directionally, i.e. the N- or the C-terminus of T1SS substrates is secreted first. We have addressed this question by constructing HlyA fusions with the rapidly folding eGFP resulting in a stalled T1SS. Differential labeling and subsequent fluorescence microscopic detection of C- and N-terminal parts of the fusions allowed us to demonstrate vectorial transport of HlyA through the T1SS with the C-terminus appearing first outside the bacterial cells.

Comparison of colony and stool blots for detection of enteropathogens by DNA probes

1991 ◽  
Vol 37 (5) ◽  
pp. 407-410
Author(s):  
Mônica A. M. Vieira ◽  
Beatriz E. C. Guth ◽  
Tânia A. T. Gomes
Keyword(s):  
Escherichia Coli ◽  
Key Words ◽  
Sensitivity And Specificity ◽  
Dna Probes ◽  
Type I ◽  
Enteropathogenic Escherichia Coli ◽  
Key Words Dna ◽  
E Coli ◽  
Heat Stable

DNA probes that identify genes coding for heat-labile type I (LT-I) and heat-stable type 1 (ST-I) enterotoxins, enteropathogenic Escherichia coli adherence factor (EAF), and Shigella-like, invasiveness (INV) are used to evaluate the sensitivity and specificity of stool blots in comparison with the sensitivity and specificity of colony blots in detecting enteropathoghens. The sensitivities of the probes in stool blots are 91.7% for the LT-I probe, 76.9% for the ST-I probes, 78.9% for the EAF probe, and 45.5% for the INV probe. The specificity of all probes is higher than 95%. In general, the stool blot method identifies as many if not more LT-I-, ST-I-, and EAF-producing E. coli infections than the colony blots. Key words: DNA probes, stool blots, enteropathogens, diagnosis.

One-Step Preparation of Competent E. coli: Transformation and Storage of Bacterial Cells in the Same Solution

2021 ◽  
Vol 2021 (11) ◽  
pp. pdb.prot101212 ◽  
Author(s):  
Michael R. Green ◽  
Joseph Sambrook
Keyword(s):  
Escherichia Coli ◽  
Convenient Method ◽  
Plasmid Dna ◽  
Transformation Efficiency ◽  
Bacterial Cells ◽  
E Coli ◽  
One Step ◽  
And Storage

This protocol describes a convenient method for the preparation, use, and storage of competent Escherichia coli. The reported transformation efficiency of this method is ∼5 × 107 transformants/µg of plasmid DNA.

scholarly journals In vivoR–plasmid transfer in a patient with a mixed infection of shigella dysentery

1994 ◽  
Vol 112 (2) ◽  
pp. 247-252 ◽  
Author(s):  
M. P. Bratoeva ◽  
J. F. John.
Keyword(s):  
Antimicrobial Agents ◽  
Shigella Flexneri ◽  
Plasmid Transfer ◽  
Shigella Dysenteriae ◽  
Type I ◽  
E Coli ◽  
R Plasmids ◽  
Short Time

SUMMARYTransfer of shigella R–plasmidsin vivohas seldom been demonstrated. Strains ofShigella dysenteriaetype 1 andShigella flexneritype 5b were isolated from a Bulgarian traveller who visited Vietnam and developed dysentery, which was treated with trimethoprim/sulfamethoxazole (TMP/SMZ) for a short time. Both species of shigellae are unusual in Bulgaria where strains ofS. sonneipredominate. Both shigella strains were multiresistant to the same antimicrobial agents. Each strain contained a 48–kilobase plasmid that conferred the entire resistance phenotype to a susceptibleEscherichia coli. Restriction endonuclease patterns of plasmid DNA from the respective strains were identical. Transmissible plasmids of the same resistance phenotypes and restriction patterns were isolated from the patient's colonicE. coli. Transconjugants hybridized to a dihydrofolate reductase type I–DNA probe. These studies support the hypothesis that R–plasmid transfer may occur between non-pathogenic, faecal strains and pathogenic shigellae, a process that may have been facilitated by inadequate treatment with TMP/SMZ at the onset of the illness.

scholarly journals Characterization of three osteogenesis imperfecta collagen α 1(I) glycine to serine mutations demonstrating a position-dependent gradient of phenotypic severity

