scholarly journals Biophysical properties of single rotavirus particles account for the functions of protein shells in a multilayered virus

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Manuel Jiménez-Zaragoza ◽  
Marina PL Yubero ◽  
Esther Martín-Forero ◽  
Jose R Castón ◽  
David Reguera ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Calcium Ions ◽  
Transcription Initiation ◽  
Hydrophobic Interactions ◽  
Conformational Dynamics ◽  
Specific Protein ◽  
Breaking Force ◽  
Biophysical Properties ◽  
Mechanical Fatigue ◽  
Dsrna Viruses

The functions performed by the concentric shells of multilayered dsRNA viruses require specific protein interactions that can be directly explored through their mechanical properties. We studied the stiffness, breaking force, critical strain and mechanical fatigue of individual Triple, Double and Single layered rotavirus (RV) particles. Our results, in combination with Finite Element simulations, demonstrate that the mechanics of the external layer provides the resistance needed to counteract the stringent conditions of extracellular media. Our experiments, in combination with electrostatic analyses, reveal a strong interaction between the two outer layers and how it is suppressed by the removal of calcium ions, a key step for transcription initiation. The intermediate layer presents weak hydrophobic interactions with the inner layer that allow the assembly and favor the conformational dynamics needed for transcription. Our work shows how the biophysical properties of the three shells are finely tuned to produce an infective RV virion.

scholarly journals Computational Investigation of Structural Dynamics of SARS-CoV-2 Methyltransferase-Stimulatory Factor Heterodimer Nsp16/nsp10 Bound to the Cofactor SAM

2020 ◽  
Author(s):  
Md Fulbabu Sk ◽  
Nisha Amarnath Jonniya ◽  
Rajarshi Roy ◽  
Sayan Poddar ◽  
Parimal Kar
Keyword(s):  
Protein Interactions ◽  
Electrostatic Interactions ◽  
Immune Escape ◽  
Hydrophobic Interactions ◽  
Conformational Dynamics ◽  
Rna Stability ◽  
Protein Translation ◽  
Dynamics Simulation ◽  
Mtase Activity ◽  
Computational Alanine Scanning

Recently, a highly contagious novel coronavirus (COVID-19 or SARS-CoV-2) has emerged as a global threat in people's health and global economies. Identification of the potential targets and development of a vaccine or antiviral drugs is an urgent demand. The 5’-capping mechanism of eukaryotic mRNA and some viruses such as coronaviruses (CoVs) are essential for maintaining the RNA stability, protein translation, and for viral immune escape. SARSCoV encodes S-adenosyl-L-methionine dependent (SAM) methyltransferase (MTase) enzyme characterized by nsp16 (2’-O-MTase) for generating the capped structure. The present article highlights the binding mechanisms of nsp16 and nsp10 to identify the role of nsp10 in MTase activity. Furthermore, the conformational dynamics and energetic behind the SAM binding to nsp16 in its monomer and dimer form was analyzed by using an extensive molecular dynamics simulation along with the Molecular Mechanics Poisson-Boltzmann Surface Area (MM/PBSA). Our results show that the presence of nsp10 increases the favorable van der Waal and electrostatic interactions between the SAM and nsp16, thus nsp10 acts as a stimulator for its strong binding. The interaction profile suggests that hydrophobic interactions were predominately identified for protein-protein interactions. Also, the stable hydrogen bond between Ala83 (nsp16) and Tyr96 (nsp10), and between Gln87 (nsp16) and Leu45 (nsp10) plays a vital role in the nsp16-nsp10 interface. Further, Computational Alanine Scanning (CAS) mutagenesis was performed, which revealed hotspot mutants, namely I40A, V104A, and R86A for the dimer association. Therefore, the dimer interface of nsp16/nsp10 could also be a potential target to suppress the 2’-O-MTase activity of SARS-CoV-2. Overall, our study provides a comprehensive understanding of the dynamic and thermodynamic process of binding of nsp16 and nsp10 that will contribute to the novel design of peptide inhibitors based on nsp16.

scholarly journals Computational Investigation of Structural Dynamics of SARS-CoV-2 Methyltransferase-Stimulatory Factor Heterodimer Nsp16/nsp10 Bound to the Cofactor SAM

2020 ◽  
Author(s):  
Md Fulbabu Sk ◽  
Nisha Amarnath Jonniya ◽  
Rajarshi Roy ◽  
Sayan Poddar ◽  
Parimal Kar
Keyword(s):  
Protein Interactions ◽  
Electrostatic Interactions ◽  
Immune Escape ◽  
Hydrophobic Interactions ◽  
Conformational Dynamics ◽  
Rna Stability ◽  
Protein Translation ◽  
Dynamics Simulation ◽  
Mtase Activity ◽  
Computational Alanine Scanning

