scholarly journals Membrane bending by protein phase separation

2021 ◽  
Vol 118 (11) ◽  
pp. e2017435118
Author(s):  
Feng Yuan ◽  
Haleh Alimohamadi ◽  
Brandon Bakka ◽  
Andrea N. Trementozzi ◽  
Kasey J. Day ◽  
...  
Keyword(s):  
Phase Separation ◽  
Three Dimensional ◽  
Membrane Vesicles ◽  
Structural Features ◽  
Membrane Curvature ◽  
Dimensional Structure ◽  
Organelle Biogenesis ◽  
Liquid Phases ◽  
Membrane Tubules ◽  
Membrane Bending

Membrane bending is a ubiquitous cellular process that is required for membrane traffic, cell motility, organelle biogenesis, and cell division. Proteins that bind to membranes using specific structural features, such as wedge-like amphipathic helices and crescent-shaped scaffolds, are thought to be the primary drivers of membrane bending. However, many membrane-binding proteins have substantial regions of intrinsic disorder which lack a stable three-dimensional structure. Interestingly, many of these disordered domains have recently been found to form networks stabilized by weak, multivalent contacts, leading to assembly of protein liquid phases on membrane surfaces. Here we ask how membrane-associated protein liquids impact membrane curvature. We find that protein phase separation on the surfaces of synthetic and cell-derived membrane vesicles creates a substantial compressive stress in the plane of the membrane. This stress drives the membrane to bend inward, creating protein-lined membrane tubules. A simple mechanical model of this process accurately predicts the experimentally measured relationship between the rigidity of the membrane and the diameter of the membrane tubules. Discovery of this mechanism, which may be relevant to a broad range of cellular protrusions, illustrates that membrane remodeling is not exclusive to structured scaffolds but can also be driven by the rapidly emerging class of liquid-like protein networks that assemble at membranes.

scholarly journals Membrane bending by protein phase separation

2020 ◽  
Author(s):  
Feng Yuan ◽  
Haleh Alimohamadi ◽  
Brandon Bakka ◽  
Andrea N. Trementozzi ◽  
Nicolas L. Fawzi ◽  
...  
Keyword(s):  
Phase Separation ◽  
Cell Division ◽  
Compressive Stress ◽  
Membrane Surface ◽  
Membrane Curvature ◽  
Dimensional Structure ◽  
Cellular Membranes ◽  
Protein Assemblies ◽  
Membrane Tubules ◽  
Membrane Bending

AbstractMembrane bending is a ubiquitous cellular process that is required for membrane traffic, cell motility, organelle biogenesis, and cell division. Proteins that bind to membranes using specific structural features, such as wedge-like amphipathic helices and crescent-shaped scaffolds, are thought to be the primary drivers of membrane bending. However, many membrane-binding proteins have substantial regions of intrinsic disorder, which lack a stable three-dimensional structure. Interestingly, many of these disordered domains have recently been found to form networks stabilized by weak, multi-valent contacts, leading to assembly of protein liquid phases on membrane surfaces. Here we ask how membrane-associated protein liquids impact membrane curvature. We find that protein phase separation on the surfaces of synthetic and cell-derived membrane vesicles creates a substantial compressive stress in the plane of the membrane. This stress drives the membrane to bend inward, creating protein-lined membrane tubules. A simple mechanical model of this process accurately predicts the experimentally measured relationship between the rigidity of the membrane and the diameter of the membrane tubules. Discovery of this mechanism, which may be relevant to a broad range of cellular protrusions, illustrates that membrane remodeling is not exclusive to structured scaffolds, but can also be driven by the rapidly emerging class of liquid-like protein networks that assemble at membranes.Significance StatementCellular membranes take on an elaborate set of highly curved and bent shapes, which are essential to diverse cellular functions from endocytosis to cell division. The prevailing view has been that membrane bending is driven by proteins with curved shapes, which assemble at the membrane surface to form solid scaffolds. In contrast, here we show that proteins which form liquid-like assemblies on membranes are also potent drivers of bending. These “liquid scaffolds” apply compressive stress to the membrane surface, generating a diverse and dynamic family of membrane shapes. These data, which come at a time when liquid-like protein assemblies are being identified throughout the cell, suggest that liquid-like protein assemblies may play an important role in shaping cellular membranes.

