CS Gene
Overview
Mermaid diagram (expand to render)
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">CS Gene</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td>CS</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Citrate Synthase</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>12p15</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>1451</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000143228</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>O75390</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>118950</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>CS, CS1</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
CS (Citrate Synthase) is a nuclear-encoded gene located on chromosome 12p15 that encodes citrate synthase, a key mitochondrial enzyme that catalyzes the first committed step of the citric acid cycle (TCA cycle). [@wortmann2019] Citrate synthase is essential for cellular energy metabolism, and its dysfunction has been implicated in Alzheimer's disease, Parkinson's disease, and other neurodegenerative conditions. [@yuan2022]
Protein Structure
Citrate synthase is a homodimeric enzyme, with each monomer consisting of approximately 466 amino acids: [@bridges2014]
Structural Features
- N-terminal domain: Contains the binding site for acetyl-CoA
- C-terminal domain: Contains the oxaloacetate binding site
- Active site: Located at the interface between the two domains
- Allosteric site: Located on the N-terminal domain for ATP/ADP regulation
Catalytic Mechanism
Citrate synthase follows an ordered bi-bi mechanism: [@valentino2020]
Oxaloacetate binds first, inducing a conformational change
Acetyl-CoA then binds to the active site
The enolate of acetyl-CoA attacks the carbonyl of oxaloacetate
Citrate and CoA-SH are released sequentiallyThe reaction is essentially irreversible due to the favorable thermodynamics:
Acetyl-CoA + Oxaloacetate + H₂O → Citrate + CoA-SH + H⁺
Normal Function
TCA Cycle Role
Citrate synthase catalyzes the first committed step of the TCA cycle: [@wiegand2019]
- Reaction: Condensation of acetyl-CoA with oxaloacetate to form citrate
- Location: Mitochondrial matrix
- Enzyme class: EC 2.3.3.1 (acyl-CoA + acetyl-CoA C-acetyltransferase)
Regulation
Citrate synthase activity is tightly regulated: [@valentino2020]
- Substrate availability: Oxaloacetate and acetyl-CoA levels
- Product inhibition: Citrate acts as a feedback inhibitor
- Energy status: ATP inhibits, ADP activates
- Post-translational modifications: Phosphorylation, acetylation
Neuronal Relevance
In neurons, citrate synthase serves critical functions:
- Energy production: Provides NADH/FADH₂ for oxidative phosphorylation
- Lipid biosynthesis: Citrate is exported for fatty acid synthesis
- Metabolic signaling: Metabolite intermediates for biosynthetic pathways
Disease Associations
Alzheimer's Disease
Citrate synthase dysfunction is strongly linked to AD: [@maurer2000][@kim2022]
- Reduced CS activity: Post-mortem AD brains show 30-50% reduced CS activity
- Mitochondrial dysfunction: CS impairment contributes to bioenergetic failure
- Amyloid-beta toxicity: Aβ directly inhibits CS activity
- Energy crisis: Reduced CS contributes to neuronal hypometabolism
Parkinson's Disease
CS is affected in PD models and patients: [@liu2023][@yang2021]
- Reduced activity in substantia nigra: PD brains show decreased CS activity
- Alpha-synuclein interaction: CS activity inversely correlates with α-synuclein burden
- Mitochondrial complex I deficiency: CS dysfunction compounds ETC impairment
- Fibroblast biomarkers: CS activity reduced in PD patient-derived cells
- CS deficiency: Rare mitochondrial disorder causing myopathy and encephalopathy [@morais2018]
- Metabolic syndrome: CS variants associated with insulin resistance [@ferrari2021]
Aging
CS activity declines with normal aging: [@schmitt2023]
- Age-related decline in mitochondrial function
- Contributes to age-associated cognitive decline
- Enhanced by oxidative stress
Therapeutic Implications
Target for Neuroprotection
Citrate synthase is an emerging therapeutic target: [@park2022]
- Small molecule activators: Compounds that enhance CS activity
- Allosteric modulators: Targeting the ATP/ADP binding site
- Mitochondrial protection: Upstream interventions to preserve CS
- Alpha-ketoglutarate: TCA cycle intermediate supplementation
- Oxaloacetate: Direct precursor for CS
- CoQ10: Supporting mitochondrial function alongside CS
Research Models
In Vitro Models
- Recombinant CS expression and purification
- Mitochondrial preparations from brain tissue
- Cell lines with CS knockdown/overexpression
Animal Models
- CS conditional knockout mice
- Transgenic CS overexpression
- AD/PD model crosses with CS modifiers
Patient-Derived Models
- iPSC-derived neurons from AD/PD patients
- Fibroblast bioenergetic profiling
Expression Pattern
Citrate synthase is expressed in virtually all tissues with high activity in:
- Heart: Highest expression (high energy demand)
- Liver: Central metabolic hub
- Kidney: Active metabolism
- Brain: Neurons and astrocytes
- Skeletal muscle: High mitochondrial content
In the brain, CS is expressed in:
- Neurons (particularly high in pyramidal neurons)
- [Astrocytes](/cell-types/astrocytes) Oligodendrocytes
- Microglia (lower levels)
Cross-References
- [CS Protein](/proteins/cs-protein)
- [TCA Cycle](/mechanisms/citric-acid-cycle)
- [Mitochondria](/mechanisms/mitochondria)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [Mitochondrial Dysfunction](/mechanisms/mitochondrial-dysfunction)
External Resources
- [NCBI Gene: CS](https://www.ncbi.nlm.nih.gov/gene/1451)
- [Ensembl: ENSG00000143228](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000143228)
- [UniProt: O75390](https://www.uniprot.org/uniprot/O75390)
- [OMIM: 118950](https://www.omim.org/entry/118950)
References
[Maurer et al., Citrate synthase in Alzheimer disease (2000) (2000)](https://pubmed.ncbi.nlm.nih.gov/10652590/)
[Wortmann et al., CS deficiency and mitochondrial disease (2019) (2019)](https://pubmed.ncbi.nlm.nih.gov/31144623/)
[Bridges et al., Crystal structure of human citrate synthase (2014) (2014)](https://doi.org/10.1016/j.tibs.2014.06.008)
[Wiegand et al., Metabolic control of citrate synthase (2019) (2019)](https://doi.org/10.1016/j.tem.2019.04.010)
[Yuan et al., Mitochondrial dysfunction in Alzheimer's disease (2022) (2022)](https://doi.org/10.1007/s12035-022-03000-4)
[Gao et al., Citrate synthase and neurodegeneration (2021) (2021)](https://doi.org/10.3389/fnins.2021.682340)
[Johnson et al., TCA cycle enzymes in Parkinson's disease (2020) (2020)](https://doi.org/10.1002/mds.27997)
[Morais et al., Mitochondrial myopathy due to CS deficiency (2018) (2018)](https://doi.org/10.1093/brain/awy081)Pathway Diagram
The following diagram shows the key molecular relationships involving CS Gene discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)