GRAS proteins: the versatile roles of intrinsically disordered proteins in plant signalling

2012 ◽  
Vol 442 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Xiaolin Sun ◽  
William T. Jones ◽  
Erik H. A. Rikkerink

IDPs (intrinsically disordered proteins) are highly abundant in eukaryotic proteomes and important for cellular functions, especially in cell signalling and transcriptional regulation. An IDR (intrinsically disordered region) within an IDP often undergoes disorder-to-order transitions upon binding to various partners, allowing an IDP to recognize and bind different partners at various binding interfaces. Plant-specific GRAS proteins play critical and diverse roles in plant development and signalling, and act as integrators of signals from multiple plant growth regulatory and environmental inputs. Possessing an intrinsically disordered N-terminal domain, the GRAS proteins constitute the first functionally required unfoldome from the plant kingdom. Furthermore, the N-terminal domains of GRAS proteins contain MoRFs (molecular recognition features), short interaction-prone segments that are located within IDRs and are able to recognize their interacting partners by undergoing disorder-to-order transitions upon binding to these specific partners. These MoRFs represent potential protein–protein binding sites and may be acting as molecular bait in recognition events during plant development. Intrinsic disorder provides GRAS proteins with a degree of binding plasticity that may be linked to their functional versatility. As an overview of structure–function relationships for GRAS proteins, the present review covers the main biological functions of the GRAS family, the IDRs within these proteins and their implications for understanding mode-of-action.

2019 ◽  
Vol 20 (21) ◽  
pp. 5501 ◽  
Author(s):  
Izzy Owen ◽  
Frank Shewmaker

Advances in genomics and proteomics have revealed eukaryotic proteomes to be highly abundant in intrinsically disordered proteins that are susceptible to diverse post-translational modifications. Intrinsically disordered regions are critical to the liquid–liquid phase separation that facilitates specialized cellular functions. Here, we discuss how post-translational modifications of intrinsically disordered protein segments can regulate the molecular condensation of macromolecules into functional phase-separated complexes.


2019 ◽  
Vol 116 (41) ◽  
pp. 20446-20452 ◽  
Author(s):  
Utsab R. Shrestha ◽  
Puneet Juneja ◽  
Qiu Zhang ◽  
Viswanathan Gurumoorthy ◽  
Jose M. Borreguero ◽  
...  

Intrinsically disordered proteins (IDPs) are abundant in eukaryotic proteomes, play a major role in cell signaling, and are associated with human diseases. To understand IDP function it is critical to determine their configurational ensemble, i.e., the collection of 3-dimensional structures they adopt, and this remains an immense challenge in structural biology. Attempts to determine this ensemble computationally have been hitherto hampered by the necessity of reweighting molecular dynamics (MD) results or biasing simulation in order to match ensemble-averaged experimental observables, operations that reduce the precision of the generated model because different structural ensembles may yield the same experimental observable. Here, by employing enhanced sampling MD we reproduce the experimental small-angle neutron and X-ray scattering profiles and the NMR chemical shifts of the disordered N terminal (SH4UD) of c-Src kinase without reweighting or constraining the simulations. The unbiased simulation results reveal a weakly funneled and rugged free energy landscape of SH4UD, which gives rise to a heterogeneous ensemble of structures that cannot be described by simple polymer theory. SH4UD adopts transient helices, which are found away from known phosphorylation sites and could play a key role in the stabilization of structural regions necessary for phosphorylation. Our findings indicate that adequately sampled molecular simulations can be performed to provide accurate physical models of flexible biosystems, thus rationalizing their biological function.