1992 ◽  
Vol 288 (1) ◽  
pp. 131-135 ◽  
Author(s):  
J F Bateman ◽  
I Moeller ◽  
M Hannagan ◽  
D Chan ◽  
W G Cole
Keyword(s):  
Osteogenesis Imperfecta ◽  
Triple Helix ◽  
Type I Collagen ◽  
Type I ◽  
Disruptive Effect ◽  
Collagen Triple Helix ◽  
C Terminus ◽  
Glycine Substitution ◽  
C And N

Type I collagen alpha 1(I) glycine to serine substitutions, resulting from G-to-A mutations, were defined in three cases of osteogenesis imperfecta (OI). The Gly substitutions displayed a gradient of phenotypic severity according to the location of the mutation in the collagen triple helix. The most C-terminal of these, Gly565 to Ser, led to the lethal perinatal (type II) form of OI, whereas the more N-terminal mutations, Gly415 and Gly352 to Ser, led to severe OI (type III/IV) and moderate OI (type IVB) respectively. These data support the notion that glycine substitutions towards the C-terminus of the alpha 1(I) or alpha 2(I) chains will be more clinically severe than those towards the N-terminus. This results from the more disruptive effect of the mutations at the C-terminus on helix initiation and C- and N-terminal helix directional propagation. This generalization must be modified by considering the nature of the glycine substitution and the surrounding amino acid sequence, since the helix is composed of subdomains of differing stability which will affect the ability of helix re-nucleation and propagation.

scholarly journals Glycine acylation and trafficking of a new class of bacterial lipoprotein by a composite secretion system

2020 ◽  
Author(s):  
Christopher Icke ◽  
Freya J. Hodges ◽  
Karthik Puella ◽  
Samantha A. McKeand ◽  
Jack A. Bryant ◽  
...  
Keyword(s):  
Composite System ◽  
Cysteine Residue ◽  
Secretion System ◽  
Type I ◽  
Secretion Systems ◽  
Cellular Functions ◽  
E Coli ◽  
New Class ◽  
Secretion Pathway ◽  
Bacterial Lipoprotein

AbstractProtein acylation is critical for many cellular functions including signal transduction, cell division and development. In bacteria, such lipoproteins have important roles in virulence and are therefore potential targets for the development of novel antimicrobials and vaccines. To date, all known bacterial lipoproteins are secreted from the cytosol via the Sec pathway, acylated on an N-terminal cysteine residue through the action of Lgt, Lsp and Lnt, and then targeted to the appropriate cellular location. In the case of Gram-negative bacteria, the lipoprotein trafficking Lol pathway transports the lipoproteins to the outer membrane where most substrate molecules are retained within the cell. Here we identify a new secretion pathway that displays the substrate lipoprotein on the cell surface. We demonstrate that the previously identified E. coli Aat secretion system is a composite system that shares similarity with type I secretion systems and elements of the Lol pathway. Remarkably, during secretion by the Aat system, the AatD subunit acylates the substrate CexE on a highly conserved N-terminal glycine residue (rather than the canonical cysteine). Mutations in AatD or CexE that disrupt glycine acylation interfere with membrane incorporation and trafficking. Our data suggest that CexE is the first member of a new class of glycine-acylated bacterial lipoprotein, while Aat represents a new secretion system that we propose be defined as a lipoprotein secretion system (LSS).

scholarly journals Functional Type 1 Secretion System Involved in Legionella pneumophila Virulence

2014 ◽  
Vol 197 (3) ◽  
pp. 563-571 ◽  
Author(s):  
Fabien Fuche ◽  
Anne Vianney ◽  
Claire Andrea ◽  
Patricia Doublet ◽  
Christophe Gilbert
Keyword(s):  
Legionella Pneumophila ◽  
Severe Form ◽  
Secretion System ◽  
Host Cells ◽  
Type I ◽  
Secretion Systems ◽  
Content Type ◽  
Legionnaires Disease ◽  
Infectious Cycle

Legionella pneumophilais a Gram-negative pathogen found mainly in water, either in a free-living form or within infected protozoans, where it replicates. This bacterium can also infect humans by inhalation of contaminated aerosols, causing a severe form of pneumonia called legionellosis or Legionnaires' disease. The involvement of type II and IV secretion systems in the virulence ofL. pneumophilais now well documented. Despite bioinformatic studies showing that a type I secretion system (T1SS) could be present in this pathogen, the functionality of this system based on the LssB, LssD, and TolC proteins has never been established. Here, we report the demonstration of the functionality of the T1SS, as well as its role in the infectious cycle ofL. pneumophila. Using deletion mutants and fusion proteins, we demonstrated that therepeats-in-toxin protein RtxA is secreted through an LssB-LssD-TolC-dependent mechanism. Moreover, fluorescence monitoring and confocal microscopy showed that this T1SS is required for entry into the host cell, although it seems dispensable to the intracellular cycle. Together, these results underline the active participation ofL. pneumophila, via its T1SS, in its internalization into host cells.

