pta

Gene Description

Phosphate acetyltransferase (phosphotransacetylase; Pta, EC 2.3.1.8) is a cytoplasmic enzyme of central carbon metabolism that catalyzes the reversible transfer of an acetyl group between coenzyme A and inorganic phosphate (acetyl-CoA + phosphate = acetyl phosphate + CoA). Together with acetate kinase (AckA), Pta constitutes the AckA-Pta pathway that interconverts acetyl-CoA, the energy-rich intermediate acetyl phosphate, and acetate, sitting at the acetate node linking glycolysis/pyruvate dehydrogenase-derived acetyl-CoA to acetate overflow metabolism, energy conservation via substrate-level phosphorylation, and acetyl phosphate signaling. In Pseudomonas putida KT2440 the enzyme is encoded by pta (locus PP_0774); phosphotransacetylase activity is measurable in cell-free extracts and is abolished by disruption of pta, and acetyl phosphate generated by Pta can feed heterologous AckA to produce acetate and ATP. The KT2440 protein is unusually large (695 aa) and bipartite, with an N-terminal CobB/CobQ-like region (P-loop NTPase / DRTGG) preceding the C-terminal phosphate acetyltransferase catalytic domain that carries the substrate-binding site; the enzyme is predicted to assemble into a homohexamer.

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005737 cytoplasm	IEA GO_REF:0000044	ACCEPT	Summary: Cytoplasmic localization for a soluble central-metabolism enzyme acting on acetyl-CoA, acetyl phosphate, and inorganic phosphate. Reason: Consistent with the UniProt subcellular location (Cytoplasm) and with enzyme activity being routinely assayed in soluble cell-free extracts. Pta has no membrane-targeting or signal/transit features; cytoplasmic localization is appropriate.
GO:0008959 phosphate acetyltransferase activity	IEA GO_REF:0000120	ACCEPT	Summary: Precise molecular function term matching EC 2.3.1.8 and RHEA:19521 (acetyl-CoA + phosphate = acetyl phosphate + CoA); this is the core catalytic activity of Pta. Reason: This is the exact, well-supported molecular function of the gene product. Although the GOA evidence is IEA, the assignment is anchored to InterPro:IPR016475 (proteobacterial phosphate acetyltransferase signature), EC 2.3.1.8, and RHEA:19521, and is independently confirmed in P. putida KT2440 where phosphotransacetylase activity is detected in cell-free extracts and lost upon pta disruption. Core function.
GO:0016407 acetyltransferase activity	IEA GO_REF:0000002	MARK AS OVER ANNOTATED	Summary: General parent of the precise phosphate acetyltransferase activity already annotated. Reason: GO:0016407 is a broad ancestor of GO:0008959 (phosphate acetyltransferase activity), which is already annotated with a specific evidence trail. The general term adds no information beyond the precise term and is an InterPro2GO over-generalization.
GO:0016746 acyltransferase activity	IEA GO_REF:0000002	MARK AS OVER ANNOTATED	Summary: Very general acyltransferase parent of the precise phosphate acetyltransferase activity. Reason: GO:0016746 (transferring acyl groups) is an even broader ancestor of GO:0008959. It is redundant with, and far less informative than, the specific phosphate acetyltransferase activity term. Over-annotation from InterPro2GO mapping.
GO:0006085 acetyl-CoA biosynthetic process	IEA GO_REF:0000041	ACCEPT	Summary: Pathway-level process annotation reflecting the UniPathway mapping for acetyl-CoA biosynthesis from acetate (acetyl-CoA from acetate, step 2/2). Reason: Pta catalyzes the second step of the acetyl-CoA-from-acetate route (AckA forms acetyl phosphate from acetate; Pta converts acetyl phosphate to acetyl-CoA), consistent with the UniPathway UPA00340/UER00459 mapping in the UniProt record. The reaction is reversible, so in overflow metabolism Pta also runs in the acetyl-CoA-consuming direction toward acetate; the biosynthetic-process term captures one valid physiological direction and is supported by the pathway annotation. Reasonable, retain.

Core Functions

Catalyzes the reversible transfer of an acetyl group between coenzyme A and inorganic phosphate (acetyl-CoA + phosphate = acetyl phosphate + CoA), the Pta half of the AckA-Pta acetate pathway.

Molecular Function:

phosphate acetyltransferase activity

Supporting Evidence:

file:PSEPK/pta/pta-deep-research-falcon.md
Phosphotransacetylase (Pta) catalyzes the reversible transfer of an acetyl group between CoA and inorganic phosphate (acetyl-CoA + Pi = acetyl-phosphate + CoA); in P. putida KT2440 Pta activity is detected in cell-free extracts and abolished in a pta::mini-Tn5 mutant.

Interconverts acetyl-CoA, acetyl phosphate, and (with acetate kinase) acetate at the acetate node of central carbon metabolism, contributing to acetyl-CoA biosynthesis from acetate and to acetate overflow/energy metabolism.

Molecular Function:

phosphate acetyltransferase activity

Directly Involved In:

acetyl-CoA biosynthetic process

Supporting Evidence:

file:PSEPK/pta/pta-deep-research-falcon.md
Acetyl-phosphate generated by native Pta can feed heterologous AckA to produce acetate and ATP by substrate-level phosphorylation; ackA/pta is depicted as an acetate-to-acetyl-CoA assimilation route in KT2440.

Gene Description

Existing Annotations Review

Core Functions

Catalyzes the reversible transfer of an acetyl group between coenzyme A and inorganic phosphate (acetyl-CoA + phosphate = acetyl phosphate + CoA), the Pta half of the AckA-Pta acetate pathway.

Interconverts acetyl-CoA, acetyl phosphate, and (with acetate kinase) acetate at the acetate node of central carbon metabolism, contributing to acetyl-CoA biosynthesis from acetate and to acetate overflow/energy metabolism.

References

Deep Research

Falcon

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