| 1. |
- Cellini, Andrea, 1991, et al.
(författare)
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Directed ultrafast conformational changes accompany electron transfer in a photolyase as resolved by serial crystallography.
- 2024
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Ingår i: Nature chemistry. - 1755-4349.
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Tidskriftsartikel (refereegranskat)abstract
- Charge-transfer reactions in proteins are important for life, such as in photolyases which repair DNA, but the role of structural dynamics remains unclear. Here, using femtosecond X-ray crystallography, we report the structural changes that take place while electrons transfer along a chain of four conserved tryptophans in the Drosophila melanogaster (6-4) photolyase. At femto- and picosecond delays, photoreduction of the flavin by the first tryptophan causes directed structural responses at a key asparagine, at a conserved salt bridge, and by rearrangements of nearby water molecules. We detect charge-induced structural changes close to the second tryptophan from 1 ps to 20 ps, identifying a nearby methionine as an active participant in the redox chain, and from 20 ps around the fourth tryptophan. The photolyase undergoes highly directed and carefully timed adaptations of its structure. This questions the validity of the linear solvent response approximation in Marcus theory and indicates that evolution has optimized fast protein fluctuations for optimal charge transfer.
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| 2. |
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| 3. |
- Antoszczak, Michał, et al.
(författare)
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Biological activity of doubly modified salinomycin analogs – Evaluation in vitro and ex vivo
- 2018
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Ingår i: European Journal of Medicinal Chemistry. - : Elsevier BV. - 0223-5234. ; 156, s. 510-523
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Tidskriftsartikel (refereegranskat)abstract
- The polyether ionophore salinomycin has recently captured much interest due to its potent activity against multi-drug resistant cancer cells and cancer stem cells. Previous studies have shown that either acylation of the C20 position or esterification/amidation of the C1 carboxylate moiety is beneficial in terms of biological properties. In this paper, we present the first analogs combining such modifications. Evaluation of the anti-proliferative activity against a series of cancer cell lines showed that acylation of the C20 hydroxyl group improves the activity of salinomycin C1 amides but not of the corresponding C1 esters. Importantly, the activity of several of the doubly modified analogs surpasses that of commonly used cytostatic drugs cisplatin and doxorubicin in the LoVo/DX multi-drug resistant cell line. All analogs were tested against primary acute lymphoblastic leukemia cells in standard cell viability assays; three were more potent than salinomycin. Further studies revealed that selected analogs induced characteristics of apoptotic cell death and increased expression of p53. Additionally, using an ex vivo model of breast tumor, tumor cell viability significantly decreased after treatment with salinomycin or its double-modified derivative (3a) in a time-dependent manner. The present findings indicate that double-modified salinomycin derivatives constitute promising lead compounds for targeting various types of cancer.
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| 4. |
- Antoszczak, Michał, et al.
(författare)
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Bivalent polyether ionophores : Synthesis and biological evaluation of C2-symmetric salinomycin dimers
- 2017
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Ingår i: Tetrahedron Letters. - : Elsevier BV. - 0040-4039. ; 58:24, s. 2396-2399
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Tidskriftsartikel (refereegranskat)abstract
- Efficient methods for the synthesis of C2-symmetric dimers of salinomycin joined at either the C1 or C20 positions are reported. Similarly to the native structure, the C20-O-terephthalate dimer displayed activity in the low μM range against a series of cancer cell lines, while dimers joined at the C1 position were essentially inactive.
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| 5. |
- Bharmoria, Pankaj, 1985, et al.
(författare)
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Protein cohabitation: long-term immunoglobulin G storage at room temperature
- 2023
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Ingår i: Journal of Materials Chemistry B. - : Royal Society of Chemistry. - 2050-750X .- 2050-7518. ; 11:24, s. 5400-5405
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Tidskriftsartikel (refereegranskat)abstract
- Long-term functional storage of therapeutic proteins at room temperature has been an eternal challenge. Inspired by the cellular cooperativity of proteins, we have taken a step forward to address this challenge by cohabitating Immunoglobulin G (IgG1) with a food protein gelatin in the solid-state at room temperature. Interestingly, IgG1 remained functionally active for a record 14 months revealed from the western-blot assay. Further quantification by HP-LC analysis showed 100% structural integrity of IgG1 with no degradation in the gelatin matrix during this period. The developed formulation has a direct application in oral medical nutrition therapy to cure gastrointestinal microbial infections. Also the strategy provides a robust energy economic alternative to the protein engineering methods for long-term functional storage of therapeutic proteins at room temperature.
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| 6. |
- Carrillo, M., et al.
(författare)
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High-resolution crystal structures of transient intermediates in the phytochrome photocycle
- 2021
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Ingår i: Structure. - : Elsevier BV. - 0969-2126. ; 29:7, s. 743-
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes are red/far-red light photoreceptors in bacteria to plants, which elicit a variety of important physiological responses. They display a reversible photocycle between the resting Pr state and the light-activated Pfr state. Light signals are transduced as structural change through the entire protein to modulate its activity. It is unknown how the Pr-to-Pfr interconversion occurs, as the structure of intermediates remains notoriously elusive. Here, we present short-lived crystal structures of the photosensory core modules of the bacteriophytochrome from myxobacterium Stigmatella aurantiaca captured by an X-ray free electron laser 5 ns and 33 ms after light illumination of the Pr state. We observe large structural displacements of the covalently bound bilin chromophore, which trigger a bifurcated signaling pathway that extends through the entire protein. The snapshots show with atomic precision how the signal progresses from the chromophore, explaining how plants, bacteria, and fungi sense red light.
