Regulation of the Arginine Deiminase System by ArgR2 Interferes with Arginine Metabolism and Fitness of <named-content content-type="genus-species">Streptococcus pneumoniae</named-content>

ABSTRACT Streptococcus pneumoniae is auxotrophic for arginine, and molecular analysis of the pneumococcal genome showed that the gene encoding an arginine-ornithine antiporter (ArcD) is organized in a cluster together with the arcABC genes encoding the arginine deiminase system (ADS) of pneumococci....

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Autores principales:	Christian Schulz, Philipp Gierok, Lothar Petruschka, Michael Lalk, Ulrike Mäder, Sven Hammerschmidt
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2014
Materias:	Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/7ef28e7d51f9427b888f39b44c74c881
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spelling	oai:doaj.org-article:7ef28e7d51f9427b888f39b44c74c8812021-11-15T15:47:03ZRegulation of the Arginine Deiminase System by ArgR2 Interferes with Arginine Metabolism and Fitness of <named-content content-type="genus-species">Streptococcus pneumoniae</named-content>10.1128/mBio.01858-142150-7511https://doaj.org/article/7ef28e7d51f9427b888f39b44c74c8812014-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.01858-14https://doaj.org/toc/2150-7511ABSTRACT Streptococcus pneumoniae is auxotrophic for arginine, and molecular analysis of the pneumococcal genome showed that the gene encoding an arginine-ornithine antiporter (ArcD) is organized in a cluster together with the arcABC genes encoding the arginine deiminase system (ADS) of pneumococci. The ADS consists of the arginine deiminase (AD), the catabolic ornithine carbamoyltransferase (cOCT), and the carbamate kinase (CK). Pneumococcal genomes contain three ArgR-type regulators (ArgR1, ArgR2, and AhrC) that are supposed to be involved in the regulation of arginine metabolism. Here, we identified ArgR2 of TIGR4 as the regulator of the ADS and ArcD. ArgR2 binds to promoter sequences of the arc operon, and the deficiency of ArgR2 in TIGR4 abrogates expression of the ADS, including the arginine-ornithine antiporter ArcD. Intranasal infection of mice and real-time bioimaging revealed that deletion of the arcABCDT genes attenuates TIGR4. However, the acute-pneumonia model and coinfection experiments indicated that the arginine-ornithine antiporter ArcD is essential to maintain fitness, while the deficiency of ADS enzymes has a minor impact on pneumococcal fitness under in vivo conditions. Strikingly, argR2 mutant TIGR4 outcompeted the wild type in the respiratory tract, suggesting an increase in fitness and further regulatory functions of ArgR2. In contrast to TIGR4, other pneumococci, such as D39, lacking expression of ArgR2, constitutively express the ADS with a truncated nonfunctional AD. On the basis of these results, we propose that the arginine-ornithine antiporter is essential to maintain pneumococcal fitness and that the genes of the ADS cluster are positively regulated in a strain-specific manner by ArgR2. IMPORTANCE Pneumococci are the major etiologic agents of community-acquired pneumonia, causing more than 1.5 million deaths annually worldwide. These versatile pathogens are highly adapted to the nutrients provided by the host niches encountered. Physiological fitness is of major importance for colonization of the nasopharyngeal cavity and dissemination during invasive infections. This work identifies the regulator ArgR2 as the activator of the S. pneumoniae TIGR4 ADS and the arginine-ornithine transporter ArcD, which is needed for uptake of the essential amino acid arginine. Although ArgR2 activates ArcD expression and uptake of arginine is required to maintain pneumococcal fitness, the deficiency of ArgR2 increases TIGR4 virulence under in vivo conditions, suggesting that other factors regulated by ArgR2 counterbalance the reduced uptake of arginine by ArcD. Thus, this work illustrates that the physiological homeostasis of pneumococci is complex and that ArgR2 plays a key role in maintaining bacterial fitness.Christian SchulzPhilipp GierokLothar PetruschkaMichael LalkUlrike MäderSven HammerschmidtAmerican Society for MicrobiologyarticleMicrobiologyQR1-502ENmBio, Vol 5, Iss 6 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Microbiology QR1-502
spellingShingle	Microbiology QR1-502 Christian Schulz Philipp Gierok Lothar Petruschka Michael Lalk Ulrike Mäder Sven Hammerschmidt Regulation of the Arginine Deiminase System by ArgR2 Interferes with Arginine Metabolism and Fitness of <named-content content-type="genus-species">Streptococcus pneumoniae</named-content>
description	ABSTRACT Streptococcus pneumoniae is auxotrophic for arginine, and molecular analysis of the pneumococcal genome showed that the gene encoding an arginine-ornithine antiporter (ArcD) is organized in a cluster together with the arcABC genes encoding the arginine deiminase system (ADS) of pneumococci. The ADS consists of the arginine deiminase (AD), the catabolic ornithine carbamoyltransferase (cOCT), and the carbamate kinase (CK). Pneumococcal genomes contain three ArgR-type regulators (ArgR1, ArgR2, and AhrC) that are supposed to be involved in the regulation of arginine metabolism. Here, we identified ArgR2 of TIGR4 as the regulator of the ADS and ArcD. ArgR2 binds to promoter sequences of the arc operon, and the deficiency of ArgR2 in TIGR4 abrogates expression of the ADS, including the arginine-ornithine antiporter ArcD. Intranasal infection of mice and real-time bioimaging revealed that deletion of the arcABCDT genes attenuates TIGR4. However, the acute-pneumonia model and coinfection experiments indicated that the arginine-ornithine antiporter ArcD is essential to maintain fitness, while the deficiency of ADS enzymes has a minor impact on pneumococcal fitness under in vivo conditions. Strikingly, argR2 mutant TIGR4 outcompeted the wild type in the respiratory tract, suggesting an increase in fitness and further regulatory functions of ArgR2. In contrast to TIGR4, other pneumococci, such as D39, lacking expression of ArgR2, constitutively express the ADS with a truncated nonfunctional AD. On the basis of these results, we propose that the arginine-ornithine antiporter is essential to maintain pneumococcal fitness and that the genes of the ADS cluster are positively regulated in a strain-specific manner by ArgR2. IMPORTANCE Pneumococci are the major etiologic agents of community-acquired pneumonia, causing more than 1.5 million deaths annually worldwide. These versatile pathogens are highly adapted to the nutrients provided by the host niches encountered. Physiological fitness is of major importance for colonization of the nasopharyngeal cavity and dissemination during invasive infections. This work identifies the regulator ArgR2 as the activator of the S. pneumoniae TIGR4 ADS and the arginine-ornithine transporter ArcD, which is needed for uptake of the essential amino acid arginine. Although ArgR2 activates ArcD expression and uptake of arginine is required to maintain pneumococcal fitness, the deficiency of ArgR2 increases TIGR4 virulence under in vivo conditions, suggesting that other factors regulated by ArgR2 counterbalance the reduced uptake of arginine by ArcD. Thus, this work illustrates that the physiological homeostasis of pneumococci is complex and that ArgR2 plays a key role in maintaining bacterial fitness.
format	article
author	Christian Schulz Philipp Gierok Lothar Petruschka Michael Lalk Ulrike Mäder Sven Hammerschmidt
author_facet	Christian Schulz Philipp Gierok Lothar Petruschka Michael Lalk Ulrike Mäder Sven Hammerschmidt
author_sort	Christian Schulz
title	Regulation of the Arginine Deiminase System by ArgR2 Interferes with Arginine Metabolism and Fitness of <named-content content-type="genus-species">Streptococcus pneumoniae</named-content>
title_short	Regulation of the Arginine Deiminase System by ArgR2 Interferes with Arginine Metabolism and Fitness of <named-content content-type="genus-species">Streptococcus pneumoniae</named-content>
title_full	Regulation of the Arginine Deiminase System by ArgR2 Interferes with Arginine Metabolism and Fitness of <named-content content-type="genus-species">Streptococcus pneumoniae</named-content>
title_fullStr	Regulation of the Arginine Deiminase System by ArgR2 Interferes with Arginine Metabolism and Fitness of <named-content content-type="genus-species">Streptococcus pneumoniae</named-content>
title_full_unstemmed	Regulation of the Arginine Deiminase System by ArgR2 Interferes with Arginine Metabolism and Fitness of <named-content content-type="genus-species">Streptococcus pneumoniae</named-content>
title_sort	regulation of the arginine deiminase system by argr2 interferes with arginine metabolism and fitness of <named-content content-type="genus-species">streptococcus pneumoniae</named-content>
publisher	American Society for Microbiology
publishDate	2014
url	https://doaj.org/article/7ef28e7d51f9427b888f39b44c74c881
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Regulation of the Arginine Deiminase System by ArgR2 Interferes with Arginine Metabolism and Fitness of <named-content content-type="genus-species">Streptococcus pneumoniae</named-content>

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