The Essential Functions of NEDD8 Are Mediated via Distinct Surface Regions, and Not by Polyneddylation in Schizosaccharomyces pombe

The ubiquitin-like protein NEDD8 is highly conserved in eukaryotes, from man to Schizosaccharomyces pombe. NEDD8 conjugation to cullin proteins is a prerequisite for cullin based E3 ubiquitin ligase activity, and essential for S. pombe viability. Here, we have performed alanine scanning mutagenesis of all conserved surface residues and show that the majority of essential residues were located around the hydrophobic patch and the C-terminus. However, we further identified essential residues not previously reported to be involved in ubiquitin ligase regulation that importantly do not prevent Ned8p conjugation. We also find that mutation of all conserved lysine residues in Ned8p, did not affect yeast viability, suggesting that mono-neddylation is sufficient for yeast viability under most conditions

Targeting the NEDP1 enzyme to ameliorate ALS phenotypes through stress granule disassembly

The elimination of aberrant inclusions is regarded as a therapeutic approach in neurodegeneration. In amyotro-phic lateral sclerosis (ALS), mutations in proteins found within cytoplasmic condensates called stress granules (SGs) are linked to the formation of pathological SGs, aberrant protein inclusions, and neuronal toxicity. We found that inhibition of NEDP1, the enzyme that processes/deconjugates the ubiquitin-like molecule NEDD8, promotes the disassembly of physiological and pathological SGs. Reduction in poly(ADP-ribose) polymerase1 activity through hyper-NEDDylation is a key mechanism for the observed phenotype. These effects are related to improved cell survival in human cells, and in C. elegans, nedp1 deletion ameliorates ALS phenotypes related to animal motility. Our studies reveal NEDP1 as potential therapeutic target for ALS, correlated to the disassembly of pathological SGs

The Balance between Mono- and NEDD8-Chains Controlled by NEDP1 upon DNA Damage Is a Regulatory Module of the HSP70 ATPase Activity

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Interplay between SUMOylation and NEDDylation regulates RPL11 localization and function

The ribosomal protein L11 (RPL11) integrates different types of stress into a p53‐mediated response. Here, we analyzed the impact of the ubiquitin‐like protein SUMO on the RPL11‐mouse double‐minute 2 homolog‐p53 signaling. We show that small ubiquitin‐related modifier (SUMO)1 and SUMO2 covalently modify RPL11. We find that SUMO negatively modulates the conjugation of the ubiquitin‐like protein neural precursor cell‐expressed developmentally downregulated 8 (NEDD8) to RPL11 and promotes the translocation of the RP outside of the nucleoli. Moreover, the SUMO‐conjugating enzyme, Ubc9, is required for RPL11‐mediated activation of p53. SUMOylation of RPL11 is triggered by ribosomal stress, as well as by alternate reading frame protein upregulation. Collectively, our data identify SUMO protein conjugation to RPL11 as a new regulator of the p53‐mediated cellular response to different types of stress and reveal a previously unknown SUMO‐NEDD8 interplay

Novel substrates and functions for the ubiquitin-like molecule NEDD8

Genetic experiments have established an important role for the ubiquitin-like molecule NEDD8 (neural-precursor-cell-expressed developmentally down-regulated 8) in the regulation of cell growth, viability and development. It is therefore essential to identify the molecular targets for the pathway. Until recently, the cullin family of proteins was characterized as the only substrates for NEDDylation. However, through either direct biological approaches or the use of proteomics, it is now evident that the NEDD8 proteome is more diverse than thought previously. The present review describes the biological significance of NEDDylation for the novel identified substrates and the emerging evidence for the co-operation between the ubiquitin and NEDD8 pathways to control protein function