| 1. |
- Molin, Mikael, 1973, et al.
(författare)
-
Protein kinase A controls yeast growth in visible light
- 2020
-
Ingår i: BMC Biology. - : Springer Science and Business Media LLC. - 1741-7007. ; 18:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: A wide variety of photosynthetic and non-photosynthetic species sense and respond to light, having developed protective mechanisms to adapt to damaging effects on DNA and proteins. While the biology of UV light-induced damage has been well studied, cellular responses to stress from visible light (400–700 nm) remain poorly understood despite being a regular part of the life cycle of many organisms. Here, we developed a high-throughput method for measuring growth under visible light stress and used it to screen for light sensitivity in the yeast gene deletion collection. Results: We found genes involved in HOG pathway signaling, RNA polymerase II transcription, translation, diphthamide modifications of the translational elongation factor eEF2, and the oxidative stress response to be required for light resistance. Reduced nuclear localization of the transcription factor Msn2 and lower glycogen accumulation indicated higher protein kinase A (cAMP-dependent protein kinase, PKA) activity in many light-sensitive gene deletion strains. We therefore used an ectopic fluorescent PKA reporter and mutants with constitutively altered PKA activity to show that repression of PKA is essential for resistance to visible light. Conclusion: We conclude that yeast photobiology is multifaceted and that protein kinase A plays a key role in the ability of cells to grow upon visible light exposure. We propose that visible light impacts on the biology and evolution of many non-photosynthetic organisms and have practical implications for how organisms are studied in the laboratory, with or without illumination.
|
|
| 2. |
- Saenz Mendez, Patricia, et al.
(författare)
-
Homology models of human all-trans retinoic acid metabolizing enzymes CYP26B1 and CYP26B1 spliced-variant.
- 2012
-
Ingår i: Journal of Chemical Information and Modeling. - Washington, USA : American Chemical Society (ACS). - 1549-9596 .- 1549-960X. ; 52:10, s. 2631-2637
-
Tidskriftsartikel (refereegranskat)abstract
- Homology models of CYP26B1 (cytochrome P450RAI2) and CYP26B1 spliced variant were derived using the crystal structure of cyanobacterial CYP120A1 as template for the model building. The quality of the homology models generated were carefully evaluated, and the natural substrate all-trans-retinoic acid (atRA), several tetralone-derived retinoic acid metabolizing blocking agents (RAMBAs), and a well-known potent inhibitor of CYP26B1 (R115866) were docked into the homology model of full-length cytochrome P450 26B1. The results show that in the model of the full-length CYP26B1, the protein is capable of distinguishing between the natural substrate (atRA), R115866, and the tetralone derivatives. The spliced variant of CYP26B1 model displays a reduced affinity for atRA compared to the full-length enzyme, in accordance with recently described experimental information.
|
|
| 3. |
- Eriksson, Leif A., 1964-, et al.
(författare)
-
Tetrazole derivatives as cytochrome p450 inhibitors
- 2019
-
Patent (populärvet., debatt m.m.)abstract
- According to the invention there is provided a compound of formula I, wherein R1 and R2 have meanings given in the description, which compounds are useful in the treatment of skin disorders and other diseases.
|
|
| 4. |
- Czegeny, G., et al.
(författare)
-
Hydrogen peroxide contributes to the ultraviolet-B (280-315 nm) induced oxidative stress of plant leaves through multiple pathways
- 2014
-
Ingår i: Febs Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 588:14, s. 2255-2261
-
Tidskriftsartikel (refereegranskat)abstract
- Solar UV-B (280-315 nm) radiation is a developmental signal in plants but may also cause oxidative stress when combined with other environmental factors. Using computer modeling and in solution experiments we show that UV-B is capable of photosensitizing hydroxyl radical production from hydrogen peroxide. We present evidence that the oxidative effect of UV-B in leaves is at least twofold: (i) it increases cellular hydrogen peroxide concentrations, to a larger extent in pyridoxine antioxidant mutant pdx1.3-1 Arabidopsis and; (ii) is capable of a partial photo-conversion of both 'natural' and 'extra' hydrogen peroxide to hydroxyl radicals. As stress conditions other than UV can increase cellular hydrogen peroxide levels, synergistic deleterious effects of various stresses may be expected already under ambient solar UV-B. (C) 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
|
|
| 5. |
- Wu, Min, 1986, et al.
