UQCRFS1 Gene

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UQCRFS1 Gene

Overview

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UQCRFS1 Gene

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">UQCRFS1 Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>UQCRFS1</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Ubiquinol-Cytochrome c Reductase Core Protein 1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>19q12</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>27089</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>191317</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000127540</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P31930</td>
</tr>
<tr>
<td class="label">Protein Class</td>
<td>Mitochondrial complex III subunit (2Fe-2S protein)</td>
</tr>
<tr>
<td class="label">Tissue Expression</td>
<td>High in brain, heart, muscle</td>
</tr>
<tr>
<td class="label">Brain Region</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Cerebral Cortex</td>
<td>High</td>
</tr>
<tr>
<td class="label">Hippocampus</td>
<td>High</td>
</tr>
<tr>
<td class="label">Cerebellum</td>
<td>High</td>
</tr>
<tr>
<td class="label">Substantia Nigra</td>
<td>High</td>
</tr>
<tr>
<td class="label">Basal Ganglia</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Brainstem</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">CoQ10</td>
<td>Electron carrier</td>
</tr>
<tr>
<td class="label">MitoQ</td>
<td>Mitochondria-targeted antioxidant</td>
</tr>
<tr>
<td class="label">Idebenone</td>
<td>Complex III protectant</td>
</tr>
<tr>
<td class="label">Vitamin E</td>
<td>ROS scavenging</td>
</tr>
<tr>
<td class="label">Therapeutic</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">Ubiquinol (CoQ10)</td>
<td>Electron carrier, antioxidant</td>
</tr>
<tr>
<td class="label">MitoQ</td>
<td>Mitochondria-targeted CoQ10</td>
</tr>
<tr>
<td class="label">Idebenone</td>
<td>Synthetic CoQ10 analog</td>
</tr>
<tr>
<td class="label">EUK-134</td>
<td>Catalytic antioxidant</td>
</tr>
<tr>
<td class="label">Szeto-Schiller peptides</td>
<td>Mitochondrial antioxidants</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction</td>
</tr>
<tr>
<td class="label">UQCRFS1 (RISP)</td>
<td>Forms bc1 complex</td>
</tr>
<tr>
<td class="label">Cytochrome c1</td>
<td>Electron transfer</td>
</tr>
<tr>
<td class="label">Cytochrome b</td>
<td>Qo/Qi sites</td>
</tr>
<tr>
<td class="label">Iron-sulfur cluster</td>
<td>Catalytic center</td>
</tr>
<tr>
<td class="label">Rieske protein</td>
<td>Subunit assembly</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">10 edges</a></td>
</tr>
</table>

UQCRFS1 (Ubiquinol-Cytochrome c Reductase Core Protein 1), also known as Rieske iron-sulfur protein (RISP), is a nuclear-encoded mitochondrial protein that serves as a critical core component of complex III (cytochrome bc1 complex) in the electron transport chain[@craft2011]. The protein contains a 2Fe-2S iron-sulfur cluster that transfers electrons from ubiquinol to cytochrome c1, a key step in the Q-cycle that generates the proton gradient essential for ATP synthesis. UQCRFS1 is essential for oxidative phosphorylation and is implicated in various neurodegenerative diseases through mitochondrial dysfunction.

Structure and Function

Protein Structure

UQCRFS1 (274 amino acids) is a key component of the cytochrome bc1 complex:

N-terminal transit peptide: Mitochondrial targeting sequence (cleaved after import)
Rieske domain: Contains the 2Fe-2S cluster
C-terminal helix: Anchors to the matrix side of the inner membrane
Iron-sulfur cluster: [2Fe-2S] center with unique ligation (Cys/His)

The 2Fe-2S cluster is coordinated by:

Two cysteine residues
Two histidine residues
Unique among iron-sulfur proteins

Catalytic Function in Complex III

UQCRFS1 is the heart of the Q-cycle in complex III[@giachin2016]:

First electron transfer: QH₂ (ubiquinol) → 2Fe-2S (UQCRFS1)

Generates semiquinone (Q•⁻) at Qo site
Releases 2H⁺ to intermembrane space

2. Second electron transfer: 2Fe-2S → cytochrome c1 → cytochrome c

Electron transfers to cytochrome c

3. Second Q cycle: Second electron reduces another Q at Qo site

Forms QH₂ at Qi site

This process creates the proton gradient (3-4 H⁺ pumped per electron pair).

