The Autolysin LytA Contributes to Efficient Bacteriophage Progeny Release in
            <i>Streptococcus pneumoniae</i>

Frias, María Joáo; Melo‐Cristino, José; Ramírez, Mario

doi:10.1128/jb.00477-09

Cited by 31 publications

(63 citation statements)

References 55 publications

(72 reference statements)

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“…In the case of phage SV1 of Streptococcus pneumoniae, the autolysin LytA was able to lyse the host cells after induction with holin and, consequently, SV1 phage was shown to form plaques in the absence of its endolysin. This observation underlines the importance of LytA for efficient release of phage particles (Frias et al, 2009). A similar property of autolysin induction by phage was previously reported in the case of Micrococcus lysodeikticus infected with phage N1 (Goepfert & Naylor, 1967).…”

Section: Regulation By Inactivationsupporting

confidence: 58%

Insights into the regulation of bacteriophage endolysin: multiple means to the same end

Pohane¹,

Jain²

2015

Microbiology

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Antibiotics are the molecules of choice to treat bacterial infections. However, because of the rapid emergence of drug-resistant bacteria, alternative modes of combating infections are being envisaged. Bacteriophages, which infect and lyse bacterial cells, may function as effective antimicrobial agents. Most bacteriophages produce their own peptidoglycan hydrolase called endolysin or lysin, which breaks down the cell wall of bacteria and aids in the release of newly assembled virions. Here, we discuss several findings that help us in understanding how endolysins are regulated. We observe that there is no common mechanism that is followed in all cases. Many different modes of activity regulation have been observed in endolysins, including regulation of protein expression, translocation across the cell membrane and post-translational modifications. These processes not only demonstrate how endolysins are made dependent on other accessory proteins and non-protein factors for their synthesis, translocation across the cytoplasmic membrane and activity, but also show how autoregulation helps in maintaining the enzyme in an inactive form. Various regulatory mechanisms that are discussed are particularly applicable to endolysins. Nevertheless, a detailed study of these methods opens new avenues of investigation in the area of protein translocation systems and the novel ways of enzyme activation and regulation in bacteria.

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Section: Regulation By Inactivationsupporting

confidence: 58%

Insights into the regulation of bacteriophage endolysin: multiple means to the same end

Pohane¹,

Jain²

2015

Microbiology

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“…1D). Despite the expression of lytic genes, we were unable to identify plaques on any indicator strain using a plaque assay that was previously described for S. pneumoniae (22). Additionally, there was no evidence of phage particles using a DNase protection assay or in transmission electron micrographs of strain P1121.…”

Section: Resultsmentioning

confidence: 89%

“…The presence of Spn1 correlates with delay in autolysis. The phage lysin, Mml, and the major autolysin of S. pneumoniae, LytA, are homologous and thought to be functionally redundant cell wall amidases (22). In order to determine if autolysis is affected by the presence of Spn1, we measured bacterial growth in nutrient broth medium over a period of 24 h. Autolysis was delayed in the…”

Section: Resultsmentioning

confidence: 99%

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Tolerance of a Phage Element by Streptococcus pneumoniae Leads to a Fitness Defect during Colonization

et al. 2014

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The pathogenesis of the disease caused by Streptococcus pneumoniae begins with colonization of the upper respiratory tract. Temperate phages have been identified in the genomes of up to 70% of clinical isolates. How these phages affect the bacterial host during colonization is unknown. Here, we examined a clinical isolate that carries a novel prophage element, designated Spn1, which was detected in both integrated and episomal forms. Surprisingly, both lytic and lysogenic Spn1 genes were expressed under routine growth conditions. Using a mouse model of asymptomatic colonization, we demonstrate that the Spn1 ؊ strain outcompeted the Spn1 ؉ strain >70-fold. To determine if Spn1 causes a fitness defect through a trans-acting factor, we constructed an Spn1؉ mutant that does not become an episome or express phage genes. This mutant competed equally with the Spn1 ؊ strain, indicating that expression of phage genes or phage lytic activity is required to confer this fitness defect. In vitro, we demonstrate that the presence of Spn1 correlated with a defect in LytA-mediated autolysis. Furthermore, the Spn1 ؉ strain displayed increased chain length and resistance to lysis by penicillin compared to the Spn ؊ strain, indicating that Spn1 alters the cell wall physiology of its host strain. We posit that these changes in cell wall physiology allow for tolerance of phage gene products and are responsible for the relative defect of the Spn1 ؉ strain during colonization. This study provides new insight into how bacteria and prophages interact and affect bacterial fitness in vivo.

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“…Colombet, et al [17] proposed using PEG (polyethylene glycol) precipitation as an alternative to density gradient ultracentrifugation for purifying viruses. Concentrating bacteriophages by ultrafiltration is a further alternative to ultracentrifugation and has several advantages, including the removal of proteins that could cause bacterial lysis [18,19]. Precipitation using PEG followed by ultrafiltration was therefore the method of choice for preparing the phage stock in this work.…”

Section: Phage Lysate Preparationmentioning

confidence: 99%

Potentiometric Investigation of the Dynamics of Bacteriophage - Induced Potassium Ion Efflux in Escherichia coli

Galgalkar¹

2016

Ely J Micro

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Potassium is a very stable component of biological systems and contributes to maintaining positive turgor pressure of the cells. Although ion-selective electrodes (ISEs) have been used previously for measuring bacteriophage -induced potassium ion efflux in bacteria, the dynamics of this outcome remain unclear. In this study, the effects of incubation time, reaction volume, and phage/bacterial concentration on bacteriophage-induced potassium ion efflux were studied using a commercial ISE. A phage-bacteria reaction volume of 200 µl incubated at 37°C for 30 minutes was found to be optimal for detecting potassium ion efflux using the ISE. Potassium ion efflux was found to be directly proportional to phage multiplicity of infection and ~5 × 10 7 cfu/ml appeared to be the lowest bacterial concentration at which potassium ion efflux could be measured reliably. Furthermore, the differences in potassium ion efflux between control (bacteria + assay buffer) and test (bacteria + phage) samples were statistically significant (p < 0.05) and the results were consistent across assays performed on different days. The average of absolute concentrations of effluxed potassium ions was 1.4 mg/L for ~5 × 10 8 cfu/ml of bacteria (MOI (Multiplicity of infection) = 100). The method uses simple bench-top technology, has a rapid turnaround time, is label-free, and has the potential for incorporation in bacterial detection systems.

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The Autolysin LytA Contributes to Efficient Bacteriophage Progeny Release in Streptococcus pneumoniae

Cited by 31 publications

References 55 publications

Insights into the regulation of bacteriophage endolysin: multiple means to the same end

Insights into the regulation of bacteriophage endolysin: multiple means to the same end

Tolerance of a Phage Element by Streptococcus pneumoniae Leads to a Fitness Defect during Colonization

Potentiometric Investigation of the Dynamics of Bacteriophage - Induced Potassium Ion Efflux in Escherichia coli

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