Dataset Information

Tadpole-like conformations of polyglutamine-expanded soluble huntingtin exon 1 engenders novel interactions

ABSTRACT: Soluble huntingtin exon 1 (Httex1) with expanded polyglutamine (polyQ) engenders neurotoxicity in Huntington’s disease. To understand the structural basis of this toxicity, we characterized the structure of monomeric Httex1 for two polyQ lengths using hydrogen-deuterium exchange and nuclear magnetic resonance experiments. NMR analysis of Httex1 with polyQ length of 25 glutamines showed the presence of helical structure in the N-terminal region which continued into the polyQ tract. Within these regions the 15N{1H} NOE averages about 0.4, consistent with a protein that lacks structure, but also consistent with Httex1 being not fully disordered. However, both NMR and mass spectrometry hydrogen-deuterium exchange experiments showed no protection suggesting a lack of any stabilizing hydrogen bonds. Atomistic simulations showed that these seemingly conflicting features originated from tadpole-like topologies composed of a globular head that included the N-terminal amphipathic region adsorbed on a collapsed polyQ domain and a semi-flexible C-terminal proline-rich region tail. The surface area of the disordered globular domain increased with polyQ length to promote gain-of-function interactions with a range of proteins in a mouse neuroblastoma cell model, which included the stress granule protein Fus. Overexpression of Fus potently reduced toxicity in cells with soluble, polyQ-expanded Httex1. These results collectively suggested that the tadpole-like structure of Httex1 stimulates novel gain-of-function interactions that can be harmful to cell viability and can be sequestered competitively by interactions with other proteins sharing similar low complexity structures such as Fus.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Cell Culture

SUBMITTER: Estella Newcombe

LAB HEAD: Danny Martin Hatters

PROVIDER: PXD006792 | Pride | 2019-11-08

REPOSITORIES: Pride

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Publications

Tadpole-like Conformations of Huntingtin Exon 1 Are Characterized by Conformational Heterogeneity that Persists regardless of Polyglutamine Length.

Newcombe Estella A EA Ruff Kiersten M KM Sethi Ashish A Ormsby Angelique R AR Ramdzan Yasmin M YM Fox Archa A Purcell Anthony W AW Gooley Paul R PR Pappu Rohit V RV Hatters Danny M DM

Journal of molecular biology 20180405 10

Soluble huntingtin exon 1 (Httex1) with expanded polyglutamine (polyQ) engenders neurotoxicity in Huntington's disease. To uncover the physical basis of this toxicity, we performed structural studies of soluble Httex1 for wild-type and mutant polyQ lengths. Nuclear magnetic resonance experiments show evidence for conformational rigidity across the polyQ region. In contrast, hydrogen-deuterium exchange shows absence of backbone amide protection, suggesting negligible persistence of hydrogen bonds ...[more]

PMID: 29627459

Similar Datasets

Project description:Protein aggregation is a hallmark of many neurodegenerative diseases. In order to cope with misfolding and aggregation, cells have evolved an elaborate network of molecular chaperones, composed of different families. But while chaperoning mechanisms for different families are well established, functional and regulatory diversification within chaperone families is still largely a mystery. Here we decided to explore chaperone functional diversity, through the lens of pathological aggregation. We revealed that different naturally-occurring isoforms of DNAJ chaperones showed differential effects on different types of aggregates. We performed a chaperone screen for modulators of two neurodegeneration-related aggregating proteins, the Huntington’s disease-related HTT-polyQ, and the ALS-related mutant FUS (mutFUS). The screen identified known modulators of HTT-polyQ aggregation, confirming the validity of our approach. Surprisingly, modulators of mutFUS aggregation were completely different than those of HTT-polyQ. Interestingly, different naturally-occurring isoforms of DNAJ chaperones had opposing effects on HTT-polyQ vs. mutFUS aggregation. We identified a complex of the full length (FL) DNAJB14 and DNAJB12 isoforms which substantially alleviated mutFUS aggregation, in an HSP70-dependent manner. Their naturally occurring short isoforms were unable to form the complex, nor to interact with HSP70, and lost their ability to reduce mutFUS aggregation. In contrast, the short isoform of DNAJB12 significantly alleviated HTT-polyQ aggregation, while DNAJB12-FL aggravated HTT-polyQ aggregation. Finally, we demonstrated that full-length DNAJB14 ameliorated mutFUS aggregation compared to DNAJB14-short in primary neurons. Together, our data unraveled distinct molecular properties required for aggregation protection in different neurodegenerative diseases, and revealed a new layer of complexity of the chaperone network elicited by naturally occurring J-protein isoforms, highlighting functional diversity among the DNAJ family.

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