Search

Your search keyword '"Charles Van der Henst"' showing total 4 results
Start Over Author "Charles Van der Henst" Publisher american society for microbiology
4 results on '"Charles Van der Henst"'

1. Phenotypic Characterization and Heterogeneity among Modern Clinical Isolates of Acinetobacter baumannii

Author

Adam Valcek, Chantal Philippe, Clémence Whiteway, Etienne Robino, Kristina Nesporova, Mona Bové, Tom Coenye, Tim De Pooter, Wouter De Coster, Mojca Strazisar, and Charles Van der Henst

Subjects
Acinetobacter baumannii, macrocolonies, transmission electron microscopy, bacterial capsule, capsular polysaccharide, genotypes, Microbiology, QR1-502
Abstract

ABSTRACT Acinetobacter baumannii is an opportunistic pathogenic bacterium prioritized by WHO and CDC because of its increasing antibiotic resistance. Heterogeneity among strains represents the hallmark of A. baumannii bacteria. We wondered to what extent extensively used strains, so-called reference strains, reflect the dynamic nature and intrinsic heterogeneity of these bacteria. We analyzed multiple phenotypic traits of 43 nonredundant, modern, and multidrug-resistant, extensively drug-resistant, and pandrug-resistant clinical isolates and broadly used strains of A. baumannii. Comparison of these isolates at the genetic and phenotypic levels confirmed a high degree of heterogeneity. Importantly, we observed that a significant portion of modern clinical isolates strongly differs from several historically established strains in the light of colony morphology, cellular density, capsule production, natural transformability, and in vivo virulence. The significant differences between modern clinical isolates of A. baumannii and established strains could hamper the study of A. baumannii, especially concerning its virulence and resistance mechanisms. Hence, we propose a variable collection of modern clinical isolates that are characterized at the genetic and phenotypic levels, covering a wide range of the phenotypic spectrum, with six different macrocolony type groups, from avirulent to hypervirulent phenotypes, and with naturally noncapsulated to hypermucoid strains, with intermediate phenotypes as well. Strain-specific mechanistic observations remain interesting per se, and established “reference” strains have undoubtedly been shown to be very useful to study basic mechanisms of A. baumannii biology. However, any study based on a specific strain of A. baumannii should be compared to modern and clinically relevant isolates. IMPORTANCE Acinetobacter baumannii is a bacterium prioritized by the CDC and WHO because of its increasing antibiotic resistance, leading to treatment failures. The hallmark of this pathogen is the high heterogeneity observed among isolates, due to a very dynamic genome. In this context, we tested if a subset of broadly used isolates, considered “reference” strains, was reflecting the genetic and phenotypic diversity found among currently circulating clinical isolates. We observed that the so-called reference strains do not cover the whole diversity of the modern clinical isolates. While formerly established strains successfully generated a strong base of knowledge in the A. baumannii field and beyond, our study shows that a rational choice of strain, related to a specific biological question, should be taken into consideration. Any data obtained with historically established strains should also be compared to modern and clinically relevant isolates, especially concerning drug screening, resistance, and virulence contexts.

Published
2023
Full Text
View/download PDF

2. BtaE, an Adhesin That Belongs to the Trimeric Autotransporter Family, Is Required for Full Virulence and Defines a Specific Adhesive Pole of Brucella suis

Author

Gastón Maximiliano Arocena, Rodrigo Sieira, Angeles Zorreguieta, Xavier De Bolle, Silvia M. Estein, Charles Van der Henst, Fernando Ariel Martin, Diana M. Posadas, Verónica Ruiz-Ranwez, Patricia Lorena Abdian, and Department of Bio-engineering Sciences

Subjects
Brucella suis, Immunology, Mutant, Virulence, Brucella, ADHESION, Biology, medicine.disease_cause, Microbiology, Bacterial Adhesion, Brucellosis, Ciencias Biológicas, purl.org/becyt/ford/1 [https], Mice, Biología Celular, Microbiología, Escherichia coli, Brucella Suis, medicine, Animals, BRUCELLA, Adhesins, Bacterial, purl.org/becyt/ford/1.6 [https], Mice, Inbred BALB C, Cellular Microbiology: Pathogen-Host Cell Molecular Interactions, Strain (chemistry), Ciencias Veterinarias, Cell Polarity, Gene Expression Regulation, Bacterial, Autotranporters, biology.organism_classification, Antibodies, Bacterial, Phenotype, Btae, Bacterial adhesin, Infectious Diseases, CIENCIAS AGRÍCOLAS, Multigene Family, POLE, Parasitology, ADHESIVE, purl.org/becyt/ford/4.3 [https], Carrier Proteins, CIENCIAS NATURALES Y EXACTAS, purl.org/becyt/ford/4 [https]
Abstract

