Only One of the Five Ralstonia solanacearum Long-Chain 3-Ketoacyl-Acyl Carrier Protein Synthase Homologues Functions in Fatty Acid Synthesis

ABSTRACTRalstonia solanacearum, a major phytopathogenic bacterium, causes a bacterial wilt disease in diverse plants. Although fatty acid analyses of total membranes ofR. solanacearumshowed that they contain primarily palmitic (C16:0), palmitoleic (C16:1) andcis-vaccenic (C18:1) acids, little is known regardingR. solanacearumfatty acid synthesis. TheR. solanacearumGMI1000 genome is unusual in that it contains four genes (fabF1,fabF2,fabF3, andfabF4) annotated as encoding 3-ketoacyl-acyl carrier protein synthase II homologues and one gene (fabB) annotated as encoding 3-ketoacyl-acyl carrier protein synthase I. We have analyzed this puzzling apparent redundancy and found that only one of these genes,fabF1, encoded a long-chain 3-ketoacyl-acyl carrier protein synthase, whereas the other homologues did not play roles inR. solanacearumfatty acid synthesis. Mutant strains lackingfabF1are nonviable, and thus, FabF1 is essential forR. solanacearumfatty acid biosynthesis. Moreover,R. solanacearumFabF1 has the activities of both 3-ketoacyl-acyl carrier protein synthase II and 3-ketoacyl-acyl carrier protein synthase I.

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NovelXanthomonas campestrisLong-Chain-Specific 3-Oxoacyl-Acyl Carrier Protein Reductase Involved in Diffusible Signal Factor Synthesis

mBio ◽

10.1128/mbio.00596-18 ◽

2018 ◽

Vol 9 (3) ◽

Cited By ~ 7

Author(s):

Zhe Hu ◽

Huijuan Dong ◽

Jin-Cheng Ma ◽

Yonghong Yu ◽

Kai-Hui Li ◽

...

Keyword(s):

Fatty Acid ◽

Fatty Acid Synthesis ◽

Xanthomonas Campestris ◽

Octanoic Acid ◽

Acyl Carrier Protein ◽

Acid Synthesis ◽

Carrier Protein ◽

Content Type ◽

Diffusible Signal Factor ◽

Acyl Chains

ABSTRACTThe precursors of the diffusible signal factor (DSF) family signals ofXanthomonas campestrispv.campestrisare 3-hydroxyacyl-acyl carrier protein (3-hydroxyacyl-ACP) thioesters having acyl chains of 12 to 13 carbon atoms produced by the fatty acid biosynthetic pathway. We report a novel 3-oxoacyl-ACP reductase encoded by theX. campestrispv.campestrisXCC0416 gene (fabG2), which is unable to participate in the initial steps of fatty acyl synthesis. This was shown by the failure of FabG2 expression to allow growth at the nonpermissive temperature of anEscherichia colifabGtemperature-sensitive strain. However, when transformed into theE. colistrain together with a plasmid bearing theVibrio harveyiacyl-ACP synthetase gene (aasS), growth proceeded, but only when the medium contained octanoic acid.In vitroassays showed that FabG2 catalyzes the reduction of long-chain (≥C8) 3-oxoacyl-ACPs to 3-hydroxyacyl-ACPs but is only weakly active with shorter-chain (C4, C6) substrates. FabG1, the housekeeping 3-oxoacyl-ACP reductase encoded within the fatty acid synthesis gene cluster, could be deleted in a strain that overexpressedfabG2but only in octanoic acid-supplemented media. Growth of theX. campestrispv.campestrisΔfabG1strain overexpressingfabG2requiredfabHfor growth with octanoic acid, indicating that octanoyl coenzyme A is elongated byX. campestrispv.campestrisfabH. Deletion offabG2reduced DSF family signal production, whereas overproduction of either FabG1 or FabG2 in the ΔfabG2strain restored DSF family signal levels.IMPORTANCEQuorum sensing mediated by DSF signaling molecules regulates pathogenesis in several different phytopathogenic bacteria, includingXanthomonas campestrispv.campestris. DSF signaling also plays a key role in infection by the human pathogenBurkholderia cepacia. The acyl chains of the DSF molecules are diverted and remodeled from a key intermediate of the fatty acid synthesis pathway. We report aXanthomonas campestrispv.campestrisfatty acid synthesis enzyme, FabG2, of novel specificity that seems tailored to provide DSF signaling molecule precursors.

