scholarly journals Conformational landscape alternations promote oncogenic activities of Ras-related C3 botulinum toxin substrate 1 as revealed by NMR

2019 ◽  
Vol 5 (3) ◽  
pp. eaav8945 ◽  
Author(s):  
Yuki Toyama ◽  
Kenji Kontani ◽  
Toshiaki Katada ◽  
Ichio Shimada
Keyword(s):  
Botulinum Toxin ◽  
Bound States ◽  
Conformational Equilibrium ◽  
Bound State ◽  
Activation Mechanism ◽  
Resonance Spectroscopy ◽  
Guanosine Triphosphate ◽  
Guanosine Diphosphate ◽  
Conformational Landscape ◽  
Solution Nuclear Magnetic Resonance

Ras-related C3 botulinum toxin substrate 1 (Rac1) plays critical roles in the maintenance of cell morphology by cycling between inactive guanosine diphosphate (GDP)–bound and active guanosine triphosphate (GTP)–bound states. Rac1 P29S mutant is known to strongly promote oncogenesis by facilitating its intrinsic GDP dissociation and thereby increasing the level of the GTP-bound state. Here, we used solution nuclear magnetic resonance spectroscopy to investigate the activation mechanism of the oncogenic P29S mutant. We demonstrate that the conformational landscape is markedly altered in the mutant, and the preexisting equilibrium is shifted toward the conformation with reduced affinity for Mg2+, a cofactor that is critical for maintaining stable GDP binding. Our results suggest that the alternation of the preexisting conformational equilibrium of proteins is one of the fundamental mechanisms underlying their oncogenic activities.

scholarly journals Decreased conformational stability in the oncogenic N92I mutant of Ras-related C3 botulinum toxin substrate 1

2019 ◽  
Vol 5 (8) ◽  
pp. eaax1595
Author(s):  
Yuki Toyama ◽  
Kenji Kontani ◽  
Toshiaki Katada ◽  
Ichio Shimada
Keyword(s):  
Botulinum Toxin ◽  
Conformational Stability ◽  
Bound State ◽  
Activation Mechanism ◽  
Resonance Spectroscopy ◽  
Activation Process ◽  
Dissociation Reaction ◽  
Static Structure ◽  
Guanosine Diphosphate ◽  
Solution Nuclear Magnetic Resonance

Ras-related C3 botulinum toxin substrate 1 (Rac1) functions as a molecular switch by cycling between an inactive guanosine diphosphate (GDP)–bound state and an active guanosine triphosphate (GTP)–bound state. An oncogenic mutant of Rac1, an N92I mutant, strongly promotes cell proliferation and subsequent oncogenic activities by facilitating the intrinsic GDP dissociation in the inactive GDP-bound state. Here, we used solution nuclear magnetic resonance spectroscopy to investigate the activation mechanism of the N92I mutant. We found that the static structure of the GDP binding site is not markedly perturbed by the mutation, but the overall conformational stability decreases in the N92I mutant, which then facilitates GDP dissociation by lowering the activation energy for the dissociation reaction. On the basis of these results, we proposed the activation mechanism of the N92I mutant, in which the decreased conformational stability plays important roles in its activation process.

scholarly journals Bound states of a Klein–Gordon particle in the presence of a smooth potential well

2020 ◽  
Vol 35 (23) ◽  
pp. 2050140
Author(s):  
Eduardo López ◽  
Clara Rojas
Keyword(s):  
Bound States ◽  
Gordon Equation ◽  
Bound State ◽  
Potential Well ◽  
One Dimensional ◽  
Smooth Potential ◽  
Klein Gordon ◽  
The One ◽  
Potential Parameters ◽  
Klein Gordon Equation

We solve the one-dimensional time-independent Klein–Gordon equation in the presence of a smooth potential well. The bound state solutions are given in terms of the Whittaker [Formula: see text] function, and the antiparticle bound state is discussed in terms of potential parameters.

RETARDATION EFFECTS IN COVARIANT THREE-DIMENSIONAL BOUND STATE WAVE FUNCTIONS

2005 ◽  
Vol 14 (06) ◽  
pp. 931-947 ◽  
Author(s):  
F. PILOTTO ◽  
M. DILLIG
Keyword(s):  
Bound States ◽  
Three Dimensional ◽  
Bound State ◽  
Relative Energy ◽  
Wave Functions ◽  
Three Dimensions ◽  
State Wave ◽  
Scalar Diquark ◽  
Bound State Wave Function ◽  
Retardation Effects

We investigate the influence of retardation effects on covariant 3-dimensional wave functions for bound hadrons. Within a quark-(scalar) diquark representation of a baryon, the four-dimensional Bethe–Salpeter equation is solved for a 1-rank separable kernel which simulates Coulombic attraction and confinement. We project the manifestly covariant bound state wave function into three dimensions upon integrating out the non-static energy dependence and compare it with solutions of three-dimensional quasi-potential equations obtained from different kinematical projections on the relative energy variable. We find that for long-range interactions, as characteristic in QCD, retardation effects in bound states are of crucial importance.

