N-terminal Domain of TDP43 Enhances Liquid-Liquid Phase Separation of Globular Proteins

Carter, G. Campbell; Hsiung, Chia-Heng; Simpson, Leman Wi; Yang, Haopeng; Zhang, Xin

doi:10.1016/j.jmb.2021.166948

Cited by 41 publications

(30 citation statements)

References 53 publications

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“…BAG2 oligomerization (Fig. 3a ) likely lowers the energy barriers for LLPS 18 due to heterogeneous nucleation on the surface of the oligomer complexes. Based upon classical nucleation theory, heterogeneous LLPS lowers the free-energetic barrier for nucleation relative to homogeneous LLPS due to increased multivalent and heterotypic interactions in presence of the oligomers.…”

Section: Resultsmentioning

confidence: 99%

Stress routes clients to the proteasome via a BAG2 ubiquitin-independent degradation condensate

et al. 2022

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The formation of membraneless organelles can be a proteotoxic stress control mechanism that locally condenses a set of components capable of mediating protein degradation decisions. The breadth of mechanisms by which cells respond to stressors and form specific functional types of membraneless organelles, is incompletely understood. We found that Bcl2-associated athanogene 2 (BAG2) marks a distinct phase-separated membraneless organelle, triggered by several forms of stress, particularly hyper-osmotic stress. Distinct from well-known condensates such as stress granules and processing bodies, BAG2-containing granules lack RNA, lack ubiquitin and promote client degradation in a ubiquitin-independent manner via the 20S proteasome. These organelles protect the viability of cells from stress and can traffic to the client protein, in the case of Tau protein, on the microtubule. Components of these ubiquitin-independent degradation organelles include the chaperone HSP-70 and the 20S proteasome activated by members of the PA28 (PMSE) family. BAG2 condensates did not co-localize with LAMP-1 or p62/SQSTM1. When the proteasome is inhibited, BAG2 condensates and the autophagy markers traffic to an aggresome-like structure.

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Section: Resultsmentioning

confidence: 99%

Stress routes clients to the proteasome via a BAG2 ubiquitin-independent degradation condensate

et al. 2022

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“…It has been proposed to be responsible for the oligomerisation of the entire full-length protein [12,[14][15][16][17][18][19][20]. Oligomerisation of full-length TDP-43 mediated by the NTD is essential for TDP-43 function [14,15,19,20], but also favours liquid-liquid phase separation and solid-phase inclusion formation of the full-length protein [20][21][22]. The structural plasticity of the TDP-43 NTD resulting in its in dimerisation/oligomerisation is also observed in its folding process from a fully unfolded state, in which the protein domain forms a number of partially folded states before achieving the fully folded dimeric structure, and even populates, at low denaturant concentrations, a native-like dimeric state distinct from the fully native dimeric conformation [24].…”

Section: Discussionmentioning

confidence: 99%

“…Although NTD-mediated TDP-43 dimerisation/oligomerisation appears to be essential for TDP-43 function [14,15,19,20], extensive NTD-mediated TDP-43 oligomerisation was also found to enhance the liquid-liquid phase separation (LLPS) at physiological concentrations [20][21][22], as well as formation of solid phase cytotoxic inclusions in the cytoplasm [15,23].…”

Section: Introductionmentioning

confidence: 99%

Conversion of the Native N-Terminal Domain of TDP-43 into a Monomeric Alternative Fold with Lower Aggregation Propensity

et al. 2022

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TAR DNA-binding protein 43 (TDP-43) forms intraneuronal cytoplasmic inclusions associated with amyotrophic lateral sclerosis and ubiquitin-positive frontotemporal lobar degeneration. Its N-terminal domain (NTD) can dimerise/oligomerise with the head-to-tail arrangement, which is essential for function but also favours liquid-liquid phase separation and inclusion formation of full-length TDP-43. Using various biophysical approaches, we identified an alternative conformational state of NTD in the presence of Sulfobetaine 3-10 (SB3-10), with higher content of α-helical structure and tryptophan solvent exposure. NMR shows a highly mobile structure, with partially folded regions and β-sheet content decrease, with a concomitant increase of α-helical structure. It is monomeric and reverts to native oligomeric NTD upon SB3-10 dilution. The equilibrium GdnHCl-induced denaturation shows a cooperative folding and a somewhat lower conformational stability. When the aggregation processes were compared with and without pre-incubation with SB3-10, but at the identical final SB3-10 concentration, a slower aggregation was found in the former case, despite the reversible attainment of the native conformation in both cases. This was attributed to protein monomerization and oligomeric seeds disruption by the conditions promoting the alternative conformation. Overall, the results show a high plasticity of TDP-43 NTD and identify strategies to monomerise TDP-43 NTD for methodological and biomedical applications.

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“…Modular proteins can also act as scaffolds when recruiting clients that harbor IDRs, which in turn form a multi-modal interaction network to enhance the avidity of weak interactions in the condensed phase [ 37 , 38 ]. In addition to IDRs, oligomerization domains have also recently been shown to enhance the LLPS of protein domains and can potentially serve as an alternative molecular signature associated with LLPS [ 39 ].…”

Section: Intranuclear Phase Separation: Physico-chemical Properties A...mentioning

confidence: 99%

Phase Separation-Mediated Chromatin Organization and Dynamics: From Imaging-Based Quantitative Characterizations to Functional Implications

Sielaff²,

Zhao³

2022

IJMS

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As an effective and versatile strategy to compartmentalize cellular components without the need for lipid membranes, phase separation has been found to underpin a wide range of intranuclear processes, particularly those involving chromatin. Many of the unique physico-chemical properties of chromatin-based phase condensates are harnessed by the cell to accomplish complex regulatory functions in a spatially and temporally controlled manner. Here, we survey key recent findings on the mechanistic roles of phase separation in regulating the organization and dynamics of chromatin-based molecular processes across length scales, packing states and intranuclear functions, with a particular emphasis on quantitative characterizations of these condensates enabled by advanced imaging-based approaches. By illuminating the complex interplay between chromatin and various chromatin-interacting molecular species mediated by phase separation, this review sheds light on an emerging multi-scale, multi-modal and multi-faceted landscape that hierarchically regulates the genome within the highly crowded and dynamic nuclear space. Moreover, deficiencies in existing studies also highlight the need for mechanism-specific criteria and multi-parametric approaches for the characterization of chromatin-based phase separation using complementary techniques and call for greater efforts to correlate the quantitative features of these condensates with their functional consequences in close-to-native cellular contexts.

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N-terminal Domain of TDP43 Enhances Liquid-Liquid Phase Separation of Globular Proteins

Cited by 41 publications

References 53 publications

Stress routes clients to the proteasome via a BAG2 ubiquitin-independent degradation condensate

Stress routes clients to the proteasome via a BAG2 ubiquitin-independent degradation condensate

Conversion of the Native N-Terminal Domain of TDP-43 into a Monomeric Alternative Fold with Lower Aggregation Propensity

Phase Separation-Mediated Chromatin Organization and Dynamics: From Imaging-Based Quantitative Characterizations to Functional Implications

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