scholarly journals The S. Typhi effector StoD is an E3/E4 ubiquitin ligase which binds K48- and K63-linked diubiquitin

2019 ◽  
Vol 2 (3) ◽  
pp. e201800272
Author(s):  
Melanie A McDowell ◽  
Alexander MP Byrne ◽  
Elli Mylona ◽  
Rebecca Johnson ◽  
Agnes Sagfors ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Type Iii Secretion ◽  
Intracellular Signaling ◽  
Binding Assays ◽  
Secretion Systems ◽  
E Coli ◽  
T3ss Effector ◽  
C Terminus ◽  
Type Iii Secretion Systems ◽  
Β Sheet

Salmonella enterica (e.g., serovars Typhi and Typhimurium) relies on translocation of effectors via type III secretion systems (T3SS). Specialization of typhoidal serovars is thought to be mediated via pseudogenesis. Here, we show that the Salmonella Typhi STY1076/t1865 protein, named StoD, a homologue of the enteropathogenic Escherichia coli/enterohemorrhagic E. coli/Citrobacter rodentium NleG, is a T3SS effector. The StoD C terminus (StoD-C) is a U-box E3 ubiquitin ligase, capable of autoubiquitination in the presence of multiple E2s. The crystal structure of the StoD N terminus (StoD-N) at 2.5 Å resolution revealed a ubiquitin-like fold. In HeLa cells expressing StoD, ubiquitin is redistributed into puncta that colocalize with StoD. Binding assays showed that StoD-N and StoD-C bind the same exposed surface of the β-sheet of ubiquitin, suggesting that StoD could simultaneously interact with two ubiquitin molecules. Consistently, StoD interacted with both K63- (KD = 5.6 ± 1 μM) and K48-linked diubiquitin (KD = 15 ± 4 μM). Accordingly, we report the first S. Typhi–specific T3SS effector. We suggest that StoD recognizes and ubiquitinates pre-ubiquitinated targets, thus subverting intracellular signaling by functioning as an E4 enzyme.

scholarly journals Multiple Signals Direct the Assembly and Function of a Type 1 Secretion System

2010 ◽  
Vol 192 (15) ◽  
pp. 3861-3869 ◽  
Author(s):  
Muriel Masi ◽  
Cécile Wandersman
Keyword(s):  
Atp Hydrolysis ◽  
Protein A ◽  
Secretion System ◽  
Secretion Systems ◽  
Tight Coupling ◽  
Secretion Signal ◽  
Abc Protein ◽  
C Terminus ◽  
Wide Range

ABSTRACT Type 1 secretion systems (T1SS) are present in a wide range of Gram-negative bacteria and are involved in the secretion of diverse substrates such as proteases, lipases, and hemophores. T1SS consist of three proteins: an inner membrane ABC (ATP binding cassette) protein, a periplasmic adaptor, and an outer membrane channel of the TolC family. Assembly of the tripartite complex is transient and induced upon binding of the substrate to the ABC protein. It is generally accepted that T1SS-secreted proteins have a C-terminal secretion signal required for secretion and that this signal interacts with the ABC protein. However, we have previously shown that for the Serratia marcescens hemophore HasA, interactions with the ABC protein and subsequent T1SS assembly require additional regions. In this work, we characterize these regions and demonstrate that they are numerous, distributed throughout the HasA polypeptide, and most likely linear. Together with the C-terminal signal, these elements maximize the secretion of HasA. The data also show that the C-terminal signal of HasA triggers HasD-driven ATP hydrolysis, leading to disassembly of the complex. These data support a model of type 1 secretion involving a multistep interaction between the substrate and the ABC protein that stabilizes the assembled secretion system until the C terminus is presented. This model also supports tight coupling between synthesis and secretion.

scholarly journals Two Type VI Secretion Systems in Vibrio coralliilyticus RE22Sm exhibit differential target specificity for bacteria prey and oyster larvae

