| 1. |
- Iakovleva, Irina, et al.
(författare)
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Structural basis for transthyretin amyloid formation in vitreous body of the eye
- 2021
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid transthyretin (ATTR) amyloidosis is characterized by the abnormal accumulation of ATTR fibrils in multiple organs. However, the structure of ATTR fibrils from the eye is poorly understood. Here, we used cryo-EM to structurally characterize vitreous body ATTR fibrils. These structures were distinct from previously characterized heart fibrils, even though both have the same mutation and type A pathology. Differences were observed at several structural levels: in both the number and arrangement of protofilaments, and the conformation of the protein fibril in each layer of protofilaments. Thus, our results show that ATTR protein structure and its assembly into protofilaments in the type A fibrils can vary between patients carrying the same mutation. By analyzing and matching the interfaces between the amino acids in the ATTR fibril with those in the natively folded TTR, we are able to propose a mechanism for the structural conversion of TTR into a fibrillar form.
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| 2. |
- Kazempour, Daniyal, et al.
(författare)
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Compound segmentation via clustering on Mol2Vec-based embeddings
- 2021
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Ingår i: 2021 IEEE 17th International Conference on eScience (eScience). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665403610 - 9781665447089 ; , s. 60-69
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Konferensbidrag (refereegranskat)abstract
- During different steps in the process of discovering drug candidates for diseases, it can be supportive to identify groups of molecules that share similar properties, i.e. common overall structural similarity. The existing methods for computing (dis)similarities between chemical structures rely on a priori domain knowledge. Here we investigate the clustering of compounds that are applied on embeddings generated from a recently published Mol2Vec technique which enables an entirely unsupervised vector representation of compounds. A research question we address in this work is: do existent well-known clustering algorithms such as k-means or hierarchical clustering methods yield meaningful clusters on the Mol2Vec embeddings? Further, we investigate how far subspace clustering can be utilized to compress the data by reducing the dimensionality of the compounds vector representation. Our first conducted experiments on a set of COVID-19 drug candidates reveal that well-established methods yield meaningful clusters. Preliminary results from subspace clusterings indicate that a compression of the vector representations seems viable.
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| 3. |
- Krypotou, Emilia, et al.
(författare)
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Control of Bacterial Virulence through the Peptide Signature of the Habitat
- 2019
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Ingår i: Cell Reports. - : Elsevier. - 2211-1247. ; 26:7, s. 1815-1827
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Tidskriftsartikel (refereegranskat)abstract
- To optimize fitness, pathogens selectively activate their virulence program upon host entry. Here, we report that the facultative intracellular bacterium Listeria monocytogenes exploits exogenous oligopeptides, a ubiquitous organic N source, to sense the environment and control the activity of its virulence transcriptional activator, PrfA. Using a genetic screen in adsorbent- treated ( PrfA-inducing) medium, we found that PrfA is functionally regulated by the balance between activating and inhibitory nutritional peptides scavenged via the Opp transport system. Activating peptides provide essential cysteine precursor for the PrfA-inducing cofactor glutathione ( GSH). Non-cysteine-containing peptides cause promiscuous PrfA inhibition. Biophysical and co-crystallization studies reveal that peptides inhibit PrfA through steric blockade of the GSH binding site, a regulation mechanism directly linking bacterial virulence and metabolism. L. monocytogenes mutant analysis in macrophages and our functional data support a model in which changes in the balance of antagonistic Oppimported oligopeptides promote PrfA induction intra-cellularly and PrfA repression outside the host.
