LYRM7 (LYR Motif Containing 7) is a nuclear-encoded mitochondrial protein that plays a critical role in the assembly and stability of mitochondrial complex III (cytochrome bc1 complex). The protein contains an LYR motif (Leucine-Tyrosine-Arginine) that facilitates interaction with other mitochondrial proteins and is essential for proper electron transport chain function.
| Property |
Value |
| Gene Symbol |
LYRM7 |
| Full Name |
LYR Motif Containing 7 |
| Chromosomal Location |
5q31.1 |
| NCBI Gene ID |
57103 |
| OMIM |
615826 |
| Ensembl ID |
ENSG00000164022 |
| UniProt ID |
Q8N5S0 |
| Protein Class |
Mitochondrial assembly factor |
| Tissue Expression |
High in brain, heart, muscle |
¶ Structure and Function
LYRM7 (~300 amino acids) is a mitochondrial matrix protein:
- N-terminal mitochondrial targeting sequence: Cleaved after import
- LYR domain: Conserved motif for protein-protein interactions
- C-terminal region: Interacts with complex III subunits
- Tetramer formation: Functions as a multimeric complex
The LYR motif is shared with other LYRM family members and mediates binding to acyl carrier proteins and other mitochondrial factors.
LYRM7 is essential for proper complex III assembly:
- Early assembly: Associates with nascent complex III subunits
- Iron-sulfur cluster delivery: Facilitates incorporation of UQCRFS1 (RISP)
- Quality control: Ensures proper subunit incorporation
- Stabilization: Maintains complex III integrity
LYRM7 directly interacts with:
- UQCRFS1 (Rieske iron-sulfur protein)
- UQCRB (core subunit)
- Other bc1 complex components
In healthy mitochondria, LYRM7 supports:
- Complex III assembly: Essential for bc1 complex formation
- Electron transfer: Supports Q-cycle function
- Proton gradient: Contributes to ATP synthesis
- ROS regulation: Controls electron leak
In neurons, LYRM7 supports:
- Oxidative phosphorylation: Primary ATP production
- Synaptic function: High energy demands
- Calcium handling: Mitochondrial calcium balance
- Axonal maintenance: Energy-intensive processes
Mutations in LYRM7 cause complex III deficiency:
- Encephalomyopathy: Brain and muscle involvement
- Growth failure: Developmental impairment
- Lactic acidosis: Metabolic dysfunction
- Neurological regression: Progressive symptoms
- MELAS syndrome: Complex III involvement
- Leigh syndrome: Progressive encephalopathy
- Mitochondrial DNA depletion: Combined deficiencies
Complex III dysfunction contributes to:
-
Alzheimer's Disease
- Complex III activity reduced in AD brain
- Electron transport impairment
- Increased ROS production
- Amyloid-β interaction with mitochondria
-
Parkinson's Disease
- Complex III compensatory changes
- ROS overproduction
- Dopaminergic neuron vulnerability
-
Aging
- Declining complex III function
- Accumulated mtDNA mutations
- Reduced mitochondrial quality control
Impaired complex III leads to:
- ATP depletion: Reduced oxidative phosphorylation
- NAD⁺ loss: Impaired metabolic function
- Synaptic failure: Energy-dependent processes cease
- Neuronal death: Energy crisis triggers apoptosis
Complex III is a major ROS source:
- Electron leak: At Qo site during Q-cycle
- Superoxide production: O₂⁻ generation
- DNA damage: Oxidative lesions accumulate
- Protein oxidation: Aggregation and dysfunction
- Fission/fusion imbalance: Altered morphology
- Mitophagy defects: Impaired clearance
- mtDNA mutations: Accumulate with age
| Brain Region |
Expression Level |
| Cerebral Cortex |
High |
| Hippocampus |
High |
| Cerebellum |
High |
| Substantia Nigra |
Moderate-High |
| Basal Ganglia |
Moderate |
- Neurons: High expression
- Astrocytes: Moderate expression
- Oligodendrocytes: High (ATP-dependent)
- Microglia: Lower expression
- Coenzyme Q10: Electron carrier supplementation
- MitoQ: Mitochondria-targeted antioxidant
- Idebenone: Complex III protectant
- Functional LYRM7 delivery: Viral vector approaches
- CRISPR correction: Future therapeutic avenue
- NAD⁺ precursors: Support mitochondrial function
- Alpha-ketoglutarate: Metabolic intermediate
- Pyruvate: Energy substrate
¶ Interactions and Pathways
| Partner |
Function |
| UQCRFS1 |
Complex III core subunit |
| UQCRB |
Complex III subunit |
| UQCRQ |
Complex III subunit |
| Mitochondrial LYRM proteins |
Assembly factors |
graph TD
A["LYRM7"] --> B["Complex III Assembly"]
B --> C["Electron Transport"]
C --> D["ATP Synthesis"]
C --> E["ROS Production"]
D --> F["Neuronal Function"]
E --> G["Oxidative Stress"]
G --> H["Neurodegeneration"]
- UQCRFS1 — Complex III core subunit
- UQCRB — Complex III subunit
- UQCRQ — Complex III subunit