1,687 research outputs found

    Ribosomal Incorporation of Aromatic Oligoamides as Peptide Sidechain Appendages

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    Derivatives of 4‐aminomethyl‐l ‐phenylalanine with aromatic oligoamide foldamers as sidechain appendages were successfully charged on tRNA by means of flexizymes. Their subsequent incorporation both at the C‐terminus of, and within, peptide sequences by the ribosome, was demonstrated. These results expand the registry of chemical structures tolerated by the ribosome to sidechains significantly larger and more structurally defined than previously demonstrated

    A person-centered perspective on working with people who have experienced psychological trauma and helping them move forward to posttraumatic growth

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    Over the past decade posttraumatic growth (PTG) has become a major topic for theory, research and practice in mainstream trauma psychology. The aim of this paper is to discuss the implications of PTG for the person-centered approach. It is argued that PTG provides a new non-medical language for understanding psychological trauma that is consistent with the person-centered approach. Person-centered personality theory provides an explanation for how PTG arises and leads to new testable predictions for research into how person-centered therapy may be able to facilitate PTG

    Quantifying the UV-continuum slopes of galaxies to z ˜ 10 using deep Hubble+Spitzer/IRAC observations

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    Measurements of the UV-continuum slopes β provide valuable information on the physical properties of galaxies forming in the early universe, probing the dust reddening, age, metal content, and even the escape fraction. While constraints on these slopes generally become more challenging at higher redshifts as the UV-continuum shifts out of the Hubble Space Telescope bands (particularly at z > 7), such a characterization actually becomes abruptly easier for galaxies in the redshift window z = 9.5-10.5 due to the Spitzer/Infrared Array Camera 3.6 μm-band probing the rest-UV continuum and the long wavelength baseline between this Spitzer band and the Hubble Hf160w band. Higher S/N constraints on β are possible at z ˜ 10 than at z = 8. Here, we take advantage of this opportunity and five recently discovered bright z = 9.5-10.5 galaxies to present the first measurements of the mean β for a multi-object sample of galaxy candidates at z ˜ 10. We find the measured βobs's of these candidates are -2.1 ± 0.3 ± 0.2 (random and systematic), only slightly bluer than the measured β's (βobs ≈ -1.7) at 3.5 < z < 7.5 for galaxies of similar luminosities. Small increases in the stellar ages, metallicities, and dust content of the galaxy population from z ˜ 10 to z ˜ 7 could easily explain the apparent evolution in β

    Plasmodium falciparum ligand binding to erythrocytes induce alterations in deformability essential for invasion

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    The most lethal form of malaria in humans is caused by Plasmodium falciparum. These parasites invade erythrocytes, a complex process involving multiple ligand-receptor interactions. The parasite makes initial contact with the erythrocyte followed by dramatic deformations linked to the function of the Erythrocyte binding antigen family and P. falciparum reticulocyte binding-like families. We show EBA-175 mediates substantial changes in the deformability of erythrocytes by binding to glycophorin A and activating a phosphorylation cascade that includes erythrocyte cytoskeletal proteins resulting in changes in the viscoelastic properties of the host cell. TRPM7 kinase inhibitors FTY720 and waixenicin A block the changes in the deformability of erythrocytes and inhibit merozoite invasion by directly inhibiting the phosphorylation cascade. Therefore, binding of P. falciparum parasites to the erythrocyte directly activate a signaling pathway through a phosphorylation cascade and this alters the viscoelastic properties of the host membrane conditioning it for successful invasion

    Interplay between partner and ligand facilitates the folding and binding of an intrinsically disordered protein.

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    Protein-protein interactions are at the heart of regulatory and signaling processes in the cell. In many interactions, one or both proteins are disordered before association. However, this disorder in the unbound state does not prevent many of these proteins folding to a well-defined, ordered structure in the bound state. Here we examine a typical system, where a small disordered protein (PUMA, p53 upregulated modulator of apoptosis) folds to an α-helix when bound to a groove on the surface of a folded protein (MCL-1, induced myeloid leukemia cell differentiation protein). We follow the association of these proteins using rapid-mixing stopped flow, and examine how the kinetic behavior is perturbed by denaturant and carefully chosen mutations. We demonstrate the utility of methods developed for the study of monomeric protein folding, including β-Tanford values, Leffler α, Φ-value analysis, and coarse-grained simulations, and propose a self-consistent mechanism for binding. Folding of the disordered protein before binding does not appear to be required and few, if any, specific interactions are required to commit to association. The majority of PUMA folding occurs after the transition state, in the presence of MCL-1. We also examine the role of the side chains of folded MCL-1 that make up the binding groove and find that many favor equilibrium binding but, surprisingly, inhibit the association process.This is the final version. It was first published online by PNAS via http://dx.doi.org/10.1073/pnas.140912211

    A theory on reports of constructive (real) and illusory posttraumatic growth

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    It has been suggested that self-reported posttraumatic growth could sometimes be considered as a way for people to protect themselves from the distress of trauma. In this case, reports of posttraumatic growth could be illusory. We suggest a theory on self-reported constructive (real) posttraumatic growth and illusory posttraumatic growth by using Rogers’s (1959) theory and the work by Vaillant (1995). Through this theoretical framework we attempt to explain when reports of posttraumatic growth are likely to be constructive and real and when such reports are likely to represent aspects of illusions. We will also consider the implications for research practice

    Planet Hunters VII. Discovery of a New Low-Mass, Low-Density Planet (PH3 c) Orbiting Kepler-289 with Mass Measurements of Two Additional Planets (PH3 b and d)

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    We report the discovery of one newly confirmed planet (P=66.06P=66.06 days, RP=2.68±0.17RR_{\rm{P}}=2.68\pm0.17R_\oplus) and mass determinations of two previously validated Kepler planets, Kepler-289 b (P=34.55P=34.55 days, RP=2.15±0.10RR_{\rm{P}}=2.15\pm0.10R_\oplus) and Kepler-289-c (P=125.85P=125.85 days, RP=11.59±0.10RR_{\rm{P}}=11.59\pm0.10R_\oplus), through their transit timing variations (TTVs). We also exclude the possibility that these three planets reside in a 1:2:41:2:4 Laplace resonance. The outer planet has very deep (1.3\sim1.3%), high signal-to-noise transits, which puts extremely tight constraints on its host star's stellar properties via Kepler's Third Law. The star PH3 is a young (1\sim1 Gyr as determined by isochrones and gyrochronology), Sun-like star with M=1.08±0.02MM_*=1.08\pm0.02M_\odot, R=1.00±0.02RR_*=1.00\pm0.02R_\odot, and Teff=5990±38T_{\rm{eff}}=5990\pm38 K. The middle planet's large TTV amplitude (5\sim5 hours) resulted either in non-detections or inaccurate detections in previous searches. A strong chopping signal, a shorter period sinusoid in the TTVs, allows us to break the mass-eccentricity degeneracy and uniquely determine the masses of the inner, middle, and outer planets to be M=7.3±6.8MM=7.3\pm6.8M_\oplus, 4.0±0.9M4.0\pm0.9M_\oplus, and M=132±17MM=132\pm17M_\oplus, which we designate PH3 b, c, and d, respectively. Furthermore, the middle planet, PH3 c, has a relatively low density, ρ=1.2±0.3\rho=1.2\pm0.3 g/cm3^3 for a planet of its mass, requiring a substantial H/He atmosphere of 2.10.3+0.82.1^{+0.8}_{-0.3}% by mass, and joins a growing population of low-mass, low-density planets.Comment: 21 pages, 10 figures, 5 tables, accepted into Ap
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