The mechanisms used by enteropathogenic Escherichia coli to control filopodia dynamics

Enteropathogenic Escherichia coli (EPEC) subverts actin dynamics in eukaryotic cells by injecting effector proteins via a type III secretion system. First, WxxxE effector Map triggers transient formation of filopodia. Then, following recovery from the filopodial signals, EPEC triggers robust actin polymerization via a signalling complex comprising Tir and the adaptor proteins Nck. In this paper we show that Map triggers filopodia formation by activating Cdc42; expression of dominant-negative Cdc42 or knock-down of Cdc42 by siRNA impaired filopodia formation. In addition, Map binds PDZ1 of NHERF1. We show that Map–NHERF1 interaction is needed for filopodia stabilization in a process involving ezrin and the RhoA/ROCK cascade; expression of dominant-negative ezrin and RhoA or siRNA knock-down of RhoA lead to rapid elimination of filopodia. Moreover, we show that formation of the Tir-Nck signalling complex leads to filopodia withdrawal. Recovery from the filopodial signals requires phosphorylation of a Tir tyrosine (Y474) residue and actin polymerization pathway as both infection of cells with EPEC expressing TirY474S or infection of Nck knockout cells with wild-type EPEC resulted in persistence of filopodia. These results show that EPEC effectors modulate actin dynamics by temporal subverting the Rho GTPases and other actin polymerization pathways for the benefit of the adherent pathogen

The T3SS effector EspT defines a new category of invasive enteropathogenic E. coli (EPEC) which form intracellular actin pedestals.

Enteropathogenic Escherichia coli (EPEC) strains are defined as extracellular pathogens which nucleate actin rich pedestal-like membrane extensions on intestinal enterocytes to which they intimately adhere. EPEC infection is mediated by type III secretion system effectors, which modulate host cell signaling. Recently we have shown that the WxxxE effector EspT activates Rac1 and Cdc42 leading to formation of membrane ruffles and lamellipodia. Here we report that EspT-induced membrane ruffles facilitate EPEC invasion into non-phagocytic cells in a process involving Rac1 and Wave2. Internalized EPEC resides within a vacuole and Tir is localized to the vacuolar membrane, resulting in actin polymerization and formation of intracellular pedestals. To the best of our knowledge this is the first time a pathogen has been shown to induce formation of actin comets across a vacuole membrane. Moreover, our data breaks the dogma of EPEC as an extracellular pathogen and defines a new category of invasive EPEC

Caracterización y diversidad genética de variedades autóctonas de cerezo mediante SSRs

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The S-layer protein of a Clostridium difficile SLCT-11 strain displays a complex glycan required for normal cell growth and morphology.

Clostridium difficile is a bacterial pathogen that causes major health challenges worldwide. It has a well-characterized surface (S)-layer, a para-crystalline proteinaceous layer surrounding the cell wall. In many bacterial and archaeal species, the S-layer is glycosylated, but no such modifications have been demonstrated in C. difficile. Here, we show that a C. difficile strain of S-layer cassette type 11, Ox247, has a complex glycan attached via an O-linkage to Thr-38 of the S-layer low-molecular-weight subunit. Using MS and NMR, we fully characterized this glycan. We present evidence that it is composed of three domains: (i) a core peptide-linked tetrasaccharide with the sequence -4-α-Rha-3-α-Rha-3-α-Rha-3-β-Gal-peptide; (ii) a repeating pentasaccharide with the sequence -4-β-Rha-4-α-Glc-3-β-Rha-4-(α-Rib-3-)β-Rha-; and (iii) a nonreducing end-terminal 2,3 cyclophosphoryl-rhamnose attached to a ribose-branched sub-terminal rhamnose residue. The Ox247 genome contains a 24-kb locus containing genes for synthesis and protein attachment of this glycan. Mutations in genes within this locus altered or completely abrogated formation of this glycan, and their phenotypes suggested that this S-layer modification may affect sporulation, cell length, and biofilm formation of C. difficile In summary, our findings indicate that the S-layer protein of SLCT-11 strains displays a complex glycan and suggest that this glycan is required for C. difficile sporulation and control of cell shape, a discovery with implications for the development of antimicrobials targeting the S-layer

Distribution of espM and espT among enteropathogenic and enterohaemorrhagic Escherichia coli

Enterohaemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) translocate dozens of type III secretion system effectors, including the WxxxE effectors Map, EspM and EspT that activate Rho GTPases. While map, which is carried on the LEE pathogenicity island, is absolutely conserved among EPEC and EHEC strains, the prevalence of espM and espT is not known. Here we report the results of a large screen aimed at determining the prevalence of espM and espT among clinical EPEC and EHEC isolates. The results suggest that espM, detected in 51 % of the tested strains, is more commonly found in EPEC and EHEC serogroups that are linked to severe human infections. In contrast, espT was absent from all the EHEC isolates and was found in only 1.8 % of the tested EPEC strains. Further characterization of the virulence gene repertoire of the espT-positive strains led to the identification of a new ζ2 intimin variant. All the espT-positive strains but two contained the tccP gene. espT was first found in Citrobacter rodentium and later in silico in EPEC E110019, which is of particular interest as this strain was responsible for a particularly severe diarrhoeal outbreak in Finland in 1987 that affected 650 individuals in a school complex and an additional 137 associated household members. Comparing the protein sequences of EspT to that of E110019 showed a high level of conservation, with only three strains encoding EspT that differed in 6 amino acids. At present, it is not clear why espT is so rare, and what impact EspM and EspT have on EPEC and EHEC infection

