scholarly journals The Effect of FG-Nup Phosphorylation on NPC Selectivity: A One-Bead-Per-Amino-Acid Molecular Dynamics Study

2019 ◽  
Vol 20 (3) ◽  
pp. 596 ◽  
Author(s):  
Ankur Mishra ◽  
Wouter Sipma ◽  
Liesbeth Veenhoff ◽  
Erik Van der Giessen ◽  
Patrick Onck
Keyword(s):  
Molecular Dynamics ◽  
Amino Acid ◽  
Intrinsically Disordered Proteins ◽  
Protein Complexes ◽  
Disordered Proteins ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Intrinsically Disordered ◽  
Dynamics Simulations ◽  
Pore Complexes

Nuclear pore complexes (NPCs) are large protein complexes embedded in the nuclear envelope separating the cytoplasm from the nucleoplasm in eukaryotic cells. They function as selective gates for the transport of molecules in and out of the nucleus. The inner wall of the NPC is coated with intrinsically disordered proteins rich in phenylalanine-glycine repeats (FG-repeats), which are responsible for the intriguing selectivity of NPCs. The phosphorylation state of the FG-Nups is controlled by kinases and phosphatases. In the current study, we extended our one-bead-per-amino-acid (1BPA) model for intrinsically disordered proteins to account for phosphorylation. With this, we performed molecular dynamics simulations to probe the effect of phosphorylation on the Stokes radius of isolated FG-Nups, and on the structure and transport properties of the NPC. Our results indicate that phosphorylation causes a reduced attraction between the residues, leading to an extension of the FG-Nups and the formation of a significantly less dense FG-network inside the NPC. Furthermore, our simulations show that upon phosphorylation, the transport rate of inert molecules increases, while that of nuclear transport receptors decreases, which can be rationalized in terms of modified hydrophobic, electrostatic, and steric interactions. Altogether, our models provide a molecular framework to explain how extensive phosphorylation of FG-Nups decreases the selectivity of the NPC.

scholarly journals The molecular mechanism of nuclear transport revealed by atomic-scale measurements

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Loren E Hough ◽  
Kaushik Dutta ◽  
Samuel Sparks ◽  
Deniz B Temel ◽  
Alia Kamal ◽  
...  
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Atomic Scale ◽  
Disordered Proteins ◽  
Nuclear Pore ◽  
Resonance Spectroscopy ◽  
Nuclear Pore Complexes ◽  
Selective Filter ◽  
Intrinsically Disordered ◽  
Cellular Environment ◽  
Pore Complexes

Nuclear pore complexes (NPCs) form a selective filter that allows the rapid passage of transport factors (TFs) and their cargoes across the nuclear envelope, while blocking the passage of other macromolecules. Intrinsically disordered proteins (IDPs) containing phenylalanyl-glycyl (FG)-rich repeats line the pore and interact with TFs. However, the reason that transport can be both fast and specific remains undetermined, through lack of atomic-scale information on the behavior of FGs and their interaction with TFs. We used nuclear magnetic resonance spectroscopy to address these issues. We show that FG repeats are highly dynamic IDPs, stabilized by the cellular environment. Fast transport of TFs is supported because the rapid motion of FG motifs allows them to exchange on and off TFs extremely quickly through transient interactions. Because TFs uniquely carry multiple pockets for FG repeats, only they can form the many frequent interactions needed for specific passage between FG repeats to cross the NPC.

scholarly journals The molecular chaperone DNAJB6 provides surveillance of FG-Nups and is required for interphase nuclear pore complex biogenesis

2021 ◽  
Author(s):  
E. F. Elsiena Kuiper ◽  
Paola Gallardo ◽  
Tessa Bergsma ◽  
Muriel Mari ◽  
Maiara Kolbe Musskopf ◽  
...  
Keyword(s):  
Molecular Chaperone ◽  
Intrinsically Disordered Proteins ◽  
Disordered Proteins ◽  
Nuclear Pore ◽  
Permeability Barrier ◽  
Nuclear Pore Complexes ◽  
Annulate Lamellae ◽  
Intrinsically Disordered ◽  
Pore Complexes

Biogenesis of nuclear pore complexes (NPCs) includes the formation of the permeability barrier composed of phenylalanine-glycine-rich nucleoporins (FG-Nups) that regulate the selective passage/crossing of biomolecules. The FG-Nups are intrinsically disordered and prone to liquid-liquid phase separate and aggregate when isolated. It has remained largely unclear how FG-Nups are protected from making inappropriate interactions during NPC biogenesis. We found that DNAJB6, a molecular chaperone of the heat shock protein network, formed foci next to NPCs. The number of these foci decreases upon removal of proteins involved in the early steps of interphase NPC biogenesis. Reversely, when this process is stalled in the last steps, the number of DNAJB6-containing foci increases and they could be identified as herniations at the nuclear envelope (NE). Immunoelectron tomography showed that DNAJB6 localizes inside the lumen of the herniations arising at NPC biogenesis intermediates. Interestingly, loss of DNAJB6 results in annulate lamellae, which are structures containing partly assembled NPCs associated with disturbances in NPC biogenesis. We find that DNAJB6 binds to FG-Nups and can prevent the aggregation of the FG-region of several FG-Nups in cells and in vitro. Together, our data show that DNAJB6 provides quality control during NPC biogenesis and is the first molecular chaperone that is involved in the surveillance of native intrinsically disordered proteins, including FG-Nups.