THE NEXT STEP IN LEPTONIC DECAYS OF ETA AND KL BOUND STATES

1992 ◽  
Vol 07 (09) ◽  
pp. 1935-1951 ◽  
Author(s):  
G.A. KOZLOV
Keyword(s):  
Field Theory ◽  
Transition Form Factor ◽  
Bound States ◽  
Three Dimensional ◽  
Bound State ◽  
Quantum Field ◽  
Relative Momentum ◽  
Transition Form ◽  
Structure Transition ◽  
Leptonic Decays

A systematic discussion of the probability of eta and KL bound-state decays—[Formula: see text] and [Formula: see text](l=e, μ)—within a three-dimensional reduction to the two-body quantum field theory is presented. The bound-state vertex function depends on the relative momentum of constituent-like particles. A structure-transition form factor is defined by a confinement-type quark-antiquark wave function. The phenomenology of this kind of decays is analyzed.

scholarly journals Structural insights into the mechanism of the DEAH-box RNA helicase Prp43

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Marcel J Tauchert ◽  
Jean-Baptiste Fourmann ◽  
Reinhard Lührmann ◽  
Ralf Ficner
Keyword(s):  
Conformational Changes ◽  
Bound States ◽  
Rna Binding ◽  
Atp Hydrolysis ◽  
Bound State ◽  
Rna Helicases ◽  
Large Rearrangements ◽  
Rna Complex ◽  
Structural Insights ◽  
Terminal Domains

The DEAH-box helicase Prp43 is a key player in pre-mRNA splicing as well as the maturation of rRNAs. The exact modus operandi of Prp43 and of all other spliceosomal DEAH-box RNA helicases is still elusive. Here, we report crystal structures of Prp43 complexes in different functional states and the analysis of structure-based mutants providing insights into the unwinding and loading mechanism of RNAs. The Prp43•ATP-analog•RNA complex shows the localization of the RNA inside a tunnel formed by the two RecA-like and C-terminal domains. In the ATP-bound state this tunnel can be transformed into a groove prone for RNA binding by large rearrangements of the C-terminal domains. Several conformational changes between the ATP- and ADP-bound states explain the coupling of ATP hydrolysis to RNA translocation, mainly mediated by a β-turn of the RecA1 domain containing the newly identified RF motif. This mechanism is clearly different to those of other RNA helicases.

THE BETHE–SALPETER EQUATION APPROACH TO BOUND STATE: SCALAR–FERMION CASE AND SCALAR–SCALAR CASE

2007 ◽  
Vol 22 (39) ◽  
pp. 2979-2992 ◽  
Author(s):  
JIAO-KAI CHEN ◽  
ZHENG-XIN TANG ◽  
QING-DONG CHEN
Keyword(s):  
Bound States ◽  
Bound State ◽  
Wave Functions ◽  
Scalar Case ◽  
Equation Approach

The general form of the Bethe–Salpeter wave functions for bound states comprising one scalar constituent and one fermion, or two scalars is presented. Using the reduced Salpeter equation obtained, we can work out the effective nonrelativistic potentials. And one new version of reduced Bethe–Salpeter equation is proposed by extending Gross approximation.

scholarly journals Instability of charged massive scalar fields in bound states around Kerr–Sen black holes

2015 ◽  
Vol 24 (14) ◽  
pp. 1550102 ◽  
Author(s):  
Haryanto M. Siahaan
Keyword(s):  
Black Holes ◽  
Bound States ◽  
Gordon Equation ◽  
Scalar Fields ◽  
Bound State ◽  
Imaginary Component ◽  
Scalar Perturbation ◽  
Massive Scalar ◽  
Massive Scalar Field ◽  
Klein Gordon

In this paper, we show the instability of a charged massive scalar field in bound states around Kerr–Sen black holes. By matching the near and far region solutions of the radial part in the corresponding Klein–Gordon equation, one can show that the frequency of bound state scalar fields contains an imaginary component which gives rise to an amplification factor for the fields. Hence, the unstable modes for a charged and massive scalar perturbation in Kerr–Sen background can be shown.

Bound States of Spinless Particles in a Short-Range Potential

2015 ◽  
Vol 70 (4) ◽  
pp. 245-249 ◽  
Author(s):  
Hassan Hassanabadi ◽  
Antonio Soares de Castro
Keyword(s):  
Short Range ◽  
Bound States ◽  
Bound State ◽  
Scalar Coupling ◽  
Spinless Particle ◽  
Vector Coupling ◽  
Short Range Potential ◽  
Range Potential ◽  
Constraint Relation ◽  
Potential Parameters

AbstractWith a general mixing of vector and scalar couplings in a two-dimensional world, a short-range potential is used to explore certain features of the bound states of a spinless particle. Bound-state solutions are found in terms of the Gauss hypergeometric series when the potential parameters obey a certain constraint relation limiting the dosage of a vector coupling. The appearance of the Schiff–Snyder–Weinberg effect for a strong vector coupling and a short-range potential as well as its suppression by the addition of a scalar coupling is discussed.

scholarly journals Comment on: “Some quantum aspects of a particle with electric quadrupole moment interacting with an electric field subject to confining potentials”

2020 ◽  
Vol 35 (25) ◽  
pp. 2075002
Author(s):  
Francisco M. Fernández
Keyword(s):  
Electric Field ◽  
Quadrupole Moment ◽  
Bound States ◽  
Electric Quadrupole ◽  
Bound State ◽  
Electric Quadrupole Moment ◽  
Bound State Spectrum ◽  
Moving Particle ◽  
Quantum Aspects

We analyze the results obtained from a model consisting of the interaction between the electric quadrupole moment of a moving particle and an electric field. We argue that the system does not support bound states because the motion along the [Formula: see text] axis is unbounded. It is shown that the author obtains a wrong bound-state spectrum for the motion in the [Formula: see text] plane and that the existence of allowed cyclotron frequencies is an artifact of the approach.

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