Identification and characterization of a high-affinity choline uptake system of Brucella abortus
Phosphatidylcholine (PC), a common phospholipid of the eukaryotic cell membrane, is present in the cell envelope of the intracellular pathogen Brucella abortus, the etiological agent of bovine brucellosis. In this pathogen, the biosynthesis of PC proceeds mainly through the phosphatidylcholine synth...
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2013
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219193_v195_n3_p493_Herrmann http://hdl.handle.net/20.500.12110/paper_00219193_v195_n3_p493_Herrmann |
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paper:paper_00219193_v195_n3_p493_Herrmann2023-06-08T14:43:13Z Identification and characterization of a high-affinity choline uptake system of Brucella abortus choline ChoX protein periplasmic binding protein phosphatidylcholine unclassified drug article binding affinity binding assay Brucella abortus cell migration cell vacuole choline uptake controlled study fluorescence gene disruption isotope labeling mutant nonhuman phospholipid synthesis priority journal protein analysis Amino Acid Sequence Animals ATP-Binding Cassette Transporters Bacterial Proteins Biological Transport, Active Brucella abortus Cell Membrane Choline Female Gene Expression Regulation, Bacterial Macrophages Mice Mice, Inbred BALB C Molecular Sequence Data Open Reading Frames Phosphatidylcholines Phosphatidylcholine (PC), a common phospholipid of the eukaryotic cell membrane, is present in the cell envelope of the intracellular pathogen Brucella abortus, the etiological agent of bovine brucellosis. In this pathogen, the biosynthesis of PC proceeds mainly through the phosphatidylcholine synthase pathway; hence, it relies on the presence of choline in the milieu. These observations imply that B. abortus encodes an as-yet-unknown choline uptake system. Taking advantage of the requirement of choline uptake for PC synthesis, we devised a method that allowed us to identify a homologue of ChoX, the high-affinity periplasmic binding protein of the ABC transporter ChoXWV. Disruption of the choX gene completely abrogated PC synthesis at low choline concentrations in the medium, thus indicating that it is a high-affinity transporter needed for PC synthesis via the PC synthase (PCS) pathway. However, the synthesis of PC was restored when the mutant was incubated in media with higher choline concentrations, suggesting the presence of an alternative low-affinity choline uptake activity. By means of a fluorescence-based equilibrium- binding assay and using the kinetics of radiolabeled choline uptake, we show that ChoX binds choline with an extremely high affinity, and we also demonstrate that its activity is inhibited by increasing choline concentrations. Cell infection assays indicate that ChoX activity is required during the first phase of B. abortus intracellular traffic, suggesting that choline concentrations in the early and intermediate Brucella-containing vacuoles are limited. Altogether, these results suggest that choline transport and PC synthesis are strictly regulated in B. abortus. © 2013, American Society for Microbiology. 2013 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219193_v195_n3_p493_Herrmann http://hdl.handle.net/20.500.12110/paper_00219193_v195_n3_p493_Herrmann |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
choline ChoX protein periplasmic binding protein phosphatidylcholine unclassified drug article binding affinity binding assay Brucella abortus cell migration cell vacuole choline uptake controlled study fluorescence gene disruption isotope labeling mutant nonhuman phospholipid synthesis priority journal protein analysis Amino Acid Sequence Animals ATP-Binding Cassette Transporters Bacterial Proteins Biological Transport, Active Brucella abortus Cell Membrane Choline Female Gene Expression Regulation, Bacterial Macrophages Mice Mice, Inbred BALB C Molecular Sequence Data Open Reading Frames Phosphatidylcholines |
| spellingShingle |
choline ChoX protein periplasmic binding protein phosphatidylcholine unclassified drug article binding affinity binding assay Brucella abortus cell migration cell vacuole choline uptake controlled study fluorescence gene disruption isotope labeling mutant nonhuman phospholipid synthesis priority journal protein analysis Amino Acid Sequence Animals ATP-Binding Cassette Transporters Bacterial Proteins Biological Transport, Active Brucella abortus Cell Membrane Choline Female Gene Expression Regulation, Bacterial Macrophages Mice Mice, Inbred BALB C Molecular Sequence Data Open Reading Frames Phosphatidylcholines Identification and characterization of a high-affinity choline uptake system of Brucella abortus |
| topic_facet |
choline ChoX protein periplasmic binding protein phosphatidylcholine unclassified drug article binding affinity binding assay Brucella abortus cell migration cell vacuole choline uptake controlled study fluorescence gene disruption isotope labeling mutant nonhuman phospholipid synthesis priority journal protein analysis Amino Acid Sequence Animals ATP-Binding Cassette Transporters Bacterial Proteins Biological Transport, Active Brucella abortus Cell Membrane Choline Female Gene Expression Regulation, Bacterial Macrophages Mice Mice, Inbred BALB C Molecular Sequence Data Open Reading Frames Phosphatidylcholines |
| description |
Phosphatidylcholine (PC), a common phospholipid of the eukaryotic cell membrane, is present in the cell envelope of the intracellular pathogen Brucella abortus, the etiological agent of bovine brucellosis. In this pathogen, the biosynthesis of PC proceeds mainly through the phosphatidylcholine synthase pathway; hence, it relies on the presence of choline in the milieu. These observations imply that B. abortus encodes an as-yet-unknown choline uptake system. Taking advantage of the requirement of choline uptake for PC synthesis, we devised a method that allowed us to identify a homologue of ChoX, the high-affinity periplasmic binding protein of the ABC transporter ChoXWV. Disruption of the choX gene completely abrogated PC synthesis at low choline concentrations in the medium, thus indicating that it is a high-affinity transporter needed for PC synthesis via the PC synthase (PCS) pathway. However, the synthesis of PC was restored when the mutant was incubated in media with higher choline concentrations, suggesting the presence of an alternative low-affinity choline uptake activity. By means of a fluorescence-based equilibrium- binding assay and using the kinetics of radiolabeled choline uptake, we show that ChoX binds choline with an extremely high affinity, and we also demonstrate that its activity is inhibited by increasing choline concentrations. Cell infection assays indicate that ChoX activity is required during the first phase of B. abortus intracellular traffic, suggesting that choline concentrations in the early and intermediate Brucella-containing vacuoles are limited. Altogether, these results suggest that choline transport and PC synthesis are strictly regulated in B. abortus. © 2013, American Society for Microbiology. |
| title |
Identification and characterization of a high-affinity choline uptake system of Brucella abortus |
| title_short |
Identification and characterization of a high-affinity choline uptake system of Brucella abortus |
| title_full |
Identification and characterization of a high-affinity choline uptake system of Brucella abortus |
| title_fullStr |
Identification and characterization of a high-affinity choline uptake system of Brucella abortus |
| title_full_unstemmed |
Identification and characterization of a high-affinity choline uptake system of Brucella abortus |
| title_sort |
identification and characterization of a high-affinity choline uptake system of brucella abortus |
| publishDate |
2013 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00219193_v195_n3_p493_Herrmann http://hdl.handle.net/20.500.12110/paper_00219193_v195_n3_p493_Herrmann |
| _version_ |
1768546193099456512 |