scholarly journals Light-dependent THRUMIN1 phosphorylation regulates its association with actin filaments and 14-3-3 proteins

2021 ◽  
Author(s):  
Matthew E Dwyer ◽  
Roger P. Hangarter
Keyword(s):  
Aspartic Acid ◽  
Actin Filaments ◽  
Chloroplast Movement ◽  
Cell Surfaces ◽  
Intrinsically Disordered ◽  
C Terminus ◽  
Intrinsically Disordered Region ◽  
Chloroplast Movements ◽  
Cell Layers

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.

scholarly journals Conformational Ensemble and Biological Role of the TCTP Intrinsically Disordered Region: Influence of Calcium and Phosphorylation

2018 ◽  
Vol 430 (11) ◽  
pp. 1621-1639 ◽  
Author(s):  
Florian Malard ◽  
Nadine Assrir ◽  
Mouad Alami ◽  
Samir Messaoudi ◽  
Ewen Lescop ◽  
...  
Keyword(s):  
Biological Role ◽  
Conformational Ensemble ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Region

scholarly journals Evidence of a conserved intrinsically disordered region in the C-terminus of the stringent response protein Rel from mycobacteria

FEBS Letters ◽  
2014 ◽  
Vol 588 (9) ◽  
pp. 1839-1849 ◽  
Author(s):  
Lakhan Ekal ◽  
Bylapudi Ganesh ◽  
Himanshu Joshi ◽  
Dilraj Lama ◽  
Vikas Jain
Keyword(s):  
Stringent Response ◽  
Intrinsically Disordered ◽  
C Terminus ◽  
Intrinsically Disordered Region ◽  
Stringent Response Protein

scholarly journals Control of mRNA decapping by autoinhibition

2018 ◽  
Author(s):  
David R Paquette ◽  
Ryan W Tibble ◽  
Tristan S Daifuku ◽  
John D Gross
Keyword(s):  
Transition State ◽  
Linear Interaction ◽  
Mrna Decapping ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Cytoplasmic Rna ◽  
C Terminus ◽  
Inactive Form ◽  
Combinatorial Control

5’ mediated cytoplasmic RNA decay is a conserved cellular process in eukaryotes. While the functions of the structured core domains in this pathway are understood, the role of abundant intrinsically disordered regions (IDRs) is lacking. Here we reconstitute the Dcp1:Dcp2 complex containing a portion of the disordered C-terminus and show its activity is autoinhibited by linear interaction motifs. Enhancers of decapping (Edc) 1 and 3 cooperate to activate decapping by different mechanisms: Edc3 alleviates auto-inhibition by binding IDRs and destabilizing an inactive form of the enzyme, whereas Edc1 stabilizes the transition state for catalysis. Both activators are required to fully stimulate an autoinhibited Dcp1:Dcp2 as Edc1 alone cannot overcome the decrease in activity attributed to the C-terminal extension. Our data provide a mechanistic framework for combinatorial control of decapping by protein cofactors, a principle that is likely conserved in multiple 5’ mRNA decay pathways.

scholarly journals A 20S proteasome receptor for degradation of intrinsically disordered proteins

2017 ◽  
Author(s):  
Assaf Biran ◽  
Nadav Myers ◽  
Julia Adler ◽  
Karin Broennimann ◽  
Nina Reuven ◽  
...  
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Proteasomal Degradation ◽  
Disordered Proteins ◽  
20S Proteasome ◽  
Intrinsically Disordered ◽  
C Terminus ◽  
Protein Interactome

AbstractDegradation of intrinsically disordered proteins (IDPs) by the 20S proteasome, unlike ubiquitin-dependent 26S proteasomal degradation, does not require proteasomal targeting by polyubiquitin. However, how these proteins are recognized by the proteasome was unknown. We report here on a mechanism of 20S proteasome targeting. Analysis of protein interactome datasets revealed that the proteasome subunit PSMA3 interacts with many IDPs. By employing in vivo and cell-free experiments we demonstrated that the PSMA3 C-terminus binds p21, c-Fos and p53, all IDPs and 20S proteasome substrates. A 69 amino-acids long fragment is autonomously functional in interacting with IDP substrates. Remarkably, this fragment in isolation blocks the degradation of a large number of IDPs in vitro and increases the half-life of proteins in vivo. We propose a model whereby the PSMA3 C-terminal region plays a role of substrate receptor in the process of proteasomal degradation of many IDPs.

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 ◽  
...  
Keyword(s):  
Protein Domain ◽  
Chain Elongation ◽  
Ubiquitin Chain ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Region ◽  
Regulatory Particle ◽  
Unstructured Protein

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.

scholarly journals A phospho-regulated ensemble signal motif of α-TAT1 drives dynamic microtubule acetylation

2020 ◽  
Author(s):  
Abhijit Deb Roy ◽  
Evan G. Gross ◽  
Gayatri S. Pillai ◽  
Shailaja Seetharaman ◽  
Sandrine Etienne-Manneville ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Molecular Mechanisms ◽  
Cellular Functions ◽  
Intrinsically Disordered ◽  
Phosphorylated Form ◽  
C Terminus ◽  
Cancer Mutations ◽  
Functional Consequences ◽  
Dynamic Microtubule