The Q-Cycle Mechanism

Qo site Qi site
┌─────────────┐ ┌─────────────┐
│ │ │ │
QH₂ ──→│ UQCRFS1 │───cyt c1───cyt c ←───│ Q │
│ (2Fe-2S) │ ↓ │ (ox) │
│ │ │ │
└─────────────┘ └─────────────┘
↓ H⁺ ↓ H⁺
(intermembrane space) (intermembrane space)

Normal Function

Electron Transport Chain

UQCRFS1 is essential for complex III function[@wang2020]:

Electron transfer: From ubiquinol to cytochrome c
Proton pumping: 4 H⁺ per pair of electrons
Ubiquinone cycling: Q-cycle mechanism
ATP synthesis: Powers ATP synthase

Mitochondrial Respiration

In neurons, complex III supports:

Oxidative phosphorylation: Primary ATP production
NADH regeneration: Maintains NAD⁺/NADH ratio
Calcium handling: Mitochondrial calcium uptake
Synaptic energy: High energy demands of neurotransmission

Regulation of Apoptosis

UQCRFS1 plays a role in intrinsic apoptosis[@birk2011]:

Cytochrome c release: Complex III can release cytochrome c
ROS signaling: Elevated ROS triggers apoptosis
Bcl-2 family interaction: Cross-talk with apoptotic proteins

Disease Associations

Mitochondrial Complex III Deficiency

Mutations in UQCRFS1 cause complex III deficiency[@ellis2011]:

Encephalomyopathy: Brain and muscle involvement
Lactic acidosis: Accumulation of lactate
Failure to thrive: Growth impairment
Myopathy: Muscle weakness
Ataxia: Coordination problems

Leigh Syndrome

UQCRFS1 mutations can cause Leigh syndrome[@chen2012]:

Progressive neurodegeneration: Characteristic brainstem lesions
Bilateral basal ganglia involvement: Necrotic lesions
Developmental regression: Loss of milestones
Respiratory failure: Brainstem dysfunction

Parkinson's Disease

Complex III dysfunction is implicated in PD[@schapira2012]:

Complex I deficiency: PD primarily affects complex I
Compensatory complex III changes: Altered function
ROS overproduction: From impaired electron transport
Dopaminergic neuron vulnerability: Energy-demanding cells

Alzheimer's Disease

Mitochondrial complex III in AD[@moreira2010]:

Complex III activity reduced: 20-40% decrease
Electron transport impairment: Causes energy failure
ROS production: Increased oxidative stress
Amyloid-β interaction: Aβ impairs complex III

Other Neurodegenerative Conditions

Amyotrophic Lateral Sclerosis (ALS): Mitochondrial dysfunction
Huntington's Disease: Complex III alterations
Leber's hereditary optic neuropathy: Complex I/III defects

Amyotrophic Lateral Sclerosis

Complex III dysfunction is observed in ALS and contributes to motor neuron degeneration. Studies have shown that UQCRFS1 activity is reduced in spinal cord tissue from ALS patients, and this reduction correlates with disease progression. The mechanisms include both sporadic dysfunction and genetic factors affecting complex III assembly[@gomez2017].

Huntington's Disease

In Huntington's disease, mutant huntingtin protein directly impairs mitochondrial function, including complex III activity. The decreased activity leads to:

Enhanced ROS production
Impaired energy metabolism
Increased susceptibility to excitotoxicity
Progressive neuronal dysfunction

Mechanism of Neurodegeneration

Energy Failure

Impaired complex III leads to[@sorrentino2016]:

ATP depletion: Reduced oxidative phosphorylation
NAD⁺ loss: Impaired metabolic function
Ion gradient collapse: Cellular dysfunction
Synaptic failure: Energy-dependent processes cease

Reactive Oxygen Species

Complex III is a major ROS source[@murphy2009]:

Electron leak: At Qo site during Q-cycle
Superoxide production: O₂⁻ generation
Hydrogen peroxide: From dismutated superoxide
Hydroxyl radicals: Most damaging (via Fenton)

Mitochondrial Dynamics

Quality control mechanisms fail[@van2012]:

Fission/fusion imbalance: Altered mitochondrial morphology
Mitophagy defects: Impaired clearance of damaged mitochondria
Mitochondrial DNA mutations: Accumulate with age

Apoptotic Cascade

Cell death pathways activate[@czabot2011]:

Cytochrome c release: Triggers apoptosome formation
Caspase activation: Executioner caspases
PARP cleavage: DNA repair failure
Neurological symptoms: Resulting from neuron loss

Brain Expression

Regional Distribution

UQCRFS1 is expressed throughout the brain:

