Molecular interactions of FG nucleoporin repeats at high resolution

Proteins that contain repeat phenylalanine-glycine (FG) residues phase separate into oncogenic transcription factor condensates in malignant leukaemias, form the permeability barrier of the nuclear pore complex and mislocalize in neurodegenerative diseases. Insights into the molecular interactions of FG-repeat nucleoporins have, however, remained largely elusive. Using a combination of NMR spectroscopy and cryoelectron microscopy, we have identified uniformly spaced segments of transient β-structure and a stable preformed α-helix recognized by messenger RNA export factors in the FG-repeat domain of human nucleoporin 98 (Nup98). In addition, we have determined at high resolution the molecular organization of reversible FG–FG interactions in amyloid fibrils formed by a highly aggregation-prone segment in Nup98. We have further demonstrated that amyloid-like aggregates of the FG-repeat domain of Nup98 have low stability and are reversible. Our results provide critical insights into the molecular interactions underlying the self-association and phase separation of FG-repeat nucleoporins in physiological and pathological cell activities

The 3D structure of lipidic fibrils of alpha-synuclein

α-synuclein misfolding and aggregation into fibrils is a common feature of α-synucleinopathies, such as Parkinson’s disease, in which α-synuclein fibrils are a characteristic hallmark of neuronal inclusions called Lewy bodies. Studies on the composition of Lewy bodies extracted postmortem from brain tissue of Parkinson’s patients revealed that lipids and membranous organelles are also a significant component. Interactions between α-synuclein and lipids have been previously identified as relevant for Parkinson’s disease pathology, however molecular insights into their interactions have remained elusive. Here we present cryo-electron microscopy structures of six α-synuclein fibrils in complex with lipids, revealing specific lipid-fibril interactions. We observe that phospholipids promote an alternative protofilament fold, mediate an unusual arrangement of protofilaments, and fill the central cavities of the fibrils. Together with our previous studies, these structures also indicate a mechanism for fibril-induced lipid extraction, which is likely to be involved in the development of α-synucleinopathies. Specifically, one potential mechanism for the cellular toxicity is the disruption of intracellular vesicles mediated by fibrils and oligomers, and therefore the modulation of these interactions may provide a promising strategy for future therapeutic interventions

The clinical drug candidate anle138b binds in a cavity of lipidic alpha-synuclein fibrils

Aggregation of amyloidogenic proteins is a characteristic of multiple neuro- degenerative diseases. Atomic resolution of small molecule binding to such pathological protein aggregates is of interest for the development of ther- apeutics and diagnostics. Here we investigate the interaction between α- synuclein fibrils and anle138b, a clinical drug candidate for disease modifying therapy in neurodegeneration and a promising scaffold for positron emission tomography tracer design. We used nuclear magnetic resonance spectroscopy and the cryogenic electron microscopy structure of α-synuclein fibrils grown in the presence of lipids to locate anle138b within a cavity formed between two β-strands. We explored and quantified multiple binding modes of the com- pound in detail using molecular dynamics simulations. Our results reveal stable polar interactions between anle138b and backbone moieties inside the tubular cavity of the fibrils. Such cavities are common in other fibril structures as well

Amino acid synthesis deficiencies

In recent years the number of disorders known to affect amino acid synthesis has grown rapidly. Nor is it just the number of disorders that has increased: the associated clinical phenotypes have also expanded spectacularly, primarily due to the advances of next generation sequencing diagnostics. In contrast to the "classical" inborn errors of metabolism in catabolic pathways, in which elevated levels of metabolites are easily detected in body fluids, synthesis defects present with low values of metabolites or, confusingly, even completely normal levels of amino acids. This makes the biochemical diagnosis of this relatively new group of metabolic diseases challenging. Defects in the synthesis pathways of serine metabolism, glutamine, proline and, recently, asparagine have all been reported. Although these amino acid synthesis defects are in unrelated metabolic pathways, they do share many clinical features. In children the central nervous system is primarily affected, giving rise to (congenital) microcephaly, early onset seizures and varying degrees of mental disability. The brain abnormalities are accompanied by skin disorders such as cutis laxa in defects of proline synthesis, collodion-like skin and ichthyosis in serine deficiency, and necrolytic erythema in glutamine deficiency. Hypomyelination with accompanying loss of brain volume and gyration defects can be observed on brain MRI in all synthesis disorders. In adults with defects in serine or proline synthesis, spastic paraplegia and several forms of polyneuropathy with or without intellectual disability appear to be the major symptoms in these late-presenting forms of amino acid disorders. This review provides a comprehensive overview of the disorders in amino acid synthesis

Disability profiles and needs of disability grant recipients in Kleinmond, Western Cape, South Africa / Annette Freig.

