Interactions in the cpSRP Dependent Targeting of Light Harvesting Chlorophyll Binding Protein to the Thylakoid Membrane

Targeting of proteins is a critical component of cellular function. A universally conserved targeting system of the cytosol utilizes a signal recognition particle (SRP) to target many proteins contranslationally to the endoplasmic reticulum in eukaryotes or the inner membrane in prokaryotes. A homologous SRP system exists in the chloroplast that delivers light harvesting chlorophyll binding proteins (LHCP) to they thylakoid membrane. The chloroplast SRP (cpSRP) is a heterodimer composed of a novel 43 kDa subunit and a 54 kDa subunit homologous to a component of the SRP system, SRP54. Many details regarding the interactions between the proteins of the cpSRP system have been determined. However, the three-dimensional arrangement of the cpSRP43 and cpSRP54 domains as well as their influence on one another has not been determined. The results of this study demonstrate both cpSRP43 and cpSRP54 are characterized by a significant amount of structural flexibility. Specifically, the domains of cpSRP43 and cpSRP54 are flexibly linked allowing for rapid conformational sampling of the domains. This flexibility allows cpSRP43 to sense the presence of cpSRP54 and subsequently alter its affinity for LHCP. Conversely, cpSRP54 domain flexibility allows it to scan cpSRP43 for the third transmembrane segment of LHCP in a manner surprisingly similar to SRP54 scanning for signal sequences at the ribosome. Together, the results of this structural investigation of the free and bound proteins has lead to the speculation of a cpSRP-LHCP transit complex structure capable of rationalizing the steps leading to the integration of LHCP

Access Copyright and Fair Dealing Guidelines in Higher Educational Institutions in Canada: A Survey

Information about the acceptance by Canadian Higher Education Institutions (HEI) of the Access Copyright (AC) tariff is important for educators even though only a minority of HEIs in Canada have committed to the AC tariff. In addition, the copyright “pentalogy,” the five major decisions of the Supreme Court of Canada (SCC), and its interpretation of fair dealing has become relevant for the institutions, faculty and students. Many universities and community colleges in Canada have adopted the Universities Canada (UC) guidelines on fair dealing, while some have adopted the “six-point test” as their guideline. In some cases, institutions have not adopted any policy or guidelines on any aspect of copyright. This paper will investigate these issues to provide one view of the behaviour Canadian HEIs exhibit in their adherence to AC and their use of policy and guidelines at their institutions

The association between restricted activity and patient outcomes in older adults: systematic literature review and meta-analysis

Background: Restricted activity is a potential early marker of declining health in older adults. Previous studies of this association with patient outcomes have been inconclusive. This review aimed to evaluate the extent to which restricted activity is associated with decline in health. Methods: A search was conducted for studies including people over 65 years old which investigated the association between measures of restricted activity and hospitalisation, cognitive decline, and mortality. Following data extraction by two reviewers, eligible studies were summarised using Inverse Variance Heterogeneity meta-analysis. Results: The search identified 8,434 unique publications, with 11 eligible studies. Three measures of restricted activity were identified: bed rest, restricted movement, and dependency for activities of daily living (ADL). Three studies looked at hospitalisations, with two finding a significant association with bed rest or restricted movement and one showing no evidence of an association. Restricted activity was associated with a significant increase in mortality across all three measures (bed rest odds ratio [OR] 6.34, 95%CI 2.51–16.02, I2 = 76%; restricted movement OR 5.38 95%CI 2.60–11.13, I2 = 69%; general ADL dependency OR 4.65 95%CI 2.25–9.26, I2 = 84%). The significant heterogeneity observed could not be explained by restricting the analysis by length of follow-up, or measure of restricted activity. No meta-analysis was conducted on the limited evidence for cognitive decline outcomes. Conclusions: Limited studies have considered the prognostic value of restricted activity in terms of predicting future declining health. Current evidence suggests restricted activity is associated with hospitalisation and mortality, and therefore could identify a group for whom early intervention might be possible

Microsecond dynamics control the HIV-1 Envelope conformation

The HIV-1 Envelope (Env) glycoprotein facilitates host cell fusion through a complex series of receptor-induced structural changes. Although remarkable progress has been made in understanding the structures of various Env conformations, microsecond timescale dynamics have not been studied experimentally. Here, we used time-resolved, temperature-jump small-angle x-ray scattering to monitor structural rearrangements in an HIV-1 Env SOSIP ectodomain construct with microsecond precision. In two distinct Env variants, we detected a transition that correlated with known Env structure rearrangements with a time constant in the hundreds of microseconds range. A previously unknown structural transition was also observed, which occurred with a time constant below 10 μs, and involved an order-to-disorder transition in the trimer apex. Using this information, we engineered an Env SOSIP construct that locks the trimer in the prefusion closed state by connecting adjacent protomers via disulfides. Our findings show that the microsecond timescale structural dynamics play an essential role in controlling the Env conformation with impacts on vaccine design

UNE SCULPTURE D\u27IVAN DUKNOVlĆ

L\u27auteur clecrit la sculpture en pierre representant Saint Jean I\u27Evangeliste — I\u27un des chefs cl\u27oeuvre de I\u27artiste, bien connu, c le la Renaissance: Ivan Duknović ( lohannes Dalmata) qui se trouve clans une chapelle cle la cathedrale cle la ville croate de Tlogl I . Dans la grande exposition cl\u27Art yougoslave qui s\u27est tenue a Paris en 1971 cette statue a et e exposee; a cette occasion, et pour la premiere fois, en ont ćte photographiee les cotes, le dos et la base sur lacluelle est gravee la signature du sculpteur, que I\u27auteur cle cet ar ticle avait cleja remarquee et publiće. Grace a ces cliches cles cleux profils et cl u clos, cette oeuvre a r evele I\u27habilete cl\u27Ivan Duknović qui, en plein volume, moclele un personnage humain grancleur naturelle, de merne qu\u27i l I \u27avait fai t lors de I\u27execution du peti t »put to« a i l ć clui a et e recemment trouvć a Trogir, l icu cle naissance de I\u27artiste, et qui a et e public clans le dernier numero cle cette revue