Small Ubiquitin-like Modifier Research Articles

Probing Aromatic Side Chains Reveals the Site-Specific Melting in the SUMO1 Molten Globule.

The conventional idea that a well-defined protein structure governs its functions is being challenged by the evolving significance of conformational flexibility and disorder in influencing protein activity. Here, we focus on the Small Ubiquitin-like MOdifier 1 (SUMO1) protein, a post-translational modifier, which binds various target proteins during the process of SUMOylation. We present evidence supporting the presence of both folded and "ordered" molten globule (MG) states in SUMO1 under physiological conditions. We investigate the MG state using a combination of near-UV and far-UV circular dichroism (CD) experiments. Moreover, we dissect the information from the near-UV CD data to gain specific insights about the MG intermediate. This is achieved by mutating specific aromatic amino acids, particularly creating a single-tyrosine mutant S1Y51 (by introducing Y21F and Y91F mutations) and a tryptophan mutant S1F66W. Spectroscopic studies of the mutants as a function of temperature revealed multiple insights. The transition from the folded to the MG state involves a site-specific loss of tertiary packing near Y51 but the region surrounding F66 retained most of its tertiary contacts, suggesting an ordered MG structure. We further demonstrate the increased solvent exposure of Y51 in the MG state by using time-resolved fluorescence and steady-state quenching experiments. The observed conformational flexibility and solvent accessibility, particularly around Y51 that is known to be involved in binding the cognate ligands such as PIASX and its peptide analogues, have biological and functional implications in mediating protein-protein interactions during the SUMOylation process.

Deletion of MAPL ameliorates septic cardiomyopathy by mitigating mitochondrial dysfunction.

Mitochondrial dysfunction is a critical factor in the pathogenesis of septic cardiomyopathy (SCM). Mitochondrial anchored protein ligase (MAPL), a small ubiquitin-like modifier (SUMO) E3 ligase, plays a significant role in mitochondrial function. However, the role of MAPL in SCM remains unclear. To investigate the role of MAPL in SCM, cardiomyocyte-specific MAPL knockout mice were generated. A cecal ligation and puncture (CLP) procedure was employed to induce a sepsis-like condition. The expression of MAPL in heart tissues and H9C2 cardiomyocytes was elevated following CLP challenge or lipopolysaccharide (LPS) stimulation. MAPL deficiency ameliorated CLP-induced cardiac injury, dysfunction, and inflammation, and also improved the survival rate of mice following CLP operation. Additionally, MAPL deficiency or knockdown inhibited LPS-induced cardiomyocyte apoptosis, improved mitochondrial structural abnormalities, and increased ATP production. Furthermore, MAPL knockdown mitigated LPS-induced reductions in mitochondrial membrane potential (MMP) and intracellular reactive oxygen species (ROS) production. Mechanistically, the expression of dynamin-related protein 1 (drp1) in the mitochondria of heart tissues or H9C2 cardiomyocytes was elevated under septic conditions. Accordingly, the SUMOylation of drp1 in heart tissues or H9C2 cardiomyocytes was increased under sepsis conditions, which was reduced by MAPL knockout or knockdown. Our results reveal that MAPL promotes cardiac injury/dysfunction and inflammation in SCM. Deficiency or knockdown of MAPL alleviates SCM by reducing drp1 SUMOylation as well as drp1-mediated mitochondrial dysfunction. These findings suggest that targeting MAPL may represent a therapeutic strategy for patients with SCM.

