scholarly journals Combinatorial multivalent interactions drive cooperative assembly of the COPII coat

2020 ◽  
Vol 219 (11) ◽  
Author(s):  
Viktoriya G. Stancheva ◽  
Xiao-Han Li ◽  
Joshua Hutchings ◽  
Natalia Gomez-Navarro ◽  
Balaji Santhanam ◽  
...  
Keyword(s):  
Membrane Curvature ◽  
Outer Coat ◽  
Vesicle Traffic ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Region ◽  
Local Assembly ◽  
Multivalent Interactions ◽  
Coat Layer ◽  
Cooperative Assembly ◽  
Binding Interfaces

Protein secretion is initiated at the endoplasmic reticulum by the COPII coat, which self-assembles to form vesicles. Here, we examine the mechanisms by which a cargo-bound inner coat layer recruits and is organized by an outer scaffolding layer to drive local assembly of a stable structure rigid enough to enforce membrane curvature. An intrinsically disordered region in the outer coat protein, Sec31, drives binding with an inner coat layer via multiple distinct interfaces, including a newly defined charge-based interaction. These interfaces combinatorially reinforce each other, suggesting coat oligomerization is driven by the cumulative effects of multivalent interactions. The Sec31 disordered region could be replaced by evolutionarily distant sequences, suggesting plasticity in the binding interfaces. Such a multimodal assembly platform provides an explanation for how cells build a powerful yet transient scaffold to direct vesicle traffic.

scholarly journals A multivalent fuzzy interface drives reversible COPII coat assembly

2020 ◽  
Author(s):  
Viktoriya G. Stancheva ◽  
Joshua Hutchings ◽  
Xiao-Han Li ◽  
Balaji Santhanam ◽  
M. Madan Babu ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Membrane Curvature ◽  
Cumulative Effects ◽  
Outer Coat ◽  
Vesicle Traffic ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Region ◽  
Local Assembly ◽  
Coat Layer

AbstractProtein secretion is initiated at the endoplasmic reticulum by the COPII coat, which self-assembles to form vesicles. Here, we examine the mechanisms by which the outer scaffolding layer of the coat drives local assembly of a structure rigid enough to enforce membrane curvature, yet able to readily disassemble at the Golgi. An intrinsically disordered region in the outer coat protein, Sec31, drives binding with an inner coat layer via multiple distinct interfaces. Interactions are individually dispensable but combinatorially reinforce each other, suggesting coat oligomerization is driven by the cumulative effects of multivalent interactions. Such a multimodal assembly platform could be readily reversed at the Golgi via perturbation of each individual interface. These design principles provide an explanation for how cells build a powerful yet transient scaffold to direct vesicle traffic.

scholarly journals Comparative study of curvature sensing mediated by F-BAR domain and an intrinsically disordered region of FBP17

2020 ◽  
Author(s):  
Maohan Su ◽  
Yinyin Zhuang ◽  
Xinwen Miao ◽  
Yongpeng Zeng ◽  
Weibo Gao ◽  
...  
Keyword(s):  
Lipid Bilayer ◽  
Membrane Trafficking ◽  
Membrane Curvature ◽  
Wave System ◽  
Common Belief ◽  
Bar Domain ◽  
Curvature Sensing ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Region

Membrane curvature has emerged as an intriguing physical organization principle underlying biological signaling and membrane trafficking. FBP17 of the CIP4/FBP17/Toca-1 F-BAR family is unique in the BAR family because its structurally folded F-BAR domain does not contain any hydrophobic motifs that insert into lipid bilayer. While it has been widely assumed so, whether the banana-shaped F-BAR domain alone can sense curvature has never been experimentally demonstrated. Using a nanopillar-supported lipid bilayer system, we found that the F-BAR domain of FBP17 displayed minimal curvature sensing in vitro. We further identified an alternatively spliced intrinsically disordered region (IDR) of FBP17 next to its F-BAR domain that is conserved in sequence across species. The IDR senses membrane curvature and its sensing ability greatly exceeds that of F-BAR domain alone. In living cells, presence of the IDR domain changed the dynamics of FBP17 recruitment in a curvature-coupled cortical wave system. Collectively, we propose that FBP17 does sense curvature but contrary to the common belief, its curvature sensing capability largely originates from its disordered region, not F-BAR domain itself.

scholarly journals Cavin1 intrinsically disordered domains are essential for fuzzy electrostatic interactions and caveola formation

2019 ◽  
Author(s):  
Vikas A. Tillu ◽  
James Rae ◽  
Ya Gao ◽  
Nicholas Ariotti ◽  
Matthias Floetenmeyer ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Membrane Lipid ◽  
Membrane Curvature ◽  
Caveolin 1 ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Solution Generation ◽  
Endosomal System ◽  
Cooperative Assembly

SummaryCaveolae are spherically shaped nanodomains of the plasma membrane, generated by cooperative assembly of caveolin and cavin proteins. Cavins are cytosolic peripheral membrane proteins with negatively charged intrinsically disordered regions (DR1-3) that flank positively charged α-helical regions (HR1 and HR2). Here we show that the three DR domains of Cavin1 are essential for caveola formation and dynamic trafficking of caveolae. Electrostatic interactions between DR and HR regions promote liquid-liquid phase separation behaviour of Cavin1 in vitro, assembly of Cavin1 oligomers in solution, generation of membrane curvature, association with caveolin-1 (CAV1), and Cavin1 recruitment to caveolae in cells. Removal of the first disordered region causes irreversible gel formation in vitro and results in aberrant caveola trafficking through the endosomal system. We propose a model for caveola assembly whereby fuzzy electrostatic interactions between Cavin1 and CAV1 proteins, combined with membrane lipid interactions, are required to generate membrane curvature and a metastable caveola coat.

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>

scholarly journals Cavin1 intrinsically disordered domains are essential for fuzzy electrostatic interactions and caveola formation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Vikas A. Tillu ◽  
James Rae ◽  
Ya Gao ◽  
Nicholas Ariotti ◽  
Matthias Floetenmeyer ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Membrane Lipid ◽  
Membrane Curvature ◽  
Caveolin 1 ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Solution Generation ◽  
Endosomal System ◽  
Disordered Regions

AbstractCaveolae are spherically shaped nanodomains of the plasma membrane, generated by cooperative assembly of caveolin and cavin proteins. Cavins are cytosolic peripheral membrane proteins with negatively charged intrinsically disordered regions that flank positively charged α-helical regions. Here, we show that the three disordered domains of Cavin1 are essential for caveola formation and dynamic trafficking of caveolae. Electrostatic interactions between disordered regions and α-helical regions promote liquid-liquid phase separation behaviour of Cavin1 in vitro, assembly of Cavin1 oligomers in solution, generation of membrane curvature, association with caveolin-1, and Cavin1 recruitment to caveolae in cells. Removal of the first disordered region causes irreversible gel formation in vitro and results in aberrant caveola trafficking through the endosomal system. We propose a model for caveola assembly whereby fuzzy electrostatic interactions between Cavin1 and caveolin-1 proteins, combined with membrane lipid interactions, are required to generate membrane curvature and a metastable caveola coat.

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