CesAB is an enteropathogenic Escherichia coli chaperone for the type-III translocator proteins EspA and EspB

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3639-3647 ◽  
Author(s):  
Elizabeth A. Creasey ◽  
Devorah Friedberg ◽  
Robert K. Shaw ◽  
Tatiana Umanski ◽  
Stuart Knutton ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Interactions ◽  
Type Iii Secretion ◽  
Secretion System ◽  
Effector Proteins ◽  
Enteropathogenic Escherichia Coli ◽  
Type Iii ◽  
Mucosal Surfaces ◽  
Enterocyte Effacement ◽  
Bacterial Cytoplasm

Enteropathogenic Escherichia coli (EPEC) are extracellular pathogens that colonize mucosal surfaces of the intestine via formation of attaching and effacing (A/E) lesions. The genes responsible for induction of the A/E lesions are located on a pathogenicity island, termed the locus of enterocyte effacement (LEE), which encodes the adhesin intimin and the type III secretion system needle complex, translocator and effector proteins. One of the major EPEC translocator proteins, EspA, forms a filamentous conduit along which secreted proteins travel before they arrive at the translocation pore in the plasma membrane of the host cell, which is composed of EspB and EspD. Prior to secretion, many type III proteins, including translocators, are maintained in the bacterial cytoplasm by association with a specific chaperone. In EPEC, chaperones have been identified for the effector proteins Tir, Map and EspF, and the translocator proteins EspD and EspB. In this study, CesAB (Orf3 of the LEE) was identified as a chaperone for EspA and EspB. Specific CesAB–EspA and CesAB–EspB protein interactions are demonstrated. CesAB was essential for stability of EspA within the bacterial cell prior to secretion. Furthermore, a cesAB mutant failed to secrete EspA, as well as EspB, to assemble EspA filaments, to induce A/E lesion following infection of HEp-2 cells and to adhere to, or cause haemolysis of, erythrocytes.

Distribution of espI among clinical enterohaemorrhagic and enteropathogenic Escherichia coli isolates

2004 ◽  
Vol 53 (11) ◽  
pp. 1145-1149 ◽  
Author(s):  
Rosanna Mundy ◽  
Claire Jenkins ◽  
Jun Yu ◽  
Henry Smith ◽  
Gad Frankel
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Severe Disease ◽  
Pathogenicity Island ◽  
Effector Proteins ◽  
Effector Protein ◽  
Enteropathogenic Escherichia Coli ◽  
Type Iii Effector ◽  
Type Iii

Enterohaemorrhagic (EHEC) and enteropathogenic (EPEC) Escherichia coli are important diarrhoeagenic pathogens; infection is dependent on translocation of a number of type III effector proteins. Until recently all the known effectors were encoded on the LEE pathogenicity island, which also encodes the adhesin intimin and the type III secretion apparatus. Recently, a novel non-LEE effector protein, EspI/NleA, which is required for full virulence in vivo and is encoded on a prophage, was identified. The aim of this study was to determine the distribution of espI among clinical EHEC and EPEC isolates. espI was detected in 86 % and 53 % of LEE+ EHEC and EPEC strains, respectively. Moreover, the espI gene was more commonly found in patients suffering from a more severe disease.

scholarly journals Salmonella pathogenicity island 1 (SPI-1) type III secretion of SopD involves N- and C-terminal signals and direct binding to the InvC ATPase

Microbiology ◽  
2010 ◽  
Vol 156 (6) ◽  
pp. 1805-1814 ◽  
Author(s):  
R. Boonyom ◽  
M. H. Karavolos ◽  
D. M. Bulmer ◽  
C. M. A. Khan
Keyword(s):  
Protein Interactions ◽  
Type Iii Secretion ◽  
Pathogenicity Island ◽  
Effector Proteins ◽  
Amino Acid Residues ◽  
Type Iii ◽  
Protein Protein Interaction ◽  
Secretion Signal ◽  
Serovar Typhimurium ◽  
Bacterial Cytoplasm

Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important pathogen and a causative agent of gastroenteritis. During infection, S. Typhimurium assembles molecular-needle complexes termed type III secretion (T3S) systems to translocate effector proteins from the bacterial cytoplasm directly into the host cell. The T3S signals that direct the secretion of effectors still remain enigmatic. SopD is a key T3S effector contributing to the systemic virulence of S. Typhimurium and the development of gastroenteritis. We have scrutinized the distribution of the SopD T3S signals using in silico analysis and a targeted deletion approach. We show that amino acid residues 6–10 act as the N-terminal secretion signal for Salmonella pathogenicity island 1 (SPI-1) T3S. Furthermore, we show that two putative C-terminal helical regions of SopD are essential for its secretion and also help prevent erroneous secretion through the flagellar T3S machinery. In addition, using protein–protein interaction assays, we have identified an association between SopD and the SPI-1 T3S system ATPase, InvC. These findings demonstrate that T3S of SopD involves multiple signals and protein interactions, providing important mechanistic insights into effector protein secretion.