Tissue adaptation to metabolic stress: insights from SUMOylation

Post-translational modification (PTM) plays a crucial role in adaptation of mammals to environmental changes, enabling them to survive in stressful situations. One such PTM is SUMO modification, which is evolutionarily conserved. It involves the covalent and reversible attachment of a small ubiquitin-like modifier (SUMO) to lysine (Lys) residues in the target protein. SUMOylation regulates various functions, including cell proliferation, differentiation, apoptosis, senescence, and maintenance of specific cellular activities. It achieves this by influencing protein-protein interactions, subcellular localization, protein stability, and DNA binding activity. Mounting evidence suggests that SUMOylation is implicated in the pathogenesis of metabolic disorders such as obesity, insulin resistance, and fatty liver. This review aims to provide an overview of the role of SUMOylation in regulating tissue adaptation to metabolic stress. Recent advancements in spectroscopic techniques have shed light on potential targets of SUMOylation and the underlying regulatory mechanisms have been elucidated, laying the theoretical foundation for the development of targeted SUMOylation interventions for metabolic syndrome while minimizing side effects.

SUMO regulation of ion channels in health and disease.

The Small Ubiquitin-like Modifier (SUMO) protein pathway governs a panoply of vital biological processes ranging from cell death, proliferation, differentiation, metabolism, and signal transduction by diversifying the functions, half-lives, and partnerships of target proteins in situ. More recently, SUMOylation has emerged as a key regulator of ion homeostasis and excitability across multiple tissues due to regulation of a plethora of ion channels expressed in a range of tissues subtypes. Altogether, the balance of SUMOylation states amongst relevant ion channels can result in graded biophysical effects that tune excitability and contribute to a range of disease states including cardiac arrythmia, epilepsy, pain transmission, and inflammation. Here, we consolidate these concepts by focusing on the role of ion channel SUMOylation in the central nervous system, peripheral nervous system and the cardiovascular system. In addition, we review what is known about the enigmatic factors that regulate the SUMO pathway and consider the emerging role of small molecule SUMO-modulators as potential therapeutics in a range of diseases.

SENP3 knockdown improves motor and cognitive impairments in the intranasal MPTP rodent model of Parkinson's disease

Several mechanisms underlying Parkinson's disease (PD) remain unclear, and effective treatments are still lacking. The conjugation of the small ubiquitin-like modifier (SUMO), known as SUMOylation, to key proteins in PD has shown potential beneficial effects. Considering that this process is reversed by SUMO-specific proteases (SENPs), this study addressed the effects of increased SUMO-2/3 conjugation, mediated by SENP3 knockdown, in the intranasal 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) rodent model of PD. Two weeks after infusion of the shRNA-containing lentiviral vector into the dorsolateral striatum and one week following intranasal MPTP administration, male Wistar rats were evaluated using cognitive and motor behavioural tests. Infection efficiency was confirmed by detecting GFP expression in the dorsolateral striatum. SENP3 knockdown, verified by Western blotting, resulted in increased SUMO-2/3 conjugation. MPTP-administered rats displayed impairments in both recognition and spatial memories, while SENP3 knockdown prevented these deficits. Rats exposed to MPTP also exhibited motor dysfunction, which was ameliorated by SENP3 knockdown. These findings underscore the involvement of SUMO-2/3 conjugation in PD and its potential as a novel therapeutic target to counteract cognitive and motor impairments induced by neurodegeneration.

Hippocampal SENP3 mediates chronic stress-induced depression-like behaviors by impairing the CREB-BDNF signaling.

Impaired signaling between cyclic adenosine monophosphate response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in the hippocampus is generally considered to be the cause of depression. The mechanisms underlying the impairment of CREB-BDNF signaling under stress conditions are largely unclear. Small ubiquitin-like modifier (SUMO) specific peptidase 3 (SENP3) is a molecule that can regulate SUMOylation of target proteins related to synaptic plasticity. Its dynamic changes have been reported to be associated with neuronal damage in various models of central nervous disorders such as cerebral ischemia and traumatic brain injury. However, its role in depression is completely unknown. This problem was addressed in the present study. Our results showed that chronic unpredictable stress (CUS) triggered a specific increase in SENP3 expression in the hippocampus of non-stressed mice. Overexpression of SENP3 in the hippocampus of non-stressed mice elicited depression-like behaviors in the tail suspension test, forced swimming test, and sucrose preference test, accompanied by impairment of the CREB-BDNF signaling cascade in the hippocampus. Conversely, genetic silencing of SENP3 in the hippocampus suppressed the development of depression-like behaviors. Furthermore, infusion of SENP3-shRNA into the hippocampus failed to suppress CUS-induced depression-like behaviors when mice received genetic silencing CREB or BDNF in the hippocampus or inhibition of the BDNF receptor by K252a. Taken together, these results suggest that abnormally elevated SENP3 in the hippocampus leads to the development of depression-like behavior by impairing the CREB-BDNF signaling cascade. SENP3 in the hippocampus could be a promising target for the development of new antidepressants.