Brucella is responsible for brucellosis, one of the most common zoonoses worldwide that causes important economic losses in several countries. Increasing evidence indicates that adhesion of Brucella spp. to host cells is an important step to establish infection. We have previously shown that the BmaC unipolar monomeric autotransporter mediates the binding of Brucella suis to host cells through cell-associated fibronectin. Our genome analysis shows that the B. suis genome encodes several additional potential adhesins. In this work, we characterized a predicted trimeric autotransporter that we named BtaE. By expressing btaE in a nonadherent Escherichia coli strain and by phenotypic characterization of a B. suis ΔbtaE mutant, we showed that BtaE is involved in the binding of B. suis to hyaluronic acid. The B. suis ΔbtaE mutant exhibited a reduction in the adhesion to HeLa and A549 epithelial cells compared with the wild-type strain, and it was outcompeted by the wild-type strain in the binding to HeLa cells. The knockout btaE mutant showed an attenuated phenotype in the mouse model, indicating that BtaE is required for full virulence. BtaE was immunodetected on the bacterial surface at one cell pole. Using old and new pole markers, we observed that both the BmaC and BtaE adhesins are consistently associated with the new cell pole, suggesting that, in Brucella, the new pole is functionally differentiated for adhesion. This is consistent with the inherent polarization of this bacterium, and its role in the invasion process. Fil: Ruiz, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Posadas, Diana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina Fil: Van Der Henst, Charles. University of Namur; Bélgica Fil: Estein, Silvia M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Pcia.de Bs.as.. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Invest.científicas. Centro de Investigación Veterinaria de Tandil; Argentina Fil: Arocena, Gastón Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Abdian, Patricia Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: Martin, Fernando Ariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina Fil: Sieira, Rodrigo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina Fil: De Bolle, Xavier. University of Namur; Bélgica Fil: Zorreguieta, Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina

Published
2013
Full Text
View/download PDF

3. The histidine kinase PdhS controls cell cycle progression of the pathogenic alphaproteobacterium Brucella abortus

Author

Johann Mignolet, Bernard Hallet, Jean-Jacques Letesson, Charles Van der Henst, Xavier De Bolle, Julien Colinet, Christian Didembourg, François Beaufay, UCL - SST/ISV - Institut des sciences de la vie, and Department of Bio-engineering Sciences

Subjects
Histidine Kinase, Cell division, Brucella abortus, Biology, Microbiology, Gene Expression Regulation, Enzymologic, Bacterial Proteins, Two-Hybrid System Techniques, Phosphorylation, Molecular Biology, Histidine, chemistry.chemical_classification, Kinase, Cell Cycle, Mutagenesis, Histidine kinase, Temperature, Articles, Gene Expression Regulation, Bacterial, Cell cycle, Amino acid, Luminescent Proteins, chemistry, Biochemistry, Protein Kinases, Function (biology)
Abstract

Bacterial differentiation is often associated with the asymmetric localization of regulatory proteins, such as histidine kinases. PdhS is an essential and polarly localized histidine kinase in the pathogenic alphaproteobacterium Brucella abortus . After cell division, PdhS is asymmetrically segregated between the two sibling cells, highlighting a differentiation event. However, the function(s) of PdhS in the B. abortus cell cycle remains unknown. We used an original approach, the pentapeptide scanning mutagenesis method, to generate a thermosensitive allele of pdhS . We report that a B. abortus strain carrying this pdhS allele displays growth arrest and an altered DivK-yellow fluorescent protein (YFP) polar localization at the restrictive temperature. Moreover, the production of a nonphosphorylatable PdhS protein or truncated PdhS proteins leads to dominant-negative effects by generating morphological defects consistent with the inhibition of cell division. In addition, we have used a domain mapping approach combined with yeast two-hybrid and fluorescence microscopy methods to better characterize the unusual PdhS sensory domain. We have identified a fragment of the PdhS sensory domain required for protein-protein interaction (amino acids [aa] 210 to 434), a fragment sufficient for polar localization (aa 1 to 434), and a fragment (aa 527 to 661) whose production in B. abortus correlates with the generation of cell shape alterations. The data support a model in which PdhS acts as an essential regulator of cell cycle progression in B. abortus and contribute to a better understanding of the differentiation program inherited by the two sibling cells.

Published
2012
Full Text
View/download PDF

4. PdhS, an Old-Pole-Localized Histidine Kinase, Recruits the Fumarase FumC in Brucella abortus

Author

Johann Mignolet, Delphine Dotreppe, Xavier De Bolle, Charles Van der Henst, Michaël Deghelt, Jean-Jacques Letesson, Cécile Nicolas, and Department of Bio-engineering Sciences

Subjects
Histidine Kinase, Brucella abortus, Research Support, Microbiology, Fumarate Hydratase, Microbial Cell Biology, Journal Article, Non-U.S. Gov't, ORFeome, Molecular Biology, Histidine, Sinorhizobium meliloti, biology, Caulobacter crescentus, Histidine kinase, Bacterial, Gene Expression Regulation, Bacterial, biology.organism_classification, Transport protein, Cell biology, Protein Transport, Gene Expression Regulation, Cytoplasm, Fumarase, Protein Kinases, Gene Deletion, Protein Binding
Abstract

The bacterial pathogen Brucella abortus was recently demonstrated to recruit the essential cytoplasmic histidine kinase PdhS to its old pole. Here, we report identification of the fumarase FumC as a specific partner for the N-terminal “sensing” domain of PdhS, using an ORFeome-based yeast two-hybrid screen. We observed that FumC and PdhS colocalize at the old pole of B. abortus , while the other fumarase FumA is not polarly localized. FumC is not required for PdhS localization, and polar FumC localization is not FumA dependent. FumC homologs are not polarly localized in Sinorhizobium meliloti and Caulobacter crescentus , suggesting that polar recruitment of FumC by PdhS is evolutionarily recent.

Published
2010

Catalog

Books, media, physical & digital resources
See catalog results