Regulation, secretion and activity of type III-secreted proteins of enterohaemorrhagic Escherichia coli O157

2003 ◽  
Vol 31 (1) ◽  
pp. 98-103 ◽  
Author(s):  
A.J. Roe ◽  
D.E.E. Hoey ◽  
D.L. Gally
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Fluorescent Protein ◽  
Gastrointestinal Disease ◽  
Secretion System ◽  
Effector Proteins ◽  
Intimate Contact ◽  
Ongoing Research ◽  
Type Iii ◽  
Enterohaemorrhagic Escherichia Coli

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 causes gastrointestinal disease with the potential for life-threatening sequelae. Although Shiga-like toxins are responsible for much of the serious pathology in humans, the bacterium also possesses a type III protein secretion system that is responsible for intimate attachment to host intestinal mucosa. This sophisticated interaction requires co-ordination that is governed by environmental and genetic factors. Ongoing research supports the following model for how EHEC enables and controls this process: (i) specific environmental cues that are present in the host result in the expression of a number of adhesins, including fimbriae, which allow the initial binding to the mucosal surface. The same conditions support the expression of the basal type III secretion apparatus; (ii) targeting and assembly of the translocon requires both an mRNA signal and chaperones, with coupled translation and secretion of translocon proteins, EspA, B and D; (iii) opening up of a conduit between the bacterium and host cell releases a cytoplasmic pool of effector proteins. A consequence of this is increased expression of particular effector proteins. Potentially, different proteins could be released into the cell at different times or have activities modulated with time; (iv) intimate contact between the translocated intimin receptor (Tir) and the bacterial surface factor intimin requires translocon expression to be down-regulated and translocon filaments to be lost. Fluorescent protein fusions allow contact-mediated regulation and protein targeting through the type III secretion system to be studied in detail.

scholarly journals A Degenerate Type III Secretion System from Septicemic Escherichia coli Contributes to Pathogenesis

2005 ◽  
Vol 187 (23) ◽  
pp. 8164-8171 ◽  
Author(s):  
Diana Ideses ◽  
Uri Gophna ◽  
Yossi Paitan ◽  
Roy R. Chaudhuri ◽  
Mark J. Pallen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Gene Clusters ◽  
Secretion System ◽  
Effector Proteins ◽  
E Coli ◽  
Type Iii

ABSTRACT The type III secretion system (T3SS) is an important virulence factor used by several gram-negative bacteria to deliver effector proteins which subvert host cellular processes. Enterohemorrhagic Escherichia coli O157 has a well-defined T3SS involved in attachment and effacement (ETT1) and critical for virulence. A gene cluster potentially encoding an additional T3SS (ETT2), which resembles the SPI-1 system in Salmonella enterica, was found in its genome sequence. The ETT2 gene cluster has since been found in many E. coli strains, but its in vivo role is not known. Many of the ETT2 gene clusters carry mutations and deletions, raising the possibility that they are not functional. Here we show the existence in septicemic E. coli strains of an ETT2 gene cluster, ETT2sepsis, which, although degenerate, contributes to pathogenesis. ETT2sepsis has several premature stop codons and a large (5 kb) deletion, which is conserved in 11 E. coli strains from cases of septicemia and newborn meningitis. A null mutant constructed to remove genes coding for the putative inner membrane ring of the secretion complex exhibited significantly reduced virulence. These results are the first demonstration of the importance of ETT2 for pathogenesis.

scholarly journals Functional Characterization of EscK (Orf4), a Sorting Platform Component of the Enteropathogenic Escherichia coli Injectisome

2016 ◽  
Vol 199 (1) ◽  
Author(s):  
Eduardo Soto ◽  
Norma Espinosa ◽  
Miguel Díaz-Guerrero ◽  
Meztlli O. Gaytán ◽  
José L. Puente ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Diarrheal Disease ◽  
Functional Characterization ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Content Type ◽  
Enterocyte Effacement