Cellular Localization

Neurons: High expression in energy-demanding neurons
Astrocytes: Moderate expression
Oligodendrocytes: High (myelin production needs ATP)
Microglia: Lower expression

Subcellular Distribution

Within neurons, UQCRFS1 is localized primarily to:

Mitochondrial cristae: Highest concentration in the inner membrane folds where electron transport occurs

Somatic mitochondria: Perikaryal mitochondria in the cell body

Axonal mitochondria: Distributed along long axons for energy supply

Synaptic mitochondria: Enriched at presynaptic terminals where ATP demand is highest

The distribution of UQCRFS1 along axons is particularly relevant for neurodegenerative diseases because axonal transport deficits precede cell body degeneration in both AD and PD[@bhat2021].

Therapeutic Targeting

Antioxidant Strategies

Emerging Therapeutic Approaches

Beyond traditional antioxidants, several novel approaches show promise:

Small molecule UQCRFS1 activators: Compounds that enhance the catalytic efficiency of the Rieske protein

Iron-sulfur cluster protectors: Molecules that stabilize the 2Fe-2S cluster against oxidative damage

Gene therapy: Viral vector-mediated delivery of functional UQCRFS1

Cell-penetrating peptides: Peptides that target mitochondria and deliver protective compounds

Research into these approaches has accelerated due to advances in structural biology that have revealed the detailed mechanism of UQCRFS1 function.

Mitochondrial Modulation

Complex III enhancers: Increase enzyme activity
Electron transfer mediators: Improve function
Gene therapy: Deliver functional UQCRFS1

Biomarkers and Diagnostics

The measurement of complex III activity in various tissues holds diagnostic potential:

Skeletal muscle biopsy: Direct enzyme activity measurement
Platelet mitochondria: Peripheral assessment of complex III function
Fibroblast culture: Patient-specific functional studies

These approaches are particularly valuable for diagnosing mitochondrial complex III deficiency syndromes and for monitoring therapeutic response.

Metabolic Approaches

NAD⁺ precursors: Support mitochondrial function
Alpha-ketoglutarate: Metabolic intermediate
Pyruvate supplementation: Energy substrate

Clinical Implications

Complex III dysfunction has significant clinical implications for neurodegenerative diseases. The progressive nature of mitochondrial dysfunction correlates with disease staging in both Alzheimer's and Parkinson's disease[@brandt2018]. In Alzheimer's disease, complex III activity shows a characteristic decline that parallels cognitive deterioration, with post-mortem studies revealing 30-50% reduction in complex III activity in affected brain regions[@manes2023].

The Rieske iron-sulfur protein (UQCRFS1) represents a particularly vulnerable node in the electron transport chain due to its unique iron-sulfur cluster that is susceptible to oxidative damage. Studies have shown that oxidative modifications to the 2Fe-2S cluster lead to enzymatic dysfunction that precedes clinical symptoms in mouse models of neurodegeneration[@park2024].

Recent Research Advances

Complex III and Synaptic Dysfunction

Recent research has revealed that complex III deficiency has profound effects on synaptic function beyond energy production. The electron transport chain supports synaptic vesicle recycling, neurotransmitter release, and dendritic spine maintenance. Studies in 2022 demonstrated that UQCRFS1 dysfunction leads to impaired synaptic plasticity and long-term potentiation deficits in hippocampal neurons[@zhang2022]. This finding has important implications for understanding memory deficits in Alzheimer's disease.

Alpha-Synuclein and Complex III

A significant research advance comes from studies linking alpha-synuclein aggregation to mitochondrial complex III dysfunction. Alpha-synuclein, the protein that forms Lewy bodies in Parkinson's disease, directly inhibits complex III activity and promotes ROS production[@schondorf2022]. This creates a vicious cycle where aggregation impairs function, leading to more oxidative stress and further aggregation. Therapeutic strategies targeting this cycle are currently under investigation.

Tau Pathology and Mitochondrial Dysfunction

New research has established connections between tau pathology and complex III dysfunction. Tau oligomers directly interact with mitochondrial proteins, including complex III subunits, disrupting electron transport and promoting ROS production. The resulting oxidative stress accelerates tau hyperphosphorylation and aggregation, creating another pathogenic feedback loop[@jiang2024].

Therapeutic Targeting Advances

Recent advances in complex III-targeted therapeutics include:

Novel approaches targeting UQCRFS1 specifically include small molecules that protect the iron-sulfur cluster from oxidative damage and gene therapy approaches to deliver functional UQCRFS1 to affected neurons[@iommelli2023].

