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

The Autolysin LytA Contributes to Efficient Bacteriophage Progeny Release in Streptococcus... The Autolysin LytA Contributes to Efficient Bacteriophage Progeny Release in Streptococcus pneumoniae ▿ Maria João Frias , José Melo-Cristino , and Mário Ramirez * Unidade de Microbiologia Molecular e Infecção, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal ABSTRACT Most bacteriophages (phages) release their progeny through the action of holins that form lesions in the cytoplasmic membrane and lysins that degrade the bacterial peptidoglycan. Although the function of each protein is well established in phages infecting Streptococcus pneumoniae , the role—if any—of the powerful bacterial autolysin LytA in virion release is currently unknown. In this study, deletions of the bacterial and phage lysins were done in lysogenic S. pneumoniae strains, allowing the evaluation of the contribution of each lytic enzyme to phage release through the monitoring of bacterial-culture lysis and phage plaque assays. In addition, we assessed membrane integrity during phage-mediated lysis using flow cytometry to evaluate the regulatory role of holins over the lytic activities. Our data show that LytA is activated at the end of the lytic cycle and that its triggering results from holin-induced membrane permeabilization. In the absence of phage lysin, LytA is able to mediate bacterial lysis and phage release, although exclusive dependence on the autolysin results in reduced virion egress and altered kinetics that may impair phage fitness. Under normal conditions, activation of bacterial LytA, together with the phage lysin, leads to greater phage progeny release. Our findings demonstrate that S. pneumoniae phages use the ubiquitous host autolysin to accomplish an optimal phage exiting strategy. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Bacteriology American Society For Microbiology

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

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

Journal of Bacteriology , Volume 191 (17): 5428 – Sep 1, 2009

Abstract

The Autolysin LytA Contributes to Efficient Bacteriophage Progeny Release in Streptococcus pneumoniae ▿ Maria João Frias , José Melo-Cristino , and Mário Ramirez * Unidade de Microbiologia Molecular e Infecção, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal ABSTRACT Most bacteriophages (phages) release their progeny through the action of holins that form lesions in the cytoplasmic membrane and lysins that degrade the bacterial peptidoglycan. Although the function of each protein is well established in phages infecting Streptococcus pneumoniae , the role—if any—of the powerful bacterial autolysin LytA in virion release is currently unknown. In this study, deletions of the bacterial and phage lysins were done in lysogenic S. pneumoniae strains, allowing the evaluation of the contribution of each lytic enzyme to phage release through the monitoring of bacterial-culture lysis and phage plaque assays. In addition, we assessed membrane integrity during phage-mediated lysis using flow cytometry to evaluate the regulatory role of holins over the lytic activities. Our data show that LytA is activated at the end of the lytic cycle and that its triggering results from holin-induced membrane permeabilization. In the absence of phage lysin, LytA is able to mediate bacterial lysis and phage release, although exclusive dependence on the autolysin results in reduced virion egress and altered kinetics that may impair phage fitness. Under normal conditions, activation of bacterial LytA, together with the phage lysin, leads to greater phage progeny release. Our findings demonstrate that S. pneumoniae phages use the ubiquitous host autolysin to accomplish an optimal phage exiting strategy.

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Publisher
American Society For Microbiology
Copyright
Copyright © 2009 by the American society for Microbiology.
ISSN
0021-9193
eISSN
1098-5530
DOI
10.1128/JB.00477-09
pmid
19581370
Publisher site
See Article on Publisher Site

Abstract

The Autolysin LytA Contributes to Efficient Bacteriophage Progeny Release in Streptococcus pneumoniae ▿ Maria João Frias , José Melo-Cristino , and Mário Ramirez * Unidade de Microbiologia Molecular e Infecção, Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal ABSTRACT Most bacteriophages (phages) release their progeny through the action of holins that form lesions in the cytoplasmic membrane and lysins that degrade the bacterial peptidoglycan. Although the function of each protein is well established in phages infecting Streptococcus pneumoniae , the role—if any—of the powerful bacterial autolysin LytA in virion release is currently unknown. In this study, deletions of the bacterial and phage lysins were done in lysogenic S. pneumoniae strains, allowing the evaluation of the contribution of each lytic enzyme to phage release through the monitoring of bacterial-culture lysis and phage plaque assays. In addition, we assessed membrane integrity during phage-mediated lysis using flow cytometry to evaluate the regulatory role of holins over the lytic activities. Our data show that LytA is activated at the end of the lytic cycle and that its triggering results from holin-induced membrane permeabilization. In the absence of phage lysin, LytA is able to mediate bacterial lysis and phage release, although exclusive dependence on the autolysin results in reduced virion egress and altered kinetics that may impair phage fitness. Under normal conditions, activation of bacterial LytA, together with the phage lysin, leads to greater phage progeny release. Our findings demonstrate that S. pneumoniae phages use the ubiquitous host autolysin to accomplish an optimal phage exiting strategy.

Journal

Journal of BacteriologyAmerican Society For Microbiology

Published: Sep 1, 2009

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