scholarly journals Optimization of Molecular Dynamics Simulations of c-MYC1-88—An Intrinsically Disordered System

Life ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 109 ◽  
Author(s):  
Sandra S. Sullivan ◽  
Robert O.J. Weinzierl
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Intrinsically Disordered Proteins ◽  
Disordered Proteins ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Proliferation And Apoptosis ◽  
Conventional Structure ◽  
Experimental Approaches ◽  
Dynamics Simulations

Many of the proteins involved in key cellular regulatory events contain extensive intrinsically disordered regions that are not readily amenable to conventional structure/function dissection. The oncoprotein c-MYC plays a key role in controlling cell proliferation and apoptosis and more than 70% of the primary sequence is disordered. Computational approaches that shed light on the range of secondary and tertiary structural conformations therefore provide the only realistic chance to study such proteins. Here, we describe the results of several tests of force fields and water models employed in molecular dynamics simulations for the N-terminal 88 amino acids of c-MYC. Comparisons of the simulation data with experimental secondary structure assignments obtained by NMR establish a particular implicit solvation approach as highly congruent. The results provide insights into the structural dynamics of c-MYC1-88, which will be useful for guiding future experimental approaches. The protocols for trajectory analysis described here will be applicable for the analysis of a variety of computational simulations of intrinsically disordered proteins.

scholarly journals Characterization of partially ordered states in the intrinsically disordered N-terminal domain of p53 using millisecond molecular dynamics simulations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Pablo Herrera-Nieto ◽  
Adrià Pérez ◽  
Gianni De Fabritiis
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Intrinsically Disordered Proteins ◽  
Dynamical Behavior ◽  
Disordered Proteins ◽  
Partially Ordered ◽  
Intrinsically Disordered ◽  
State Models ◽  
Dynamics Simulations

Abstract The exploration of intrinsically disordered proteins in isolation is a crucial step to understand their complex dynamical behavior. In particular, the emergence of partially ordered states has not been explored in depth. The experimental characterization of such partially ordered states remains elusive due to their transient nature. Molecular dynamics mitigates this limitation thanks to its capability to explore biologically relevant timescales while retaining atomistic resolution. Here, millisecond unbiased molecular dynamics simulations were performed in the exemplar N-terminal region of p53. In combination with state-of-the-art Markov state models, simulations revealed the existence of several partially ordered states accounting for $$\sim $$ ∼ 40% of the equilibrium population. Some of the most relevant states feature helical conformations similar to the bound structure of p53 to Mdm2, as well as novel $$\beta $$ β -sheet elements. This highlights the potential complexity underlying the energy surface of intrinsically disordered proteins.

scholarly journals Size-dependent leak of soluble and membrane proteins through the yeast nuclear pore complex

2015 ◽  
Vol 26 (7) ◽  
pp. 1386-1394 ◽  
Author(s):  
Petra Popken ◽  
Ali Ghavami ◽  
Patrick R. Onck ◽  
Bert Poolman ◽  
Liesbeth M. Veenhoff
Keyword(s):  
Molecular Dynamics ◽  
Membrane Proteins ◽  
Coarse Grained ◽  
Nuclear Pore ◽  
Permeability Barrier ◽  
Nuclear Pore Complexes ◽  
Structural And Functional Properties ◽  
Dynamics Simulations ◽  
Pore Complexes

Nuclear pore complexes (NPCs) allow selective import and export while forming a barrier for untargeted proteins. Using fluorescence microscopy, we measured in vivo the permeability of the Saccharomyces cerevisiae NPC for multidomain proteins of different sizes and found that soluble proteins of 150 kDa and membrane proteins with an extralumenal domain of 90 kDa were still partly localized in the nucleus on a time scale of hours. The NPCs thus form only a weak barrier for the majority of yeast proteins, given their monomeric size. Using FGΔ-mutant strains, we showed that specific combinations of Nups, especially with Nup100, but not the total mass of FG-nups per pore, were important for forming the barrier. Models of the disordered phase of wild-type and mutant NPCs were generated using a one bead per amino acid molecular dynamics model. The permeability measurements correlated with the density predictions from coarse-grained molecular dynamics simulations in the center of the NPC. The combined in vivo and computational approach provides a framework for elucidating the structural and functional properties of the permeability barrier of nuclear pore complexes.

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