scholarly journals The N-Terminal Region of Soybean PM1 Protein Protects Liposomes during Freeze-Thaw

2020 ◽  
Vol 21 (15) ◽  
pp. 5552
Author(s):  
Liyi Chen ◽  
Yajun Sun ◽  
Yun Liu ◽  
Yongdong Zou ◽  
Jianzi Huang ◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Membrane Fusion ◽  
Terminal Region ◽  
Freezing Stress ◽  
Disordered Proteins ◽  
Distribution Analysis ◽  
Protective Function ◽  
Freeze Thaw ◽  
Intrinsically Disordered ◽  
Induced Aggregation

Late embryogenesis abundant (LEA) group 1 (LEA_1) proteins are intrinsically disordered proteins (IDPs) that play important roles in protecting plants from abiotic stress. Their protective function, at a molecular level, has not yet been fully elucidated, but several studies suggest their involvement in membrane stabilization under stress conditions. In this paper, the soybean LEA_1 protein PM1 and its truncated forms (PM1-N: N-terminal half; PM1-C: C-terminal half) were tested for the ability to protect liposomes against damage induced by freeze-thaw stress. Turbidity measurement and light microscopy showed that full-length PM1 and PM1-N, but not PM1-C, can prevent freeze-thaw-induced aggregation of POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) liposomes and native thylakoid membranes, isolated from spinach leaves (Spinacia oleracea). Particle size distribution analysis by dynamic light scattering (DLS) further confirmed that PM1 and PM1-N can prevent liposome aggregation during freeze-thaw. Furthermore, PM1 or PM1-N could significantly inhibit membrane fusion of liposomes, but not reduce the leakage of their contents following freezing stress. The results of proteolytic digestion and circular dichroism experiments suggest that PM1 and PM1-N proteins bind mainly on the surface of the POPC liposome. We propose that, through its N-terminal region, PM1 functions as a membrane-stabilizing protein during abiotic stress, and might inhibit membrane fusion and aggregation of vesicles or other endomembrane structures within the plant cell.

scholarly journals Preferential adsorption to air–water interfaces: a novel cryoprotective mechanism for LEA proteins

2019 ◽  
Vol 476 (7) ◽  
pp. 1121-1135 ◽  
Author(s):  
Fanny Yuen ◽  
Matthew Watson ◽  
Robert Barker ◽  
Isabelle Grillo ◽  
Richard K. Heenan ◽  
...  
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Citrate Synthase ◽  
Abiotic Stress Tolerance ◽  
Interfacial Area ◽  
Disordered Proteins ◽  
General Mechanism ◽  
Lea Proteins ◽  
Freeze Thaw ◽  
Intrinsically Disordered ◽  
Induced Aggregation

Abstract Late embryogenesis abundant (LEA) proteins comprise a diverse family whose members play a key role in abiotic stress tolerance. As intrinsically disordered proteins, LEA proteins are highly hydrophilic and inherently stress tolerant. They have been shown to stabilise multiple client proteins under a variety of stresses, but current hypotheses do not fully explain how such broad range stabilisation is achieved. Here, using neutron reflection and surface tension experiments, we examine in detail the mechanism by which model LEA proteins, AavLEA1 and ERD10, protect the enzyme citrate synthase (CS) from aggregation during freeze–thaw. We find that a major contributing factor to CS aggregation is the formation of air bubbles during the freeze–thaw process. This greatly increases the air–water interfacial area, which is known to be detrimental to folded protein stability. Both model LEA proteins preferentially adsorb to this interface and compete with CS, thereby reducing surface-induced aggregation. This novel surface activity provides a general mechanism by which diverse members of the LEA protein family might function to provide aggregation protection that is not specific to the client protein.

scholarly journals Conformational propensities of intrinsically disordered proteins influence the mechanism of binding and folding

2015 ◽  
Vol 112 (31) ◽  
pp. 9614-9619 ◽  
Author(s):  
Munehito Arai ◽  
Kenji Sugase ◽  
H. Jane Dyson ◽  
Peter E. Wright
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Terminal Region ◽  
Relaxation Dispersion ◽  
Disordered Proteins ◽  
Conformational Ensemble ◽  
Induced Fit ◽  
Conformational Selection ◽  
Intrinsically Disordered ◽  
Factor C ◽  
Binding Mechanisms