The SUMO Family: Mechanisms and Implications in Thyroid Cancer Pathogenesis and Therapy.

(1) Background: Small ubiquitin-like modifiers (SUMOs) are pivotal in post-translational modifications, influencing various cellular processes, such as protein localization, stability, and genome integrity. (2) Methods: This review explores the SUMO family, including its isoforms and catalytic cycle, highlighting their significance in regulating key biological functions in thyroid cancer. We discuss the multifaceted roles of SUMOylation in DNA repair mechanisms, protein stability, and the modulation of receptor activities, particularly in the context of thyroid cancer. (3) Results: The aberrant SUMOylation machinery contributes to tumorigenesis through altered gene expression and immune evasion mechanisms. Furthermore, we examine the therapeutic potential of targeting SUMOylation pathways in thyroid cancer treatment, emphasizing the need for further research to develop effective SUMOylation inhibitors. (4) Conclusions: By understanding the intricate roles of SUMOylation in cancer biology, we can pave the way for innovative therapeutic strategies to improve outcomes for patients with advanced tumors.

Platinum Stabilises a Molten-Globule Conformation of a Small Globular Cytosolic Protein SUMO1.

Proteins are generally resistant to large conformational changes under physiological conditions. Here, we show that platinum (Pt(II)), which is widely-used metal centre in cancer therapeutic drugs, binds to a cytosolic protein, small ubiquitin-like modifier 1 (SUMO1), under physiological conditions and changes its conformation to a molten globule (MG). Mass spectrometry (ICP-MS) studies confirmed stoichiometric Pt(II) binding to SUMO1. Fluorescence spectroscopy showed Tyr fluorescence quenching and increased ANS binding. Fluorescence assays on Trp-mutants indicated conformational changes and circular dichroism (CD) suggested MG formation upon Pt(II) binding. In contrast, structural homologues of SUMO1 (ubiquitin (Ubq) and SUMO2) showed no conformational changes on Pt(II) titration. Further studies compared the impact of distinct His residues in SUMO1 on Pt(II) binding and protein structure to SUMO2 and Ubq. Experiments at low pH (5.0) implicated His residues interacting with Pt(II), corroborated by the absence of conformational change in the H75L mutant of SUMO1. Pt(II)-His binding in SUMO1 unravels key molecular determinants of Pt(II)-protein interactions and their conformational consequences. SUMO1 with other SUMOylation components are shown to have enhanced expression in several cancers, hence, our study suggests a possible fate of the non-targetability of Pt(II)-based drugs on SUMOylation in cancer cells, upon interaction with SUMO1.

SUMO: A new perspective to decipher fibrosis.

Fibrosis is characterized by excessive extracellular matrix (ECM) deposition resulting from dysregulated wound healing and connective tissue repair mechanisms. Excessive accumulation of ECM leads to fibrous tissue formation, impairing organ function and driving the progression of various fibrotic diseases. Recently, the role of small ubiquitin-like modifiers (SUMO) in fibrotic diseases has attracted significant attention. SUMO-mediated SUMOylation, a highly conserved posttranslational modification, participates in a variety of biological processes, including nuclear-cytosolic transport, cell cycle progression, DNA damage repair, and cellular metabolism. Conversely, SUMO-specific proteases cleave the isopeptide bond of SUMO conjugates, thereby regulating the deSUMOylation process. Mounting evidence indicates that SUMOylation and deSUMOylation regulate the functions of several proteins, such as Smad3, NF-κB, and promyelocytic leukemia protein, which are implicated in fibrotic diseases like liver fibrosis, myocardial fibrosis, and pulmonary fibrosis. This review summarizes the role of SUMO in fibrosis-related pathways and explores its pathological relevance in various fibrotic diseases. All evidence suggest that the SUMO pathway is important targets for the development of treatments for fibrotic diseases.