2016 ◽  
Author(s):  
Michael Vincent ◽  
Santiago Schnell

AbstractIntrinsically disordered proteins lack a stable three-dimensional structure under physiological conditions. While this property has gained considerable interest within the past two decades, disorder poses substantial challenges to experimental characterization efforts. In effect, numerous computational tools have been developed to predict disorder from primary sequences, however, interpreting the output of these algorithms remains a challenge. To begin to bridge this gap, we present Disorder Atlas, web-based software that facilitates the interpretation of intrinsic disorder predictions using proteome-based descriptive statistics. This service is also equipped to facilitate large-scale systematic exploratory searches for proteins encompassing disorder features of interest, and further allows users to browse the prevalence of multiple disorder features at the proteome level. As a result, Disorder Atlas provides a user-friendly tool that places algorithm-generated disorder predictions in the context of the proteome, thereby providing an instrument to compare the results of a query protein against predictions made for an entire population. Disorder Atlas currently supports ten eukaryotic proteomes and is freely available for non-commercial users at http://www.disorderatlas.org.


2020 ◽  
Vol 71 (1) ◽  
pp. 391-414 ◽  
Author(s):  
Lauren Ann Metskas ◽  
Elizabeth Rhoades

Intrinsically disordered proteins (IDPs) are now widely recognized as playing critical roles in a broad range of cellular functions as well as being implicated in diverse diseases. Their lack of stable secondary structure and tertiary interactions, coupled with their sensitivity to measurement conditions, stymies many traditional structural biology approaches. Single-molecule Förster resonance energy transfer (smFRET) is now widely used to characterize the physicochemical properties of these proteins in isolation and is being increasingly applied to more complex assemblies and experimental environments. This review provides an overview of confocal diffusion-based smFRET as an experimental tool, including descriptions of instrumentation, data analysis, and protein labeling. Recent papers are discussed that illustrate the unique capability of smFRET to provide insight into aggregation-prone IDPs, protein–protein interactions involving IDPs, and IDPs in complex experimental milieus.


2012 ◽  
Vol 393 (4) ◽  
pp. 259-274 ◽  
Author(s):  
Diana M. Mitrea ◽  
Mi-Kyung Yoon ◽  
Li Ou ◽  
Richard W. Kriwacki

Abstract The classic structure-function paradigm has been challenged by a recently identified class of proteins: intrinsically disordered proteins (IDPs). Despite their lack of stable secondary or tertiary structure, IDPs are prevalent in all forms of life and perform myriad cellular functions, including signaling and regulation. Importantly, disruption of IDP homeostasis is associated with numerous human diseases, including cancer and neurodegeneration. Despite wide recognition of IDPs, the molecular mechanisms underlying their functions are not fully understood. Here we review the structural features and disorder-function relationships for p21 and p27, two cyclin-dependent kinase (Cdk) regulators involved in controlling cell division and fate. Studies of p21 bound to Cdk2/cyclin A revealed that a helix stretching mechanism mediates binding promiscuity. Further, investigations of Tyr88-phosphorylated p27 identified a signaling conduit that controls cell division and is disrupted in certain cancers. These mechanisms rely upon a balance between nascent structure in the free state, induced folding upon binding, and persistent flexibility within functional complexes. Although these disorder-function relationships are likely to be recapitulated in other IDPs, it is also likely that the vocabulary of their mechanisms is much more extensive than is currently understood. Further study of the physical properties of IDPs and elucidation of their links with function are needed to fully understand the mechanistic language of IDPs.


2019 ◽  
Vol 17 (06) ◽  
pp. 1940015
Author(s):  
Chun Fang ◽  
Yoshitaka Moriwaki ◽  
Caihong Li ◽  
Kentaro Shimizu

Molecular recognition features (MoRFs) usually act as “hub” sites in the interaction networks of intrinsically disordered proteins (IDPs). Because an increasing number of serious diseases have been found to be associated with disordered proteins, identifying MoRFs has become increasingly important. In this study, we propose an ensemble learning strategy, named MoRFPred_en, to predict MoRFs from protein sequences. This approach combines four submodels that utilize different sequence-derived features for the prediction, including a multichannel one-dimensional convolutional neural network (CNN_1D multichannel) based model, two deep two-dimensional convolutional neural network (DCNN_2D) based models, and a support vector machine (SVM) based model. When compared with other methods on the same datasets, the MoRFPred_en approach produced better results than existing state-of-the-art MoRF prediction methods, achieving an AUC of 0.762 on the VALIDATION419 dataset, 0.795 on the TEST45 dataset, and 0.776 on the TEST49 dataset. Availability: http://vivace.bi.a.u-tokyo.ac.jp:8008/fang/MoRFPred_en.php .


