Biology subjects

Rudiger, S.

Publications and source records attributed to Rudiger, S..

4 recordsLinked to original sources

bioRxiv2025

FibrilPaints as a tool to bind and modulate Huntingtin amyloids

Huntingtons disease (HD) is caused by expansion of a polyglutamine tract in the huntingtin (Htt) protein, leading to aggregation of the exon 1 fragment (HttEx1) into amyloid fibrils. HttEx1 forms one of the lowest-complexity amyloid cores known, its fibril core consists of a single amino acid, glutamine. With emerging therapies improving patients prospects by silencing expression of HTT, tools to monitor HttEx1 aggregation become essential for timely intervention and next-generation therapeutics. Here, we show that the peptide FibrilPaint1 selectively binds HttEx1Q44 fibrils without interacting with monomeric protein, allowing to measure and trace HttEx1 amyloid fibrils. Using the FibrilRuler assay, we tracked fibril formation from early species to larger clustered assemblies. The non-fluorescent variant, FibrilPaint20, was used to recruit the E3 ubiquitin ligase CHIP to HttEx1 fibrils, enabling site-specific ubiquitin tagging. However, unlike Tau fibrils, ubiquitinated HttEx1 fibrils resisted proteasomal degradation. This reveals a fundamental difference in how amyloids with extremely low-complexity cores respond to cellular clearance machinery. Together, our findings establish the FibrilPaint peptide family as a toolset for the detection and molecular targeting of amyloids, providing new opportunities to study protein aggregation and act as building blocks for future diagnostic and therapeutic strategies in neurodegenerative diseases. HighlightsO_LIFibrilPaint1 selectively binds HttEx1Q44 amyloid fibrils and allows monitoring of fibril growth using the hydrodynamic radius (FibrilRuler). C_LIO_LIFibrilPaint20 recruits the E3 ligase CHIP to Htt fibrils, enabling ubiquitination. C_LIO_LIDespite successful ubiquitination, Htt fibrils resist proteasomal degradation in vitro, highlighting structural barriers. C_LIO_LIFibrilPaint provides a scaffold for functional targeting of amyloids with diagnostic and therapeutic potential. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=160 SRC="FIGDIR/small/695423v2_ufig1.gif" ALT="Figure 1"> View larger version (22K): org.highwire.dtl.DTLVardef@18acc7corg.highwire.dtl.DTLVardef@1771f3borg.highwire.dtl.DTLVardef@1a35e51org.highwire.dtl.DTLVardef@85270a_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO The FibrilRuler Test: FibrilPaint enables measurement of Huntingtin fibril size during aggregation After a short lag-phase following removal of the protective MBP tag by Factor Xa, fibrillation proceeds rapidly. Subsequent fibril clustering further accelerates growth, leading to exponential increases in aggregate size. C_FIG

biochemistry↗

bioRxiv2024

The role of specific phosphorylation patterns in the oligomerization of Tau-R4

Specific phosphorylation patterns control the activity of multiphosphorylated proteins. In case of the Tau protein, multiphosphorylation leads to the formation of different disease-related condensates and aggregates. Studying the role of these specific patterns at the protein level is crucial for understanding the molecular mechanisms of Tauopathies such as Alzheimers Disease. However, due to the extreme difficulty in obtaining recombinant proteins with specific phosphorylation patterns using kinase-based methods, it is practically impossible to study the connection between specific phosphorylation patterns and aggregation events at the protein level. Here we addressed this problem by reducing the system to the peptide level and studying the effect of specific phosphorylation patterns on the condensation and aggregation of a specific domain of Tau, R4 (residues 336-358). To achieve this aim, we have applied advanced methods to synthesize a library of multiphosphorylated peptides derived from R4. We showed that specific phosphorylation patterns stringently control the formation of Tau aggregates and condensates. Phosphorylation of Ser341 promoted aggregation of R4 while phosphorylation of Ser352 promoted its condensation. Interestingly, Ser356 phosphorylation inhibited both processes, which can be overridden by double-phosphorylation at Ser341/Ser352. Differences between the microenvironments of the phosphorylated residues lead to their different effects on R4 aggregation upon phosphorylation. Our results show that working at the domain level using advanced peptide synthesis methods is a highly useful and practical way to provide valuable information about the effects of post translational modifications on protein activity.

biochemistry↗

bioRxiv2024

Fibril fragmentation generates diversity in seed population

Neurodegenerative diseases are characterised by the formation and accumulation of protein fibrils. The mechanism underlaying this aggregation process remains poorly understood. Fibril fragmentation, resulting in seed generation, plays a role in toxicity. Here we provide a quantitative picture of the impact of ultrasound on patient-derived and recombinant fibrils from various diseases. Fragmentation of recombinant Tau fibrils and patient-derived fibrils from Alzheimers Disease, Corticobasal Degeneration and Frontotemporal Dementia generates amyloid and non-amyloid species. Interestingly, patient-derived fibrils are more susceptible to ultrasound than artificial fibrils. Understanding fibril fragmentation and the generation and nature of seeds may provide insights to the molecular mechanism of the disease progression, contributing to the development therapeutic approaches.

biochemistry↗

bioRxiv2022

A peptide strategy for inhibiting different protein aggregation pathways in disease

Protein aggregation correlates with many human diseases. Protein aggregates differ in shape, ranging from amorphous aggregates to amyloid fibrils. Possibly for such heterogeneity, strategies to develop effective aggregation inhibitors that reach the clinic failed so far. Here, we present a new strategy by which we developed a family of peptides targeting early aggregation stages for both amorphous and fibrillar aggregates of proteins unrelated in sequence and structure. Thus, they act on dynamic precursors before a mechanistic differentiation takes place. Using a peptide array approach, we first identified peptides inhibiting the predominantly amorphous aggregation of a molten globular, aggregation-prone protein, a thermolabile mutant of the Axin tumor suppressor. A series of optimization steps revealed that the peptides activity did not depend on their sequences but rather on their molecular determinants. The key properties that made a peptide active were a composition of 20-30% flexible, 30-40% aliphatic and 20-30% aromatic residues, a hydrophobicity/hydrophilicity ratio close to 1 and an even distribution of residues of different nature throughout the sequence. Remarkably, the optimized peptides also suppressed fibrillation of Tau, a disordered protein that forms amyloids in Alzheimers disease, and entirely unrelated to Axin. Our compounds thus target early aggregation stages, independent of the aggregation mechanism, inhibiting both amorphous and amyloid aggregation. Such cross-mechanistic, multi-targeting aggregation inhibitors may be attractive lead compounds against multiple protein aggregation diseases.

biochemistry↗