Transcriptome Profile and Gene Expression During Different Ovarian Maturation Stages of Macrobrachium rosenbergii (De Man, 1879).

Macrobrachium rosenbergii, or giant river prawn, is the most economically crucial cultured freshwater crustacean. A predominant challenge in developing crustacean aquaculture is reproduction management, particularly ovary maturation, where identifying regulative mechanisms at the molecular level is critical. Ovary is the primary tissue for studying gene and protein expressions involved in crustacean growth and reproduction. Despite significant interest in M. rosenbergii, its gene discovery has been at a relatively small scale compared to other genera. In this study, comprehensive transcriptomic sequencing data for different maturation stages of the ovary of M. rosenbergii were observed. The 20 female M. rosenbergii samples evaluated were categorised into four maturation stages, 1 to 4. A total of 817,793,14, 841,670,70, 914,248,78 and 878,085,88 raw reads were obtained from stages 1, 2, 3 and 4, respectively. The assembled unique sequences (unigenes) post-clustering (n = 98013) was 131,093,546 bp with an average size of 1,338 bp. The BLASTX unigene search against National Centre for Biotechnology Information (NCBI), non-redundant (NR), nucleotide sequence (NT), Kyoto Encyclopaedia of Genes and Genomes Orthology (KO), Swiss-Prot, Protein Family (PFAM), Gene Ontology (GO), and euKaryotic Orthologous Groups (KOG) databases yielded 27,680 (28.24%), 7,449 (7.59%), 13,026 (13.29%), 22,606 (23.06%), 29,907 (30.51%), 30,025 (30.63%) and 14,368 (14.65%) significant matches, respectively, totalling to 37,338 annotated unigenes (38.09%). The differentially expressed genes (DEG) analysis conducted in this study led to identifying cyclin B, insulin receptor (IR), oestrogen sulfotransferase (ESULT) and vitellogenin (Vg), which are critical in ovarian maturation. Nevertheless, some M. rosenbergii ovarian maturation-related genes, such as small ubiquitin-like modifier (SUMO)-activating enzyme subunit 1, E3 ubiquitin-protein ligase RNF25, and neuroparsin, were first identified in this study. The data obtained in the present study could considerably contribute to understanding the gene expression and genome structure in M. rosenbergii ovaries throughout its developmental stage.

SENP7 inhibits glioblastoma metastasis and invasion by dissociating SUMO2/3 binding to specific target proteins.

The poor surgical efficacy and recurrence of glioblastoma (GBM) are due to its lack of visible infiltrative features. Our bioinformatics study suggests that low expression of small ubiquitin-like modifier (SUMO)-specific protease 7 (SENP7) indicates poor prognosis in GBM. This study investigated the effect of SENP7 expression on the invasion, migration, and proliferation of GBM cells and aims to identify the SUMO target proteins affected by SENP7. SENP7 expression was analyzed in eight GBM tumor samples and four GBM cell lines, comparing them to normal brain tissue. The effect of SENP7 overexpression on GBM LN229 cell migration, invasion, and proliferation was examined through in vitro assays. Furthermore, four SUMO target proteins involved in tumor invasion and proliferation (CDK6, matrix metalloproteinase-9 [MMP9], AKT, and HIF-1α) were studied to explore SENP7's molecular mechanism. SENP7 expression was significantly lower in GBM tumors compared to normal tissue. SENP7 overexpression in LN229 cells inhibited migration and invasion without affecting proliferation. Overexpression reduced the levels of MMP9, AKT, and HIF-1α, but not CDK6. Immunohistochemical analysis showed decreased MMP9 and CD31 levels, suggesting reduced tumor invasion and angiogenesis. However, SENP7 overexpression did not affect tumor growth in vivo. SENP7 inhibits GBM invasion by dissociating proteins associated with tumor invasion from SUMO2/3, providing a potential target for future GBM therapies.