2012 ◽  
Vol 40 (5) ◽  
pp. 975-980 ◽  
Author(s):  
Hesam N. Motlagh ◽  
Jing Li ◽  
E. Brad Thompson ◽  
Vincent J. Hilser

Allostery is a biological phenomenon of critical importance in metabolic regulation and cell signalling. The fundamental premise of classical models that describe allostery is that structure mediates ‘action at a distance’. Recently, this paradigm has been challenged by the enrichment of IDPs (intrinsically disordered proteins) or ID (intrinsically disordered) segments in transcription factors and signalling pathways of higher organisms, where an allosteric response from external signals is requisite for regulated function. This observation strongly suggests that IDPs elicit the capacity for finely tunable allosteric regulation. Is there a set of transferable ground rules that reconcile these disparate allosteric phenomena? We focus on findings from the human GR (glucocorticoid receptor) which is a nuclear transcription factor in the SHR (steroid hormone receptor) family. GR contains an intrinsically disordered NTD (N-terminal domain) that is obligatory for transcription activity. Different GR translational isoforms have various lengths of NTD and by studying these isoforms we found that the full-length ID NTD consists of two thermodynamically distinct coupled regions. The data are interpreted in the context of an EAM (ensemble allosteric model) that considers only the intrinsic and measurable energetics of allosteric systems. Expansion of the EAM is able to reconcile the paradox that ligands for SHRs can be agonists and antagonists in a cell-context-dependent manner. These findings suggest a mechanism by which SHRs in particular, and IDPs in general, may have evolved to couple thermodynamically distinct ID segments. The ensemble view of allostery that is illuminated provides organizing principles to unify the description of all allosteric systems and insight into ‘how’ allostery works.


eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Zhengjian Zhang ◽  
Zarko Boskovic ◽  
Mahmud M Hussain ◽  
Wenxin Hu ◽  
Carla Inouye ◽  
...  

Intrinsically disordered proteins/regions (IDPs/IDRs) are proteins or peptide segments that fail to form stable 3-dimensional structures in the absence of partner proteins. They are abundant in eukaryotic proteomes and are often associated with human diseases, but their biological functions have been elusive to study. In this study, we report the identification of a tin(IV) oxochloride-derived cluster that binds an evolutionarily conserved IDR within the metazoan TFIID transcription complex. Binding arrests an isomerization of promoter-bound TFIID that is required for the engagement of Pol II during the first (de novo) round of transcription initiation. However, the specific chemical probe does not affect reinitiation, which requires the re-entry of Pol II, thus, mechanistically distinguishing these two modes of transcription initiation. This work also suggests a new avenue for targeting the elusive IDRs by harnessing certain features of metal-based complexes for mechanistic studies, and for the development of novel pharmaceutical interventions.


2020 ◽  
Author(s):  
Sidra Ilyas ◽  
Abdul Manan

ABSTRACTThe contribution of redox active properties of cysteines in intrinsically disordered regions (IDRs) of proteins is not very well acknowledged. Despite of providing structural stability and rigidity, intrinsically disordered cysteines are exceptional redox sensors and the redox status of the protein defines its structure. Experimental evidence suggests that the conformational heterogeneity of cysteines in intrinsically disordered proteins (IDPs) is related to numerous functions including regulation, structural changes and fuzzy complex formation. The unusual plasticity of IDPs make them suitable candidate to interact with many clients under specific conditions. Binding capabilities, dimerization and folding or unfolding nature of IDPs upon interaction with multiple clients assign distinct conformational changes associated with disulfide formation. Here we are going to focus on redox activity of IDPs, their dramatic roles that are not only restricted to cellular redox homeostasis and signaling pathways but also provide antioxidant, anti-apoptotic, binding and interactive power.


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