Regulation of competence for genetic transformation in <i>Streptococcus pneumoniae</i>

Claverys, Jean‐Pierre; Dintilhac, Agnès; Mortier‐Barrière, Isabelle; Martin, Bernard; Alloing, Geneviève

doi:10.1046/j.1365-2672.83.s1.4.x

Cited by 10 publications

(7 citation statements)

References 5 publications

(10 reference statements)

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“…A 1000‐ to 10 000‐fold reduction in competence was observed for other comD mutations. The various ComD mutants, except ComD T233I , were concluded to be only partially self‐activated in the absence of circulating CSP, including ComD D299N ( trt1 ) that was previously reported to restore transformability in a comA − context (D. Morrison, personal communication; cited in Claverys et al ., 1997). These results also indicated that CSP‐dependent autoinduction of comCDE contributed to the ComCDE UP phenotype of all suppressors, including ciaR knock‐outs and the ComE R120S mutant, except for the ComD T233I mutant.…”

Section: Resultsmentioning

confidence: 99%

Cross‐regulation of competence pheromone production and export in the early control of transformation in Streptococcus pneumoniae

Martin¹,

Prudhomme²,

Alloing

et al. 2000

Molecular Microbiology

174

200

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SummaryTwo operons, comAB and comCDE, play a key role in the co-ordination of spontaneous competence development in cultures of Streptococcus pneumoniae. ComAB is required for export of the comC-encoded competence-stimulating peptide (CSP). Upon CSP binding, the histidine kinase ComD activates ComE, its cognate response regulator, required for autoinduction of comCDE and for induction of the late competence genes. To understand better the early control of competence development, mutants upregulating comCDE (ComCDE UP ) were isolated using a comC±lacZ transcriptional fusion. Mutants were generated by polymerase chain reaction mutagenesis of the comCDE region and by in vitro transposon mutagenesis of the chromosome. Both types of ComCDE UP mutants exhibited similar phenotypes.They differed from wild type in displaying trypsinresistant transformation, competence under acid growth conditions and expression of comCDE under microaerobiosis; increased production of CSP in the mutants could account for the various phenotypes. The ComCDE UP transposon mutations included four independent insertions in the ciaR gene, which encodes the response regulator of a two-component system previously found to affect competence, and two immediately upstream of the comAB operon. The latter two resulted in comAB overexpression, indicating that CSP export is rate limiting. Among comDE point mutations, a single amino acid change in ComD (T233I) conferred constitutive, CSP-independent competence and resulted in comAB overexpression, providing support for the hypothesis that ComE regulates comAB; a ComE mutant (R120S) exhibited altered kinetics of competence shut-off. Collectively, these data indicate that pheromone autoinduction, cross-regulation of the comAB and comCDE operons and, possibly, competence shut-off contribute to the early control of competence development in S. pneumoniae. They argue for a metabolic control of competence, mediated directly or indirectly by CiaR, and they suggest that both comAB and comCDE are potential targets for regulation.

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Section: Resultsmentioning

confidence: 99%

Cross‐regulation of competence pheromone production and export in the early control of transformation in Streptococcus pneumoniae

Martin¹,

Prudhomme²,

Alloing

et al. 2000

Molecular Microbiology

174

200

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“…4, I) and is referred to as Campbelltype recombination (see comment in24). However, models of integration must take into account the breakage of donor DNA that occurs upon binding and the subsequent uptake of single strands.31 In view of the higher absolute efficiency of integra- 4. Models for insertion-duplication, cassette insertion, and insertion-deletion events during transformation in S. pneumoniae.…”

Section: Substitutive Recombinationmentioning

confidence: 99%

Control of Recombination Rate During Transformation ofStreptococcus pneumoniae: An Overview

Mortier‐Barrière¹,

Humbert²,

Martin³

et al. 1997

Microbial Drug Resistance

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Despite the fact that natural transformation was described long ago in Streptococcus pneumoniae, only a limited number of recombination genes have been identified. Two of them have recently been characterized at the molecular level, recA which encodes a protein essential for homologous recombination and mmsA which encodes the homologue of the Escherichia coli RecG protein. After a survey of the available information regarding the function of RecA, RecG, and other proteins such as the mismatch repair proteins HexA and HexB that can affect the outcome of recombinants, the different levels at which horizontal genetic exchange can be controlled are discussed. It is shown that the specific induction of the recA gene which occurs in competent cells is required for full recombination proficiency. Results regarding the ability of the Hex generalized mismatch repair system to prevent recombination between partially divergent sequences during transformation are also summarized. A structural analysis of homeologous recombinants which suggests that formation of mosaic recombinants can occur independently of mismatch repair in a single-step transformation is also reported. Finally, arguments in favor of an evolutionary origin of transformation as a means of genome evolution are discussed and the different types of recombination events observed which could potentially contribute to S. pneumoniae genome evolution are listed.

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“…Genes comA-E , adcA-C, and adcR, involved in inducing competence [44], were all significantly up-regulated in G54 on contact with host cells but only slightly up-regulated in TIGR4. Eleven bacteriocin-associated genes were also regulated in this strain, contributing to the high number of down-regulated genes encoding cellular processes.…”

Section: Discussionmentioning

confidence: 99%

Phenotypic, genomic, and transcriptional characterization of Streptococcus pneumoniae interacting with human pharyngeal cells

et al. 2013

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BackgroundStreptococcus pneumoniae is a leading cause of childhood morbidity and mortality worldwide, despite the availability of effective pneumococcal vaccines. Understanding the molecular interactions between the bacterium and the host will contribute to the control and prevention of pneumococcal disease.ResultsWe used a combination of adherence assays, mutagenesis and functional genomics to identify novel factors involved in adherence. By contrasting these processes in two pneumococcal strains, TIGR4 and G54, we showed that adherence and invasion capacities vary markedly by strain. Electron microscopy showed more adherent bacteria in association with membranous pseudopodia in the TIGR4 strain. Operons for cell wall phosphorylcholine incorporation (lic), manganese transport (psa) and phosphate utilization (phn) were up-regulated in both strains on exposure to epithelial cells. Pneumolysin, pili, stress protection genes (adhC-czcD) and genes of the type II fatty acid synthesis pathway were highly expressed in the naturally more invasive strain, TIGR4. Deletion mutagenesis of five gene regions identified as regulated in this study revealed attenuation in adherence. Most strikingly, ∆SP_1922 which was predicted to contain a B-cell epitope and revealed significant attenuation in adherence, appeared to be expressed as a part of an operon that includes the gene encoding the cytoplasmic pore-forming toxin and vaccine candidate, pneumolysin.ConclusionThis work identifies a list of novel potential pneumococcal adherence determinants.

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Regulation of competence for genetic transformation in Streptococcus pneumoniae

Cited by 10 publications

References 5 publications

Cross‐regulation of competence pheromone production and export in the early control of transformation in Streptococcus pneumoniae

Cross‐regulation of competence pheromone production and export in the early control of transformation in Streptococcus pneumoniae

Control of Recombination Rate During Transformation ofStreptococcus pneumoniae: An Overview

Phenotypic, genomic, and transcriptional characterization of Streptococcus pneumoniae interacting with human pharyngeal cells

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