75 años como referente de la investigación agraria y medioambiental española en condiciones de clima mediterráneo [Sitio Web]

1 .pdf con imagen de acceso al “website”, su url y los créditos relacionados con su creación y diseño.-- Créditos: Organización, Estación Experimental de Aula Dei (EEAD-CSIC); Dirección, Jesús Val Falcón; Coordinación, Ana Álvarez-Fernandez, Jorge Álvaro-Fuentes, Ernesto Igartua; Contenido, Anunciación Abadía, Javier Abadía, Carlos Albiñana, Miguel Alfonso, Arancha Arbeloa, Raúl Arbués, Isabel Armillas, Manuel Becana, Santiago Beguería, Carmen Castañeda, Ana Castillo, José Cavero, Bruno Contreras, Azahara Díaz, Edgar García, Elena García, Juan Manuel Gascuñana, Leticia Gaspar, Yolanda Gogorcena, Juan Herrero, Victoria Lafuente, María Victoria López, Juan Antonio Marín, José Martínez, José Carlos Martínez-Giménez, Ana Pilar Mata, Manuel Matamoros, Pierre Mignard, María Ángeles Moreno, Paula Murillo, Ana Navas, Antonio Pérez, Rafael Picorel, María Pilar Vallés, Irene Villar, Inmaculada Yruela, Nery Zapata, Isabel Zarazaga; Diseño y programación: DigitalWorks (Juanjo Ascaso y Asun Dieste); Vídeo, Delegación del CSIC en Aragón (Sara Gutiérrez y Yolanda Hernáiz); Fotografía, Archivo EEAD-CSIC, Anunciación Abadía, Jorge Álvaro-Fuentes, Arancha Arbeloa, Juanjo Ascaso, Santiago Beguería, Elena García, Ernesto Igartua, Ignasi Iglesias, José Manuel Lasa, José Carlos Martínez-Giménez, Pierre Mignard, María Ángeles Moreno, Rubén Sancho, Kosana Suvocarev, María Pilar Vallés, Nery Zapata."Sitio web" de nueva creación y conmemorativo del 75 Aniversario de la EEAD-CSIC que contiene: 1) Foto esférica de su personal en activo; 2) Recopilación de sus hitos históricos más destacados, en orden cronológico; 3) Un vídeo con participación de su personal y muestra de algunas de sus instalaciones; 4) Un mapa con la distribución geográfica de los egresado del Instituto; 5) Algunas fotos, destacando las tomadas a su personal en las celebraciones del 25 y 50 Aniversarios de la EEAD-CSIC.Presentado durante la "Jornada. 75 Aniversario EEAD-CSIC (Zaragoza, Patio de la Infanta. 30 octubre 2019)".Financiación: CSIC, Vicepresidencia Adjunta de Organización y Cultura Científica.N

Quantitative real-time blood flow measurements using intravascular ultrasound.

Percutaneous transluminal coronary angioplasty (PTCA), stenting, and related techniques, are commonly used in the treatment of coronary artery disease. The main goal of these interventions is to restore blood flow in the coronary vasculature, yet the lack of quantitative real-time feedback presents real problems as the final procedure outcomes cannot be accurately determined during the intervention. Real-time quantitative blood flow measurements during balloon PTCA stent deployment would significantly improve the quality of these procedures and potentially reduce the high costs of these types of interventions. Doppler techniques are commonly used to measure flow with most ultrasound transducers. However, with intravascular ultrasound (IVUS) catheters, the flow direction inside a vessel is orthogonal to the transducer's image plane, making Doppler methods impractical. A slow-time filter-bank processing method was implemented in real-time using an intravascular ultrasound transducer array to obtain flow velocity measurements orthogonal to the image plane. The slow-time spectrum is estimated from the filtered energy under a series of narrow band pass filters centered at increasing frequencies applied to the slow-time signals. The normalized second moment of slow-time spectra is monotonically related to scatteter velocity. However, in the presence of in-plane flow this relationship changes. Slow-time spectra shift and spread with the in-plane and out-of-plane components, respectively. These two effects cause the normalized spectral second moment to increase, resulting in flow overestimates. Applying appropriate tilts to slow-time signals causes the slow-time spectrum to shift back to DC and the orthogonal estimation method can be used. Independent simulations show absolute flow rate estimation error smaller than 3.2% for plug flows of 30cm/sec and flow angles from 0° to 15°, making this method suitable for real-time validation of intravascular interventions.Ph.D.Applied SciencesBiomedical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/124658/2/3150188.pd

Spécificité de substrat et partenaires des D,D-transpeptidases intervenant dans la polymérisation du peptidoglycane et la résistance aux bêta-lactamines chez Enterococcus faecalis

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF