61 research outputs found
The discovery of SycO reveals a new function for type three secretion effector chaperones
No full textThe Type Three Secretion (T3S) system is a device used by many Gram-negative pathogens that allows bacteria to deliver effector proteins straight into the eukaryotic cell cytosol. These effectors interfere with various signaling pathways to subvert the host cell functions. The secretion machinery of the T3S system consist of a basal body spanning the bacterial inner and outer membrane followed by a stiff hollow needle outside the bacterium. The fully assembled secretion apparatus constitute a continuous hollow conduit that connects the bacteria to the eukaryotic target cell. After cell contact, virulence proteins -called effectors- are injected directly into the cytosol of the host cell via the T3S apparatus. Several effectors of the T3S system require the assistance of specific cytosolic chaperones to be efficiently exported. There are three classes of T3S chaperones. Effector proteins are assisted by Class I chaperones. Although Class I chaperones are well characterized, their main function is still a matter of controversy. In this thesis, we demonstrate that orf155 encodes a specific chaperone for the effector YopO that we called SycO. We showed that SycO enhances YopO secretion in vitro and is required for translocation of YopO into infected cells. By pulldown assay we demonstrated that residues 20 to 77 of YopO are required and sufficient for SycO binding. Using crosslinking experiments and size exclusion chromatography analysis, we determined the stoichiometry of purified SycO and YopO-SycO complexes. SycO alone forms dimers in solution and the YopO-SycO complex has a 1:2 stoichiometry. These results suggested that SycO is a typical chaperone of the Class I. YopO is a serine/theronine kinase that interacts with Rho and Rac and disrupts the cytoskeleton of the target cells. YopO has been shown to localize at the cell plasma-membrane. By transfection of YopO-EGFP hybrid proteins into HEK293T cells, we demonstrated that the chaperone-binding domain (CBD) coincides with the membrane localization domain of YopO. Nevertheless, the CBD was not needed for the kinase activity of YopO. By ultracentrifugation, we also showed that the CBD causes YopO aggregation in the bacteria, when SycO does not cover it. Further, we show that the CBD of YopE and YopT also caused aggregation in the bacteria in the absence of SycE and SycT respectively. YopE, YopT and T3S effectors in other systems also act at the membrane of the eukaryotic host cell. We propose a new hypothesis concerning the role of T3S chaperones. The sub-cellular localization domain of effectors is aggregation-prone and creates the need for a chaperone inside bacteria. We propose that masking such aggregation-prone localization domains may be a general function for type III effector chaperones
Leucandra tahuatae Klautau & Lopes & Guarabyra & Folcher & Ekins & Debitus 2020, sp. nov.
No full textLeucandra tahuatae sp. nov. (Figs 10, 11, 12, Table 10) Etymology. From the type locality (Tahuata) Type locality. Matatehoke, Tahuata, Marquesas Island, French Polynesia. Material examined. Holotype: UFRJPOR 6454 = MNHN-IP- 2018-25 — Matatehoke, Tahuata, Marquesas Island, Station MT01 (9° 53.589’ S– 149° 33.220’ W), depth: 33 m, coll. C. Debitus, 10/IX/2009, P177. Diagnosis. Sponge white, tubular, with cortical triactines, large and small choanosomal triactines, and choanosomal and atrial tetractines. Colour. White alive and beige in ethanol (Fig 10A). Morphology and anatomy. Sponge tubular with apical osculum (Figs 10A, B) surrounded by membrane (Fig 10C). Surface smooth. Large central atrium. Aquiferous system leuconoid. The cortical skeleton is composed of tangential triactines (Figs 11A, B). In the choanosome there are large triactines (larger than those of the cortex) and small choanosomal triactines and tetractines. Some of these small triactines and the small tetractines surround the choanosomal canals (Fig 10E). The subatrial skeleton is composed of triactines that point their unpaired actine to the cortex (Fig 10F). The atrial skeleton has tangential tetractines that point their apical actine into the atrium (Figs 10F, 11C, D). Spicules (Table 10) Cortical triactines. Subregular. Actines are slightly conical with sharp tips. Sometimes they are undulated. The unpaired actine is shorter than the paired ones (Fig 12A). Size: 449.0/ 32.6 µm (paired), 369.0/ 28.3 µm (unpaired). Choanosomal large triactines. Subregular. Actines are slightly conical with sharp tips. Sometimes they are undulated. The unpaired actine is shorter than the paired ones (Fig 12B). Size: 796.7/ 53.0 µm (paired), 537.8/ 50.3 µm (unpaired). Choanosomal small triactines. Strongly sagittal, with curved paired actines when they are surrounding the canals. Actines are slightly conical with sharp tips. One of the paired actines is frequently shorter than the other actines (Fig 12C). Size: 151.4/ 11.0 µm (paired), 172.1/ 12.6 µm (unpaired). Choanosomal small tetractines. Strongly sagittal with curved paired actines, as they are find surrounding the canals. Actines are slightly conical with sharp tips. The unpaired actine can present the same length of the paired ones or be shorter. The paired actines are undulated. The apical actine is much shorter and thinner. It is conical, sharp an smooth (Fig 12D). Size: 158.1/ 11.7 µm (paired), 184.1/ 13.0 µm (unpaired), 50.9/ 8.9 µm (apical). Subatrial triactines. Strongly sagittal (T-shaped). Actines are slightly conical with sharp tips. The unpaired actine is longer than the paired ones (Fig 12E). Size: 163.6/ 13.2 µm (paired), 261.3/ 16.3 µm (unpaired). Atrial tetractines. Sagittal. Actines are slightly conical with sharp tips. The basal actines show the same length and they are straight. The apical actine is shorter than the basal ones, conical, sharp and smooth (Fig 12F). Size: 214.8/ 14.9 µm (paired), 215.5/ 14.8 µm (unpaired), 50.1/ 8.1 µm (apical). Ecology. There was algae inside the atrium of this sponge. Geographical distribution. Marquesas Island, French Polynesia (present work). Remarks. Most leucandras present diactines in their skeleton but L. tahuatae sp. nov. is part of a small group of this genus without diactines. Another characteristic that differentiates the new species from most leucandras is the presence of a subatrial skeleton. However, sometimes it is very difficult to be sure if a species does not have subatrial skeleton or if its author just did not mention it. Hence, to compare our new species other species of Leucandra, we considered only those with skeleton composed of cortical triactines, choanosomal large and small triactines, choanosomal tetractines, and atrial tetractines. We found only three most similar species to L. tahuatae sp. nov.: L. ramosa (Burton, 1934), L. mozambiquensis Van Soest & De Voogd, 2018, and L. pilula Van Soest & De Voogd, 2018. Leucandra ramosa was originally described from Australia. It can be differentiated from L. tahuatae sp. nov. by its greyish-brown colour in ethanol (the new species is white) and by the size of some spicule categories. Cortical triactines: up to 210.0/ 11.0 (L. ramosa); 260.0˗ 449.0 ˗700.0/ 25.0˗ 32.6 ˗40.0—paired actine, 180.0˗ 369.0 ˗550.0/ 10.0˗ 28.3 ˗35.0—unpaired actine (L. tahuatae sp. nov.). Choanosomal large triactines: up to 960.0/ 64.0 (L. ramosa); 508.1˗ 796.7 ˗1016.1/ 37.8˗ 53.0 ˗64.9—paired actine, 378.4˗ 537.8 ˗756.7/ 37.8˗ 50.3 ˗54.1—unpaired actine (L. tahuatae sp. nov.). Choanosomal small triactines: up to 240.0/ 12.0 (L. ramosa); 108.0˗ 151.4 ˗202.5/ 9.5˗ 11.0 ˗13.5— paired actine, 129.6˗ 172.1 ˗221.4/ 10.8˗ 12.6 ˗13.5—unpaired actine (L. tahuatae sp. nov.). Leucandra mozambiquensis, recently described from Mozambique Channel, can be differentiated from the new species by its external morphology, as it is an “irregular cup-shaped hollow mass” (Van Soest & De Voogd 2018) while the new species is tubular, and mainly by the presence of tetractines instead of triactines in the subatrial skeleton. Leucandra pilula, described from Seychelles, is globose, while L. tahuatae sp. nov. is tubular. The former has oxhorn-shaped cortical triactines, while ours has equiangular cortical triactines. Besides, some of their spicule categories have sizes. Cortical triactines: 216.0˗ 281.0 ˗372.0/ 16.0˗ 21.6 ˗28.0—paired actine, 178.0˗ 245.0 ˗326.0/ 15.0˗ 22.7 ˗31.0—unpaired actine (L. pilula); 260.0˗ 449.0 ˗700.0/ 25.0˗ 32.6 ˗40.0—paired actine, 180.0˗ 369.0 ˗550.0/ 10.0˗ 28.3 ˗35.0—unpaired actine (L. tahuatae sp. nov.). Subatrial triactines: 100.0˗ 186.0 ˗303.0/ 11.0˗ 16.6 ˗29.0—paired actine, 94.0˗ 172.0 ˗254.0/ 9.0˗ 17.8 ˗26.0—unpaired actine (L. pilula); 116.1˗ 163.8 ˗243.0/ 10.2˗ 13.2 ˗16.2—paired actine, 164.7˗ 261.3 ˗335.1/ 10.8˗ 16.3 ˗21.6—unpaired actine (L. tahuatae sp. nov.). Atrial tetractines: 136.0˗ 239.0 ˗380.0/ 9.0˗ 17.1 ˗32.0—paired actine, 101.0˗ 186.0 ˗271.0/ 14.0˗ 19.4 ˗32.0—unpaired ac- tine, 45.0˗ 84.0 ˗130.0/ 4.0˗ 8.4 ˗11.0—apical actine (L. pilula); 155.0˗ 214.8 ˗325.0/ 13.5˗ 14.9 ˗15.0—paired actine, 150.0˗ 215.5 ˗300.0/ 12.5˗ 14.8 ˗15.0—unpaired actine, 30.0˗ 50.1 ˗67.5/ 6.3˗ 8.1 ˗10.0—apical actine (L. tahuatae sp. nov.)Published as part of Klautau, Michelle, Lopes, Matheus Vieira, Guarabyra, Bruna, Folcher, Eric, Ekins, Merrick & Debitus, Cécile, 2020, Calcareous sponges from the French Polynesia (Porifera: Calcarea), pp. 261-295 in Zootaxa 4748 (2) on pages 283-286, DOI: 10.11646/zootaxa.4748.2.3, http://zenodo.org/record/369877
Correction to: Synthetic Biology and the Translational Imperative
No full textThe author group of above-mentioned review paper was incorrectly published in the online article
Synthetic mammalian trigger-controlled bipartite transcription factors
No full textSynthetic biology has significantly advanced the design of synthetic control devices, gene circuits and networks that can reprogram mammalian cells in a trigger-inducible manner. Prokaryotic helix-turn-helix motifs have become the standard resource to design synthetic mammalian transcrip-tion factors that tune chimeric promoters in a small molecule-responsive manner. We have identified a family of Actinomycetes transcriptional repressor proteins showing a tandem TetR-family signature and have used a synthetic biology-inspired approach to reveal the potential control dynamics of these bi-partite regulators. Daisy-chain assembly of well-characterized prokaryotic repres
Withdrawal of maize protection by herbicides and insecticides increases mycotoxins contamination near maximum thresholds
No full textEnvironmental and economic issues affect decision-making for whether or not to control small infestations of pests and pathogens in crops. Even where no crop yield loss is expected, other risks may be evident, such as the slow accumulation of pathogen inocula. The prevalence of toxins, arising from biotic interactions with fungal diseases, can alter crop quality rather than quantity. Thus, farmer decisions for whether to tolerate pest infestation must take into account several direct and immediate and/or delayed potential risks. Published scientific evidence on the co-occurrence of risk factors resulting from the presence of different pests and pathogens are largely absent, and this has stifled the adoption of integrated pest management. Here, we tested how the withdrawal of herbicide and insecticide protection in maize, alone and in combination, might induce higher prevalence of up to 23 mycotoxins in the crop at harvest. The experiment was conducted over 4 years in 29 fields in the south west of France. The test involved a comparison of paired samples collected from treated and untreated plots. All nine major mycotoxins that were observed in more than 4 % of the samples showed highly variable concentrations both between fields and years. The overall trend following the cessation of pesticide protection, however, is for higher levels of mycotoxins and up to a six-fold increased in nivalenol mean concentration (to 202.3 mu g kg(-1) of maize seeds) compared to its treated control. Overall mycotoxin concentrations approached 55-67 % of their maximum acceptable rate, a situation of reduced security margin that could lead to economic penalties and market restrictions. We found that the removal of herbicides had a greater impact than that of insecticides on the prevalence of mycotoxins, which differs from the expectation stated in the literature. This finding is further reinforced by the observation that certain species of weeds harbor several species of Fusarium. This means that weeds not only play a role as crop competitors but also as reservoirs of inoculum in the field. Our findings illustrate the importance of sanitary evaluation when the implementation of new cropping systems will alter the distribution and occurrence of pests and pathogens
Innovative Learning for Collaborative Design in Ergonomics
No full textpeer reviewedThe proposed article deals with introducing collaborative architectural design into the training of ergonomists at the Master 2 level. The collaborative design workshop aims to confront ergonomists with the difficulties any design project involves, and which challenge architects, designers, engineers and so on: collaboration between people with different skills and different expertise; powerful time constraints; need for their work to converge; working together and/or at a distance; sharing documents; decision-making, etc. The article will present a short review of work carried out in the domains of architecture and design, and of the contribution of ergonomics within architectural projects. We shall then present the workshop’s educational aims, and give details of the way it functioned. Finally, observation results will be presented and discussed
c.-61G>A in OVOL2 is a Pathogenic 5' Untranslated Region Variant Causing Posterior Polymorphous Corneal Dystrophy 1.
No full textPURPOSE
The purpose of this study was to investigate the clinical and genetic features of a man and his daughter with posterior polymorphous corneal dystrophy (PPCD), referred to our clinic for Descemet membrane endothelial keratoplasty. No other known relatives were affected.
METHODS
Ophthalmic examination and histology, including electron microscopy, were performed. Genetic testing was conducted by means of whole exome sequencing, and variant analysis was achieved by using an internal in silico pipeline. Molecular tests included a dual-luciferase assay.
RESULTS
Slowly progressive blurred vision was reported from childhood by the daughter. The father's symptoms started at age 55. Best-corrected visual acuity was reduced in both patients (0.2-0.4). Slit-lamp examination in both patients revealed bilateral corneal clouding with gray endothelial lesions; other family members had no ophthalmological signs. Descemet membrane endothelial keratoplasty was performed uneventfully in both patients. Histology showed thickened Descemet membrane and abnormal endothelium resembling epithelial-like cells. Both patients carried the OVOL2 5' untranslated region NM_021220.4.c.-61G>A variant in the heterozygous state. This change was associated with increased promoter activity and was not present in the unaffected members of the family.
CONCLUSIONS
The 5' untranslated region mutation c.-61G>A in OVOL2 has been previously found in 1 individual with PPCD1 and reported as a variant of unknown significance because of insufficient evidence supporting its pathogenicity. Identification of the second family with 2 individuals affected by PPCD1 carrying this change, together with functional data, provides further proofs that it is disease-causing
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