Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005829 cytosol	IBA GO_REF:0000033	ACCEPT	Summary: Cytoplasmic/cytosolic localization is correct for the bacterial OGDH complex. Reason: SucA is a soluble cytosolic central-metabolism enzyme. Supporting Evidence: PMID:18304323 we identified 1103 proteins from the cytosolic fraction of the Escherichia coli
GO:0004591 oxoglutarate dehydrogenase (succinyl-transferring) activity	IBA GO_REF:0000033	ACCEPT	Summary: This is SucA's exact E1o catalytic activity. Reason: SucA catalyzes the TPP-dependent oxidative decarboxylation of 2-oxoglutarate and transfers the succinyl intermediate to the SucB lipoyl arm.
GO:0006099 tricarboxylic acid cycle	IBA GO_REF:0000033	ACCEPT	Summary: SucA acts in the TCA cycle as the E1 component of 2-oxoglutarate dehydrogenase. Reason: The OGDH complex converts 2-oxoglutarate to succinyl-CoA in the TCA cycle. Supporting Evidence: PMID:17367808 The OGDH complex is comprised of multiple copies of three types of component enzymes: a 2-oxoglutarate decarboxylase dependent on thiamine diphosphate (E1o, EC 1.2.4.2), a lipoylated succinyl transferase (E2o, EC 2.3.1.6), and a dihydrolipoyl dehydrogenase (E3, EC 1.8.1.4).
GO:0045252 oxoglutarate dehydrogenase complex	IBA GO_REF:0000033	ACCEPT	Summary: SucA is the E1 enzyme of the 2-oxoglutarate dehydrogenase complex. Reason: The OGDH complex is built from SucA/E1o, SucB/E2o and LpdA/E3.
GO:0004591 oxoglutarate dehydrogenase (succinyl-transferring) activity	IEA GO_REF:0000120	ACCEPT	Summary: This is SucA's exact E1o catalytic activity. Reason: SucA catalyzes the TPP-dependent oxidative decarboxylation of 2-oxoglutarate and transfers the succinyl intermediate to the SucB lipoyl arm.
GO:0016624 oxidoreductase activity, acting on the aldehyde or oxo group of donors, disulfide as acceptor	IEA GO_REF:0000002	MODIFY	Summary: oxidoreductase activity, acting on the aldehyde or oxo group of donors, disulfide as acceptor is a broad parent of SucA E1o activity. Reason: Replace the broad oxidoreductase grouping with the exact GO:0004591 term. Proposed replacements: oxoglutarate dehydrogenase (succinyl-transferring) activity
GO:0030976 thiamine pyrophosphate binding	IEA GO_REF:0000002	ACCEPT	Summary: thiamine pyrophosphate binding is part of SucA's thiamine-diphosphate-dependent E1 active site. Reason: The holo-E1o structure contains thiamine diphosphate and Mg2+, which are required for the oxoglutarate dehydrogenase reaction.
GO:0005515 protein binding	IPI PMID:15690043 Interaction network containing conserved and essential prote...	REMOVE	Summary: A generic high-throughput protein-binding row. Reason: Bare GO:0005515 is uninformative; SucA's physiological interaction with SucB is already captured by its OGDH catalytic activity and complex membership.
GO:0005515 protein binding	IPI PMID:15690043 Interaction network containing conserved and essential prote...	REMOVE	Summary: A generic high-throughput protein-binding row. Reason: Bare GO:0005515 is uninformative; SucA's physiological interaction with SucB is already captured by its OGDH catalytic activity and complex membership.
GO:0005515 protein binding	IPI PMID:19402753 Global functional atlas of Escherichia coli encompassing pre...	REMOVE	Summary: A generic high-throughput protein-binding row. Reason: Bare GO:0005515 is uninformative; SucA's physiological interaction with SucB is already captured by its OGDH catalytic activity and complex membership.
GO:0005515 protein binding	IPI PMID:24561554 The binary protein-protein interaction landscape of Escheric...	REMOVE	Summary: A generic high-throughput protein-binding row. Reason: Bare GO:0005515 is uninformative; SucA's physiological interaction with SucB is already captured by its OGDH catalytic activity and complex membership.
GO:0042802 identical protein binding	IPI PMID:16858726 A complexomic study of Escherichia coli using two-dimensiona...	KEEP AS NON CORE	Summary: Identical protein binding reflects SucA homodimerization. Reason: SucA functions as a homodimer, but dimerization is structural support for the E1o reaction rather than the catalytic output.
GO:0042802 identical protein binding	IPI PMID:24561554 The binary protein-protein interaction landscape of Escheric...	KEEP AS NON CORE	Summary: Identical protein binding reflects SucA homodimerization. Reason: SucA functions as a homodimer, but dimerization is structural support for the E1o reaction rather than the catalytic output.
GO:0005737 cytoplasm	IDA PMID:18304323 Protein abundance profiling of the Escherichia coli cytosol.	ACCEPT	Summary: Cytoplasmic/cytosolic localization is correct for the bacterial OGDH complex. Reason: SucA is a soluble cytosolic central-metabolism enzyme. Supporting Evidence: PMID:18304323 we identified 1103 proteins from the cytosolic fraction of the Escherichia coli
GO:0006099 tricarboxylic acid cycle	IDA PMID:17367808 Crystal structure of the E1 component of the Escherichia col...	ACCEPT	Summary: SucA acts in the TCA cycle as the E1 component of 2-oxoglutarate dehydrogenase. Reason: The OGDH complex converts 2-oxoglutarate to succinyl-CoA in the TCA cycle. Supporting Evidence: PMID:17367808 The OGDH complex is comprised of multiple copies of three types of component enzymes: a 2-oxoglutarate decarboxylase dependent on thiamine diphosphate (E1o, EC 1.2.4.2), a lipoylated succinyl transferase (E2o, EC 2.3.1.6), and a dihydrolipoyl dehydrogenase (E3, EC 1.8.1.4).
GO:0045252 oxoglutarate dehydrogenase complex	IPI PMID:16338405 Electron cryotomography of the E. coli pyruvate and 2-oxoglu...	ACCEPT	Summary: SucA is the E1 enzyme of the 2-oxoglutarate dehydrogenase complex. Reason: The OGDH complex is built from SucA/E1o, SucB/E2o and LpdA/E3.
GO:0000287 magnesium ion binding	IDA PMID:17367808 Crystal structure of the E1 component of the Escherichia col...	ACCEPT	Summary: magnesium ion binding is part of SucA's thiamine-diphosphate-dependent E1 active site. Reason: The holo-E1o structure contains thiamine diphosphate and Mg2+, which are required for the oxoglutarate dehydrogenase reaction. Supporting Evidence: PMID:17367808 positive electron density matching the shape of thiamine diphosphate and a divalent cation, assumed to be Mg2+
GO:0030976 thiamine pyrophosphate binding	IDA PMID:17367808 Crystal structure of the E1 component of the Escherichia col...	ACCEPT	Summary: thiamine pyrophosphate binding is part of SucA's thiamine-diphosphate-dependent E1 active site. Reason: The holo-E1o structure contains thiamine diphosphate and Mg2+, which are required for the oxoglutarate dehydrogenase reaction. Supporting Evidence: PMID:17367808 positive electron density matching the shape of thiamine diphosphate and a divalent cation, assumed to be Mg2+
GO:0005829 cytosol	IDA PMID:18304323 Protein abundance profiling of the Escherichia coli cytosol.	ACCEPT	Summary: Cytoplasmic/cytosolic localization is correct for the bacterial OGDH complex. Reason: SucA is a soluble cytosolic central-metabolism enzyme. Supporting Evidence: PMID:18304323 we identified 1103 proteins from the cytosolic fraction of the Escherichia coli
GO:0004591 oxoglutarate dehydrogenase (succinyl-transferring) activity	IDA PMID:17367808 Crystal structure of the E1 component of the Escherichia col...	ACCEPT	Summary: This is SucA's exact E1o catalytic activity. Reason: SucA catalyzes the TPP-dependent oxidative decarboxylation of 2-oxoglutarate and transfers the succinyl intermediate to the SucB lipoyl arm. Supporting Evidence: PMID:17367808 The activity of the complex was monitored by measuring the formation of NADH at 340 nm.
GO:0005829 cytosol	HDA PMID:16858726 A complexomic study of Escherichia coli using two-dimensiona...	ACCEPT	Summary: Cytoplasmic/cytosolic localization is correct for the bacterial OGDH complex. Reason: SucA is a soluble cytosolic central-metabolism enzyme.

