<italic toggle="yes">Enterococcus faecalis</italic> Encodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids

ABSTRACT Acyl carrier proteins (ACPs) play essential roles in the synthesis of fatty acids and transfer of long fatty acyl chains into complex lipids. The Enterococcus faecalis genome contains two annotated acp genes, called acpA and acpB. AcpA is encoded within the fatty acid synthesis (fab) operon...

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Autores principales:	Lei Zhu, Qi Zou, Xinyun Cao, John E. Cronan
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2019
Materias:	FabT phospholipids acyl carrier protein fatty acid synthesis transcriptional regulation Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/4aa1cd5771fb4817b0f23554d92952ae
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spelling	oai:doaj.org-article:4aa1cd5771fb4817b0f23554d92952ae2021-11-15T15:55:25Z<italic toggle="yes">Enterococcus faecalis</italic> Encodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids10.1128/mBio.00577-192150-7511https://doaj.org/article/4aa1cd5771fb4817b0f23554d92952ae2019-06-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00577-19https://doaj.org/toc/2150-7511ABSTRACT Acyl carrier proteins (ACPs) play essential roles in the synthesis of fatty acids and transfer of long fatty acyl chains into complex lipids. The Enterococcus faecalis genome contains two annotated acp genes, called acpA and acpB. AcpA is encoded within the fatty acid synthesis (fab) operon and appears essential. In contrast, AcpB is an atypical ACP, having only 30% residue identity with AcpA, and is not essential. Deletion of acpB has no effect on E. faecalis growth or de novo fatty acid synthesis in media lacking fatty acids. However, unlike the wild-type strain, where growth with oleic acid resulted in almost complete blockage of de novo fatty acid synthesis, the ΔacpB strain largely continued de novo fatty acid synthesis under these conditions. Blockage in the wild-type strain is due to repression of fab operon transcription, leading to levels of fatty acid synthetic proteins (including AcpA) that are insufficient to support de novo synthesis. Transcription of the fab operon is regulated by FabT, a repressor protein that binds DNA only when it is bound to an acyl-ACP ligand. Since AcpA is encoded in the fab operon, its synthesis is blocked when the operon is repressed and acpA thus cannot provide a stable supply of ACP for synthesis of the acyl-ACP ligand required for DNA binding by FabT. In contrast to AcpA, acpB transcription is unaffected by growth with exogenous fatty acids and thus provides a stable supply of ACP for conversion to the acyl-ACP ligand required for repression by FabT. Indeed, ΔacpB and ΔfabT strains have essentially the same de novo fatty acid synthesis phenotype in oleic acid-grown cultures, which argues that neither strain can form the FabT-acyl-ACP repression complex. Finally, acylated derivatives of both AcpB and AcpA were substrates for the E. faecalis enoyl-ACP reductases and for E. faecalis PlsX (acyl-ACP; phosphate acyltransferase). IMPORTANCE AcpB homologs are encoded by many, but not all, lactic acid bacteria (Lactobacillales), including many members of the human microbiome. The mechanisms regulating fatty acid synthesis by exogenous fatty acids play a key role in resistance of these bacteria to those antimicrobials targeted at fatty acid synthesis enzymes. Defective regulation can increase resistance to such inhibitors and also reduce pathogenesis.Lei ZhuQi ZouXinyun CaoJohn E. CronanAmerican Society for MicrobiologyarticleFabTphospholipidsacyl carrier proteinfatty acid synthesistranscriptional regulationMicrobiologyQR1-502ENmBio, Vol 10, Iss 3 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	FabT phospholipids acyl carrier protein fatty acid synthesis transcriptional regulation Microbiology QR1-502
spellingShingle	FabT phospholipids acyl carrier protein fatty acid synthesis transcriptional regulation Microbiology QR1-502 Lei Zhu Qi Zou Xinyun Cao John E. Cronan <italic toggle="yes">Enterococcus faecalis</italic> Encodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids
description	ABSTRACT Acyl carrier proteins (ACPs) play essential roles in the synthesis of fatty acids and transfer of long fatty acyl chains into complex lipids. The Enterococcus faecalis genome contains two annotated acp genes, called acpA and acpB. AcpA is encoded within the fatty acid synthesis (fab) operon and appears essential. In contrast, AcpB is an atypical ACP, having only 30% residue identity with AcpA, and is not essential. Deletion of acpB has no effect on E. faecalis growth or de novo fatty acid synthesis in media lacking fatty acids. However, unlike the wild-type strain, where growth with oleic acid resulted in almost complete blockage of de novo fatty acid synthesis, the ΔacpB strain largely continued de novo fatty acid synthesis under these conditions. Blockage in the wild-type strain is due to repression of fab operon transcription, leading to levels of fatty acid synthetic proteins (including AcpA) that are insufficient to support de novo synthesis. Transcription of the fab operon is regulated by FabT, a repressor protein that binds DNA only when it is bound to an acyl-ACP ligand. Since AcpA is encoded in the fab operon, its synthesis is blocked when the operon is repressed and acpA thus cannot provide a stable supply of ACP for synthesis of the acyl-ACP ligand required for DNA binding by FabT. In contrast to AcpA, acpB transcription is unaffected by growth with exogenous fatty acids and thus provides a stable supply of ACP for conversion to the acyl-ACP ligand required for repression by FabT. Indeed, ΔacpB and ΔfabT strains have essentially the same de novo fatty acid synthesis phenotype in oleic acid-grown cultures, which argues that neither strain can form the FabT-acyl-ACP repression complex. Finally, acylated derivatives of both AcpB and AcpA were substrates for the E. faecalis enoyl-ACP reductases and for E. faecalis PlsX (acyl-ACP; phosphate acyltransferase). IMPORTANCE AcpB homologs are encoded by many, but not all, lactic acid bacteria (Lactobacillales), including many members of the human microbiome. The mechanisms regulating fatty acid synthesis by exogenous fatty acids play a key role in resistance of these bacteria to those antimicrobials targeted at fatty acid synthesis enzymes. Defective regulation can increase resistance to such inhibitors and also reduce pathogenesis.
format	article
author	Lei Zhu Qi Zou Xinyun Cao John E. Cronan
author_facet	Lei Zhu Qi Zou Xinyun Cao John E. Cronan
author_sort	Lei Zhu
title	<italic toggle="yes">Enterococcus faecalis</italic> Encodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids
title_short	<italic toggle="yes">Enterococcus faecalis</italic> Encodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids
title_full	<italic toggle="yes">Enterococcus faecalis</italic> Encodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids
title_fullStr	<italic toggle="yes">Enterococcus faecalis</italic> Encodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids
title_full_unstemmed	<italic toggle="yes">Enterococcus faecalis</italic> Encodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids
title_sort	<italic toggle="yes">enterococcus faecalis</italic> encodes an atypical auxiliary acyl carrier protein required for efficient regulation of fatty acid synthesis by exogenous fatty acids
publisher	American Society for Microbiology
publishDate	2019
url	https://doaj.org/article/4aa1cd5771fb4817b0f23554d92952ae
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<italic toggle="yes">Enterococcus faecalis</italic> Encodes an Atypical Auxiliary Acyl Carrier Protein Required for Efficient Regulation of Fatty Acid Synthesis by Exogenous Fatty Acids

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