Crystal structure of the hinge domain of Smchd1 reveals its dimerization mode and nucleic acid–binding residues

2020 ◽  
Vol 13 (636) ◽  
pp. eaaz5599 ◽  
Author(s):  
Kelan Chen ◽  
Richard W. Birkinshaw ◽  
Alexandra D. Gurzau ◽  
Iromi Wanigasuriya ◽  
Ruoyun Wang ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Muscular Dystrophy ◽  
Three Dimensional ◽  
Underlying Mechanism ◽  
Structural Features ◽  
Facioscapulohumeral Muscular Dystrophy ◽  
Dimensional Structure ◽  
Nucleic Acid Binding ◽  
X Ray Crystallography ◽  
Hinge Domain

Structural maintenance of chromosomes flexible hinge domain containing 1 (SMCHD1) is an epigenetic regulator in which polymorphisms cause the human developmental disorder, Bosma arhinia micropthalmia syndrome, and the degenerative disease, facioscapulohumeral muscular dystrophy. SMCHD1 is considered a noncanonical SMC family member because its hinge domain is C-terminal, because it homodimerizes rather than heterodimerizes, and because SMCHD1 contains a GHKL-type, rather than an ABC-type ATPase domain at its N terminus. The hinge domain has been previously implicated in chromatin association; however, the underlying mechanism involved and the basis for SMCHD1 homodimerization are unclear. Here, we used x-ray crystallography to solve the three-dimensional structure of the Smchd1 hinge domain. Together with structure-guided mutagenesis, we defined structural features of the hinge domain that participated in homodimerization and nucleic acid binding, and we identified a functional hotspot required for chromatin localization in cells. This structure provides a template for interpreting the mechanism by which patient polymorphisms within the SMCHD1 hinge domain could compromise function and lead to facioscapulohumeral muscular dystrophy.

scholarly journals PROTEIN TEACHING: AN APPROACH FOR TEACHER TRAINING APPLIED TO STUDENTS OF THE BIOLOGICAL SCIENCES COURSE AT UFRN

2015 ◽  
Vol 13 ◽  
pp. 34
Author(s):  
J. K.S. NASCIMENTO et al
Keyword(s):  
Biological Sciences ◽  
Teaching Practice ◽  
Basic Education ◽  
New Technologies ◽  
Lesson Plan ◽  
Three Dimensional ◽  
Structural Features ◽  
Dimensional Structure ◽  
Educational Models ◽  
Teaching Learning

Teaching biochemistry in higher education is increasingly becoming a challenge. It is notoriously difficult for students to assimilate the topic; in addition there are many complaints about the complexity of subjects and a lack of integration with the day-to-day. A recurrent problem in undergraduate courses is the absence of teaching practice in specific disciplines. This work aimed to stimulate students in the biological sciences course who were enrolled in the discipline of MOLECULAR DIVERSITY (MD), to create hypothetical classes focused on basic education highlighting the proteins topic. The methodology was applied in a class that contained 35 students. Seven groups were formed, and each group chose a protein to be used as a source of study for elementary school classes. A lesson plan was created focusing on the methodology that the group would use to manage a class. The class was to be presented orally. Students were induced to be creative and incorporate a teacher figure, and to propose teaching methodologies for research using the CTS approach (Science, Technology and Society). Each group presented a three-dimensional structure of the protein they had chosen, explained their structural features and functions and how they would develop the theme for a class of basic education, and what kind of methodology they would use for this purpose. At the end of the presentations, a questionnaire was given to students in order to evaluate the effectiveness of the methodology in the teaching-learning process. The activity improved the teacher’s training and developed skills and abilities, such as creativity, didactical planning, teaching ability, development of educational models and the use of new technologies. The methodology used in this work was extremely important to the training of future teachers, who were able to better understand the content covered in the discipline and relate it to day-to-day life.

scholarly journals Repeat elements organize 3D genome structure and mediate transcription in the filamentous fungusEpichloë festucae

2018 ◽  
Author(s):  
David J Winter ◽  
Austen RD Ganley ◽  
Carolyn A Young ◽  
Ivan Liachko ◽  
Christopher L Schardl ◽  
...  
Keyword(s):  
Genome Structure ◽  
Regulation Of Gene Expression ◽  
Three Dimensional ◽  
Structural Features ◽  
Dimensional Structure ◽  
In Planta ◽  
Repeat Elements ◽  
Symbiotic Relationships ◽  
3D Genome ◽  
Transcriptional Changes

AbstractStructural features of genomes, including the three-dimensional arrangement of DNA in the nucleus, are increasingly seen as key contributors to the regulation of gene expression. However, studies on how genome structure and nuclear organization influence transcription have so far been limited to a handful of model species. This narrow focus limits our ability to draw general conclusions about the ways in which three-dimensional structures are encoded, and to integrate information from three-dimensional data to address a broader gamut of biological questions. Here, we generate a complete and gapless genome sequence for the filamentous fungus,Epichloë festucae. Coupling it with RNAseq and HiC data, we investigate how the structure of the genome contributes to the suite of transcriptional changes that anEpichloëspecies needs to maintain symbiotic relationships with its grass host. Our results reveal a unique “patchwork” genome, in which repeat-rich blocks of DNA with discrete boundaries are interspersed by gene-rich sequences. In contrast to other species, the three-dimensional structure of the genome is anchored by these repeat blocks, which act to isolate transcription in neighbouring gene-rich regions. Genes that are differentially expressed in planta are enriched near the boundaries of these repeat-rich blocks, suggesting that their three-dimensional orientation partly encodes and regulates the symbiotic relationship formed by this organism.

