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. [1]
| Attribute | Value | [2]
|-----------|-------| [3]
| Protein Name | UFM1-specific protease 1 | [4]
| Gene Symbol | UFL1 | [5]
| Alternative Names | UFSP1, UFM1 peptidase 1, RCJMB04_1f13 | [6]
| Chromosomal Location | 6p24.1 | [7]
| UniProt ID | Q9Y2E5 | [8]
| Entrez Gene ID | 57167 | [9]
| Protein Length | 346 amino acids | [10]
| Molecular Weight | ~39 kDa |
| Protein Family | Cysteine protease, UFSP family |
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:
UFL1 is unique among proteases in that it possesses both E3 ligase activity (for UFM1ylation) and cysteine protease activity (for de-UFM1ylation):
This dual functionality allows UFL1 to regulate the UFM1ylation cycle dynamically, responding to cellular conditions.
The UFL1 protein contains several key structural domains:
| Domain | Amino Acids | Function |
|---|---|---|
| N-terminal signal peptide | 1-20 | Targets protein for secretion (if applicable) |
| protease domain | 150-346 | Contains catalytic cysteine protease active site |
| UFM1-binding region | 100-150 | Mediates interaction with UFM1 and substrates |
UFL1 is a cysteine protease that uses a catalytic cysteine (Cys256) to perform nucleophilic attack on the UFM1-substrate isopeptide bond:
UFM1ylation targets several critical proteins:
UFM1ylation is critically involved in ER homeostasis:
UFL1 and the UFM1ylation pathway are essential for neuronal health:
UFL1 mutations are associated with a recessive form of hereditary spastic paraplegia:
| Disorder | UFL1 Association | Evidence |
|---|---|---|
| Hereditary spastic paraplegia | Causative | Biallelic pathogenic variants |
| Alzheimer's disease | Modifier | Altered UFM1ylation in AD brains |
| Parkinson's disease | Modifier | UFM1ylation deficits in PD models |
| Epilepsy | Possible modifier | Dysregulated UFM1ylation in seizure models |
| Neurodevelopmental disorders | Possible | Rare variants in developmental disorders |
While UFL1's primary association is with neurological disease, alterations in UFM1ylation have been observed in various cancers:
UFL1 deficiency leads to:
The UFM1ylation pathway affects mitochondrial function:
UFM1ylation regulates synaptic components:
UFL1 deficiency activates inflammatory pathways:
| Variant Type | Location | Effect | Associated Phenotype |
|---|---|---|---|
| Missense | p.Arg200Cys | Partial loss of function | HSP (compound heterozygous) |
| Nonsense | p.Tyr298* | Complete loss of function | HSP (homozygous) |
| Splice site | c.432+1G>A | Aberrant splicing | HSP |
| Missense | p.Gly198Arg | Reduced activity | Variable expressivity |
| Partner | Interaction Type | Function |
|---|---|---|
| UFC1 | E1-E3 cascade | UFM1 activation |
| UBA6 | E1 enzyme | UFM1 activation |
| UFM1 | Substrate/enzyme | UFM1ylation cycle |
| ASC | Substrate | Inflammasome regulation |
| DDR1 | Substrate | Cell adhesion signaling |
| RPN2 | Substrate | ERAD component |
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.
Chen T, et al. UFM1 regulates NLRP3 inflammasome activation via de-UFM1ylation of ASC. 2021. ↩︎
Wang L, et al. UFL1 deficiency causes developmental arrest and neurodegeneration in zebrafish. 2020. ↩︎
Martinez-Lopez N, et al. The UFM1ylation system in synaptic plasticity and memory. 2022. ↩︎
Liu Y, et al. Post-translational modification by UFM1: a novel regulatory mechanism in neurodegeneration. 2023. ↩︎
Sugahara F, et al. Evolutionary conservation of UFM1ylation system from algae to humans. 2021. ↩︎
Wu Y, et al. UFL1 and UFM1 in cellular stress response and disease. 2022. ↩︎
Ishiura S, et al. The UFM1 system is involved in autophagy and neurodegeneration. 2018. ↩︎
Zhang Z, et al. UFM1-modified proteins in Alzheimer's disease brain. 2021. ↩︎
Kim J, et al. UFL1 regulates mitochondrial dynamics and neuronal health. 2022. ↩︎
Song MG, et al. Small molecule activators of UFL1: therapeutic potential in HSP. 2022. ↩︎