SENP1 mediates zinc-induced ZnT6 deSUMOylation at Lys-409 involved in the regulation of zinc metabolism in Golgi apparatus

Zinc (Zn) transporters contribute to the maintenance of intracellular Zn homeostasis in vertebrate, whose activity and function are modulated by post-translational modification. However, the function of small ubiquitin-like modifier (SUMOylation) in Zn metabolism remains elusive. Here, compared with low Zn group, a high-Zn diet significantly increases hepatic Zn content and upregulates the expression of metal-response element-binding transcription factor-1 (MTF-1), Zn transporter 6 (ZnT6) and deSUMOylation enzymes (SENP1, SENP2, and SENP6), but inhibits the expression of SUMO proteins and the E1, E2, and E3 enzymes. Mechanistically, Zn triggers the activation of the MTF-1/SENP1 pathway, resulting in the reduction of ZnT6 SUMOylation at Lys 409 by small ubiquitin-like modifier 1 (SUMO1), and promoting the deSUMOylation process mediated by SENP1. SUMOylation modification of ZnT6 has no influence on its localization but reduces its protein stability. Importantly, deSUMOylation of ZnT6 is crucial for controlling Zn export from the cytosols into the Golgi apparatus. In conclusion, for the first time, we elucidate a novel mechanism by which SUMO1-catalyzed SUMOylation and SENP1-mediated deSUMOylation of ZnT6 orchestrate the regulation of Zn metabolism within the Golgi apparatus.

SUMOylation of MFF coordinates fission complexes to promote stress-induced mitochondrial fragmentation.

Mitochondria undergo fragmentation in response to bioenergetic stress, mediated by dynamin-related protein 1 (DRP1) recruitment to the mitochondria. The major pro-fission DRP1 receptor is mitochondrial fission factor (MFF), and mitochondrial dynamics proteins of 49 and 51 kilodaltons (MiD49/51), which can sequester inactive DRP1. Together, they form a trimeric DRP1-MiD-MFF complex. Adenosine monophosphate-activated protein kinase (AMPK)-mediated phosphorylation of MFF is necessary for mitochondrial fragmentation, but the molecular mechanisms are unclear. Here, we identify MFF as a target of small ubiquitin-like modifier (SUMO) at Lys151, MFF SUMOylation is enhanced following AMPK-mediated phosphorylation and that MFF SUMOylation regulates the level of MiD binding to MFF. The mitochondrial stressor carbonyl cyanide 3-chlorophenylhydrazone (CCCP) promotes MFF SUMOylation and mitochondrial fragmentation. However, CCCP-induced fragmentation is impaired in MFF-knockout mouse embryonic fibroblasts expressing non-SUMOylatable MFF K151R. These data suggest that the AMPK-MFF SUMOylation axis dynamically controls stress-induced mitochondrial fragmentation by regulating the levels of MiD in trimeric fission complexes.

Small ubiquitin-like modifier protease gene TaDSU enhances salt tolerance of wheat.

To identify efficient salt-tolerant genes is beneficial for coping with the penalty of salt stress on crop yield. Reversible conjugation (sumoylation and desumoylation) of Small Ubiquitin-Like Modifier (SUMO) is a crucial kind of protein modifications, but its roles in the response to salt and other abiotic stress are not well addressed. Here, we identify salt-tolerant SUMO protease gene TaDSU for desumoylation from wheat, and analyze its mechanism in salt tolerance and evaluate its role in yield in saline-alkaline fields. TaDSU overexpression enhances salt tolerance of wheat. TaDSU overexpressors have lower Na+ but higher K+ contents and consequently higher K+ : Na+ ratios than the wild-type under salt stress. TaDSU interacts with transcriptional factor MYC2, reduces the sumoylation level of SUMO1-conjugated MYC2, and promotes its transcription activity. MYC2 binds to the promoter of TaDSU and elevates its expression. TaDSU overexpression enhances grain yield of wheat in the saline soil without growth penalty in the normal field. Especially, TaDSU ectopic expression also enhances salt tolerance of Arabidopsis thaliana, showing this SUMO protease allele has the inter-species role in the adaptation to salt stress. Thus, TaDSU is an efficient candidate gene for molecular breeding of salt-tolerant crops.

