Biology subjects

Domenech, A.

Publications and source records attributed to Domenech, A..

6 recordsLinked to original sources

bioRxiv2022

Competence remodels the pneumococcal cell wall providing resistance to fratricide and surface exposing key virulence factors

Competence development in the human pathogen Streptococcus pneumoniae controls several features such as genetic transformation, biofilm formation and virulence. Competent bacteria produce so called fratricins such as CbpD, that kill non-competent siblings by cleaving peptidoglycan (PGN). CbpD is a choline-binding protein (CBP) that binds to phosphorylcholine residues found on wall- and lipoteichoic acids (WTA and LTA) that together with PGN are major constituents of the pneumococcal cell wall. Competent pneumococci are protected against fratricide by producing the immunity protein ComM. How competence and fratricide contribute to virulence is unknown. Here, using a genome-wide CRISPRi-seq screen, we show that genes involved in teichoic acid biosynthesis are essential during competence. We demonstrate that LytR is the major enzyme mediating the final step in WTA formation, and that, together with ComM, is essential for immunity against CbpD. Importantly, we show that key virulence factors PspA and PspC become more surface-exposed at midcell during competence, in a CbpD-dependent manner. Together, our work supports a model in which activation of competence is crucial for host adherence by increased surface exposure of its various CBPs.

microbiology↗

bioRxiv2022

Pneumolysin promotes host cell necroptosis and bacterial competence during pneumococcal meningitis as shown by whole animal dual RNA-seq

Pneumolysin is a major virulence factor of Streptococcus pneumoniae that plays a key role in interaction with the host during invasive disease. How pneumolysin influences these dynamics between host and pathogen interaction during early phase of central nervous system infection in pneumococcal meningitis remains unclear. Using a whole animal in vivo dual RNA-seq approach, we identified pneumolysin-specific transcriptional responses in both S. pneumoniae and zebrafish (Danio rerio) during early pneumococcal meningitis. By functional enrichment analysis we identified host pathways known to be activated by pneumolysin, and discovered the importance of necroptosis for host survival. Inhibition of this pathway using the drugs necrostatin-5 or GSK872 increased host mortality during pneumococcal meningitis. On the pathogens side, we find that pneumolysin-dependent competence activation is crucial for intra-host replication and virulence and that not all bacteria activate competence at the same time. Altogether, this study provides new insights into pneumolysin-specific transcriptional responses and identifies key pathways involved in pneumococcal meningitis. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/479878v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1214d1aorg.highwire.dtl.DTLVardef@14d0e8corg.highwire.dtl.DTLVardef@1f6133aorg.highwire.dtl.DTLVardef@685955_HPS_FORMAT_FIGEXP M_FIG C_FIG HIGHLIGHTSO_LIPneumolysin-specific host and bacterial responses as identified by whole animal dual RNA-seq, available at https://veeninglab.com/dual-danio C_LIO_LIDiscovery of a functional necroptosis or necroptosis-like pathway in zebrafish C_LIO_LIHeterogeneity in competence development during infection C_LIO_LICompetence development is an important virulence determinant C_LI

microbiology↗

bioRxiv2019

Fighting the spread of antibiotic resistance with bacterial competence inhibitors

Streptococcus pneumoniae is a commensal of the human nasopharynx, but it can also cause severe life-threatening antibiotic-resistant infections. Antibiotic consumption drives the spread of resistance by inducing S. pneumoniae competence leading to the uptake of exogenous DNA and horizontal gene transfer (HGT). We have identified potent inhibitors of competence, collectively called COM-blockers. We show that COM-blockers inhibit HGT by perturbing the proton motive force, thereby disrupting the export of the peptide that regulates competence. COM-blockers do not affect growth or compromise antibiotic activity at their active concentrations, and we did not observe any resistance development against them. Used as adjuvants of antibiotics, COM-blockers provide a strategy to reduce the spread of virulence factors and antibiotic resistance in human pathogens.\n\nOne Sentence SummaryAntibiotic adjuvants block competence

microbiology↗

bioRxiv2018

Antibiotic-induced cell chaining triggers pneumococcal competence by reshaping quorum sensing to autocrine signaling