Thesis (MPhil (Rehabilitation))--University of Stellenbosch, 2000.ENGLISH ABSTRACT: The South African National Census (1996) reports a disability prevalence of 6,6% in South Africa. In November 1999 the government paid out 635 881 temporary or permanent disability grants. Legislation is in place to allow the Department of Social Services to administer the grants. For this study demographic information of disability grant recipients in a semi-rural area was sought in order to improve understanding of disability and to assist in service delivery. The study was executed in Kleinmond, a coastal town in the Western Cape with a population of 3 918, where 189 people reported a disability during the 1996 census. Objective The objective of this study was to determine the disability profile, caregiver utilization and needs of disability grant recipients in Kleinmond, Western Cape, South Africa. METHODS A descriptive survey was the study design of choice. The study population consisted of recipients of a permanent disability grant who collected their grants at the Kleinmond Post Office in June 1999. In order to capture the necessary information, a questionnaire was developed based on the disability catalogue of the International Classification of Impairment, Disability and Handicap (ICIDH) of the World Health Organisation. Pilot studies were conducted and the researcher interviewed 29 grantees during the main study in Kleinmond in June/July 1999. Repeatability of the questionnaire was tested. Ninety six percent of the responses were the same on the second visit to four randomly selected grantees. Data was analysed with the statistical software package STATISTICA. RESULTS The response rate was 90% (29/32). The mean age of the mainly male grantees was 42 years (range: 18 - 64). Most grantees were single, but the majority stayed with someone else. Ninety three percent (27/29) were unemployed while 69% (20/29) felt they were able to work. Most grantees took regular medication and the majority accessed health services at the primary level local clinic. Twenty five grantees (86%or 25/29) reported multiple disabilities, while one person did not fit into any of the categories. The most common disability category was situational disability (82% or 24/29). Nineteen persons with disabilities (66% or 19/29) relied on help which was mainly given by the parents. Assistance was needed with activities such as collecting the disability grant, shopping and managing money. With regard to needs of grantees, most found it important to have the clinic closer to their homes (52% or 15/29), to increase the amount of the disability grant (76% or 22/29) and to raise awareness of disability in the community (69% or 20/29). CONCLUSION Most disability grant recipients in this study reported problems in many of the seven disability categories of the ICIDH, i.e. multiple disabilities. This is consistent with the assumption that only severely disabled people qualify for a permanent disability grant in South Africa. This might explain why the majority of the grantees utilized a caregiver for some tasks. Needs with regard to health and social services of this defined group of persons with disabilities in Kleinmond will be brought to the attention of the authorities, who are planning a new community centre and clinic.AFRIKAANSE OPSOMMING: Volgens die Nasionale Sensus opname van 1996 is die prevalensie van ongeskiktheid in Suid- Afrika 6.6%. Bevindinge dui aan dat 635881 individue 'n ongskiktheidstoelaag ontvang. Hierdie toelae word volgens wetgewing deur die Departement van Maatskaplike Dienste ge-administreer. In hierdie studie is demografiese inligting van individue wat 'n ongeskiktheidstoelaag ontvang ingesamel in 'n poging om insig in gestremdheid en dienslewering aan gestremdes te verbeter. Die studiepopulasie het bestaan uit individue wat 'n ongeskiktheidstoelaag in die Wes-Kaapse kusdorp Kleinmond ontvang. Kleinmond het 'n populasie van 3 918 waarvan 189 individue ongeskik is volgens die 1996 sensus. DOEL Die doel van die studie was om 'n ongesiktheidsprofiel van individue in Kleinmond te bepaal, asook te evalueer of hulle versorgers benodig het en om hulle behoeftes te bepaal. METODOLOGIE Daar is gebruik gemaak van 'n beskrywende studie. Die studiepopulasie het bestaan uit aile individue woonagtig in Kleinmond wat 'n permanente ongeskiktheidstoelaag ontvang het en dit by die poskantoor afgehaal het. Data is deur middel van 'n vraelys ingesamel. Die vraelys is gebaseer op die ongeskiktheids katalogus van die Internasionale Klassifikasie van Gebrek, Ongeskiktheid en Gestremdheid (ICIDH) van die Wereld Gesondheidsorganisasie. Die vraelys is getoets deur middel van loodsstudies. Die betroubaarheid van die vraelys is ook getoets deur tydens die navorsing dieselfde vrae tydens 'n tweede besoek aan vier kandidate te stel. Hierdie vier individue is ewekansig geselekteer en 96% van die response het ooreen gestem met die van die eerste besoek. Data is verkry van 29 individue gedurende Junie/Julie 1999. Data analise is met behulp van STATISTICA, 'n statistiese sagteware pakket, gedoen.RESULTATE Die responskoers was 90% (29/32). Die meerderheid van die studiepopulasie was manlik met 'n gemiddelde ouderdom van 42 jaar (rykwydte: 18 - 64). Individue was meerendeels ongetroud en het wonings met ander persone gedeel. Uit die studiepopulasie was 93% (27/29) individue werkloos. Van hierdie groep het 69% (20/29) egter gevoel dat hulle wei een of ander vorm van arbeid kan verrig. Bykans aile individue uit die studiepopulasie het gereeld medikasie gebruik. Die plaaslike prirnere gesondheids kliniek is deur die meeste individue benut vir gesondheidssorg. Meeste individue (86% of 25/29) het meer as een ongeskiktheid gehad en een persoon het nie in enige van die kateqoriee ingepas nie. Die ongeskiktheid wat die mees algemeenste voorgekom het was situasie-gebonde ongeskiktheid (82% of 24/29). Hulp is hoofsaaklik deur ouers verskaf en 66% individue (19/29) het van hulp gebruik gemaak. Hierdie hulp was meestal nodig met aktiwiteite soos die afhaal van die ongeskiktheidtoelaag, die doen van inkopies en die bestuur van persoonlike finansies. Die studiepopulasie het 3 groot behoeftes uitgespreek naamlik 'n kliniek nader aan hulle wonings (52% of 15/29), 'n verhoging in die ongeskiktheidstoelaag (76% of 22/29) en .n groter bewustheid van ongeskiktheid in die gemeenskap (69% of 20/29). Samevatting Baie van die individue uit die studiepopulasie het ongeskikthede in meer as een van die ongeskiktheidskategoriee aangedui. Hierdie bevinding is in ooreenstemming met die aanname dat in Suid-Afrika slegs individue met erge ongeskiktheid n ongeskiktheidstoelaag ontvang. Dit kan moontlik ook verklaar waarom die meerderheid van die populasie versorgers benodig het vir die uitvoer van sekere take. Die behoeftes van hierdie studiepopulasie sal onder die aandag van die plaaslike owerheid, wat tans besig is met die beplanning van 'n nuwe gemeensskapssentrum en kliniek, gebring word

