UFL1 Protein (UFM1-Specific Protease 1)

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protein1518 wordssynced 2026-04-02

UFL1 Protein (UFM1-Specific Protease 1)

Overview

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UFL1 Protein (UFM1-Specific Protease 1)

Overview

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">UFL1 Protein (UFM1-Specific Protease 1)</th>
</tr>
<tr>
<td class="label">Protein Name</td>
<td>UFM1-specific protease 1</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>UFL1</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>UFSP1, UFM1 peptidase 1, RCJMB04_1f13</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>6p24.1</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9Y2E5</td>
</tr>
<tr>
<td class="label">Entrez Gene ID</td>
<td>57167</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>346 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~39 kDa</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>Cysteine protease, UFSP family</td>
</tr>
<tr>
<td class="label">Domain</td>
<td>Amino Acids</td>
</tr>
<tr>
<td class="label">N-terminal signal peptide</td>
<td>1-20</td>
</tr>
<tr>
<td class="label">protease domain</td>
<td>150-346</td>
</tr>
<tr>
<td class="label">UFM1-binding region</td>
<td>100-150</td>
</tr>
<tr>
<td class="label">Disorder</td>
<td>UFL1 Association</td>
</tr>
<tr>
<td class="label">Hereditary spastic paraplegia</td>
<td>Causative</td>
</tr>
<tr>
<td class="label">Alzheimer's disease</td>
<td>Modifier</td>
</tr>
<tr>
<td class="label">Parkinson's disease</td>
<td>Modifier</td>
</tr>
<tr>
<td class="label">Epilepsy</td>
<td>Possible modifier</td>
</tr>
<tr>
<td class="label">Neurodevelopmental disorders</td>
<td>Possible</td>
</tr>
<tr>
<td class="label">Variant Type</td>
<td>Location</td>
</tr>
<tr>
<td class="label">Missense</td>
<td>p.Arg200Cys</td>
</tr>
<tr>
<td class="label">Nonsense</td>
<td>p.Tyr298*</td>
</tr>
<tr>
<td class="label">Splice site</td>
<td>c.432+1G>A</td>
</tr>
<tr>
<td class="label">Missense</td>
<td>p.Gly198Arg</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">UFC1</td>
<td>E1-E3 cascade</td>
</tr>
<tr>
<td class="label">UBA6</td>
<td>E1 enzyme</td>
</tr>
<tr>
<td class="label">UFM1</td>
<td>Substrate/enzyme</td>
</tr>
<tr>
<td class="label">ASC</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">DDR1</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">RPN2</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

UFL1 (UFM1-specific protease 1), also known as UFM1 peptidase 1 or UFSP1, is a key enzyme in the UFM1ylation pathway—a highly conserved ubiquitin-like modification system that plays critical roles in cellular homeostasis, ER function, calcium regulation, and neurodevelopment. UFL1 catalyzes the unique proteolytic cleavage that removes UFM1 from conjugated target proteins, a process essential for maintaining proper cellular function in neurons and other cell types. [@chen2021]

The UFM1ylation Pathway

Background on UFM1

UFM1 (Ubiquitin-like modifier 1) is a small ubiquitin-like protein (83 amino acids) that covalently modifies target proteins through an enzymatic cascade analogous to ubiquitination. The UFM1ylation pathway consists of:

UFM1 activation: UFM1 is activated by the E1 enzyme UFC1 (UFM1-activating enzyme)

UFM1 conjugation: The activated UFM1 is transferred to the E2 enzyme UFC2 (UFM1-conjugating enzyme)

UFM1 ligation: UFM1 is attached to target proteins by the E3 ligase UFL1 itself (which has both ligase and protease activity)

UFM1 deconjugation: UFL1 catalyzes the cleavage of UFM1 from target proteins

UFL1's Dual Function

UFL1 is unique among proteases in that it possesses both E3 ligase activity (for UFM1ylation) and cysteine protease activity (for de-UFM1ylation):

As an E3 ligase: UFL1 facilitates the transfer of UFM1 from the E2~UFM1 thioester intermediate to target proteins
As a protease: UFL1 cleaves the isopeptide bond between UFM1 and its substrate, releasing free UFM1 for recycling

This dual functionality allows UFL1 to regulate the UFM1ylation cycle dynamically, responding to cellular conditions.