Intrinsically disordered proteins (IDPs) frequently function in protein interaction networks that regulate crucial cellular signaling pathways. Many IDPs undergo transitions from disordered conformational ensembles to folded structures upon binding to their cellular targets. Several possible binding mechanisms for coupled folding and binding have been identified: folding of the IDP after association with the target (“induced fit”), or binding of a prefolded state in the conformational ensemble of the IDP to the target protein (“conformational selection”), or some combination of these two extremes. The interaction of the intrinsically disordered phosphorylated kinase-inducible domain (pKID) of the cAMP-response element binding (CREB) protein with the KIX domain of a general transcriptional coactivator CREB-binding protein (CBP) provides an example of the induced-fit mechanism. Here we show by NMR relaxation dispersion experiments that a different intrinsically disordered ligand, the transactivation domain of the transcription factor c-Myb, interacts with KIX at the same site as pKID but via a different binding mechanism that involves elements of conformational selection and induced fit. In contrast to pKID, the c-Myb activation domain has a strong propensity for spontaneous helix formation in its N-terminal region, which binds to KIX in a predominantly folded conformation. The C-terminal region of c-Myb exhibits a much smaller helical propensity and likely folds via an induced-fit process after binding to KIX. We propose that the intrinsic secondary structure propensities of pKID and c-Myb determine their binding mechanisms, consistent with their functions as inducible and constitutive transcriptional activators.

scholarly journals Multisite Phosphorylation and Binding Alter Conformational Dynamics of the 4E-BP2 Protein

2022 ◽  
Author(s):  
Spencer Smyth ◽  
Zhenfu Zhang ◽  
Alaji Bah ◽  
Thomas Tsangaris ◽  
Jennifer Dawson ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Intrinsically Disordered Proteins ◽  
Regulatory Protein ◽  
Conformational Dynamics ◽  
Correlation Spectroscopy ◽  
Terminal Region ◽  
Disordered Proteins ◽  
Initiation Factor ◽  
Dependent Manner ◽  
Intrinsically Disordered

Intrinsically disordered proteins (IDPs) play critical roles in regulatory protein interactions, but detailed structural/dynamics characterization of their ensembles remain challenging, both in isolation and they form dynamic fuzzy complexes. Such is the case for mRNA cap-dependent translation initiation, which is regulated by the interaction of the predominantly folded eukaryotic initiation factor 4E (eIF4E) with the intrinsically disordered eIF4E binding proteins (4E-BPs) in a phosphorylation-dependent manner. Single-molecule Forster resonance energy transfer showed that the conformational changes of 4E-BP2 induced by binding to eIF4E are non-uniform along the sequence; while a central region containing both motifs that bind to eIF4E expands and becomes stiffer, the C-terminal region is less affected. Fluorescence anisotropy decay revealed a nonuniform segmental flexibility around six different labelling sites along the chain. Dynamic quenching of these fluorescent probes by intrinsic aromatic residues measured via fluorescence correlation spectroscopy report on transient intra- and inter-molecular contacts on nanosecond-microsecond timescales. Upon hyperphosphorylation, which induces folding of ~40 residues in 4E-BP2, the quenching rates decreased at labelling sites closest to the phosphorylation sites and within the folded domain, and increased at the other sites. The chain dynamics around sites in the C-terminal region far away from the two binding motifs were significantly reduced upon binding to eIF4E, suggesting that this region is also involved in the highly dynamic 4E-BP2:eIF4E complex. Our time-resolved fluorescence data paint a sequence-level rigidity map of three states of 4E-BP2 differing in phosphorylation or binding status and distinguish regions that form contacts with eIF4E. This study adds complementary structural and dynamics information to recent studies of 4E-BP2, and it constitutes an important step towards a mechanistic understanding of this important IDP via integrative modelling.

scholarly journals Structural dynamics and transient lipid binding of synaptobrevin-2 tune SNARE assembly and membrane fusion

2019 ◽  
Vol 116 (18) ◽  
pp. 8699-8708 ◽  
Author(s):  
Nils-Alexander Lakomek ◽  
Halenur Yavuz ◽  
Reinhard Jahn ◽  
Ángel Pérez-Lara
Keyword(s):  
Membrane Fusion ◽  
Intrinsically Disordered Proteins ◽  
Membrane Binding ◽  
Lipid Binding ◽  
Snare Complex ◽  
Snare Proteins ◽  
Disordered Proteins ◽  
Intrinsically Disordered ◽  
C Terminus ◽  
Repulsive Forces

