scholarly journals An intrinsically disordered region of RPN10 plays a key role in restricting ubiquitin chain elongation in RPN10 monoubiquitination

2015 ◽  
Vol 469 (3) ◽  
pp. 455-467 ◽  
Author(s):  
Pilar Puig-Sàrries ◽  
Marie-José Bijlmakers ◽  
Alice Zuin ◽  
Anne Bichmann ◽  
Miquel Pons ◽  
...  

The proteasomal ubiquitin receptor Rpn10 (regulatory particle non-ATPase 10) is monoubiquitinated by Rsp5 (reverses SPT-phenotype protein 5). We show that a disordered region flanking the ubiquitin-interacting motif of Rpn10 is required for restricting polyubiquitination in the process of Rpn10 monoubiquitination. A novel role of an unstructured protein domain in controlling ubiquitin chain elongation is proposed.

2018 ◽  
Vol 430 (11) ◽  
pp. 1621-1639 ◽  
Author(s):  
Florian Malard ◽  
Nadine Assrir ◽  
Mouad Alami ◽  
Samir Messaoudi ◽  
Ewen Lescop ◽  
...  

2021 ◽  
Author(s):  
Matthew E Dwyer ◽  
Roger P. Hangarter

Light-dependent chloroplast movements in leaf cells contribute to the optimization of photosynthesis. Low light conditions induce chloroplast accumulation along periclinal cell surfaces, providing greater access to the available light, whereas high light induces movement of chloroplasts to anticlinal cell surfaces providing photodamage protection and allowing more light to reach underlying cell layers. The THRUMIN1 protein is required for normal chloroplast movements in Arabidopsis thaliana and has been shown to localize at the plasma membrane and to undergo rapid light-dependent interactions with actin filaments through the N-terminal intrinsically disordered region. A predicted WASP-Homology 2 (WH2) domain was found in the intrinsically disordered region but mutations in this domain did not disrupt localization of THRUMIN1:YFP to actin filaments. A series of other protein truncations and site-directed mutations of known and putative phosphorylation sites indicated that a phosphomimetic mutation (serine to aspartic acid) at position 170 disrupted localization of THRUMIN1 with actin filaments. However, the phosphomimetic mutant rescued the thrumin1-2 mutant phenotype for chloroplast movement and raises questions about the role of THRUMIN1's interaction with actin. Mutation of serine 146 to aspartic acid also resulted in cytoplasmic localization of THRUMIN1:YFP in Nicotiana benthamiana. Mutations to a group of putative zinc-binding cysteine clusters implicates the C-terminus of THRUMIN1 in chloroplast movement. Phosphorylation-dependent association of THRUMIN1 with 14-3-3 KAPPA and OMEGA were also identified. Together, these studies provide new insights into the mechanistic role of THRUMIN1 in light-dependent chloroplast movements.


2018 ◽  
Author(s):  
Sarah Klass ◽  
Matthew J. Smith ◽  
Tahoe Fiala ◽  
Jessica Lee ◽  
Anthony Omole ◽  
...  

Herein, we describe a new series of fusion proteins that have been developed to self-assemble spontaneously into stable micelles that are 27 nm in diameter after enzymatic cleavage of a solubilizing protein tag. The sequences of the proteins are based on a human intrinsically disordered protein, which has been appended with a hydrophobic segment. The micelles were found to form across a broad range of pH, ionic strength, and temperature conditions, with critical micelle concentration (CMC) values below 1 µM being observed in some cases. The reported micelles were found to solubilize hydrophobic metal complexes and organic molecules, suggesting their potential suitability for catalysis and drug delivery applications.


2019 ◽  
Author(s):  
Duy Phuoc Tran ◽  
Akio Kitao

<p>We investigate association and dissociation mechanisms of a typical intrinsically disordered region (IDR), transcriptional activation subdomain of tumor repressor protein p53 (TAD-p53) with murine double-minute clone 2 protein (MDM2). Using the combination of cycles of association and dissociation parallel cascade molecular dynamics, multiple standard MD, and Markov state model, we are successful in obtaining the lowest free energy structure of MDM2/TAD-p53 complex as the structure very close to that in crystal without prior knowledge. This method also reproduces the experimentally measured standard binding free energy, and association and dissociation rate constants solely with the accumulated MD simulation cost of 11.675 μs, in spite of the fact that actual dissociation occurs in the order of a second. Although there exist a few complex intermediates with similar free energies, TAD-p53 first binds MDM2 as the second lowest free energy intermediate dominantly (> 90% in flux), taking a form similar to one of the intermediate structures in its monomeric state. The mechanism of this step has a feature of conformational selection. In the second step, dehydration of the interface, formation of π-π stackings of the side-chains, and main-chain relaxation/hydrogen bond formation to complete α-helix take place, showing features of induced fit. In addition, dehydration (dewetting) is a key process for the final relaxation around the complex interface. These results demonstrate a more fine-grained view of the IDR association/dissociation beyond classical views of protein conformational change upon binding.</p>


Author(s):  
M. Fayyaz Rehman ◽  
M. Jeeves ◽  
E. I. Hyde

AbstractIncC from the low-copy number plasmid RK2, is a member of the ParA family of proteins required for partitioning DNA in many bacteria and plasmids. It is an ATPase that binds DNA and its ParB protein partner, KorB. Together, the proteins move replicated DNA to appropriate cellular positions, so that each daughter cell inherits a copy on cell division. IncC from RK2 is expressed in two forms. IncC2 is homologous to bacterial ParA proteins, while IncC1 has an N-terminal extension of 105 amino acids and is similar in length to ParA homologues in other plasmids. We have been examining the role of this extension, here called IncC NTD. We present its backbone NMR chemical shift assignments and show that it is entirely intrinsically disordered. The assignments were achieved using C-detected, CON-based spectra, complemented by HNN spectra to obtain connectivities from three adjacent amino acids. We also observed evidence of deamidation of the protein at a GNGG sequence, to give isoAsp, giving 2 sets of peaks for residues up to 5 amino acids on either side of the modification. We have assigned resonances from around the position of modification for this form of the protein.


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