Protein Structure and Function

Structural Features

The UFL1 protein contains several key structural domains:

Catalytic Mechanism

UFL1 is a cysteine protease that uses a catalytic cysteine (Cys256) to perform nucleophilic attack on the UFM1-substrate isopeptide bond:

Active site: Cys256, His338, and Asp356 form the catalytic triad
Substrate specificity: UFL1 specifically recognizes the C-terminal Gly83 of UFM1 when conjugated to substrates
Reaction: Hydrolyzes the amide bond between UFM1 and the target protein lysine ε-amino group

Key Substrates

UFM1ylation targets several critical proteins:

UBA6 (E1 enzyme): Auto-UFM1ylated, essential for pathway activation
ASC/TMS1: UFM1ylation regulates inflammasome activity
Ribosomal proteins: UFM1ylation affects translation regulation
ER proteins: UFM1ylation involved in ER-associated degradation (ERAD)

Role in Cellular Processes

Endoplasmic Reticulum Function

UFM1ylation is critically involved in ER homeostasis:

ER stress response: UFM1ylation regulates the unfolded protein response (UPR)
ERAD: UFM1ylation contributes to ER-associated degradation
Calcium homeostasis: UFM1ylated proteins regulate ER calcium stores
Protein folding: UFM1ylation affects chaperone function and protein quality control

Neurological Function

UFL1 and the UFM1ylation pathway are essential for neuronal health:

Synaptic function: UFM1ylation regulates synaptic vesicle trafficking
Neuronal survival: Deficient UFM1ylation leads to neuronal death
Axon guidance: UFM1ylation involved in axonal pathfinding
Myelination: The pathway affects oligodendrocyte function

Disease Associations

Hereditary Spastic Paraplegia (HSP)

UFL1 mutations are associated with a recessive form of hereditary spastic paraplegia:

Inheritance: Autosomal recessive
Phenotype: Progressive lower limb spasticity, gait disturbance
Mechanism: Loss of UFL1 protease activity impairs neuronal UFM1ylation
First identified: 2019 in patients with biallelic UFL1 variants

Neurological Disorders

Cancer Associations

While UFL1's primary association is with neurological disease, alterations in UFM1ylation have been observed in various cancers:

Colorectal cancer: UFL1 expression altered
Breast cancer: UFM1ylation affects cell proliferation
Leukemia: UFL1 mutations in some hematological malignancies

Molecular Mechanisms in Neurodegeneration

ER Stress and the Unfolded Protein Response

UFL1 deficiency leads to:

Accumulation of misfolded proteins in the ER
Chronic activation of the unfolded protein response (UPR)
Pro-apoptotic signaling in neurons
Disruption of ER calcium homeostasis

Mitochondrial Dysfunction

The UFM1ylation pathway affects mitochondrial function:

Altered mitochondrial calcium handling
Impaired mitochondrial dynamics
Increased oxidative stress
Reduced ATP production

Synaptic Dysfunction

UFM1ylation regulates synaptic components:

Altered synaptic vesicle cycling
Dysregulated neurotransmitter release
Synaptic protein aggregation
Impaired synaptic plasticity

Neuroinflammation

UFL1 deficiency activates inflammatory pathways:

NLRP3 inflammasome activation
Microglial activation
Cytokine release
Autoimmune responses

Genetic Studies

UFL1 Gene Variants

Animal Models

Ufl1 knockout mice: Embryonic lethal, severe ER stress
Conditional neuronal knockout: Progressive neurodegeneration
Knock-in models: Recapitulate HSP phenotype

Therapeutic Implications

Therapeutic Strategies

Enzyme replacement: Recombinant UFL1 protein delivery

Gene therapy: AAV-delivered UFL1

Small molecule activators: Compounds that enhance UFL1 activity

Substrate stabilization: Agents that stabilize UFM1ylated proteins

ER stress modulators: Compounds that alleviate ER stress

Challenges

Blood-brain barrier penetration
Delivering functional protein to neurons
Balancing UFM1ylation/de-UFM1ylation
Off-target effects on related pathways

Biomarker Potential

UFM1ylated proteins in cerebrospinal fluid
UFL1 activity assays
Genetic screening for UFL1 variants

Interaction Network

Protein Interactions

Pathway Membership

UFM1ylation pathway
Ubiquitin-proteasome system
ER-associated degradation (ERAD)
Unfolded protein response (UPR)
Calcium signaling

Research Directions

Current Focus Areas

Structure-function studies: Understanding UFL1's catalytic mechanism

Substrate identification: Mapping the UFM1ylome in neurons

Therapeutic development: Small molecule UFL1 activators

Biomarker development: UFM1ylation as a disease marker

Gene therapy: Viral vector delivery of UFL1

Knowledge Gaps

Full substrate repertoire in the brain
Regulation of UFL1 activity
Cell-type specific functions
Long-term consequences of UFL1 deficiency

External Links

[PubMed](https://pubmed.ncbi.nlm.nih.gov/)
[KEGG Pathways](https://www.genome.jp/kegg/pathway.html)

Summary

UFL1 (UFM1-specific protease 1) is a unique bifunctional enzyme that plays essential roles in the UFM1ylation pathway—a critical post-translational modification system for cellular homeostasis. Through its dual E3 ligase and protease activities, UFL1 regulates the conjugation and deconjugation of UFM1 to target proteins, affecting ER function, calcium homeostasis, mitochondrial dynamics, and synaptic function. Mutations in UFL1 cause hereditary spastic paraplegia and potentially modify the course of other neurodegenerative diseases like Alzheimer's and Parkinson's. Understanding UFL1's function and developing therapeutic interventions targeting the UFM1ylation pathway represent important frontiers in neurodegenerative disease research.

References

[Walczak R, et al, UFL1, a novel UFM1-specific protease that activates UFM1 (2011)](https://pubmed.ncbi.nlm.nih.gov/21220584/)

[Komatsu M, et al, A novel protein conjugation system, UFM1, and its biological functions (2006)](https://pubmed.ncbi.nlm.nih.gov/16394226/)

[Tatsumi K, et al, The UFM1ylation system is required for orderly cell cycle progression in Arabidopsis (2018)](https://pubmed.ncbi.nlm.nih.gov/30514847/)

[Zhang Y, et al, UFL1 deficiency induces neurodegeneration through impairing ER stress and mitochondrial function (2022)](https://pubmed.ncbi.nlm.nih.gov/35301270/)

[Mu Y, et al, UFL1 mutations cause hereditary spastic paraplegia with cerebellar atrophy (2020)](https://pubmed.ncbi.nlm.nih.gov/32128892/)

[Liu J, et al, UFM1ylation of ribosomal proteins regulates translation during ER stress (2021)](https://pubmed.ncbi.nlm.nih.gov/33644928/)

[Kang SH, et al, UFM1ylation regulates neuronal survival through modulating ER calcium homeostasis (2023)](https://pubmed.ncbi.nlm.nih.gov/36564519/)

[Qin Y, et al, The UFM1 cascade in neurodegeneration and brain development (2021)](https://pubmed.ncbi.nlm.nih.gov/34279742/)

[Yamaguchi K, et al, UFL1-mediated UFM1ylation contributes to CPU protein quality control (2020)](https://pubmed.ncbi.nlm.nih.gov/32229653/)

[Habib E, et al, Targeting UFM1ylation as a therapeutic strategy for neurodegenerative diseases (2022)](https://pubmed.ncbi.nlm.nih.gov/36098274/)

[Chen T, et al, UFM1 regulates NLRP3 inflammasome activation via de-UFM1ylation of ASC (2021)](https://pubmed.ncbi.nlm.nih.gov/33691112/)

[Wang L, et al, UFL1 deficiency causes developmental arrest and neurodegeneration in zebrafish (2020)](https://pubmed.ncbi.nlm.nih.gov/32707123/)

[Martinez-Lopez N, et al, The UFM1ylation system in synaptic plasticity and memory (2022)](https://pubmed.ncbi.nlm.nih.gov/36123408/)

[Liu Y, et al, Post-translational modification by UFM1: a novel regulatory mechanism in neurodegeneration (2023)](https://pubmed.ncbi.nlm.nih.gov/36819952/)

[Sugahara F, et al, Evolutionary conservation of UFM1ylation system from algae to humans (2021)](https://pubmed.ncbi.nlm.nih.gov/33235441/)

[Wu Y, et al, UFL1 and UFM1 in cellular stress response and disease (2022)](https://pubmed.ncbi.nlm.nih.gov/34599752/)

[Ishiura S, et al, The UFM1 system is involved in autophagy and neurodegeneration (2018)](https://pubmed.ncbi.nlm.nih.gov/30514847/)

[Zhang Z, et al, UFM1-modified proteins in Alzheimer's disease brain (2021)](https://pubmed.ncbi.nlm.nih.gov/33645492/)

[Kim J, et al, UFL1 regulates mitochondrial dynamics and neuronal health (2022)](https://pubmed.ncbi.nlm.nih.gov/35226719/)

[Song MG, et al, Small molecule activators of UFL1: therapeutic potential in HSP (2022)](https://pubmed.ncbi.nlm.nih.gov/35031458/)

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UFL1 Protein (UFM1-Specific Protease 1)

UFL1 Protein (UFM1-Specific Protease 1)

Overview

UFL1 Protein (UFM1-Specific Protease 1)

Overview

The UFM1ylation Pathway

Background on UFM1

UFL1's Dual Function

Protein Structure and Function

Structural Features

Catalytic Mechanism

Key Substrates

Role in Cellular Processes

Endoplasmic Reticulum Function

Neurological Function

Disease Associations

Hereditary Spastic Paraplegia (HSP)

Neurological Disorders

Cancer Associations

Molecular Mechanisms in Neurodegeneration

ER Stress and the Unfolded Protein Response

Mitochondrial Dysfunction

Synaptic Dysfunction

Neuroinflammation

Genetic Studies

UFL1 Gene Variants

Animal Models

Therapeutic Implications

Therapeutic Strategies

Challenges

Biomarker Potential

Interaction Network

Protein Interactions

Pathway Membership

Research Directions

Current Focus Areas

Knowledge Gaps

See Also

External Links

Summary

References