Intrinsically disordered proteins (IDPs) and their conformational transitions play an important role in neurotransmitter release at the neuronal synapse. Here, the SNARE proteins are essential by forming the SNARE complex that drives vesicular membrane fusion. While it is widely accepted that the SNARE proteins are intrinsically disordered in their monomeric prefusion form, important mechanistic aspects of this prefusion conformation and its lipid interactions, before forming the SNARE complex, are not fully understood at the molecular level and remain controversial. Here, by a combination of NMR and fluorescence spectroscopy methods, we find that vesicular synaptobrevin-2 (syb-2) in its monomeric prefusion conformation shows high flexibility, characteristic for an IDP, but also a high dynamic range and increasing rigidity from the N to C terminus. The gradual increase in rigidity correlates with an increase in lipid binding affinity from the N to C terminus. It could also explain the increased rate for C-terminal SNARE zippering, known to be faster than N-terminal SNARE zippering. Also, the syb-2 SNARE motif and, in particular, the linker domain show transient and weak membrane binding, characterized by a high off-rate and low (millimolar) affinity. The transient membrane binding of syb-2 may compensate for the repulsive forces between the two membranes and/or the SNARE motifs and the membranes, helping to destabilize the hydrophilic-hydrophobic boundary in the bilayer. Therefore, we propose that optimum flexibility and membrane binding of syb-2 regulate SNARE assembly and minimize repulsive forces during membrane fusion.

scholarly journals Structural and Functional Dynamics of Dehydrins: A Plant Protector Protein under Abiotic Stress

2018 ◽  
Vol 19 (11) ◽  
pp. 3420 ◽  
Author(s):  
Zhengyang Yu ◽  
Xin Wang ◽  
Linsheng Zhang
Keyword(s):  
Abiotic Stress ◽  
Regulatory Networks ◽  
Intrinsically Disordered Proteins ◽  
Stress Factors ◽  
Disordered Proteins ◽  
Transcriptional Level ◽  
Gene Expressions ◽  
Intrinsically Disordered ◽  
Functional Dynamics

Abiotic stress affects the growth and development of crops tremendously, worldwide. To avoid adverse environmental effects, plants have evolved various efficient mechanisms to respond and adapt to harsh environmental factors. Stress conditions are associated with coordinated changes in gene expressions at a transcriptional level. Dehydrins have been extensively studied as protectors in plant cells, owing to their vital roles in sustaining the integrity of membranes and lactate dehydrogenase (LDH). Dehydrins are highly hydrophilic and thermostable intrinsically disordered proteins (IDPs), with at least one Lys-rich K-segment. Many dehydrins are induced by multiple stress factors, such as drought, salt, extreme temperatures, etc. This article reviews the role of dehydrins under abiotic stress, regulatory networks of dehydrin genes, and the physiological functions of dehydrins. Advances in our understanding of dehydrin structures, gene regulation and their close relationships with abiotic stresses demonstrates their remarkable ability to enhance stress tolerance in plants.

scholarly journals Cellular Chaperone Function of Intrinsically Disordered Dehydrin ERD14

2021 ◽  
Vol 22 (12) ◽  
pp. 6190
Author(s):  
Nikoletta Murvai ◽  
Lajos Kalmar ◽  
Beata Szabo ◽  
Eva Schad ◽  
András Micsonai ◽  
...  
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Stress Protein ◽  
Early Response ◽  
Disordered Proteins ◽  
Proper Function ◽  
Sequence Motifs ◽  
Protective Function ◽  
Cellular Protection ◽  
Conserved Sequence ◽  
Intrinsically Disordered

Disordered plant chaperones play key roles in helping plants survive in harsh conditions, and they are indispensable for seeds to remain viable. Aside from well-known and thoroughly characterized globular chaperone proteins, there are a number of intrinsically disordered proteins (IDPs) that can also serve as highly effective protecting agents in the cells. One of the largest groups of disordered chaperones is the group of dehydrins, proteins that are expressed at high levels under different abiotic stress conditions, such as drought, high temperature, or osmotic stress. Dehydrins are characterized by the presence of different conserved sequence motifs that also serve as the basis for their categorization. Despite their accepted importance, the exact role and relevance of the conserved regions have not yet been formally addressed. Here, we explored the involvement of each conserved segment in the protective function of the intrinsically disordered stress protein (IDSP) A. thaliana’s Early Response to Dehydration (ERD14). We show that segments that are directly involved in partner binding, and others that are not, are equally necessary for proper function and that cellular protection emerges from the balanced interplay of different regions of ERD14.

scholarly journals Towards Targeting the Disordered SARS-CoV-2 Nsp2 C-terminal Region: Partial Structure and Dampened Mobility Revealed by NMR Spectroscopy

2020 ◽  
Author(s):  
Miguel Mompeán ◽  
Miguel Á. Treviño ◽  
Douglas V. Laurents
Keyword(s):  
Nmr Spectroscopy ◽  
Drug Targets ◽  
Intrinsically Disordered Proteins ◽  
Small Population ◽  
Terminal Region ◽  
Disordered Proteins ◽  
X Ray Crystallography ◽  
Intrinsically Disordered ◽  
Level Information ◽  
Human Proteins

