Design, synthesis and antibacterial activity of minor groove binders: the role of non-cationic tail groups

he design and synthesis of a new class of minor groove binder (MGBs) in which, the cationic tail group has been replaced by a neutral, polar variant including cyanoguanidine, nitroalkene, and trifluoroacetamide groups. Antibacterial activity (against Gram positive bacteria) was found for both the nitroalkene and trifluoroacetamide groups. For the case of the nitroalkene tail group, strong binding of a minor groove binder containing this tail group was demonstrated by both DNA footprinting and melting temperature measurements, showing a correlation between DNA binding and antibacterial activity. The compounds have also been evaluated for binding to the hERG ion channel to determine whether non-cationic but polar substituents might have an advantage compared with conventional cationic tail groups in avoiding hERG binding. In this series of compounds, it was found that whilst non-cationic compounds generally had lower affinity to the hERG ion channel, all of the compounds studied bound weakly to the hERG ion channel, probably associated with the hydrophobic head groups

Rural masters and urban militants in early twentieth-century South Africa

White farmers in South Africa, a landowning class that subordinated black tenants and workers, also participated in the suppression of white workers’ movements before and after the First World War. This article explores how class interest limited and then overrode the farmers’ expected ethnic and political solidarities. It focuses especially on the contradictory ways in which farmers related to the great mineworkers’ strike and rebellion of 1922. Some contemporaries expected that racial solidarity, Afrikaner nationalism, and familial links would lead landowners to side, even militarily, with the white workers. Appeals were made to farmers by both sides of the struggle in 1922, and there was some significant support for the strikers from them. But the upheaval ran counter to landowners’ interests, notably by dislocating their primary urban market at a time of severe economic difficulty. In the end, farmers rode once more into the towns against the workers

The cation diffusion facilitator protein MamM's cytoplasmic domain exhibits metal-type dependent binding modes and discriminates against Mn2+

Cation diffusion facilitator (CDF) proteins are a conserved family of divalent transition metal cation transporters. CDF proteins are usually composed of two domains: the transmembrane domain (TMD), in which the metal cations are transported through, and a regulatory cytoplasmic C-terminal domain (CTD). Each CDF protein transports either one specific metal, or multiple metals, from the cytoplasm, and it is not known if the CTD takes an active regulatory role in metal recognition and discrimination during cation transport. Here, the model CDF protein MamM, an iron transporter from magnetotactic bacteria, was used to probe the role of the CTD in metal recognition and selectivity. Using a combination of biophysical and structural approaches, the binding of different metals to MamM CTD was characterized. Results reveal that different metals bind distinctively to MamM CTD in terms of their binding sites, thermodynamics and binding-dependent conformations, both in crystal form and in solution, which suggests a varying level of functional discrimination between CDF domains. Furthermore, these results provide the first direct evidence that CDF CTDs play a role in metal selectivity. We demonstrate that MamM's CTD can discriminate against Mn2+, supporting its postulated role in preventing magnetite formation poisoning in magnetotactic bacteria via Mn2+ incorporation

Methadone maintenance treatment in New South Wales and Victoria: Takeaways, diversion and other key issues

The project on which this report is based investigated the role takeaways play in MMT in New South Wales and Victoria, and looked closely at the conditions under which methadone is diverted to street sale and to other forms of sharing and circulation. In the process, it also identified a range of other issues of significance to MMT clients, service providers and policy makers in Australia today

Metal binding to the dynamic cytoplasmic domain of the cation diffusion facilitator (CDF) protein MamM induces a 'locked-in' configuration

Cation diffusion facilitator (CDF) proteins are a conserved family of transmembrane transporters that ensure cellular homeostasis of divalent transition metal cations. Metal cations bind to CDF protein's cytoplasmic C-terminal domain (CTD), leading to closure from its apo open V-shaped dimer to a tighter packed structure, followed by a conformational change of the transmembrane domain thus enabling transport of the metal cation. By implementing a comprehensive range of biochemical and biophysical methods, we studied the molecular mechanism of metal binding to the magnetotactic bacterial CDF protein MamM CTD. Our results reveal that the CTD is rather dynamic in its apo form, and that two dependent metal binding sites, a single central binding site and two symmetrical, peripheral sites, are available for metal binding. However, only cation binding to the peripheral sites leads to conformational changes that lock the protein in a compact state. Thus, this work reveals how metal binding is regulating the sequential uptakes of metal cations by MamM, and extends our understanding of the complex regulation mechanism of CDF proteins. This article is protected by copyright. All rights reserved

Saturation transfer difference NMR on the integral trimeric membrane transport protein GltPh determines cooperative substrate binding

UID/Multi/04378/2019 Grant no. BB/P010660/1 grant number BB/M011216/1Saturation-transfer difference (STD) NMR spectroscopy is a fast and versatile method which can be applied for drug-screening purposes, allowing the determination of essential ligand binding affinities (KD). Although widely employed to study soluble proteins, its use remains negligible for membrane proteins. Here the use of STD NMR for KD determination is demonstrated for two competing substrates with very different binding affinities (low nanomolar to millimolar) for an integral membrane transport protein in both detergent-solubilised micelles and reconstituted proteoliposomes. GltPh, a homotrimeric aspartate transporter from Pyrococcus horikoshii, is an archaeal homolog of mammalian membrane transport proteins—known as excitatory amino acid transporters (EAATs). They are found within the central nervous system and are responsible for fast uptake of the neurotransmitter glutamate, essential for neuronal function. Differences in both KD’s and cooperativity are observed between detergent micelles and proteoliposomes, the physiological implications of which are discussed.publishersversionpublishe

Understanding Urban Demand for Wild Meat in Vietnam: Implications for Conservation Actions

