A5029107560- Pneumonia and Respiratory Infections
- Bacterial Genetics and Biotechnology
- RNA and protein synthesis mechanisms
- Bacterial Infections and Vaccines
- Probiotics and Fermented Foods
- Genomics and Phylogenetic Studies
- Bacteriophages and microbial interactions
- Escherichia coli research studies
- Viral gastroenteritis research and epidemiology
- Enzyme Structure and Function
- Enterobacteriaceae and Cronobacter Research
- Streptococcal Infections and Treatments
- Transplantation: Methods and Outcomes
- Antibiotic Resistance in Bacteria
- Carbohydrate Chemistry and Synthesis
- Glycosylation and Glycoproteins Research
- CRISPR and Genetic Engineering
- Cell Image Analysis Techniques
- Digital Holography and Microscopy
- Neurogenetic and Muscular Disorders Research
- Advanced Fluorescence Microscopy Techniques
- Antimicrobial Resistance in Staphylococcus
- Monoclonal and Polyclonal Antibodies Research
- Microbial Natural Products and Biosynthesis
- Antimicrobial Peptides and Activities
Laboratoire de Microbiologie et Génétique Moléculaires
2013-2025
Université Toulouse III - Paul Sabatier
2012-2025
Centre National de la Recherche Scientifique
2002-2023
Université de Toulouse
2010-2022
Harvard University
2004-2018
University of Groningen
2004
Despite years of intensive research, much remains to be discovered understand the regulatory networks coordinating bacterial cell growth and division. The mechanisms by which Streptococcus pneumoniae achieves its characteristic ellipsoid-cell shape remain largely unknown. In this study, we analyzed interplay division paralogs DivIVA GpsB with ser/thr kinase StkP. We observed that deletion divIVA hindered elongation resulted in shortening rounding. By contrast, absence hampered triggered...
Natural genetic transformation is widely distributed in bacteria and generally occurs during a genetically programmed differentiated state called competence. This process promotes genome plasticity adaptability Gram-negative Gram-positive bacteria. Transformation requires the binding internalization of exogenous DNA, mechanisms which are unclear. Here, we report discovery pilus at surface competent Streptococcus pneumoniae cells. Type IV-like pilus, primarily composed ComGC pilin, required...
Current super-resolution microscopy (SRM) methods suffer from an intrinsic complexity that might curtail their routine use in cell biology. We describe here random illumination (RIM) for live-cell imaging at super-resolutions matching of 3D structured microscopy, a robust fashion. Based on speckled and statistical image reconstruction, easy to implement user-friendly, RIM is unaffected by optical aberrations the excitation side, linear brightness, compatible with multicolor over extended...
Summary Most bacterial proteins destined to leave the cytoplasm are exported extracellular compartments or imported into cytoplasmic membrane via highly conserved SecA‐YEG pathway. In present studies, subcellular distributions of core components this pathway, SecA and SecY, secretory protein pre‐AmyQ, were analysed using green fluorescent fusions, immunostaining and/or immunogold labelling techniques. It is shown that SecA, SecY (pre‐)AmyQ located at specific sites near in Bacillus subtilis....
A secreted competence-stimulating peptide (CSP), encoded by comC, constitutes, together with the two-component system ComD-ComE, master switch for competence induction in Streptococcus pneumoniae. Interaction between CSP and its membrane-bound histidine-kinase receptor, ComD, is believed to lead autophosphorylation of which then transphosphorylates ComE response regulator activate transcription a limited set genes, including comCDE operon. This generates positive feedback loop, amplifying...
Abstract Bacterial cells are known to produce inhibitors of cell division in response stress responses and developmental programs. Knowledge the underlying molecular mechanisms remains however largely limited. In this study, we investigated mechanism transient inhibition observed during development competence for transformation human pathogen Streptococcus pneumoniae . species, ComM, a membrane protein specifically produced competence, transiently inhibits preserve genomic integrity...
Transformation promotes genome plasticity in bacteria via RecA-driven homologous recombination. In the Gram-positive human pathogen Streptococcus pneumoniae , transformasome a multiprotein complex, internalizes, protects, and processes transforming DNA to generate chromosomal recombinants. Double-stranded is internalized as single strands, onto which transformation-dedicated processing protein A (DprA) ensures loading of RecA form presynaptic filaments. We report that structure DprA consists...
Genetic transformation, in which cells internalize exogenous DNA and integrate it into their chromosome, is widespread the bacterial kingdom. It involves a specialized membrane-associated machinery for binding double-stranded (ds) uptake of single-stranded (ss) fragments. In human pathogen Streptococcus pneumoniae, this specifically assembled at competence. The EndA nuclease, constitutively expressed virulence factor, recruited during competence to play key role converting dsDNA ssDNA...
Abstract Competence for genetic transformation is a differentiation program during which exogenous DNA imported into the cell and integrated chromosome. In Streptococcus pneumoniae , competence develops transiently synchronously in all cells exponential phase, accompanied by pause growth. Here, we reveal that this linked to cycle. At least two parallel pathways impair peptidoglycan synthesis competent cells. Single-cell analyses demonstrate ComM, membrane protein induced competence, inhibits...