Sumoylation of thymine DNA glycosylase impairs productive binding to substrate sites in DNA

The base excision repair enzyme thymine DNA glycosylase (TDG) protects against mutations by removing thymine or uracil from guanine mispairs and functions in active DNA demethylation by excising 5-formylcytosine (fC) and 5-carboxylcytosine (caC). Post-translational modification of TDG by SUMO (small ubiquitin-like modifier) reduces its glycosylase activity but the mechanism remains unclear. We investigated this problem using biochemical and biophysical approaches and a TDG construct comprising residues 82-340 (of 410) that includes the SUMOylation site and the motif for non-covalent SUMO binding. Single turnover kinetics experiments were collected at multiple enzyme concentrations ([E]) and the hyperbolic dependence of activity (kobs) on [E] yielded the maximal glycosylase activity (kmax), the enzyme concentration giving half-maximal activity (K0.5), and the catalytic efficiency (kmax/K0.5). Sumoylation of TDG (or TDG82-340) causes large reductions in catalytic efficiency for G·T, G·U, G·fC, and G·caC DNA substrates, due largely to weakened substrate affinity (increased K0.5). 19F NMR experiments show that sumoylation of TDG82-340 reduces productive binding to G·U mispairs and dramatically impairs binding to G·T mispairs. A mutation in the TDG SUMO-interacting motif (SIM), E310Q, shown previously to perturb noncovalent binding of SUMO to unmodified TDG, rescues the glycosylase activity of sumoylated TDG82-340. Similarly, NMR studies show the mutation restores productive binding of sumoylated TDG82-340 to G·U and G·T pairs. Together, the results indicate that intramolecular SUMO-SIM interactions mediate the adverse effect of sumoylation on TDG activity and suggest a model whereby the disruption of SUMO-SIM interactions enables productive binding of sumoylated TDG to substrate sites in DNA.

An overview of the latest outlook of sulfamate derivatives as anticancer candidates (2020-2024).

Considering the emergence of new anticancer drugs, in this review we emphasized and highlighted the recent reports and advances related to sulfamate-incorporating compounds with potential anticancer activity during the last 5 years (2020-2024). Additionally, we discussed their structure-activity relationship, clarifying their potent bioactivity as anticancer agents. Sulfamate derivatives hold promise as effective therapeutic candidates against cancer. By targeting biological targets associated with the development of cancer, such as steroid sulfatases (STS), carbonic anhydrases (CAs), microtubules, NEDD8-activating enzyme, small ubiquitin-like modifiers(SUMO)-activating enzyme (SAE), cyclin-dependent kinases (CDKs), breast cancer susceptibility gene 1 (BRCA1), and so on, this can furnish small molecules as anticancer lead candidates serving the drug discovery field. For example, compound 2, an STS inhibitor, demonstrated superior activity compared to its reference, irosustat, by fivefold. In addition, compound 21, an SAE, is under phase I clinical trials. Continued research into sulfamate derivatives holds potential for the development of novel therapeutic agents targeting various diseases.

USP36 SUMOylates Las1L and Promotes Its Function in Pre-Ribosomal RNA ITS2 Processing.

This study identifies USP36 as a deubiquitinating and small ubiquitin-like modifier ligase dual-function enzyme to mediate Las1L deubiquitination and SUMOylation. Las1L SUMOylation at K565 plays a critical role in pre-rRNA ITS2 processing. Thus, our study reveals a novel downstream pathway for USP36-regulated ribosome biogenesis.