scholarly journals Structural Features of a Bacteroidetes-Affiliated Cellulase Linked with a Polysaccharide Utilization Locus

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
A.E. Naas ◽  
A.K. MacKenzie ◽  
B. Dalhus ◽  
V.G.H. Eijsink ◽  
P.B. Pope
Keyword(s):  
Active Site ◽  
Three Dimensional ◽  
Structural Features ◽  
Structure And Function ◽  
Dimensional Structure ◽  
Active Site Cleft ◽  
Polysaccharide Utilization Locus ◽  
And Function ◽  
Rumen Metagenome

Abstract Previous gene-centric analysis of a cow rumen metagenome revealed the first potentially cellulolytic polysaccharide utilization locus, of which the main catalytic enzyme (AC2aCel5A) was identified as a glycoside hydrolase (GH) family 5 endo-cellulase. Here we present the 1.8 Å three-dimensional structure of AC2aCel5A and characterization of its enzymatic activities. The enzyme possesses the archetypical (β/α)8-barrel found throughout the GH5 family and contains the two strictly conserved catalytic glutamates located at the C-terminal ends of β-strands 4 and 7. The enzyme is active on insoluble cellulose and acts exclusively on linear β-(1,4)-linked glucans. Co-crystallization of a catalytically inactive mutant with substrate yielded a 2.4 Å structure showing cellotriose bound in the −3 to −1 subsites. Additional electron density was observed between Trp178 and Trp254, two residues that form a hydrophobic “clamp”, potentially interacting with sugars at the +1 and +2 subsites. The enzyme’s active-site cleft was narrower compared to the closest structural relatives, which in contrast to AC2aCel5A, are also active on xylans, mannans and/or xyloglucans. Interestingly, the structure and function of this enzyme seem adapted to less-substituted substrates such as cellulose, presumably due to the insufficient space to accommodate the side-chains of branched glucans in the active-site cleft.

Structural characterization of intrinsically disordered proteins by the combined use of NMR and SAXS

2012 ◽  
Vol 40 (5) ◽  
pp. 955-962 ◽  
Author(s):  
Nathalie Sibille ◽  
Pau Bernadó
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Dynamic Models ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Main Tool ◽  
Structural Features ◽  
Disordered Proteins ◽  
Dimensional Structure ◽  
Intrinsically Disordered ◽  
Conformational Preferences

In recent years, IDPs (intrinsically disordered proteins) have emerged as pivotal actors in biology. Despite IDPs being present in all kingdoms of life, they are more abundant in eukaryotes where they are involved in the vast majority of regulation and signalling processes. The realization that, in some cases, functional states of proteins were partly or fully disordered was in contradiction to the traditional view where a well defined three-dimensional structure was required for activity. Several experimental evidences indicate, however, that structural features in IDPs such as transient secondary-structural elements and overall dimensions are crucial to their function. NMR has been the main tool to study IDP structure by probing conformational preferences at residue level. Additionally, SAXS (small-angle X-ray scattering) has the capacity to report on the three-dimensional space sampled by disordered states and therefore complements the local information provided by NMR. The present review describes how the synergy between NMR and SAXS can be exploited to obtain more detailed structural and dynamic models of IDPs in solution. These combined strategies, embedded into computational approaches, promise the elucidation of the structure–function properties of this important, but elusive, family of biomolecules.

Zona Pellucida Proteins, Fibrils, and Matrix

2020 ◽  
Vol 89 (1) ◽  
pp. 695-715
Author(s):  
Eveline S. Litscher ◽  
Paul M. Wassarman
Keyword(s):  
Extracellular Matrix ◽  
Zona Pellucida ◽  
Three Dimensional ◽  
Structural Features ◽  
Biological Properties ◽  
Preimplantation Development ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Early Embryos ◽  
N Terminus

The zona pellucida (ZP) is an extracellular matrix that surrounds all mammalian oocytes, eggs, and early embryos and plays vital roles during oogenesis, fertilization, and preimplantation development. The ZP is composed of three or four glycosylated proteins, ZP1–4, that are synthesized, processed, secreted, and assembled into long, cross-linked fibrils by growing oocytes. ZP proteins have an immunoglobulin-like three-dimensional structure and a ZP domain that consists of two subdomains, ZP-N and ZP-C, with ZP-N of ZP2 and ZP3 required for fibril assembly. A ZP2–ZP3 dimer is located periodically along ZP fibrils that are cross-linked by ZP1, a protein with a proline-rich N terminus. Fibrils in the inner and outer regions of the ZP are oriented perpendicular and parallel to the oolemma, respectively, giving the ZP a multilayered appearance. Upon fertilization of eggs, modification of ZP2 and ZP3 results in changes in the ZP's physical and biological properties that have important consequences. Certain structural features of ZP proteins suggest that they may be amyloid-like proteins.