AbstractSpatiotemporal patterns of microtubule modifications such as acetylation underlie diverse cellular functions. While the molecular identity of the acetylating agent, α-tubulin N-acetyltransferase 1 (α-TAT1), as well as the functional consequences of microtubule acetylation have been revealed, the molecular mechanisms that regulate multi-tasking α-TAT1 action for dynamic acetylation remain obscure. Here we identified a signal motif in the intrinsically disordered C-terminus of α-TAT1, which comprises three functional elements - nuclear export, nuclear import and cytosolic retention. Their balance is tuned via phosphorylation by serine-threonine kinases to determine subcellular localization of α-TAT1. While the phosphorylated form binds to 14-3-3 adapters and accumulates in the cytosol for maximal substrate access, the non-phosphorylated form is sequestered inside the nucleus, thus keeping microtubule acetylation minimal. As cancer mutations have been reported to this motif, the unique ensemble regulation of α-TAT1 localization may hint at a role of microtubule acetylation in aberrant physiological conditions.

scholarly journals The Retrieval Function of the KDEL Receptor Requires PKA Phosphorylation of Its C-Terminus

2003 ◽  
Vol 14 (10) ◽  
pp. 4114-4125 ◽  
Author(s):  
Margarita Cabrera ◽  
Manuel Muñiz ◽  
Josefina Hidalgo ◽  
Lucia Vega ◽  
María Esther Martín ◽  
...  
Keyword(s):  
Aspartic Acid ◽  
Retrograde Transport ◽  
Integral Membrane Protein ◽  
Truncated Form ◽  
Permeabilized Cells ◽  
C Terminus ◽  
Intermediate Compartment ◽  
Peptide Binding Assay ◽  
Kdel Receptor

The KDEL receptor is a Golgi/intermediate compartment-located integral membrane protein that carries out the retrieval of escaped ER proteins bearing a C-terminal KDEL sequence. This occurs throughout retrograde traffic mediated by COPI-coated transport carriers. The role of the C-terminal cytoplasmic domain of the KDEL receptor in this process has been investigated. Deletion of this domain did not affect receptor subcellular localization although cells expressing this truncated form of the receptor failed to retain KDEL ligands intracellularly. Permeabilized cells incubated with ATP and GTP exhibited tubular processes-mediated redistribution from the Golgi area to the ER of the wild-type receptor, whereas the truncated form lacking the C-terminal domain remained concentrated in the Golgi. As revealed with a peptide-binding assay, this domain did not interact with both coatomer and ARF-GAP unless serine 209 was mutated to aspartic acid. In contrast, alanine replacement of serine 209 inhibited coatomer/ARF-GAP recruitment, receptor redistribution into the ER, and intracellular retention of KDEL ligands. Serine 209 was phosphorylated by both cytosolic and recombinant protein kinase A (PKA) catalytic subunit. Inhibition of endogenous PKA activity with H89 blocked Golgi-ER transport of the native receptor but did not affect redistribution to the ER of a mutated form bearing aspartic acid at position 209. We conclude that PKA phosphorylation of serine 209 is required for the retrograde transport of the KDEL receptor from the Golgi complex to the ER from which the retrieval of proteins bearing the KDEL signal depends.

Factor Xa Enhances the Binding of Tissue Factor Pathway Inhibitor to Acidic Phospholipids

1996 ◽  
Vol 75 (05) ◽  
pp. 796-800 ◽  
Author(s):  
Sanne Valentin ◽  
Inger Schousboe
Keyword(s):  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Factor Xa ◽  
Microtitre Plate ◽  
C Terminus ◽  
Microtitre Plate Assay ◽  
Kunitz Domain ◽  
Tissue Factor Pathway ◽  
Acidic Phospholipids

SummaryIn the present study, the interaction between tissue factor pathway inhibitor (TFPI) and phospholipids has been characterized using a microtitre plate assay. TFPI was shown to bind calcium-independently to an acidic phospholipid surface composed of phosphatidylserine, but not a surface composed of the neutral phosphatidylcholine. The interaction was demonstrated to be dependent on the presence of the TFPI C-terminus. The presence of heparin (1 U/ml, unfractionated) was able to significantly reduce the binding of TFPI to phospholipid. The interaction of TFPI with phosphatidylserine was significantly decreased in the presence of calcium, but this was counteracted, and even enhanced, following complex formation of TFPI with factor Xa prior to incubation with the phospholipid surface. Moreover, a TFPI variant, not containing the third Kunitz domain and the C-terminus, was unable to bind to phospholipid. However, following the formation of a TFPI/factor Xa-complex this TFPI variant was capable of interacting with the phospholipid surface. This indicates that the role of factor Xa as a TFPI cofactor, at least in part, is to mediate the binding of TFPI to the phospholipid surface.

Association/dissociation Mechanisms of Intrinsically Disordered Region of Protein Beyond Conformational Selection and Induced Fit

2019 ◽  
Author(s):  
Duy Phuoc Tran ◽  
Akio Kitao
Keyword(s):  
Free Energy ◽  
Transcriptional Activation ◽  
Binding Free Energy ◽  
Energy Structure ◽  
Induced Fit ◽  
Hydrogen Bond Formation ◽  
Conformational Selection ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Region ◽  
Dissociation Mechanisms

<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>

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