Molecular Mechanisms

Iron-Sulfur Cluster Assembly

The 2Fe-2S cluster of UQCRFS1 requires specialized assembly machinery for proper insertion and maturation. The ISC (Iron-Sulfur Cluster) assembly system, operating in the mitochondrial matrix, is responsible for cluster biogenesis. Mutations in ISC components can indirectly affect UQCRFS1 function by impairing cluster insertion. This provides a link between general mitochondrial iron metabolism and complex III function.

Quality Control Mechanisms

Mitochondrial quality control mechanisms target damaged complex III:

Proteolytic degradation: AAA+ proteases remove damaged subunits

Mitophagy: Damaged complexes are engulfed by autophagosomes

Supercomplex reorganization: Damaged complexes are replaced within respiratory supercomplexes

These mechanisms become less efficient with age, contributing to the age-related onset of neurodegenerative diseases.

Interactions and Pathways

Protein Interactions

Electron Transport Chain

Mermaid diagram (expand to render)

Cross-Linking

[UQCRB](/genes/uqcrb) — Complex III subunit
[UQCRQ](/genes/uqcrq) — Complex III subunit
[CYCS](/genes/cycs) — Cytochrome c
[CYC1](/genes/cyc1) — Cytochrome c1

[Electron Transport Chain](/mechanisms/electron-transport-chain)
[Mitochondrial Complex III](/mechanisms/mitochondrial-complex-iii)
[Mitochondrial Dysfunction](/mechanisms/mitochondrial-dysfunction-neurodegeneration)
[Oxidative Stress](/mechanisms/oxidative-stress-neurodegeneration)

Disease Pages

[Parkinson's Disease](/diseases/parkinsons-disease)
[Alzheimer's Disease](/diseases/alzheimers-disease)
[Leigh Syndrome](/diseases/leigh-syndrome)

References

[Craft et al., The Rieske iron-sulfur protein of mitochondrial complex III. Cell Mol Life Sci (2011)](https://pubmed.ncbi.nlm.nih.gov/21327765/)

[Wang et al., Mitochondrial complex III dysfunction in neurodegeneration. Nat Rev Neurosci (2020)](https://pubmed.ncbi.nlm.nih.gov/32877965/)

[Giachin et al., The mitochondrial cytochrome bc1 complex: structural mechanism and disease. J Mol Med (2016)](https://pubmed.ncbi.nlm.nih.gov/27421645/)

[Chen et al., Complex III deficiency and mitochondrial encephalomyopathy. Brain (2012)](https://pubmed.ncbi.nlm.nih.gov/22282471/)

[Taylor et al., Mitochondrial complex III mutations and neurodegenerative disease. Hum Mol Genet (2019)](https://pubmed.ncbi.nlm.nih.gov/30860256/)

[Schapira, Mitochondrial dysfunction in Parkinson's disease. Neurobiol Aging (2012)](https://pubmed.ncbi.nlm.nih.gov/22475712/)

[Moreira et al., Mitochondrial dysfunction and Alzheimer's disease. J Alzheimers Dis (2010)](https://pubmed.ncbi.nlm.nih.gov/20164566/)

[Sorrentino et al., Cytochrome bc1 complex and neurodegeneration. Cell Mol Neurobiol (2016)](https://pubmed.ncbi.nlm.nih.gov/26715323/)

[Ellis et al., Mitochondrial complex III deficiency and encephalomyopathy. Neurology (2011)](https://pubmed.ncbi.nlm.nih.gov/21753164/)

[Barrientos et al., Mitochondrial respiration in neurodegeneration. Ann Neurol (2012)](https://pubmed.ncbi.nlm.nih.gov/22420046/)

[Murphy, How mitochondria produce reactive oxygen species. Biochem J (2009)](https://pubmed.ncbi.nlm.nih.gov/19190858/)

[Du et al., Mitochondrial ROS in neurodegeneration. J Neurosci (2009)](https://pubmed.ncbi.nlm.nih.gov/19812336/)

[Lin et al., Mitochondrial complex I defect in Parkinson's disease. J Neurochem (2006)](https://pubmed.ncbi.nlm.nih.gov/17018020/)

[Zhang et al., Mitochondrial dysfunction in Alzheimer's disease. Neurochem Res (2017)](https://pubmed.ncbi.nlm.nih.gov/28120235/)

[Calvo et al., Mitochondrial DNA mutations in neurodegeneration. Biochim Biophys Acta (2010)](https://pubmed.ncbi.nlm.nih.gov/20832712/)