Selection and application of control instruments in the sustainable tourism development. An examination of the Golden Circle, Iceland

kein Abstract vorhande

Towards Restoring Catalytic Activity of Glutamine Synthetase With a Clinically Relevant Mutation

Glutamine synthetase (GS) is an essential enzyme in nitrogen metabolism and catalyses the ATP-dependent ligation of glutamate and toxic ammonia to glutamine. So far, three GS mutants with clinically relevant pathologies are known. These mutations lead to hyperammonemia and a global glutamine deficiency. Recently, we investigated the molecular mechanisms underlying these mutations. However, an adequate treatment for a patient carrying the R324S mutation, now eleven years old, remains elusive. Here, we investigate by means of unbiased molecular dynamics simulations if and how the compatible solute betaine, successfully used for the treatment of liver diseases, can restore GS catalytic activity in the case of R324S GS. Upon free ligand diffusion, betaine enters the R324S GS binding site and forms hydrogen bonds with S324 and weak electrostatic interactions with ATP. Thus, betaine could act as a non-covalently bound ATP binding-enhancer in the case of R324S GS

Hydro-mechanical modeling of damage due to underground excavation in hardened clay

peer reviewedA zone with significant irreversible processes and significant changes in flow and transport properties is expected to be formed after underground excavations. The perturbation of the excavation could lead to a significant increase of the permeability, related to diffuse and/or localized crack proliferation in the material. The main objective of the study is to model these processes at large scale in order to assess their impacts on the performance of radioactive waste geological repositories. This paper concerns more particularly the hydro-mechanical modeling of a long term dilatometer experiment performed in Mont Terri Rock Laboratory in Switzerland. The proposed model defines the permeability as a function of the aperture of the cracks that are generated during the excavation. With this model, the permeability tensor becomes anisotropic. These developments are validated with the results of the experiment

Hydrogeologie und Grundwasserhydraulik des Einzugsgebietes des Wasserwerkes Freiburg-Ebnet

Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman