PMID:26305336

Citation	Mao, YH, Ma, JC, Li, F, Hu, Z and Wang, HH (2015) Ralstonia solanacearum RSp0194 Encodes a Novel 3-Keto-Acyl Carrier Protein Synthase III. PLoS ONE 10:e0136261
Abstract	Fatty acid synthesis (FAS), a primary metabolic pathway, is essential for survival of bacteria. Ralstonia solanacearum, a β-proteobacteria member, causes a bacterial wilt affecting more than 200 plant species, including many economically important plants. However, thus far, the fatty acid biosynthesis pathway of R. solanacearum has not been well studied. In this study, we characterized two forms of 3-keto-ACP synthase III, RsFabH and RsFabW, in R. solanacearum. RsFabH, the homologue of Escherichia coli FabH, encoded by the chromosomal RSc1050 gene, catalyzes the condensation of acetyl-CoA with malonyl-ACP in the initiation steps of fatty acid biosynthesis in vitro. The RsfabH mutant lost de novo fatty acid synthetic ability, and grows in medium containing free fatty acids. RsFabW, a homologue of Pseudomonas aeruginosa PA3286, encoded by a megaplasmid gene, RSp0194, condenses acyl-CoA (C2-CoA to C10-CoA) with malonyl-ACP to produce 3-keto-acyl-ACP in vitro. Although the RsfabW mutant was viable, RsfabW was responsible for RsfabH mutant growth on medium containing free fatty acids. Our results also showed that RsFabW could condense acyl-ACP (C4-ACP to C8-ACP) with malonyl-ACP, to produce 3-keto-acyl-ACP in vitro, which implies that RsFabW plays a special role in fatty acid synthesis of R. solanacearum. All of these data confirm that R. solanacearum not only utilizes acetyl-CoA, but also, utilizes medium-chain acyl-CoAs or acyl-ACPs as primers to initiate fatty acid synthesis.
Links	PubMed PMC4549310 Online version:10.1371/journal.pone.0136261
Keywords	3-Oxoacyl-(Acyl-Carrier-Protein) Synthase/genetics; 3-Oxoacyl-(Acyl-Carrier-Protein) Synthase/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Fatty Acids/metabolism; Gene Expression; Multigene Family; Ralstonia solanacearum/genetics; Ralstonia solanacearum/metabolism; Recombinant Proteins/genetics; Recombinant Proteins/isolation & purification; Sequence Deletion; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Substrate Specificity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
RALSO:FABH		GO:0033818: beta-ketoacyl-acyl-carrier-protein synthase III activity	ECO:0000315:		F		Ralstonia solanacearum with RsfabH KO was unable to grow on media lacking Octanoic acid, while it was able to grow on the media where it was included. Growth on octanoic was rescued when the fabH gene was put back. Specifically, beta-ketoacyl-acyl-carrier protein synthase III activity was observed, as seen in figure 2A and 2B.	complete CACAO 12938
RALSO:FABH		GO:0044579: butyryl-CoA biosynthetic process from acetyl-CoA	ECO:0000315:		P		Addition of EcFabH or RsFabH to the reaction mixture led to formation of butyryl-ACP (S1B fig, lane 1 and lane 2). Upon addition of the long chain E. coli 3-ketoacyl-ACP synthase I, FabB, to the reactions, all reactions produced long chain acyl-ACP species (S1B fig, lane 3 and lane 4). This data supports the notion that like E. coli FabH, RsFabH could complete the initial cycle of fatty acid synthesis to produce butyryl-ACP. Organism: Ralstonia solanacearum	complete CACAO 12955
ECOBD:A0A140N913		GO:0044579: butyryl-CoA biosynthetic process from acetyl-CoA	ECO:0000315:		P		Addition of EcFabH or RsFabH to the reaction mixture led to formation of butyryl-ACP (S1B fig, lane 1 and lane 2). Upon addition of the long chain E. coli 3-ketoacyl-ACP synthase I, FabB, to the reactions, all reactions produced long chain acyl-ACP species (S1B fig, lane 3 and lane 4). This data supports the notion that like E. coli FabH, RsFabH could complete the initial cycle of fatty acid synthesis to produce butyryl-ACP. Organism & Strain: E. coli (strain B / BL21-DE3)	complete CACAO 12956
RALSO:Q8XTB9		GO:0033818: beta-ketoacyl-acyl-carrier-protein synthase III activity	ECO:0000315:		F		Fig. 3 results confirmed that fabW is responsible for growth of strain RsmH on BG medium in the presence of fatty acids, and confirmed that RsfabW encodes a 3-ketoacyl-ACP synthase III. Organism: Ralstonia solanacearum	complete CACAO 12968

References

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