Vietnam is a significant consumer of wildlife, particularly wild meat, in urban restaurant settings. To meet this demand, poaching of wildlife is widespread, threatening regional and international biodiversity. Previous interventions to tackle illegal and potentially unsustainable consumption of wild meat in Vietnam have generally focused on limiting supply. While critical, they have been impeded by a lack of resources, the presence of increasingly organised criminal networks and corruption. Attention is, therefore, turning to the consumer, but a paucity of research investigating consumer demand for wild meat will impede the creation of effective consumer-centred interventions. Here we used a mixed-methods research approach comprising a hypothetical choice modelling survey and qualitative interviews to explore the drivers of wild meat consumption and consumer preferences among residents of Ho Chi Minh City, Vietnam. Our findings indicate that demand for wild meat is heterogeneous and highly context specific. Wild-sourced, rare, and expensive wild meat-types are eaten by those situated towards the top of the societal hierarchy to convey wealth and status and are commonly consumed in lucrative business contexts. Cheaper, legal and farmed substitutes for wild-sourced meats are also consumed, but typically in more casual consumption or social drinking settings. We explore the implications of our results for current conservation interventions in Vietnam that attempt to tackle illegal and potentially unsustainable trade in and consumption of wild meat and detail how our research informs future consumer-centric conservation actions

Particulate methane monooxygenase contains only mononuclear copper centers

Bacteria that oxidize methane to methanol are central to mitigating emissions of methane, a potent greenhouse gas. The nature of the copper active site in the primary metabolic enzyme of these bacteria, particulate methane monooxygenase (pMMO), has been controversial owing to seemingly contradictory biochemical, spectroscopic, and crystallographic results. We present biochemical and electron paramagnetic resonance spectroscopic characterization most consistent with two monocopper sites within pMMO: one in the soluble PmoB subunit at the previously assigned active site (CuB) and one ~2 nanometers away in the membrane-bound PmoC subunit (CuC). On the basis of these results, we propose that a monocopper site is able to catalyze methane oxidation in pMMO

The task of the inclusive leader in educational centers in disadvantaged and favored areas

El liderazgo participativo, democrático y transformacional del director ejerce una influencia positiva en la práctica del profesorado y en la calidad de los aprendizajes y participación de todos los estudiantes, así como en la mejora de los centros y en la creación de una cultura inclusiva. Se realiza un cuantitativo ex-post facto, de tipo transversal cuyo objeto es conocer las tareas de la dirección que promueven la inclusión y determinar qué características, de los directores y los centros, correlacionan positivamente. En este artículo, se presenta los resultados del cuestionario: Liderando la Educación Inclusiva (LEI-Q) aplicado a 397 miembros de familias y equipos docentes de 17 centros educativos. En análisis de datos es de tipo descriptivo e inferencial, mediante la prueba no paramétrica U Man-Whitney. Los resultados muestran que los miembros de la comunidad educativa (equipo docente y familias) de todos los centros participantes consideran que sus equipos directivos han implantado “sustancialmente” la mayor parte de las acciones que contribuyen a que sus centros sean inclusivos. Sin embargo, los equipos directivos de centros situados en contextos favorecidos lo han hecho mayormente que aquellos que se encuentran en contextos desfavorecidos y, de forma más significativa, en las acciones pertenecientes a comunidad profesional de aprendizaje y gestionar procesos de enseñanza-aprendizaje.The participative, democratic and transformational leadership of the director exerts a positive influence on the practice of the teaching staff and on the quality of the learning and participation of all the students, as well as on the improvement of the centers and the creation of an inclusive culture. An ex-post facto quantitative, cross-sectional type is carried out whose purpose is to know the management tasks that promote inclusion and determine which characteristics, of the directors and centers, correlate positively. In this article, we present the results of the questionnaire: Leading Inclusive Education (LEI-Q) applied to 397 family members and teaching teams from 17 educational centers. In data analysis, it is descriptive and inferential, using the non-parametric U Man-Whitney test. The results show that the members of the educational community (teaching staff and families) of all the participating centers consider that their management teams have implemented "substantially" most of the actions that contribute to their centers being inclusive. However, the management teams of centers located in favored contexts have done so more than those in disadvantaged contexts and, more significantly, in the actions pertaining to the professional learning community and managing teaching-learning processes

Exposing the Interplay Between Enzyme Turnover, Protein Dynamics and the Membrane Environment in Monoamine Oxidase B

There is an increasing realization that structure-based drug design may show improved success rates by understanding the ensemble of conformations and sub-states accessible to an enzyme and how the environment affects this ensemble. Human monoamine oxidase B (MAO-B) catalyzes the oxidation of amines and is inhibited for the treatment of both Parkinson’s disease and depression. Despite its clinical importance, its catalytic mechanism remains unclear and routes to drugging this target would be valuable and relevant. Evidence of a radical in either the transition state or resting state of MAO-B is present throughout the literature, and is suggested to be a flavin semiquinone, a tyrosyl radical or both. Here we see evidence of a resting state flavin semiquinone, via absorption redox studies and electron paramagnetic resonance, suggesting that the anionic semiquinone is biologically relevant. Based on enzyme kinetic studies, enzyme variants and molecular dynamics simulations we find evidence for the crucial importance of the membrane environment in mediating the activity of MAO-B and that this mediation is related to effects on the protein dynamics of MAO-B. Further, our MD simulations identify a hitherto undescribed entrance for substrate binding, membrane modulated substrate access, and indications for half-site reactivity: only one active site is accessible to binding at a time. Our study combines both experimental and computational evidence to illustrate the subtle interplay between enzyme activity, protein dynamics and the immediate membrane environment. Understanding key biomedical enzymes to this level of detail will be crucial to inform strategies (and binding sites) for rational drug design for these drug targets