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The Two Functional Enoyl-Acyl Carrier Protein Reductases of Enterococcus faecalis Do Not Mediate Triclosan Resistance

mBio ◽

10.1128/mbio.00613-13 ◽

2013 ◽

Vol 4 (5) ◽

Cited By ~ 26

Author(s):

Lei Zhu ◽

Hongkai Bi ◽

Jincheng Ma ◽

Zhe Hu ◽

Wenbin Zhang ◽

...

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Enterococcus Faecalis ◽

Fatty Acid Synthesis ◽

Acyl Carrier Protein ◽

Acid Synthesis ◽

Carrier Protein ◽

Content Type ◽

Enoyl Acp Reductase ◽

Triclosan Resistance

ABSTRACTEnoyl-acyl carrier protein (enoyl-ACP) reductase catalyzes the last step of the elongation cycle in the synthesis of bacterial fatty acids. TheEnterococcus faecalisgenome contains two genes annotated as enoyl-ACP reductases, a FabI-type enoyl-ACP reductase and a FabK-type enoyl-ACP reductase. We report that expression of either of the two proteins restores growth of anEscherichia colifabItemperature-sensitive mutant strain under nonpermissive conditions.In vitroassays demonstrated that both proteins support fatty acid synthesis and are active with substrates of all fatty acid chain lengths. Although expression ofE. faecalis fabKconfers toE. colihigh levels of resistance to the antimicrobial triclosan, deletion offabKfrom theE. faecalisgenome showed that FabK does not play a detectable role in the inherent triclosan resistance ofE. faecalis. Indeed, FabK seems to play only a minor role in modulating fatty acid composition. Strains carrying a deletion offabKgrow normally without fatty acid supplementation, whereasfabIdeletion mutants make only traces of fatty acids and are unsaturated fatty acid auxotrophs.IMPORTANCEThe finding that exogenous fatty acids support growth ofE. faecalisstrains defective in fatty acid synthesis indicates that inhibitors of fatty acid synthesis are ineffective in counteringE. faecalisinfections because host serum fatty acids support growth of the bacterium.

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Enoyl-Acyl Carrier Protein Reductase I (FabI) Is Essential for the Intracellular Growth of Listeria monocytogenes

Infection and Immunity ◽

10.1128/iai.00647-16 ◽

2016 ◽

Vol 84 (12) ◽

pp. 3597-3607 ◽

Cited By ~ 8

Author(s):