AbstractIntrinsically disordered proteins (IDPs) play essential roles in regulating physiological processes in eukaryotic cells. Many virus use their own IDPs to “hack” these processes to disactive host defenses and promote viral growth. Thus, viral IDPs are attractive drug targets. While IDPs are hard to study by X-ray crystallography or cryo-EM, atomic level information on their conformational perferences and dynamics can be obtained using NMR spectroscopy. SARS-CoV-2 Nsp2 interacts with human proteins that regulate translation initiation and endosome vesicle sorting, and the C-terminal region of this protein is predicted to be disordered. Molecules that block these interactions could be valuable leads for drug development. To enable inhibitor screening and to uncover conformational preferences and dynamics, we have expressed and purified the 13C,15N-labeled C-terminal region of Nsp2. The 13Cβ and backbone 13CO, 1HN, 13Cα and 15N nuclei were assigned by analysis of a series of 2D 1H-15N HSQC and 13C-15N CON as well as 3D HNCO, HNCA, CBCAcoNH and HncocaNH spectra. Overall, the chemical shift data confirm that this region is chiefly disordered, but contains two five-residue segments that adopt a small population of β-strand structure. Whereas the region is flexible on ms/ms timescales as gauged by T1ρ measurements, the {1H}-15N NOEs reveal a flexibility on ns/ps timescales that is midway between a fully flexible and a completely rigid chain.

scholarly journals Plant Dehydrins: Expression, Regulatory Networks, and Protective Roles in Plants Challenged by Abiotic Stress

2021 ◽  
Vol 22 (23) ◽  
pp. 12619
Author(s):  
Zhenping Sun ◽  
Shiyuan Li ◽  
Wenyu Chen ◽  
Jieqiong Zhang ◽  
Lixiao Zhang ◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Regulatory Networks ◽  
Plasma Membranes ◽  
Intrinsically Disordered Proteins ◽  
Plant Stress ◽  
Protective Role ◽  
Late Embryogenesis Abundant ◽  
Disordered Proteins ◽  
Intrinsically Disordered ◽  
Wide Range

Dehydrins, also known as Group II late embryogenesis abundant (LEA) proteins, are classic intrinsically disordered proteins, which have high hydrophilicity. A wide range of hostile environmental conditions including low temperature, drought, and high salinity stimulate dehydrin expression. Numerous studies have furnished evidence for the protective role played by dehydrins in plants exposed to abiotic stress. Furthermore, dehydrins play important roles in seed maturation and plant stress tolerance. Hence, dehydrins might also protect plasma membranes and proteins and stabilize DNA conformations. In the present review, we discuss the regulatory networks of dehydrin gene expression including the abscisic acid (ABA), mitogen-activated protein (MAP) kinase cascade, and Ca2+ signaling pathways. Crosstalk among these molecules and pathways may form a complex, diverse regulatory network, which may be implicated in regulating the same dehydrin.

scholarly journals Late Embryogenesis Abundant Protein–Client Protein Interactions

Plants ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 814
Author(s):  
Lynnette M. A. Dirk ◽  
Caser Ghaafar Abdel ◽  
Imran Ahmad ◽  
Izabel Costa Silva Neta ◽  
Cristiane Carvalho Pereira ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Late Embryogenesis Abundant ◽  
Disordered Proteins ◽  
Late Embryogenesis Abundant Protein ◽  
Client Protein ◽  
Protective Function ◽  
Abundant Protein ◽  
Intrinsically Disordered ◽  
Late Embryogenesis ◽  
Client Proteins

The intrinsically disordered proteins belonging to the LATE EMBRYOGENESIS ABUNDANT protein (LEAP) family have been ascribed a protective function over an array of intracellular components. We focus on how LEAPs may protect a stress-susceptible proteome. These examples include instances of LEAPs providing a shield molecule function, possibly by instigating liquid-liquid phase separations. Some LEAPs bind directly to their client proteins, exerting a holdase-type chaperonin function. Finally, instances of LEAP–client protein interactions have been documented, where the LEAP modulates (interferes with) the function of the client protein, acting as a surreptitious rheostat of cellular homeostasis. From the examples identified to date, it is apparent that client protein modulation also serves to mitigate stress. While some LEAPs can physically bind and protect client proteins, some apparently bind to assist the degradation of the client proteins with which they associate. Documented instances of LEAP–client protein binding, even in the absence of stress, brings to the fore the necessity of identifying how the LEAPs are degraded post-stress to render them innocuous, a first step in understanding how the cell regulates their abundance.

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