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| 4. |
- Oelker, Melanie, 1988-
(författare)
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Disarming bacteria : a structure-based approach to design an anti-virulence drug against Listeria monocytogenes
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antibiotic resistances are one of the biggest threats to global health and if we don’t change our behavior and way of using antibiotics we will end up in a ‘post-antibiotic era’, in which common infections and minor injuries can once kill again and up to 10 million deaths per year may occur by 2050. Therefore, there is a high need for new anti-bacterial drugs, especially of alternatives to existing antibiotics with already described resistances. Classical antibiotics target the essential processes of survival and growth in bacteria and therefore put a high selective pressure on them to develop resistances. In contrast, the ability to infect or damage a host, the virulence, is less essential for bacteria. Thus, targeting the virulence is supposed to cause a lower selective pressure and this alternative mode-of-action could help to decelerate the development of antibiotic resistances.The aims in this work were to proceed with the structure-based design of an anti-virulence drug against the food-borne pathogen Listeria monocytogenes, but also to deepen our understanding of the complex regulation system for the virulence of this bacterium. PrfA, the master regulator of virulence in Listeria monocytogenes, is a member of a large family of bacterial transcription factors, which are regulated by a conformational change and allosteric modulation by different regulator molecules. Furthermore, its critical role in virulence regulations makes is a suitable target for an anti-virulence drug. In this work new lead compounds based on the previously identified ring-fused 2-pyridone scaffold were designed, synthesized and analyzed by different biological, biophysical, computational and structural biology methods. Three new binding sites and binding modes of these compounds in PrfA were evaluated for their potential use in future designs and a compound with improved activity was identified. In a second study another structurally different lead compound was discovered to inhibit PrfA. Furthermore, the studies on proposed natural regulators of PrfA uncovered the underlying mechanism for the virulence regulation by the peptide signature of the environment and in a follow-up study the structural basis of the binding of inhibitory peptides to PrfA was further investigated. Finally, a structural review on all available structure of PrfA provided more insights into the allosteric regulation mechanism of PrfA activity.This work will hopefully support in the successful development of an anti-virulence drug against Listeria monocytogenes and thus contribute to the reduction of the problem of antibiotic resistances.
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| 5. |
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| 6. |
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| 7. |
- Tischlik, Sonja, et al.
(författare)
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Insights into Enzymatic Catalysis from Binding and Hydrolysis of Diadenosine Tetraphosphate by E. coli Adenylate Kinase
- 2023
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 62:15, s. 2238-2243
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Tidskriftsartikel (refereegranskat)abstract
- Adenylate kinases play a crucial role in cellular energy homeostasis through the interconversion of ATP, AMP, and ADP in all living organisms. Here, we explore how adenylate kinase (AdK) from Escherichia coli interacts with diadenosine tetraphosphate (AP4A), a putative alarmone associated with transcriptional regulation, stress, and DNA damage response. From a combination of EPR and NMR spectroscopy together with X-ray crystallography, we found that AdK interacts with AP4A with two distinct modes that occur on disparate time scales. First, AdK dynamically interconverts between open and closed states with equal weights in the presence of AP4A. On a much slower time scale, AdK hydrolyses AP4A, and we suggest that the dynamically accessed substrate-bound open AdK conformation enables this hydrolytic activity. The partitioning of the enzyme into open and closed states is discussed in relation to a recently proposed linkage between active site dynamics and collective conformational dynamics.
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| 8. |
- Tran, Thao Thanh, et al.
(författare)
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Inhibition of the master regulator of Listeria monocytogenes virulence enables bacterial clearance from spacious replication vacuoles in infected macrophages
- 2022
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Ingår i: PLoS Pathogens. - : Public Library Science. - 1553-7366 .- 1553-7374. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- A hallmark of Listeria (L.) monocytogenes pathogenesis is bacterial escape from maturing entry vacuoles, which is required for rapid bacterial replication in the host cell cytoplasm and cell-to-cell spread. The bacterial transcriptional activator PrfA controls expression of key virulence factors that enable exploitation of this intracellular niche. The transcriptional activity of PrfA within infected host cells is controlled by allosteric coactivation. Inhibitory occupation of the coactivator site has been shown to impair PrfA functions, but consequences of PrfA inhibition for L. monocytogenes infection and pathogenesis are unknown. Here we report the crystal structure of PrfA with a small molecule inhibitor occupying the coactivator site at 2.0 Å resolution. Using molecular imaging and infection studies in macrophages, we demonstrate that PrfA inhibition prevents the vacuolar escape of L. monocytogenes and enables extensive bacterial replication inside spacious vacuoles. In contrast to previously described spacious Listeria-containing vacuoles, which have been implicated in supporting chronic infection, PrfA inhibition facilitated progressive clearance of intracellular L. monocytogenes from spacious vacuoles through lysosomal degradation. Thus, inhibitory occupation of the PrfA coactivator site facilitates formation of a transient intravacuolar L. monocytogenes replication niche that licenses macrophages to effectively eliminate intracellular bacteria. Our findings encourage further exploration of PrfA as a potential target for antimicrobials and highlight that intra-vacuolar residence of L. monocytogenes in macrophages is not inevitably tied to bacterial persistence.
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