Jiangwei Yao ◽

Megan E. Ericson ◽

Matthew W. Frank ◽

Charles O. Rock

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Fatty Acid Synthesis ◽

Acyl Carrier Protein ◽

Acid Synthesis ◽

Carrier Protein ◽

Type Ii ◽

Intracellular Growth ◽

Content Type ◽

Bacterial Fatty Acid

Enoyl-acyl carrier protein reductase catalyzes the last step in each elongation cycle of type II bacterial fatty acid synthesis and is a key regulatory protein in bacterial fatty acid synthesis. Genes of the facultative intracellular pathogenListeria monocytogenesencode two functional enoyl-acyl carrier protein isoforms based on their ability to complement the temperature-sensitive growth phenotype ofEscherichia colistrain JP1111 [fabI(Ts)]. The FabI isoform was inactivated by the FabI selective inhibitor AFN-1252, but the FabK isoform was not affected by the drug, as expected. Inhibition of FabI by AFN-1252 decreased endogenous fatty acid synthesis by 80% and lowered the growth rate ofL. monocytogenesin laboratory medium. Robust exogenous fatty acid incorporation was not detected inL. monocytogenesunless the pathway was partially inactivated by AFN-1252 treatment. However, supplementation with exogenous fatty acids did not restore normal growth in the presence of AFN-1252. FabI inactivation prevented the intracellular growth ofL. monocytogenes, showing that neither FabK nor the incorporation of host cellular fatty acids was sufficient to support the intracellular growth ofL. monocytogenes. Our results show that FabI is the primary enoyl-acyl carrier protein reductase of type II bacterial fatty acid synthesis and is essential for the intracellular growth ofL. monocytogenes.

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The Francisella tularensis FabI Enoyl-Acyl Carrier Protein Reductase Gene Is Essential to Bacterial Viability and Is Expressed during Infection

Journal of Bacteriology ◽

10.1128/jb.01957-12 ◽

2012 ◽

Vol 195 (2) ◽

pp. 351-358 ◽

Cited By ~ 15

Author(s):

Luke C. Kingry ◽

Jason E. Cummings ◽

Kerry W. Brookman ◽

Gopal R. Bommineni ◽

Peter J. Tonge ◽

...

Keyword(s):

Fatty Acid ◽

Francisella Tularensis ◽

Fatty Acid Biosynthesis ◽

De Novo ◽

Acyl Carrier Protein ◽

Transcriptional Profiling ◽

Acid Synthesis ◽

Content Type ◽

Enoyl Acp Reductase ◽

Long Chain

ABSTRACTFrancisella tularensisis classified as a category A priority pathogen and causes fatal disseminated disease in humans upon inhalation of less than 50 bacteria. Although drugs are available for treatment, they are not ideal because of toxicity and route of delivery, and in some cases patients relapse upon withdrawal. We have an ongoing program to develop novel FAS-II FabI enoyl-ACP reductase enzyme inhibitors forFrancisellaand other select agents. To establishF. tularensisFabI (FtFabI) as a clinically relevant drug target, we demonstrated that fatty acid biosynthesis and FabI activity are essential for growth even in the presence of exogenous long-chain lipids and that FtfabIis not transcriptionally altered in the presence of exogenous long-chain lipids. Inhibition of FtFabI or fatty acid synthesis results in loss of viability that is not rescued by exogenous long-chain lipid supplementation. Importantly, whole-genome transcriptional profiling ofF. tularensiswith DNA microarrays from infected tissues revealed that FtfabIandde novofatty acid biosynthetic genes are transcriptionally active during infection. This is the first demonstration that the FabI enoyl-ACP-reductase enzyme encoded byF. tularensisis essential and not bypassed by exogenous fatty acids and thatde novofatty acid biosynthetic components encoded inF. tularensisare transcriptionally active during infection in the mouse model of tularemia.

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Suppression offabBMutation byfabF1Is Mediated by Transcription Read-through in Shewanella oneidensis

Journal of Bacteriology ◽

10.1128/jb.00463-16 ◽

2016 ◽

Vol 198 (22) ◽

pp. 3060-3069 ◽

Cited By ~ 7

Author(s):

Meng Li ◽

Qiu Meng ◽

Huihui Fu ◽

Qixia Luo ◽

Haichun Gao

Keyword(s):