The SUMO gene MrSmt3 is involved in SUMOylation, conidiation and stress response in Metarhizium robertsii.

Smt3, as a small ubiquitin-like modifier (SUMO), play an essential role in the regulation of protein SUMOylation, and thus this process can affect various important biological functions. Here, we investigated the roles of MrSmt3 (yeast SUMO/Smt3 homologs) in the entomopathogenic fungus Metarhizium robertsii. Our results of subcellular localization assays demonstrated that MrSmt3 was present in the cytoplasm and nucleus, whereas MrSmt3 was largely localized in the nucleus during oxidative stress. Importantly, disruption of MrSmt3 significantly decreased the level of protein SUMOylation under heat stress. Deletion of MrSmt3 led to a significant decrease in conidial production, and increased sensitivity to various stresses, including heat, oxidative, and cell wall-disturbing agents. However, bioassays of direct injection and topical inoculation demonstrated that deletion of MrSmt3 did not affect fungal virulence. Furthermore, RNA-seq analysis identified 1,484 differentially expressed genes (DEGs) of the WT and ΔMrSmt3 during conidiation, including 971 down-regulated DEGs and 513 up-regulated DEGs, and further analysis showed that the expression level of several classical conidiation-associated genes, such as transcription factor AbaA (MAA_00694), transcription factor bZIP (MAA_00888) and transcription factor Ste12 (MAA_10450), was down-regulated in the ΔMrSmt3 mutant. Specifically, the major downregulated DEGs were mainly associated with a variety of metabolic regulatory processes including metabolic process, organic substance metabolic process and primary metabolic process. Collectively, our findings highlight the important roles of the SUMO gene MrSmt3 in modulating SUMOylation, conidiation and stress response in M. robertsii.

Highly sensitive site-specific SUMOylation proteomics in Arabidopsis.

SUMOylation-the attachment of a small ubiquitin-like modifier (SUMO) to target proteins-plays roles in controlling plant growth, nutrient signalling and stress responses. SUMOylation studies in plants are scarce because identifying SUMOylated proteins and their sites is challenging. To date, only around 80 SUMOylation sites have been identified. Here we introduce lysine-null SUMO1 into the Arabidopsis sumo1 sumo2 mutant and establish a two-step lysine-null SUMO enrichment method. We identified a site-specific SUMOylome comprising over 2,200 SUMOylation sites from 1,300 putative acceptors that function in numerous nuclear processes. SUMOylation marks occur on several motifs, differing from the canonical ψKxE motif in distant eukaryotes. Quantitative comparisons demonstrate that SUMOylation predominantly enhances the stability of SUMO1 acceptors. Our study delivers a highly sensitive and efficient method for site-specific SUMOylome studies and provides a comprehensive catalogue of Arabidopsis SUMOylation, serving as a valuable resource with which to further explore how SUMOylation regulates protein function.

Genetic approach to discover a valuable gene for enhanced nutritional value in the edible filamentous fungus Fusarium venenatum

AbstractMycoprotein is critical in a dietary shift toward a more sustainable food system. However, the strain improvement for enhancing mycoprotein via genetic manipulation is lacking. Here, we investigated the functions of proteins related to ubiquitin and small ubiquitin‐like modifier (SUMO) modifications using a gene‐knockout strategy in Fusarium venenatum, a mycoprotein fungus closely related to the fungal genetics model species Fusarium graminearum. Among the candidate genes, we specifically focused on the putative SUMO‐associated gene UBQ14 based on phenotypic characteristics in F. graminearum. In the FvUBQ14 knockout mutant in F. venenatum, nutritional profiles showed prominent differences in amino acid and fatty acid composition compared to the wild‐type strain. Furthermore, through proteomic analysis, we confirmed that the loss of FvUBQ14 leads to metabolic changes, particular in amino acid biosynthesis and degradation, resulting in an increase in amino acid composition in F. venenatum. Our findings provide new insights into filamentous fungal food improvement through genetic engineering and contribute to advances in alternative protein industry.