2021 ◽  
Author(s):  
Christian W Schuttert ◽  
Marta Gomez-Chiarri ◽  
David C Rowley ◽  
David R Nelson
Keyword(s):  
Large Scale ◽  
Eastern Oyster ◽  
Bacterial Cells ◽  
Wild Type ◽  
Secretion Systems ◽  
Prey Cell ◽  
E Coli ◽  
Bacterial Antagonism ◽  
Type Vi Secretion ◽  
Vibrio Coralliilyticus

Vibrio coralliilyticus is an extracellular bacterial pathogen and a causative agent of vibriosis in larval oysters. Host mortality rates can quickly reach 100% during vibriosis outbreaks in oyster hatcheries. Type VI Secretion Systems (T6SS) are rapidly polymerizing, contact dependent injection apparatus for prey cell intoxication and play important roles in pathogenesis. DNA sequencing of V. coralliilyticus RE22Sm indicated the likely presence of two functional T6SSs with one on each of two chromosomes. Here, we investigated the antibacterial and anti-eukaryotic roles of the two T6SSs (T6SS1 and T6SS2) against E. coli Sm10 cells and Crassostrea virginica larvae, respectively. Mutations in hcp and vgrG genes were created and characterized for their effects upon bacterial antagonism and eukaryotic host virulence. Mutations in hcp1 and hcp2 resulted in significantly reduced antagonism against E. coli Sm10, with the hcp2 mutation demonstrating the greater impact. In contrast, mutations in vgrG1 or vgrG2 had little effect on E. coli killing. In eastern oyster larval challenge assays, T6SS1 mutations in either hcp1 or vgrG1 dramatically attenuated virulence against C. virginica larvae. Strains with restored wild type hcp or vgrG genes reestablished T6SS-mediated killing to that of wild type V. coralliilyticus RE22Sm. These data suggest that the T6SS1 of V. coralliilyticus RE22Sm principally targets eukaryotes and secondarily bacteria, while the T6SS2 primarily targets bacterial cells and secondarily eukaryotes. Attenuation of pathogenicity was observed in all T6SS mutants, demonstrating the requirement for proper assembly of the T6SS systems to maintain maximal virulence. Importance: Vibriosis outbreaks lead to large-scale hatchery losses of oyster larvae (product and seed) where Vibrio sp. associated losses of 80 to 100 percent are not uncommon. Practical and proactive biocontrol measures can be taken to help mitigate larval death by Vibrio sp. by better understanding the underlying mechanisms of virulence in V. coralliilyticus. In this study, we demonstrate the presence of two Type VI Secretion Systems (T6SS) in V. coralliilyticus RE22Sm and interrogate the roles of each T6SS in bacterial antagonism and pathogenesis against a eukaryotic host. Specifically, we show that the loss of T6SS1 function results in the loss of virulence against oyster larvae.

Structural comparison of the transport units of type V secretion systems

2013 ◽  
Vol 394 (11) ◽  
pp. 1385-1398 ◽  
Author(s):  
Iris Gawarzewski ◽  
Sander H.J. Smits ◽  
Lutz Schmitt ◽  
Joachim Jose
Keyword(s):  
Outer Membrane ◽  
Crystal Structure Analysis ◽  
Type I ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
X Ray ◽  
Outer Membranes ◽  
One Step ◽  
Type V Secretion ◽  
Type V

Abstract Pathogenic gram-negative bacteria have evolved several secretion mechanisms to translocate adhesins, enzymes, toxins, and other virulence factors across the inner and outer membranes. Currently, eight different secretion systems, type I–type VIII (T1SS–T8SS) plus the chaperone-usher (CU) pathway, have been identified, which act in one-step or two-step mechanisms to traverse both membrane barriers. The type V secretion system (T5SS) is dependent first on the Sec translocon within the inner membrane. The periplasmic intermediates are then secreted through aqueous pores formed by β-barrels in the outer membrane. Until now, transport across the outer membrane has not been understood on a molecular level. With respect to special characteristics revealed by crystal structure analysis, bioinformatic and biochemical data, five subgroups of T5SS were defined. Here, we compare the transport moieties of members of four subgroups based on X-ray crystal structures. For the fifth subgroup, which was identified only recently, no structures have thus far been reported. We also discuss different models for the translocation process across the outer membrane with respect to recent findings.

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