ABSTRACT The type III secretion system (T3SS) is a supramolecular machine used by many bacterial pathogens to translocate effector proteins directly into the eukaryotic host cell cytoplasm. Enteropathogenic Escherichia coli (EPEC) is an important cause of infantile diarrheal disease in underdeveloped countries. EPEC virulence relies on a T3SS encoded within a chromosomal pathogenicity island known as the locus of enterocyte effacement (LEE). In this work, we pursued the functional characterization of the LEE-encoded protein EscK (previously known as Orf4). We provide evidence indicating that EscK is crucial for efficient T3S and belongs to the SctK (OrgA/YscK/MxiK) protein family, whose members have been implicated in the formation of a sorting platform for secretion of T3S substrates. Bacterial fractionation studies showed that EscK localizes to the inner membrane independently of the presence of any other T3SS component. Combining yeast two-hybrid screening and pulldown assays, we identified an interaction between EscK and the C-ring/sorting platform component EscQ. Site-directed mutagenesis of conserved residues revealed amino acids that are critical for EscK function and for its interaction with EscQ. In addition, we found that T3S substrate overproduction is capable of compensating for the absence of EscK. Overall, our data suggest that EscK is a structural component of the EPEC T3SS sorting platform, playing a central role in the recruitment of T3S substrates for boosting the efficiency of the protein translocation process. IMPORTANCE The type III secretion system (T3SS) is an essential virulence determinant for enteropathogenic Escherichia coli (EPEC) colonization of intestinal epithelial cells. Multiple EPEC effector proteins are injected via the T3SS into enterocyte cells, leading to diarrheal disease. The T3SS is encoded within a genomic pathogenicity island termed the locus of enterocyte effacement (LEE). Here we unravel the function of EscK, a previously uncharacterized LEE-encoded protein. We show that EscK is central for T3SS biogenesis and function. EscK forms a protein complex with EscQ, the main component of the cytoplasmic sorting platform, serving as a docking site for T3S substrates. Our results provide a comprehensive functional analysis of an understudied component of T3SSs.

scholarly journals EscA Is a Crucial Component of the Type III Secretion System of Enteropathogenic Escherichia coli

2012 ◽  
Vol 194 (11) ◽  
pp. 2819-2828 ◽  
Author(s):  
N. Sal-Man ◽  
E. Biemans-Oldehinkel ◽  
D. Sharon ◽  
M. A. Croxen ◽  
R. Scholz ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Enteropathogenic Escherichia Coli ◽  
Type Iii ◽  
Crucial Component

EscI: a crucial component of the type III secretion system forms the inner rod structure in enteropathogenic Escherichia coli

2012 ◽  
Vol 442 (1) ◽  
pp. 119-125 ◽  
Author(s):  
Neta Sal-Man ◽  
Wanyin Deng ◽  
B. Brett Finlay
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Integral Membrane Protein ◽  
Secretion System ◽  
Host Cells ◽  
Enteropathogenic Escherichia Coli ◽  
Bacterial Membranes ◽  
Type Iii ◽  
Protein Functions

The T3SS (type III secretion system) is a multi-protein complex that plays a central role in the virulence of many Gram-negative bacterial pathogens. This apparatus spans both bacterial membranes and transports virulence factors from the bacterial cytoplasm into eukaryotic host cells. The T3SS exports substrates in a hierarchical and temporal manner. The first secreted substrates are the rod/needle proteins which are incorporated into the T3SS apparatus and are required for the secretion of later substrates, the translocators and effectors. In the present study, we provide evidence that rOrf8/EscI, a poorly characterized locus of enterocyte effacement-encoded protein, functions as the inner rod protein of the T3SS of EPEC (enteropathogenic Escherichia coli). We demonstrate that EscI is essential for type III secretion and is also secreted as an early substrate of the T3SS. We found that EscI interacts with EscU, the integral membrane protein that is linked to substrate specificity switching, implicating EscI in the substrate-switching event. Furthermore, we showed that EscI self-associates and interacts with the outer membrane secretin EscC, further supporting its function as an inner rod protein. Overall, the results of the present study suggest that EscI is the YscI/PrgJ/MxiI homologue in the T3SS of attaching and effacing pathogens.

Sign in / Sign up

Export Citation Format

Share Document