scholarly journals Cell cycle regulation by the intrinsically disordered proteins p21 and p27

2012 ◽  
Vol 40 (5) ◽  
pp. 981-988 ◽  
Author(s):  
Mi-Kyung Yoon ◽  
Diana M. Mitrea ◽  
Li Ou ◽  
Richard W. Kriwacki

Today, it is widely accepted that proteins that lack highly defined globular three-dimensional structures, termed IDPs (intrinsically disordered proteins), play key roles in myriad biological processes. Our understanding of how intrinsic disorder mediates biological function is, however, incomplete. In the present paper, we review disorder-mediated cell cycle regulation by two intrinsically disordered proteins, p21 and p27. A structural adaptation mechanism involving a stretchable dynamic linker helix allows p21 to promiscuously recognize the various Cdk (cyclin-dependent kinase)–cyclin complexes that regulate cell division. Disorder within p27 mediates transmission of an N-terminal tyrosine phosphorylation signal to a C-terminal threonine phosphorylation, constituting a signalling conduit. These mechanisms are mediated by folding upon binding p21/p27′s regulatory targets. However, residual disorder within the bound state contributes critically to these functional mechanisms. Our studies provide insights into how intrinsic protein disorder mediates regulatory processes and opportunities for designing drugs that target cancer-associated IDPs.

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nishi R. Sharma ◽  
Kundlik Gadhave ◽  
Prateek Kumar ◽  
Mohammad Saif ◽  
Md. M. Khan ◽  
...  

AbstractChandipura virus (CHPV, a member of the Rhabdoviridae family) is an emerging pathogen that causes rapidly progressing influenza-like illness and acute encephalitis often leading to coma and death of the human host. Given several CHPV outbreaks in Indian sub-continent, recurring sporadic cases, neurological manifestation, and high mortality rate of this infection, CHPV is gaining global attention. The ‘dark proteome’ includes the whole proteome with special emphasis on intrinsically disordered proteins (IDP) and IDP regions (IDPR), which are proteins or protein regions that lack unique (or ordered) three-dimensional structures within the cellular milieu. These proteins/regions, however, play a number of vital roles in various biological processes, such as cell cycle regulation, control of signaling pathways, etc. and, therefore, are implicated in many human diseases. IDPs and IPPRs are also abundantly found in many viral proteins enabling their multifunctional roles in the viral life cycles and their capability to highjack various host systems. The unknown abundance of IDP and IDPR in CHPV, therefore, prompted us to analyze the dark proteome of this virus. Our analysis revealed a varying degree of disorder in all five CHPV proteins, with the maximum level of intrinsic disorder propensity being found in Phosphoprotein (P). We have also shown the flexibility of P protein using extensive molecular dynamics simulations up to 500 ns (ns). Furthermore, our analysis also showed the abundant presence of the disorder-based binding regions (also known as molecular recognition features, MoRFs) in CHPV proteins. The identification of IDPs/IDPRs in CHPV proteins suggests that their disordered regions may function as potential interacting domains and may also serve as novel targets for disorder-based drug designs.


Author(s):  
Lasse Staby ◽  
Katherine R. Kemplen ◽  
Amelie Stein ◽  
Michael Ploug ◽  
Jane Clarke ◽  
...  

Abstract Understanding the interplay between sequence, structure and function of proteins has been complicated in recent years by the discovery of intrinsically disordered proteins (IDPs), which perform biological functions in the absence of a well-defined three-dimensional fold. Disordered protein sequences account for roughly 30% of the human proteome and in many proteins, disordered and ordered domains coexist. However, few studies have assessed how either feature affects the properties of the other. In this study, we examine the role of a disordered tail in the overall properties of the two-domain, calcium-sensing protein neuronal calcium sensor 1 (NCS-1). We show that loss of just six of the 190 residues at the flexible C-terminus is sufficient to severely affect stability, dynamics, and folding behavior of both ordered domains. We identify specific hydrophobic contacts mediated by the disordered tail that may be responsible for stabilizing the distal N-terminal domain. Moreover, sequence analyses indicate the presence of an LSL-motif in the tail that acts as a mimic of native ligands critical to the observed order–disorder communication. Removing the disordered tail leads to a shorter life-time of the ligand-bound complex likely originating from the observed destabilization. This close relationship between order and disorder may have important implications for how investigations into mixed systems are designed and opens up a novel avenue of drug targeting exploiting this type of behavior.


2012 ◽  
Vol 40 (5) ◽  
pp. 955-962 ◽  
Author(s):  
Nathalie Sibille ◽  
Pau Bernadó

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.


2018 ◽  
Vol 19 (11) ◽  
pp. 3614 ◽  
Author(s):  
Do-Hyoung Kim ◽  
Kyou-Hoon Han

Intrinsically disordered proteins (IDPs) are unorthodox proteins that do not form three-dimensional structures under non-denaturing conditions, but perform important biological functions. In addition, IDPs are associated with many critical diseases including cancers, neurodegenerative diseases, and viral diseases. Due to the generic name of “unstructured” proteins used for IDPs in the early days, the notion that IDPs would be completely unstructured down to the level of secondary structures has prevailed for a long time. During the last two decades, ample evidence has been accumulated showing that IDPs in their target-free state are pre-populated with transient secondary structures critical for target binding. Nevertheless, such a message did not seem to have reached with sufficient clarity to the IDP or protein science community largely because similar but different expressions were used to denote the fundamentally same phenomenon of presence of such transient secondary structures, which is not surprising for a quickly evolving field. Here, we summarize the critical roles that these transient secondary structures play for diverse functions of IDPs by describing how various expressions referring to transient secondary structures have been used in different contexts.


2011 ◽  
Vol 44 (4) ◽  
pp. 467-518 ◽  
Author(s):  
H. Jane Dyson

AbstractProteins provide much of the scaffolding for life, as well as undertaking a variety of essential catalytic reactions. These characteristic functions have led us to presuppose that proteins are in general functional only when well structured and correctly folded. As we begin to explore the repertoire of possible protein sequences inherent in the human and other genomes, two stark facts that belie this supposition become clear: firstly, the number of apparent open reading frames in the human genome is significantly smaller than appears to be necessary to code for all of the diverse proteins in higher organisms, and secondly that a significant proportion of the protein sequences that would be coded by the genome would not be expected to form stable three-dimensional (3D) structures. Clearly the genome must include coding for a multitude of alternative forms of proteins, some of which may be partly or fully disordered or incompletely structured in their functional states. At the same time as this likelihood was recognized, experimental studies also began to uncover examples of important protein molecules and domains that were incompletely structured or completely disordered in solution, yet remained perfectly functional. In the ensuing years, we have seen an explosion of experimental and genome-annotation studies that have mapped the extent of the intrinsic disorder phenomenon and explored the possible biological rationales for its widespread occurrence. Answers to the question ‘why would a particular domain need to be unstructured?’ are as varied as the systems where such domains are found. This review provides a survey of recent new directions in this field, and includes an evaluation of the role not only of intrinsically disordered proteins but also of partially structured and highly dynamic members of the disorder–order continuum.


2018 ◽  
Author(s):  
Rashmi Rameshwari ◽  
Shilpa S Chapadgaonkar ◽  
T. V. Prasad

AbstractA methodological framework of graph traversal in Systems Biology is presented here. At present there is need to investigate system rather individual component. The proposed analysis generalizes the various idea of network representations of protein interactions. This approach highlights various methods used in construction of protein interaction graph or network using suitable algorithm. The network nodes represent protein residues. Two nodes are connected if two residues are functionally correlated during the protein interaction event. The analysis of the resulting network enables the importance of each protein for its interactions. Furthermore, the determination of the pattern of edge between residues yields insights into the function prediction of an interaction. This is of special interest to investigate intrinsically disordered proteins, since it is difficult to determine structural (three-dimensional) architecture of each proteins in protein interactions network. In present work various approaches for protein interactions network construction, models and methods along with graph theories has been discussed which can be used to reveal hidden properties and features of a network. Further effective algorithm for visualization of protein interactions is suggested. As construction of Biological network is dependent on various properties of graph. A holistic approach such as Systems Biology approach can better solve the problem. This network profiling combined with knowledge extraction will help biologist to explore hidden information in genome as well as in proteome..


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 3 (2) ◽  
Author(s):  
Michaux C

In contrast to the classical paradigm “one sequence - one structure - one function” that a given protein sequence corresponds to a well-defined three-dimensional (3D) structure and an associated function, it was discovered in the 1990s that an increasing number of proteins can be functional in the absence of a stable 3D-structure.


2021 ◽  
Author(s):  
Juan Manuel Valverde ◽  
Geronimo Dubra ◽  
Henk van den Toorn ◽  
Guido van Mierlo ◽  
Michiel Vermeulen ◽  
...  

Switch-like cyclin-dependent kinase (CDK)-1 activation is thought to underlie the abruptness of mitotic onset, but how CDKs can simultaneously phosphorylate many diverse substrates is unknown, and direct evidence for such phosphorylation dynamics in vivo is lacking. Here, we analysed protein phosphorylation states in single Xenopus embryos throughout synchronous cell cycles. Over a thousand phosphosites were dynamic in vivo, and assignment of cell cycle phases using egg extracts revealed hundreds of S-phase phosphorylations. Targeted phosphoproteomics in single embryos showed switch-like mitotic phosphorylation of diverse protein complexes. The majority of cell cycle-regulated phosphosites occurred in CDK consensus motifs, and 72% located to intrinsically disordered regions. Dynamically phosphorylated proteins, and documented substrates of cell cycle kinases, are significantly more disordered than phosphoproteins in general. Furthermore, 30-50% are components of membraneless organelles. Our results suggest that phosphorylation of intrinsically disordered proteins by cell cycle kinases, particularly CDKs, allows switch-like mitotic cellular reorganisation.


Author(s):  
Muhammad Ahmad ◽  
Aisha Tahir ◽  
Rana Salman Anjum

Proteins possess complex three-dimensional structures, and these structures are stable only within specific ranges of temperature which mostly correspond to the temperature ranges of the host organisms. However, few exceptional proteins, called heat-stable proteins, are stable at temperatures that are substantially higher than those tolerated by the host organisms themselves. Most of the heat-stable proteins possess heat stability to perform their functions at high temperatures, but some of them are intrinsically heat-stable due to their structure. Heat-stable proteins are usually divided into three or four groups depending upon the intricacies of their structures and thermal behaviors. Their peculiar property, i.e. heat-stability, makes them very valuable in applications such as polymerase chain reaction, industrial processes requiring high temperature, and protein engineering. Heat-stability also makes it feasible to purify such proteins, from the rest of the heat-labile proteins, using a simple heat-treatment method. Moreover, heat treatment can be used as a combined cell-lysis and protein purification step which, as compared to conventional methods, can result in a higher yield of heat-stable proteins. Furthermore, some special heat-stable proteins, i.e. intrinsically disordered proteins (which include the proteins involved in important neurodegenerative diseases), need heat-treatment step, in some cases, as the only way for their successful purification and study. Hence, this paper provides a first-ever comprehensive review of all major aspects of heat-stable proteins, i.e., their structure, evolution, classification, significance, and heat-treatment mediated purification.


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