Development of a Quickly Erectable Prefabricated Collapsible Construction System for Temporary Accommodation

2018 ◽  
Vol 931 ◽  
pp. 411-416
Author(s):  
S.G. Abramyan ◽  
Vladimir G. Polyakov ◽  
Svetlana I. Lipatova ◽  
O.V. Oganesyan
Keyword(s):  
Three Dimensional ◽  
Environmental Safety ◽  
Structural Features ◽  
Dimensional Structure ◽  
Labor Costs ◽  
Scientific Publications ◽  
Space Planning ◽  
Covering Set ◽  
Temporary Accommodation ◽  
Construction System

This paper considers the importance of quickly erectable construction systems, as well as their main purpose and applicability in various situations. Based on the analysis of scientific publications and the results of patent search, the authors suggest the structural features and technological solutions for installation of a new small-size quickly erectable collapsible construction system. The system is designed for temporary accommodation of a group of people involved in construction, geological exploration and other works in hard-to-reach areas, for tourists etc. Such a collapsible construction system can be adapted to serve as a temporary shelter for people surviving natural calamities. The foundation of the suggested system is an enclosed three-dimensional structure (crate) where the necessary structural elements are kept pending the assembly of the construction system, including telescopic legs and other tubular framing structures, rolls of tent covering, set of coupling elements, and supports. The specific features of this new system, as compared to similar space planning solutions, are low labor costs involved in its assembly and dismantling, small weight ensuring transportability of a collapsed and packed system, and reusability. Other benefits of the new small-size construction system include its low overall cost, environmental safety and energy efficiency.

scholarly journals Single particle cryo-EM structure of the outer hair cell motor protein prestin

2021 ◽  
Author(s):  
Carmen BUtan ◽  
Qiang Song ◽  
Jun-ping Bai ◽  
Winston Tan ◽  
Dhasakumar S Navaratnam ◽  
...  
Keyword(s):  
Hair Cell ◽  
Binding Site ◽  
Outer Hair Cell ◽  
Three Dimensional ◽  
Structural Features ◽  
Meriones Unguiculatus ◽  
Dimensional Structure ◽  
Transmembrane Segments ◽  
Anion Transporter ◽  
Mechanistic Basis

The mammalian outer hair cell (OHC) protein prestin (Slc26a5), a member of the solute carrier 26 (Slc26) family of membrane proteins, differs from other members of the family owing to its unique piezoelectric-like property that drives OHC electromotility. Prestin is required by OHCs for cochlear amplification, a process that enhances mammalian hearing. Despite substantial biophysical characterization, the mechanistic basis for the prestins electro-mechanical behavior is not fully understood. To gain insight into such behavior, we have used cryo-electron microscopy at subnanometer resolution (overall resolution of 4.0 Å) to investigate the three-dimensional structure of prestin from gerbil (Meriones unguiculatus). Our studies show that prestin dimerizes with a 3D architecture strikingly similar to the dimeric conformation observed in the Slc26a9 anion transporter in an inside open/intermediate state, which we infer, based on patch clamp recordings, to reflect the contracted state of prestin. The structure shows two well separated transmembrane (TM) subunits and two cytoplasmic sulfate transporter and anti-sigma factor antagonist (STAS) domains forming a swapped dimer. The dimerization interface is defined by interactions between the domain-swapped STAS dimer and the transmembrane domains of the opposing half unit, further strengthened by an antiparallel beta strand at its N terminus. The structure also shows that each one of its two transmembrane subunits consists of 14 transmembrane segments organized in two inverted 7-segment repeats with a topology that was first observed in the structure of the bacterial symporter UraA (Lu F, et al., Nature 472, 2011). Finally, the solved anion binding site structural features of prestin are quite similar to that of SLC26a9 and other family members. Despite this similarity, we find that SLC26a9 lacks the characteristic displacement currents (or NonLinear Capacitance(NLC)) found with prestin, and we show that mutation of prestins Cl- binding site removes salicylate competition with anions in the face of normal NLC, thus refuting the yet accepted extrinsic voltage sensor hypothesis and any associated transport-like requirements for voltage-driven electromotility.

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