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| 7. |
- Chenchiliyan, Manoop, et al.
(författare)
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Ground-state heterogeneity and vibrational energy redistribution in bacterial phytochrome observed with femtosecond 2D IR spectroscopy
- 2023
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 158:8
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes belong to a group of photoreceptor proteins containing a covalently bound biliverdin chromophore that inter-converts between two isomeric forms upon photoexcitation. The existence and stability of the photocycle products are largely determined by the protein sequence and the presence of conserved hydrogen-bonding interactions in the vicinity of the chromophore. The vibrational signatures of biliverdin, however, are often weak and obscured under more intense protein bands, limiting spectroscopic studies of its non-transient signals. In this study, we apply isotope-labeling techniques to isolate the vibrational bands from the protein-bound chromophore of the bacterial phytochrome from Deinococcus radiodurans. We elucidate the structure and ultrafast dynamics of the chromophore with 2D infra-red (IR) spectroscopy and molecular dynamics simulations. The carbonyl stretch vibrations of the pyrrole rings show the heterogeneous distribution of hydrogen-bonding structures, which exhibit distinct ultrafast relaxation dynamics. Moreover, we resolve a previously undetected 1678 cm(-1) band that is strongly coupled to the A- and D-ring of biliverdin and demonstrate the presence of complex vibrational redistribution pathways between the biliverdin modes with relaxation-assisted measurements of 2D IR cross peaks. In summary, we expect 2D IR spectroscopy to be useful in explaining how point mutations in the protein sequence affect the hydrogen-bonding structure around the chromophore and consequently its ability to photoisomerize to the light-activated states.
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| 8. |
- Claesson, Elin, 1989, et al.
(författare)
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The primary structural photoresponse of phytochrome proteins captured by a femtosecond X-ray laser
- 2020
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Ingår i: eLife. - 2050-084X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Phytochrome proteins control the growth, reproduction, and photosynthesis of plants, fungi, and bacteria. Light is detected by a bilin cofactor, but it remains elusive how this leads to activation of the protein through structural changes. We present serial femtosecond X-ray crystallographic data of the chromophore-binding domains of a bacterial phytochrome at delay times of 1 ps and 10 ps after photoexcitation. The data reveal a twist of the D-ring, which leads to partial detachment of the chromophore from the protein. Unexpectedly, the conserved so-called pyrrole water is photodissociated from the chromophore, concomitant with movement of the A-ring and a key signaling aspartate. The changes are wired together by ultrafast backbone and water movements around the chromophore, channeling them into signal transduction towards the output domains. We suggest that the observed collective changes are important for the phytochrome photoresponse, explaining the earliest steps of how plants, fungi and bacteria sense red light.
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| 9. |
- Dicke, Sidney S., et al.
(författare)
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Metastable intermediate during hIAPP aggregation catalyzed by membranes as detected with 2D IR spectroscopy
- 2022
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Ingår i: RSC CHEMICAL BIOLOGY. - : Royal Society of Chemistry (RSC). - 2633-0679. ; 3:7, s. 931-940
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Tidskriftsartikel (refereegranskat)abstract
- The aggregation of human islet amyloid polypeptide (hIAPP) into amyloid fibrils involves formation of oligomeric intermediates that are thought to be the cytotoxic species responsible for beta-cell dysfunction in type 2 diabetes. hIAPP oligomers permeating or disrupting the cellular membrane may be one mechanism of toxicity and so measuring the structural kinetics of aggregation in the presence of membranes is of much interest. In this study, we use 2D IR spectroscopy and (CO)-C-13-O-18 isotope labeling to study the secondary structure of the oligomeric intermediates formed in solution and in the presence of phospholipid vesicles at sites L12A13, L16V17, G24A25 and V32G33. Pairs of labels monitor the couplings between associated polypeptides and the dihedral angles between adjacent residues. In solution, the L12A13 residues form an oligomeric beta-sheet in addition to an alpha-helix whereas with the phospholipid vesicles they are alpha-helical throughout the aggregation process. In both solution and with DOPC vesicles, L16V17 and V32G33 have disordered structures until fibrils are formed. Similarly, under both conditions, G24A25 exhibits 3-state kinetics, created by an oligomeric intermediate with a well-defined beta-sheet structure. Amyloid fibril formation is often thought to involve intermediates with exceedingly low populations that are difficult to detect experimentally. These experiments establish that amyloid fibril formation of hIAPP when catalyzed by membranes includes a metastable intermediate and that this intermediate has a similar structure at G24A25 in the FGAIL region as the corresponding intermediate in solution, thought to be the toxic species.
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| 10. |
- Dods, Robert, 1989, et al.
(författare)
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Ultrafast structural changes within a photosynthetic reaction centre.
- 2021
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 589:7841, s. 310-314
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthetic reaction centres harvest the energy content of sunlight by transporting electrons across an energy-transducing biological membrane. Here we use time-resolved serial femtosecond crystallography1 using an X-ray free-electron laser2 to observe light-induced structural changes in the photosynthetic reaction centre of Blastochloris viridis on a timescale of picoseconds. Structural perturbations first occur at the special pair of chlorophyll molecules of the photosynthetic reaction centre that are photo-oxidized by light. Electron transfer to the menaquinone acceptor on the opposite side of the membrane induces a movement of this cofactor together with lower amplitude protein rearrangements. These observations reveal how proteins use conformational dynamics to stabilize the charge-separation steps of electron-transfer reactions.
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