Core Functions

2-oxoglutarate dehydrogenase E1 activity in the cytosolic OGDH complex.

Molecular Function:

oxoglutarate dehydrogenase (succinyl-transferring) activity

Directly Involved In:

tricarboxylic acid cycle

Cellular Locations:

cytosol

In Complex:

oxoglutarate dehydrogenase complex

Supporting Evidence:

PMID:17367808
The OGDH complex is comprised of multiple copies of three types of component enzymes: a 2-oxoglutarate decarboxylase dependent on thiamine diphosphate (E1o, EC 1.2.4.2), a lipoylated succinyl transferase (E2o, EC 2.3.1.6), and a dihydrolipoyl dehydrogenase (E3, EC 1.8.1.4).

References

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📚 Additional Documentation

Notes

(sucA-notes.md)

sucA notes

2026-09-30 re-review

Deep research was attempted with just deep-research-falcon ECOLI sucA --fallback perplexity-lite; the wrapper reported that no Falcon/Edison, OpenAI, Asta, or Perplexity credentials were configured. FEBA/RB-TnSeq fetching was also unavailable because neither the local /srv/home/cmungall/repos/feba cache nor the remote fit.genomics.lbl.gov source could be reached.

Manual evidence check:

PMID:17367808 solved SucA/E1o structures and assayed wild-type and active-site mutant E1o within reconstituted OGDH assemblies containing E1o, E2o/SucB, E3/LpdA, ThDP, MgCl2, NAD+, 2-oxoglutarate, and CoA.
The AMP pocket observed in SucA should not be promoted to a core nucleotide-binding function because UniProt explicitly notes that its physiological relevance is unclear.
High-throughput protein-binding rows to SucB/YheS do not add functional information beyond SucA OGDH complex membership and core E1 catalysis.

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