The Bactericidal Fatty Acid Mimetic 2CCA-1 Selectively Targets Pneumococcal Extracellular Polyunsaturated Fatty Acid Metabolism

ABSTRACT Streptococcus pneumoniae, a major cause of pneumonia, sepsis, and meningitis worldwide, has the nasopharynges of small children as its main ecological niche. Depletion of pneumococci from this niche would reduce the disease burden and could be achieved using small molecules with narrow-spec...

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Autores principales:	Elisabeth Reithuber, Priyanka Nannapaneni, Olena Rzhepishevska, Anders E. G. Lindgren, Oleksandr Ilchenko, Staffan Normark, Fredrik Almqvist, Birgitta Henriques-Normark, Peter Mellroth
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2020
Materias:	Streptococcus pneumoniae pneumococci LytA small antimicrobial compound extracellular fatty acid metabolism FabT Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/37a7655286df455188901d9598d4a006
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spelling	oai:doaj.org-article:37a7655286df455188901d9598d4a0062021-11-15T15:55:43ZThe Bactericidal Fatty Acid Mimetic 2CCA-1 Selectively Targets Pneumococcal Extracellular Polyunsaturated Fatty Acid Metabolism10.1128/mBio.03027-202150-7511https://doaj.org/article/37a7655286df455188901d9598d4a0062020-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.03027-20https://doaj.org/toc/2150-7511ABSTRACT Streptococcus pneumoniae, a major cause of pneumonia, sepsis, and meningitis worldwide, has the nasopharynges of small children as its main ecological niche. Depletion of pneumococci from this niche would reduce the disease burden and could be achieved using small molecules with narrow-spectrum antibacterial activity. We identified the alkylated dicyclohexyl carboxylic acid 2CCA-1 as a potent inducer of autolysin-mediated lysis of S. pneumoniae, while having low activity against Staphylococcus aureus. 2CCA-1-resistant strains were found to have inactivating mutations in fakB3, known to be required for uptake of host polyunsaturated fatty acids, as well as through inactivation of the transcriptional regulator gene fabT, vital for endogenous, de novo fatty acid synthesis regulation. Structure activity relationship exploration revealed that, besides the central dicyclohexyl group, the fatty acid-like structural features of 2CCA-1 were essential for its activity. The lysis-inducing activity of 2CCA-1 was considerably more potent than that of free fatty acids and required growing bacteria, suggesting that 2CCA-1 needs to be metabolized to exert its antimicrobial activity. Total lipid analysis of 2CCA-1 treated bacteria identified unique masses that were modeled to 2CCA-1 containing lysophosphatidic and phosphatidic acid in wild-type but not in fakB3 mutant bacteria. This suggests that 2CCA-1 is metabolized as a fatty acid via FakB3 and utilized as a phospholipid building block, leading to accumulation of toxic phospholipid species. Analysis of FabT-mediated fakB3 expression elucidates how the pneumococcus could ensure membrane homeostasis and concurrent economic use of host-derived fatty acids. IMPORTANCE Fatty acid biosynthesis is an attractive antibiotic target, as it affects the supply of membrane phospholipid building blocks. In Streptococcus pneumoniae, it is not sufficient to target only the endogenous fatty acid synthesis machinery, as uptake of host fatty acids may bypass this inhibition. Here, we describe a small-molecule compound, 2CCA-1, with potent bactericidal activity that upon interactions with the fatty acid binding protein FakB3, which is present in a limited number of Gram-positive species, becomes metabolized and incorporated as a toxic phospholipid species. Resistance to 2CCA-1 developed specifically in fakB3 and the regulatory gene fabT. These mutants reveal a regulatory connection between the extracellular polyunsaturated fatty acid metabolism and endogenous fatty acid synthesis in S. pneumoniae, which could ensure balance between efficient scavenging of host polyunsaturated fatty acids and membrane homeostasis. The data might be useful in the identification of narrow-spectrum treatment strategies to selectively target members of the Lactobacillales such as S. pneumoniae.Elisabeth ReithuberPriyanka NannapaneniOlena RzhepishevskaAnders E. G. LindgrenOleksandr IlchenkoStaffan NormarkFredrik AlmqvistBirgitta Henriques-NormarkPeter MellrothAmerican Society for MicrobiologyarticleStreptococcus pneumoniaepneumococciLytAsmall antimicrobial compoundextracellular fatty acid metabolismFabTMicrobiologyQR1-502ENmBio, Vol 11, Iss 6 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Streptococcus pneumoniae pneumococci LytA small antimicrobial compound extracellular fatty acid metabolism FabT Microbiology QR1-502