Homologous recombination between circular sister chromosomes during DNA replication in bacteria can generate chromosome dimers that must be resolved into monomers prior to cell division. In Escherichia coli, dimer resolution is achieved by site-specific recombination, Xer involving two paralogous tyrosine recombinases, XerC and XerD, a 28-bp site (dif) located at the junction of arms. tightly controlled septal protein FtsK. XerCD recombinases FtsK are found on most sequenced eubacterial...
Summary We used artificial chromosome inversions to investigate the chromosomal constraints that preserve genome organization in Gram‐positive bacterium Lactococcus lactis . Large inversions, 80–1260 kb length, disturbing symmetry of origin and terminus replication axis various extents, were constructed using site‐specific Cre‐ loxP recombination system. These all mechanistically feasible fell into classes according stability effect on cell fitness. The L. supports only some extent unbalance...
Abstract Competence for natural transformation is a central driver of genetic diversity in bacteria. In the human pathogen Streptococcus pneumoniae , competence exhibits populational character mediated by stress-induced ComABCDE quorum-sensing (QS) system. Here, we explore how this cell-to-cell communication mechanism proceeds and functional properties acquired competent cells grown under lethal stress. We show that development depends on self-induced stochastically emerging response to...
ABSTRACT Comparative analysis of chromosomal macrorestriction polymorphism the two closely related Lactococcus lactis subsp. cremoris strains MG1363 and NCDO763 revealed presence a large inversion covering half genome. To determine what kind genetic element could be implicated in this rearrangement, junctions chromosomes were cloned characterized. Nucleotide sequence showed one copy lactococcal IS 905 each junction. Each contained same nucleotide mutation that inactivates putative...
Natural genetic transformation is a conserved mechanism of bacterial horizontal gene transfer, which directed entirely by the recipient cell and facilitates acquisition new traits such as antibiotic resistance. Transformation proceeds via capture exogenous DNA, its internalisation in single strand form (ssDNA) integration into chromosome homologous recombination. While proteins involved these steps have mainly been identified, specific mechanisms at play remain poorly characterised. This...
ABSTRACT The proteolytic activation of the mother cell transcription factor pro-σ K is controlled by a signal transduction pathway during sporulation in bacterium Bacillus subtilis . processing enzyme SpoIVFB, membrane-embedded metalloprotease, held inactive two other integral membrane proteins, SpoIVFA and BofA, that surrounds forespore. Two signaling serine proteases, SpoIVB CtpB, trigger cleaving regulatory protein SpoIVFA. absolutely required to activate derived from forespore...
During the process of spore formation in Bacillus subtilis, many membrane proteins localize to polar septum where they participate morphogenesis and signal transduction. The forespore protein SpoIIQ plays a central role anchoring several mother-cell septal membrane. Here, we report that is also responsible for on side sporulation septum. Co-immunoprecipitation experiments reveal resides complex with polytopic SpoIIE. early stages sporulation, SpoIIE participates switch from medial division...
ABSTRACT We have used a new genetic strategy based on the Cre- loxP recombination system to generate large chromosomal rearrangements in Lactococcus lactis . Two sites were sequentially integrated inverse order into chromosome either at random locations by transposition or fixed points homologous recombination. The between two was highly efficient (approximately 1 × 10 −1 /cell) when Cre recombinase provided trans , and parental- inverted-type structures isolated after removal of...
The peptidoglycan is a rigid matrix required to resist turgor pressure and maintain the cellular shape. It formed by linear glycan chains composed of N-acetylmuramic acid-(β-1,4)-N-acetylglucosamine (MurNAc-GlcNAc) disaccharides associated through cross-linked peptide stems. continually remodelled synthetic hydrolytic enzymes chemical modifications, including O-acetylation MurNAc residues that occurs in most Gram-positive Gram-negative bacteria. This modification powerful strategy developed...
The spread of antimicrobial resistance and vaccine escape in the human pathogen Streptococcus pneumoniae can be largely attributed to competence-induced transformation. Here, we studied this process at single-cell level. We show that within isogenic populations, all cells become naturally competent bind exogenous DNA. find transformation is highly efficient chromosomal location integration site or whether transformed gene encoded on leading lagging strand has limited influence recombination...
The bacterial cell wall is in part composed of the peptidoglycan (PG) layer that maintains shape and sustains basic cellular processes growth division. Gram-positive bacteria also carries teichoic acids (TAs). In this work, we investigated how TAs contribute to structuration PG network through modulation hydrolytic enzymes context Streptococcus pneumoniae bacterium. Pneumococcal are decorated by phosphorylcholine residues which serve as anchors for Choline-Binding Proteins, some them acting...
Bacterial shape and division rely on the dynamics of cell wall assembly, which involves regulated synthesis cleavage peptidoglycan. In ovococci, these processes are coordinated within an annular mid-cell region with nanometric dimensions. More precisely, cross-wall synthesized by divisome is split to generate a lateral wall, whose expansion insured insertion so-called peripheral peptidoglycan elongasome. Septum are, thus, crucial remodeling events for ovococcal elongation. The structural...