Streptococcus pneumoniae can acquire antibiotic resistance by activation of competence and subsequent DNA uptake. Several antibiotics induce competence by disrupting protein-quality control or perturbing DNA replication. Here, we demonstrate that aztreonam (AZT) and clavulanic acid (CLA) also promote competence. We show that both compounds induce cell chain formation by targeting the D,D-carboxypeptidase PBP3. In support of the hypothesis that chain formation promotes competence, we demonstrate that an autolysin mutant (lytB) is hypercompetent. As competence is initiated by the binding of a small extracellular peptide (CSP) to a membrane-anchored receptor (ComD), we wondered if chain formation alters CSP diffusion and thereby sensing by ComD. Indeed, the presence of AZT or CLA affects competence synchronization by switching CSP-based quorum sensing to autocrine-like signaling, as CSP is retained to chained cells and no longer shared in a common pool. Together, these insights demonstrate the versatility of quorum sensing in integrating different stresses and highlight that certain antibiotics should be prescribed with care not to drive the spread of antibiotic resistance.

microbiology↗

bioRxiv2018

The Streptococcus pneumoniae Competence-Induced BriC Peptide Promotes Nasopharyngeal Colonization and Impacts Biofilm Development

Streptococcus pneumoniae (pneumococcus) is an opportunistic pathogen that causes otitis media, sinusitis, pneumonia, meningitis and sepsis. The progression to this pathogenic lifestyle is preceded by asymptomatic colonization of the nasopharynx. This colonization is associated with biofilm formation; the competence pathway influences the structure and stability of biofilms. However, the molecules that link the competence pathway to biofilm formation are unknown. Here, we describe a new competence-induced gene, called briC, and demonstrate that its product promotes biofilm development and stimulates colonization in a murine model. We show that expression of briC is induced by the master regulator of competence, ComE. Whereas briC does not substantially influence early biofilm development on abiotic surfaces, it significantly impacts later stages of biofilm development. Specifically, briC expression leads to increases in biofilm biomass and thickness at 72h. Consistent with the role of biofilms in colonization, briC promotes nasopharyngeal colonization in the murine model. The function of BriC appears to be conserved across pneumococci, as comparative genomics reveal that briC is widespread across isolates. Surprisingly, many isolates, including strains from clinically important PMEN1 and PMEN14 lineages, which are widely associated with colonization, encode a long briC promoter. This long form captures an instance of genomic plasticity and functions as a competence-independent expression enhancer that may serve as a precocious point of entry into this otherwise competence-regulated pathway. Moreover, overexpression of briC by the long promoter fully rescues the comE-deletion induced biofilm defect in vitro, and partially in vivo. These findings indicate that BriC may bypass the influence of competence in biofilm development and that such a pathway may be active in a subset of pneumococcal lineages. In conclusion, BriC is a part of the complex molecular network that connects signaling of the competence pathway to biofilm development and colonization.

microbiology↗

bioRxiv2016

High-throughput CRISPRi phenotyping in Streptococcus pneumoniae identifies new essential genes involved in cell wall synthesis and competence development

Genome-wide screens have discovered a large set of essential genes in the opportunistic human pathogen Streptococcus pneumoniae. However, the functions of many essential genes are still unknown, hampering vaccine development and drug discovery. Based on results from transposon-sequencing (Tn-Seq), we refined the list of essential genes in S. pneumoniae serotype 2 strain D39. Next, we created a knockdown library targeting 348 potentially essential genes by CRISPR interference (CRISPRi) and show a growth phenotype for 254 of them (73%). Using high-content microscopy screening, we searched for essential genes of unknown function with clear phenotypes in cell morphology upon CRISPRi-based depletion. We show that SPD1416 and SPD1417 (renamed to MurT and GatD, respectively) are essential for peptidoglycan synthesis, and that SPD1198 and SPD1197 (renamed to TarP and TarQ, respectively) are responsible for the polymerization of teichoic acid (TA) precursors. This knowledge enabled us to reconstruct the unique pneumococcal TA biosynthetic pathway. CRISPRi was also employed to unravel the role of the essential Clpproteolytic system in regulation of competence development and we show that ClpX is the essential ATPase responsible for ClpP-dependent repression of competence. The CRISPRi library provides a valuable tool for characterization of pneumococcal genes and pathways and revealed several promising antibiotic targets.

microbiology↗