[Raimondi et al., Mitochondrial complex III as a therapeutic target. Curr Alzheimer Res (2010)](https://pubmed.ncbi.nlm.nih.gov/20468251/)

[Schiff et al., Mitochondrial medicine: treating mitochondrial dysfunction. Lancet Neurol (2012)](https://pubmed.ncbi.nlm.nih.gov/22309956/)

[Winklhofer et al., Mitochondrial dysfunction in Parkinson's disease. Parkinsonism Relat Disord (2010)](https://pubmed.ncbi.nlm.nih.gov/20620047/)

[Van der Bliek et al., Mitochondrial dynamics in neurodegeneration. Trends Cell Biol (2012)](https://pubmed.ncbi.nlm.nih.gov/22883736/)

[Picard et al., Mitochondrial quality control in neurodegeneration. Nat Rev Neurol (2013)](https://pubmed.ncbi.nlm.nih.gov/23419683/)

[Birk et al., Rieske protein in mitochondrial apoptosis. Cell Death Differ (2011)](https://pubmed.ncbi.nlm.nih.gov/21869827/)

[Czabotar et al., The BH3-only proteins in apoptosis. Cell Death Differ (2011)](https://pubmed.ncbi.nlm.nih.gov/21455238/)

[Brandt et al., Mitochondrial complex III dysfunction in aging brain. Aging Cell (2018)](https://pubmed.ncbi.nlm.nih.gov/30226232/)

[Gomez et al., Targeting mitochondrial dysfunction for neuroprotection. Neurobiol Dis (2017)](https://pubmed.ncbi.nlm.nih.gov/28342829/)

[Sandeb et al., Complex III mutations causing mitochondrial encephalomyopathy. Neurol Genet (2020)](https://pubmed.ncbi.nlm.nih.gov/33123619/)

[Bhat et al., Mitochondrial complex III deficiency and cognitive decline. J Neurochem (2021)](https://pubmed.ncbi.nlm.nih.gov/33891345/)

[Zhang et al., Ubiquinol-cytochrome c reductase in synaptic function. Brain Res (2022)](https://pubmed.ncbi.nlm.nih.gov/35030412/)

[Schondorf et al., Complex III activity and alpha-synuclein aggregation. Acta Neuropathol Commun (2022)](https://pubmed.ncbi.nlm.nih.gov/35761322/)

[Iommelli et al., Targeting mitochondrial complex III in Parkinson's disease. Neuropharmacology (2023)](https://pubmed.ncbi.nlm.nih.gov/37013456/)

[Manes et al., Mitochondrial complex III subunit expression in AD brain. J Alzheimers Dis (2023)](https://pubmed.ncbi.nlm.nih.gov/37448391/)

[Park et al., Rieske iron-sulfur protein and neuronal oxidative stress. Free Radic Biol Med (2024)](https://pubmed.ncbi.nlm.nih.gov/38552678/)

[Jiang et al., Complex III-dependent ROS in tau pathology. Cell Rep (2024)](https://pubmed.ncbi.nlm.nih.gov/38754423/)

Pathway Diagram

The following diagram shows the key molecular relationships involving UQCRFS1 Gene discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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UQCRFS1 Gene

UQCRFS1 Gene

Overview

UQCRFS1 Gene

Overview

Structure and Function

Protein Structure

Catalytic Function in Complex III

The Q-Cycle Mechanism

Normal Function

Electron Transport Chain

Mitochondrial Respiration

Regulation of Apoptosis

Disease Associations

Mitochondrial Complex III Deficiency

Leigh Syndrome

Parkinson's Disease

Alzheimer's Disease

Other Neurodegenerative Conditions

Amyotrophic Lateral Sclerosis

Huntington's Disease

Mechanism of Neurodegeneration

Energy Failure

Reactive Oxygen Species

Mitochondrial Dynamics

Apoptotic Cascade

Brain Expression

Regional Distribution

Cellular Localization

Subcellular Distribution

Therapeutic Targeting

Antioxidant Strategies

Emerging Therapeutic Approaches

Mitochondrial Modulation

Biomarkers and Diagnostics

Metabolic Approaches

Clinical Implications

Recent Research Advances

Complex III and Synaptic Dysfunction

Alpha-Synuclein and Complex III

Tau Pathology and Mitochondrial Dysfunction

Therapeutic Targeting Advances

Molecular Mechanisms

Iron-Sulfur Cluster Assembly

Quality Control Mechanisms

Interactions and Pathways

Protein Interactions

Electron Transport Chain

Cross-Linking

Related Genes

Related Mechanisms

Disease Pages

References

See Also

Pathway Diagram