Fatty Acid ◽

Fatty Acid Synthesis ◽

Tandem Repeats ◽

Unsaturated Fatty Acids ◽

Acyl Carrier Protein ◽

Shewanella Oneidensis ◽

Acid Synthesis ◽

Carrier Protein ◽

Type Ii ◽

Content Type

ABSTRACTAs type II fatty acid synthesis is essential for the growth ofEscherichia coli, its many components are regarded as potential targets for novel antibacterial drugs. Among them, β-ketoacyl-acyl carrier protein (ACP) synthase (KAS) FabB is the exclusive factor for elongation of thecis-3-decenoyl-ACP (cis-3-C10-ACP). In our previous study, we presented evidence to suggest that this may not be the case inShewanella oneidensis, an emerging model gammaproteobacterium renowned for its respiratory versatility. Here, we identified FabF1, another KAS, as a functional replacement for FabB inS. oneidensis. InfabB+ordesA+(encoding a desaturase) cells, which are capable of making unsaturated fatty acids (UFA), FabF1 is barely produced. However, UFA auxotroph mutants devoid of bothfabBanddesAgenes can be spontaneously converted to suppressor strains, which no longer require exogenous UFAs for growth. Suppression is caused by a TGTTTT deletion in the region upstream of thefabF1gene, resulting in enhanced FabF1 production. We further demonstrated that the deletion leads to transcription read-through of the terminator foracpP, an acyl carrier protein gene immediately upstream offabF1. There are multiple tandem repeats in the region covering the terminator, and the TGTTTT deletion, as well as others, compromises the terminator efficacy. In addition, FabF2 also shows an ability to complement the FabB loss, albeit substantially less effectively than FabF1.IMPORTANCEIt has been firmly established that FabB for UFA synthesis via type II fatty acid synthesis in FabA-containing bacteria such asE. coliis essential. However,S. oneidensisappears to be an exception. In this bacterium, FabF1, when sufficiently expressed, is able to fully complement the FabB loss. Importantly, such a capability can be obtained by spontaneous mutations, which lead to transcription read-through. Therefore, our data, by identifying the functional overlap between FabB and FabFs, provide new insights into the current understanding of KAS and help reveal novel ways to block UFA synthesis for therapeutic purposes.

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Divergent Acyl Carrier Protein Mediates Mitochondrial Fe-S Cluster Biosynthesis in Malaria Parasites

10.1101/2021.04.13.439690 ◽

2021 ◽

Author(s):

Seyi Falekun ◽

Jaime Sepulveda ◽

Yasaman Jami-Alahmadi ◽

Hahnbeom Park ◽

James Wohlschlegel ◽

...

Keyword(s):

Fatty Acid ◽

Fatty Acid Synthesis ◽

Drug Targets ◽

Fatty Acid Biosynthesis ◽

Acyl Carrier Protein ◽

Acid Synthesis ◽

Complex Iii ◽

Carrier Protein ◽

Malaria Parasites ◽

Cluster Biosynthesis

Plasmodium falciparum malaria parasites are early-diverging eukaryotes with many unusual metabolic adaptations. Understanding these adaptations will give insight into parasite evolution and unveil new parasite-specific drug targets. In contrast to human cells, the Plasmodium mitochondrion lacks type II fatty acid biosynthesis (FASII) enzymes yet curiously retains a divergent acyl carrier protein (mACP) incapable of modification by a 4-phosphopantetheine (Ppant) group required for canonical ACP function as the scaffold for fatty acid synthesis. We report that ligand-dependent knockdown of mACP expression is lethal to parasites, indicating an essential FASII-independent function. Decyl-ubiquinone rescues parasites temporarily from this lethal phenotype, suggesting a dominant dysfunction of the mitochondrial electron transport chain (ETC) followed by broader defects beyond the ETC. Biochemical studies reveal that Plasmodium mACP binds and stabilizes the Isd11-Nfs1 cysteine desulfurase complex required for Fe-S cluster biosynthesis, and mACP knockdown causes loss of both Nfs1 and the Rieske Fe-S cluster protein in ETC Complex III. This work identifies Ppant-independent mACP as an essential mitochondrial adaptation in Plasmodium malaria parasites that appears to be a shared metabolic feature of Apicomplexan pathogens, including Toxoplasma and Babesia. This parasite-specific adaptation highlights the ancient, fundamental role of ACP in mitochondrial Fe-S cluster biogenesis and reveals an evolutionary driving force to retain this interaction with ACP independent of its eponymous function in fatty acid synthesis.

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