| 1. |
- Baumgart, Mona, et al.
(författare)
-
Design of buried charged networks in artificial proteins
- 2021
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Soluble proteins are universally packed with a hydrophobic core and a polar surface that drive the protein folding process. Yet charged networks within the central protein core are often indispensable for the biological function. Here, we show that natural buried ion-pairs are stabilised by amphiphilic residues that electrostatically shield the charged motif from its surroundings to gain structural stability. To explore this effect, we build artificial proteins with buried ion-pairs by combining directed computational design and biophysical experiments. Our findings illustrate how perturbation in charged networks can introduce structural rearrangements to compensate for desolvation effects. We validate the physical principles by resolving high-resolution atomic structures of the artificial proteins that are resistant towards unfolding at extreme temperatures and harsh chemical conditions. Our findings provide a molecular understanding of functional charged networks and how point mutations may alter the protein's conformational landscape.
|
|
| 2. |
- Bräuer, Alois, et al.
(författare)
-
Structural snapshots of the minimal PKS system responsible for octaketide biosynthesis
- 2020
-
Ingår i: Nature Chemistry. - : Springer Science and Business Media LLC. - 1755-4330 .- 1755-4349. ; 12:8
-
Tidskriftsartikel (refereegranskat)abstract
- The invariable core of a type II polyketide synthase has been characterized using X-ray crystallography, simulations, mutagenesis experiments and functional assays. The characterization of the ternary acyl carrier protein complexes provides a mechanistic understanding of the reactivity and could inform future engineering of this complex biosynthetic machinery. Type II polyketide synthases (PKSs) are multi-enzyme complexes that produce secondary metabolites of medical relevance. Chemical backbones of such polyketides are produced by minimal PKS systems that consist of a malonyl transacylase, an acyl carrier protein and an alpha/beta heterodimeric ketosynthase. Here, we present X-ray structures of all ternary complexes that constitute the minimal PKS system for anthraquinone biosynthesis inPhotorhabdus luminescens. In addition, we characterize this invariable core using molecular simulations, mutagenesis experiments and functional assays. We show that malonylation of the acyl carrier protein is accompanied by major structural rearrangements in the transacylase. Principles of an ongoing chain elongation are derived from the ternary complex with a hexaketide covalently linking the heterodimeric ketosynthase with the acyl carrier protein. Our results for the minimal PKS system provide mechanistic understanding of PKSs and a fundamental basis for engineering PKS pathways for future applications.
|
|
| 3. |
- Auman, Dirk, et al.
(författare)
-
Peroxy Intermediate Drives Carbon Bond Activation in the Dioxygenase AsqJ
- 2022
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 144:34, s. 15622-15632
-
Tidskriftsartikel (refereegranskat)abstract
- Dioxygenases catalyze stereoselective oxygen atom transfer in metabolic pathways of biological, industrial, and pharmaceutical importance, but their precise chemical principles remain controversial. The α-ketoglutarate (αKG)-dependent dioxygenase AsqJ synthesizes biomedically active quinolone alkaloids via desaturation and subsequent epoxidation of a carbon–carbon bond in the cyclopeptin substrate. Here, we combine high-resolution X-ray crystallography with enzyme engineering, quantum-classical (QM/MM) simulations, and biochemical assays to describe a peroxidic intermediate that bridges the substrate and active site metal ion in AsqJ. Homolytic cleavage of this moiety during substrate epoxidation generates an activated high-valent ferryl (FeIV = O) species that mediates the next catalytic cycle, possibly without the consumption of the metabolically valuable αKG cosubstrate. Our combined findings provide an important understanding of chemical bond activation principles in complex enzymatic reaction networks and molecular mechanisms of dioxygenases.
|
|
| 4. |
- Ernst, Stefan, et al.
(författare)
-
Legionella effector AnkX displaces the switch II region for Rab1b phosphocholination
- 2020
-
Ingår i: Science Advances. - : American Association for the Advancement of Science. - 2375-2548. ; 6:20
-
Tidskriftsartikel (refereegranskat)abstract
- The causative agent of Legionnaires disease, Legionella pneumophila, translocates the phosphocholine transferase AnkX during infection and thereby posttranslationally modifies the small guanosine triphosphatase (GTPase) Rab1 with a phosphocholine moiety at S76 using cytidine diphosphate (CDP)–choline as a cosubstrate. The molecular basis for Rab1 binding and enzymatic modification have remained elusive because of lack of structural information of the low-affinity complex with AnkX. We combined thiol-reactive CDP-choline derivatives with recombinantly introduced cysteines in the AnkX active site to covalently capture the heterocomplex. The resulting crystal structure revealed that AnkX induces displacement of important regulatory elements of Rab1 by placing a β sheet into a conserved hydrophobic pocket, thereby permitting phosphocholine transfer to the active and inactive states of the GTPase. Together, the combination of chemical biology and structural analysis reveals the enzymatic mechanism of AnkX and the family of filamentation induced by cyclic adenosine monophosphate (FIC) proteins.
|
|
| 5. |
|
|
| 6. |
- Geeraert, Arnout, et al.