spellingShingle	Streptococcus pneumoniae pneumococci LytA small antimicrobial compound extracellular fatty acid metabolism FabT Microbiology QR1-502 Elisabeth Reithuber Priyanka Nannapaneni Olena Rzhepishevska Anders E. G. Lindgren Oleksandr Ilchenko Staffan Normark Fredrik Almqvist Birgitta Henriques-Normark Peter Mellroth The Bactericidal Fatty Acid Mimetic 2CCA-1 Selectively Targets Pneumococcal Extracellular Polyunsaturated Fatty Acid Metabolism
description	ABSTRACT Streptococcus pneumoniae, a major cause of pneumonia, sepsis, and meningitis worldwide, has the nasopharynges of small children as its main ecological niche. Depletion of pneumococci from this niche would reduce the disease burden and could be achieved using small molecules with narrow-spectrum antibacterial activity. We identified the alkylated dicyclohexyl carboxylic acid 2CCA-1 as a potent inducer of autolysin-mediated lysis of S. pneumoniae, while having low activity against Staphylococcus aureus. 2CCA-1-resistant strains were found to have inactivating mutations in fakB3, known to be required for uptake of host polyunsaturated fatty acids, as well as through inactivation of the transcriptional regulator gene fabT, vital for endogenous, de novo fatty acid synthesis regulation. Structure activity relationship exploration revealed that, besides the central dicyclohexyl group, the fatty acid-like structural features of 2CCA-1 were essential for its activity. The lysis-inducing activity of 2CCA-1 was considerably more potent than that of free fatty acids and required growing bacteria, suggesting that 2CCA-1 needs to be metabolized to exert its antimicrobial activity. Total lipid analysis of 2CCA-1 treated bacteria identified unique masses that were modeled to 2CCA-1 containing lysophosphatidic and phosphatidic acid in wild-type but not in fakB3 mutant bacteria. This suggests that 2CCA-1 is metabolized as a fatty acid via FakB3 and utilized as a phospholipid building block, leading to accumulation of toxic phospholipid species. Analysis of FabT-mediated fakB3 expression elucidates how the pneumococcus could ensure membrane homeostasis and concurrent economic use of host-derived fatty acids. IMPORTANCE Fatty acid biosynthesis is an attractive antibiotic target, as it affects the supply of membrane phospholipid building blocks. In Streptococcus pneumoniae, it is not sufficient to target only the endogenous fatty acid synthesis machinery, as uptake of host fatty acids may bypass this inhibition. Here, we describe a small-molecule compound, 2CCA-1, with potent bactericidal activity that upon interactions with the fatty acid binding protein FakB3, which is present in a limited number of Gram-positive species, becomes metabolized and incorporated as a toxic phospholipid species. Resistance to 2CCA-1 developed specifically in fakB3 and the regulatory gene fabT. These mutants reveal a regulatory connection between the extracellular polyunsaturated fatty acid metabolism and endogenous fatty acid synthesis in S. pneumoniae, which could ensure balance between efficient scavenging of host polyunsaturated fatty acids and membrane homeostasis. The data might be useful in the identification of narrow-spectrum treatment strategies to selectively target members of the Lactobacillales such as S. pneumoniae.
format	article
author	Elisabeth Reithuber Priyanka Nannapaneni Olena Rzhepishevska Anders E. G. Lindgren Oleksandr Ilchenko Staffan Normark Fredrik Almqvist Birgitta Henriques-Normark Peter Mellroth
author_facet	Elisabeth Reithuber Priyanka Nannapaneni Olena Rzhepishevska Anders E. G. Lindgren Oleksandr Ilchenko Staffan Normark Fredrik Almqvist Birgitta Henriques-Normark Peter Mellroth
author_sort	Elisabeth Reithuber
title	The Bactericidal Fatty Acid Mimetic 2CCA-1 Selectively Targets Pneumococcal Extracellular Polyunsaturated Fatty Acid Metabolism
title_short	The Bactericidal Fatty Acid Mimetic 2CCA-1 Selectively Targets Pneumococcal Extracellular Polyunsaturated Fatty Acid Metabolism
title_full	The Bactericidal Fatty Acid Mimetic 2CCA-1 Selectively Targets Pneumococcal Extracellular Polyunsaturated Fatty Acid Metabolism
title_fullStr	The Bactericidal Fatty Acid Mimetic 2CCA-1 Selectively Targets Pneumococcal Extracellular Polyunsaturated Fatty Acid Metabolism
title_full_unstemmed	The Bactericidal Fatty Acid Mimetic 2CCA-1 Selectively Targets Pneumococcal Extracellular Polyunsaturated Fatty Acid Metabolism
title_sort	bactericidal fatty acid mimetic 2cca-1 selectively targets pneumococcal extracellular polyunsaturated fatty acid metabolism
publisher	American Society for Microbiology
publishDate	2020
url	https://doaj.org/article/37a7655286df455188901d9598d4a006
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The Bactericidal Fatty Acid Mimetic 2CCA-1 Selectively Targets Pneumococcal Extracellular Polyunsaturated Fatty Acid Metabolism

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