gltA

Gene Description

gltA (PP_4194) encodes citrate synthase (EC 2.3.3.16), the enzyme that catalyzes the committed, first step of the tricarboxylic acid (TCA) cycle. It catalyzes the Claisen-type condensation of acetyl-CoA and oxaloacetate with hydrolysis of the resulting citryl-CoA thioester to yield citrate and free CoA. The protein is a 429-residue type I (large, bacterial) citrate synthase of the citrate synthase family (PIRSF001369; TIGR01798 cit_synth_I), typically assembling as a homohexamer (trimer of dimers), with the canonical His/His/Asp catalytic machinery (active-site residues His306 and Asp364 in this sequence). It is a soluble cytoplasmic enzyme. By channeling acetyl-CoA into the TCA cycle, GltA sits at a central node of carbon and energy metabolism, governing the entry of acetyl-CoA (derived from glycolysis, fatty acid oxidation, or acetate assimilation) into oxidative metabolism and balancing respiratory energy generation against the use of acetyl-CoA for biosynthesis. In P. putida it is central to aerobic central metabolism and acetate assimilation.

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005737 cytoplasm	IEA GO_REF:0000120	ACCEPT	Summary: Citrate synthase is a soluble cytoplasmic enzyme; this localization is consistent with the enzyme class and with experimental detection of GltA in the soluble cell lysate fraction of P. putida KT2440. Reason: Bacterial citrate synthases are soluble cytosolic enzymes with no membrane anchor or signal peptide; the IEA assignment is correct and informative.
GO:0006099 tricarboxylic acid cycle	IEA GO_REF:0000120	ACCEPT	Summary: Citrate synthase catalyzes the entry/committed step of the TCA cycle (condensation of acetyl-CoA and oxaloacetate to citrate). This is the canonical biological process for the gene and is strongly supported by family membership and the UniPathway TCA assignment (UPA00223; isocitrate from oxaloacetate, step 1/2). Reason: Core biological process of the gene; directly supported by enzyme function and pathway assignment.
GO:0036440 citrate synthase activity	IEA GO_REF:0000120	ACCEPT	Summary: This is the precise molecular function of the gene product. The UniProt catalytic activity (RHEA:16845, EC 2.3.3.16; oxaloacetate + acetyl-CoA + H2O = citrate + CoA + H+), the conserved catalytic triad, and the citrate synthase family assignment all support citrate synthase activity as the core molecular function. Reason: Represents the core molecular function of gltA; well supported by sequence, family, and pathway evidence.
GO:0046912 acyltransferase activity, acyl groups converted into alkyl on transfer	IEA GO_REF:0000002	MARK AS OVER ANNOTATED	Summary: This is a broad parent class of citrate synthase activity (citrate synthase transfers an acetyl group with conversion to a carboxymethyl group). While not incorrect, it is far less informative than GO:0036440 citrate synthase activity, which is already annotated and captures the precise reaction. Reason: Redundant, less-specific ancestor of the already-annotated specific function GO:0036440; provides no additional information about gltA function.

Core Functions

Citrate synthase catalyzing the committed first step of the TCA cycle, condensing acetyl-CoA and oxaloacetate to form citrate and CoA

Molecular Function:

citrate synthase activity

Directly Involved In:

tricarboxylic acid cycle

Cellular Locations:

cytoplasm

Supporting Evidence:

GO_REF:0000120
UniProt catalytic activity RHEA:16845 / EC 2.3.3.16 (oxaloacetate + acetyl-CoA + H2O = citrate + CoA + H+); citrate synthase family assignment.

Gene Description

Existing Annotations Review

Core Functions

Citrate synthase catalyzing the committed first step of the TCA cycle, condensing acetyl-CoA and oxaloacetate to form citrate and CoA

References

Deep Research

Falcon

OpenScientist

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