(författare)
-
Good governance in international sport organizations : an analysis of the 35 Olympic sport governing bodies
- 2014
-
Ingår i: International Journal of Sport Policy and Politics. - : Taylor & Francis. - 1940-6940 .- 1940-6959. ; 6:3, s. 281-306
-
Tidskriftsartikel (refereegranskat)abstract
- In this article, structural issues with regard to the quality of the self-governance of the 35 Olympic sport governing bodies (SGBs) are analysed. First, this article presents empirical evidence on the lack of accountability arrangements in SGBs. In particular, the watchdog function of their member organizations is severely undermined by the general absence of objective criteria and transparency in the distribution of funding to members. With regard to checks and balances, arguably the most topical issue is the complete lack of independent ethics committees. Second, our survey demonstrates that most SGBs have institutionalized athlete participation. However, in the overwhelming majority of the organizations, they have not been granted a share of formal decisionmaking power. Third, with regard to executive body members, there is the rather anachronistic dominance of the European continent and also the preponderance of male officials. In addition, the general lack of term limits poses serious threats with regard to the concentration of power, which is evidenced for instance by the overall number of years SGB presidents are in office. The empirical evidence clearly supports the recent calls for improved governance in sport, according to which SGBs need to agree upon, and act in accordance with, a set of well-defined criteria of good governance.Only then will the self-governance of sport be credible and the privileged autonomy of these organizations justifiable.
|
|
| 7. |
- Kaspers, Marietta S., et al.
(författare)
-
Dephosphocholination by Legionella effector Lem3 functions through remodelling of the switch II region of Rab1b
- 2023
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
-
Tidskriftsartikel (refereegranskat)abstract
- Bacterial pathogens often make use of post-translational modifications to manipulate host cells. Legionella pneumophila, the causative agent of Legionnaires disease, secretes the enzyme AnkX that uses cytidine diphosphate-choline to post-translationally modify the human small G-Protein Rab1 with a phosphocholine moiety at Ser76. Later in the infection, the Legionella enzyme Lem3 acts as a dephosphocholinase, hydrolytically removing the phosphocholine. While the molecular mechanism for Rab1 phosphocholination by AnkX has recently been resolved, structural insights into the activity of Lem3 remained elusive. Here, we stabilise the transient Lem3:Rab1b complex by substrate mediated covalent capture. Through crystal structures of Lem3 in the apo form and in complex with Rab1b, we reveal Lem3's catalytic mechanism, showing that it acts on Rab1 by locally unfolding it. Since Lem3 shares high structural similarity with metal-dependent protein phosphatases, our Lem3:Rab1b complex structure also sheds light on how these phosphatases recognise protein substrates.
|
|
| 8. |
- Persson Waye, Kerstin, 1959, et al.
(författare)
-
Rail freight vibration impacts sleep and community response: An overview of CargoVibes
- 2014
-
Ingår i: ICBEN 2014, the 11th International Congress on Noise as a Public Health Problem. Nara, Japan, 2014 June 1 to June 5.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The European Union funded CargoVibes project involving 10 partners from 8 nations has aimed to examine ground-borne vibration affecting residents close to freight railway lines. This poster presents an overview of the work package investigating human response to vibration, with particular focus on physiological and psychological impact on sleep, community annoyance and the development of guidance in evaluating response. The effects of vibration on sleep were measured in a series of laboratory trials at the University of Gothenburg. Existing field studies of community response were supplemented with further field work in the Netherlands and Poland, and a meta-analysis conducted to determine dose-response relationships for railway vibration. Numerous outcomes of vibration exposure were found, with physiological markers such as greater heart rate response and cortical reactions during sleep, and annoyance and sleep disturbance increasing with higher vibration amplitudes. A guidance document considering current state of the art regarding vibration measurement and assessment was produced pertaining to human perception, evaluation methods, annoyance, sleep impacts, and non-exposure factors. The outcomes of this work represent a significant advance in the understanding of the human response to railway vibration and a step towards a much needed harmonisation of assessment methods. The findings presented in this poster highlight the importance of considering environmental vibration in the planning, construction, and maintenance of railways in residential environments.
|
|
| 9. |
- Waddington, David, et al.
(författare)
-
Cargovibes: Human response to vibration due to freight rail trafiic
- 2015
-
Ingår i: Proceedings of 22nd International Congress on Sound and Vibration, 12 - 16 July, Florence, Italy 2015. - : Informa UK Limited. ; 3:4, s. 233-48
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this paper is to present an overview of the research concerning human response to vibration conducted in the EU FP7 CargoVibes project. The European Union funded pro-ject CargoVibes involved ten partners from eight nations and ran from April 2011 to April 2014. The project was concerned with railway-induced ground-borne vibration affecting res-idents close to freight lines, with one work package that investigated human response to vi-bration, including sleep disturbance, community annoyance, and the production of a best practice guide for evaluating response. Laboratory trials at the University of Gothenburg were used to measure the effects of vibration on sleep. Physiological and psychological im-pacts of vibration exposure were found. TNO led a meta-analysis (N = 4129) to determine exposure-response relationships for railway vibration, with existing data for community re-sponse supplemented with field studies in the Netherlands and Poland. The University of Salford led production of a guidance document that presents the state of the art regarding vi-bration measurement and assessment. Specific topics in the guide include human perception, evaluation methods, annoyance, sleep impacts, and non-exposure factors. The outcomes pre-sented in this paper represent a significant advance in the understanding of the human re-sponse to railway vibration and a step towards much needed harmonization of assessment methods.
|
|