Recently, a highly contagious novel coronavirus (COVID-19 or SARS-CoV-2) has emerged as a global threat in people's health and global economies. Identification of the potential targets and development of a vaccine or antiviral drugs is an urgent demand. The 5’-capping mechanism of eukaryotic mRNA and some viruses such as coronaviruses (CoVs) are essential for maintaining the RNA stability, protein translation, and for viral immune escape. SARSCoV encodes S-adenosyl-L-methionine dependent (SAM) methyltransferase (MTase) enzyme characterized by nsp16 (2’-O-MTase) for generating the capped structure. The present article highlights the binding mechanisms of nsp16 and nsp10 to identify the role of nsp10 in MTase activity. Furthermore, the conformational dynamics and energetic behind the SAM binding to nsp16 in its monomer and dimer form was analyzed by using an extensive molecular dynamics simulation along with the Molecular Mechanics Poisson-Boltzmann Surface Area (MM/PBSA). Our results show that the presence of nsp10 increases the favorable van der Waal and electrostatic interactions between the SAM and nsp16, thus nsp10 acts as a stimulator for its strong binding. The interaction profile suggests that hydrophobic interactions were predominately identified for protein-protein interactions. Also, the stable hydrogen bond between Ala83 (nsp16) and Tyr96 (nsp10), and between Gln87 (nsp16) and Leu45 (nsp10) plays a vital role in the nsp16-nsp10 interface. Further, Computational Alanine Scanning (CAS) mutagenesis was performed, which revealed hotspot mutants, namely I40A, V104A, and R86A for the dimer association. Therefore, the dimer interface of nsp16/nsp10 could also be a potential target to suppress the 2’-O-MTase activity of SARS-CoV-2. Overall, our study provides a comprehensive understanding of the dynamic and thermodynamic process of binding of nsp16 and nsp10 that will contribute to the novel design of peptide inhibitors based on nsp16.

Phospholipid-Protein Interactions in the Formation of Prothrombin Activator

1965 ◽  
Vol 14 (03/04) ◽  
pp. 431-444 ◽  
Author(s):  
E. R Cole ◽  
J. L Koppel ◽  
J. H Olwin
Keyword(s):  
Complex Formation ◽  
Protein Interactions ◽  
Calcium Ions ◽  
Fixed Number ◽  
Factor V ◽  
Clotting Factors ◽  
Number Of Binding Sites ◽  
C Complex ◽  
Autoprothrombin C

SummarySince Ac-globulin (factor V) is involved in the formation of prothrombin activator, its ability to complex with phospholipids was studied. Purified bovine Ac-globulin was complexed to asolectin, there being presumably a fixed number of binding sites on the phospholipid micelle for Ac-globulin. In contrast to the requirement for calcium ions in the formation of complexes between asolectin and autoprothrombin C, calcium ions were not required for complex formation between asolectin and Ac-globulin to occur ; in fact, the presence of calcium prevented complex formation occurring, the degree of inhibition being dependent on the calcium concentration. By treating isolated, pre-formed aso- lectin-Ac-globulin complexes with calcium chloride solutions, Ac-globulin could be recovered in a much higher state of purity and essentially free of asolectin.Complete activators were formed by first preparing the asolectin-calcium- autoprothrombin C complex and then reacting the complex with Ac-globulin. A small amount of this product was very effective as an activator of purified prothrombin without further addition of calcium or any other cofactor. If the autoprothrombin C preparation used to prepare the complex was free of traces of prothrombin, the complete activator was stable for several hours at room temperature. Stable preparations of the complete activator were centrifuged, resulting in the sedimentation of most of the activity. Experimental evidence also indicated that activator activity was highest when autoprothrombin C and Ac-globulin were complexed to the same phospholipid micelle, rather than when the two clotting factors were complexed to separate micelles. These data suggested that the in vivo prothrombin activator may be a sedimentable complex composed of a thromboplastic enzyme, calcium, Ac-globulin and phospholipid.

Structure, Function, Involvement in Diseases and Targeting of 14-3-3 Proteins: An Update

2018 ◽  
Vol 25 (1) ◽  
pp. 5-21 ◽  
Author(s):  
Ylenia Cau ◽  
Daniela Valensin ◽  
Mattia Mori ◽  
Sara Draghi ◽  
Maurizio Botta
Keyword(s):  
Protein Interactions ◽  
Molecular Mechanisms ◽  
Physiological Role ◽  
Specific Protein ◽  
Protein Protein Interactions ◽  
Cellular Processes ◽  
Protein Partners ◽  
High Sequence Homology ◽  
Small Molecule Modulators

14-3-3 is a class of proteins able to interact with a multitude of targets by establishing protein-protein interactions (PPIs). They are usually found in all eukaryotes with a conserved secondary structure and high sequence homology among species. 14-3-3 proteins are involved in many physiological and pathological cellular processes either by triggering or interfering with the activity of specific protein partners. In the last years, the scientific community has collected many evidences on the role played by seven human 14-3-3 isoforms in cancer or neurodegenerative diseases. Indeed, these proteins regulate the molecular mechanisms associated to these diseases by interacting with (i) oncogenic and (ii) pro-apoptotic proteins and (iii) with proteins involved in Parkinson and Alzheimer diseases. The discovery of small molecule modulators of 14-3-3 PPIs could facilitate complete understanding of the physiological role of these proteins, and might offer valuable therapeutic approaches for these critical pathological states.

scholarly journals Novel Roles of SH2 and SH3 Domains in Lipid Binding

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1191
Author(s):  
Szabolcs Sipeki ◽  
Kitti Koprivanacz ◽  
Tamás Takács ◽  
Anita Kurilla ◽  
Loretta László ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Specific Protein ◽  
Lipid Binding ◽  
Sh2 Domain ◽  
Essential Property ◽  
Cellular Regulation ◽  
Sh3 Domains ◽  
Protein Partners ◽  
Interaction Domains ◽  
Central Paradigm

Signal transduction, the ability of cells to perceive information from the surroundings and alter behavior in response, is an essential property of life. Studies on tyrosine kinase action fundamentally changed our concept of cellular regulation. The induced assembly of subcellular hubs via the recognition of local protein or lipid modifications by modular protein interactions is now a central paradigm in signaling. Such molecular interactions are mediated by specific protein interaction domains. The first such domain identified was the SH2 domain, which was postulated to be a reader capable of finding and binding protein partners displaying phosphorylated tyrosine side chains. The SH3 domain was found to be involved in the formation of stable protein sub-complexes by constitutively attaching to proline-rich surfaces on its binding partners. The SH2 and SH3 domains have thus served as the prototypes for a diverse collection of interaction domains that recognize not only proteins but also lipids, nucleic acids, and small molecules. It has also been found that particular SH2 and SH3 domains themselves might also bind to and rely on lipids to modulate complex assembly. Some lipid-binding properties of SH2 and SH3 domains are reviewed here.

scholarly journals Interactions between RNA polymerase and the core recognition element are a determinant of transcription start site selection

2016 ◽  
Vol 113 (21) ◽  
pp. E2899-E2905 ◽  
Author(s):  
Irina O. Vvedenskaya ◽  
Hanif Vahedian-Movahed ◽  
Yuanchao Zhang ◽  
Deanne M. Taylor ◽  
Richard H. Ebright ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Transcription Start Site ◽  
Transcription Initiation ◽  
Specific Protein ◽  
Start Site ◽  
Transcription Start ◽  
Transcription Bubble ◽  
Recognition Element

During transcription initiation, RNA polymerase (RNAP) holoenzyme unwinds ∼13 bp of promoter DNA, forming an RNAP-promoter open complex (RPo) containing a single-stranded transcription bubble, and selects a template-strand nucleotide to serve as the transcription start site (TSS). In RPo, RNAP core enzyme makes sequence-specific protein–DNA interactions with the downstream part of the nontemplate strand of the transcription bubble (“core recognition element,” CRE). Here, we investigated whether sequence-specific RNAP–CRE interactions affect TSS selection. To do this, we used two next-generation sequencing-based approaches to compare the TSS profile of WT RNAP to that of an RNAP derivative defective in sequence-specific RNAP–CRE interactions. First, using massively systematic transcript end readout, MASTER, we assessed effects of RNAP–CRE interactions on TSS selection in vitro and in vivo for a library of 47 (∼16,000) consensus promoters containing different TSS region sequences, and we observed that the TSS profile of the RNAP derivative defective in RNAP–CRE interactions differed from that of WT RNAP, in a manner that correlated with the presence of consensus CRE sequences in the TSS region. Second, using 5′ merodiploid native-elongating-transcript sequencing, 5′ mNET-seq, we assessed effects of RNAP–CRE interactions at natural promoters in Escherichia coli, and we identified 39 promoters at which RNAP–CRE interactions determine TSS selection. Our findings establish RNAP–CRE interactions are a functional determinant of TSS selection. We propose that RNAP–CRE interactions modulate the position of the downstream end of the transcription bubble in RPo, and thereby modulate TSS selection, which involves transcription bubble expansion or transcription bubble contraction (scrunching or antiscrunching).

Genetic regulation of nitrogen metabolism in the fungi

1997 ◽  
Vol 61 (1) ◽  
pp. 17-32
Author(s):  
G A Marzluf
Keyword(s):  
Nitrogen Metabolism ◽  
Protein Interactions ◽  
Fungal Pathogens ◽  
Metabolic Regulation ◽  
Specific Binding ◽  
Genetic Regulation ◽  
Nitrogen Sources ◽  
Specific Protein ◽  
Genes Encoding ◽  
Gata Family

In the fungi, nitrogen metabolism is controlled by a complex genetic regulatory circuit which ensures the preferential use of primary nitrogen sources and also confers the ability to use many different secondary nitrogen sources when appropriate. Most structural genes encoding nitrogen catabolic enzymes are subject to nitrogen catabolite repression, mediated by positive-acting transcription factors of the GATA family of proteins. However, certain GATA family members, such as the yeast DAL80 factor, act negatively to repress gene expression. Selective expression of the genes which encode enzymes for the metabolism of secondary nitrogen sources is often achieved by induction, mediated by pathway-specific factors, many of which have a GAL4-like C6/Zn2 DNA binding domain. Regulation within the nitrogen circuit also involves specific protein-protein interactions, as exemplified by the specific binding of the negative-acting NMR protein with the positive-acting NIT2 protein of Neurospora crassa. Nitrogen metabolic regulation appears to play a significant role in the pathogenicity of certain animal and plant fungal pathogens.

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