(författare)
-
Proline 411 biases the conformation of the intrinsically disordered plant UVR8 photoreceptor C27 domain altering the functional properties of the peptide
- 2019
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- UVR8 (UV RESISTANCE LOCUS 8) is a UV-B photoreceptor responsible for initiating UV-B signalling in plants. UVR8 is a homodimer in its signalling inactive form. Upon absorption of UV radiation, the protein monomerizes into its photoactivated state. In the monomeric form, UVR8 binds the E3 ubiquitin ligase COP1 (CONSTITUTIVELY PHOTOMORPHOGENIC 1), triggering subsequent UV-B-dependent photomorphogenic development in plants. Recent in vivo experiments have shown that the UVR8 C-terminal region (aa 397-423; UVR8(C27)) alone is sufficient to regulate the activity of COP1. In this work, CD spectroscopy and NMR experiments showed that the UVR8(C27) domain was non-structured but gained secondary structure at higher temperatures leading to increased order. Bias-exchange metadynamics simulations were also performed to evaluate the free energy landscape of UVR8(C27). An inverted free energy landscape was revealed, with a disordered structure in the global energy minimum. Flanking the global energy minimum, more structured states were found at higher energies. Furthermore, stabilization of the low energy disordered state was attributed to a proline residue, P411, as evident from P411A mutant data. P411 is also a key residue in UVR8 binding to COP1. UVR8(C27) is therefore structurally competent to function as a molecular switch for interaction of UVR8 with different binding partners since at higher free energies different structural conformations are being induced in this peptide. P411 has a key role for this function.
|
|
| 6. |
- Elmabsout, Ali Ateia, et al.
(författare)
-
Cloning and Functional Studies of a Splice Variant of CYP26B1 Expressed in Vascular Cells
- 2012
-
Ingår i: Plos One. - San Francisco, USA : Public Library of Science (PLoS). - 1932-6203. ; 7:5
-
Tidskriftsartikel (refereegranskat)abstract
- Background: All-trans retinoic acid (atRA) plays an essential role in the regulation of gene expression, cell growth and differentiation and is also important for normal cardiovascular development but may in turn be involved in cardiovascular diseases, i.e. atherosclerosis and restenosis. The cellular atRA levels are under strict control involving several cytochromes P450 isoforms (CYPs). CYP26 may be the most important regulator of atRA catabolism in vascular cells. The present study describes the molecular cloning, characterization and function of atRA-induced expression of a spliced variant of the CYP26B1 gene. Methodology/Principal Findings: The coding region of the spliced CYP26B1 lacking exon 2 was amplified from cDNA synthesized from atRA-treated human aortic smooth muscle cells and sequenced. Both the spliced variant and full length CYP26B1 was found to be expressed in cultured human endothelial and smooth muscle cells, and in normal and atherosclerotic vessel. atRA induced both variants of CYP26B1 in cultured vascular cells. Furthermore, the levels of spliced mRNA transcript were 4.5 times higher in the atherosclerotic lesion compared to normal arteries and the expression in the lesions was increased 20-fold upon atRA treatment. The spliced CYP26B1 still has the capability to degrade atRA, but at an initial rate one-third that of the corresponding full length enzyme. Transfection of COS-1 and THP-1 cells with the CYP26B1 spliced variant indicated either an increase or a decrease in the catabolism of atRA, probably depending on the expression of other atRA catabolizing enzymes in the cells. Conclusions/Significance: Vascular cells express the spliced variant of CYP26B1 lacking exon 2 and it is also increased in atherosclerotic lesions. The spliced variant displays a slower and reduced degradation of atRA as compared to the full-length enzyme. Further studies are needed, however, to clarify the substrate specificity and role of the CYP26B1 splice variant in health and disease.
|
|
| 7. |
- Lindahl, Lina, 1984, et al.
(författare)
-
Alcohols enhance the rate of acetic acid diffusion in S. cerevisiae: biophysical mechanisms and implications for acetic acid tolerance
- 2018
-
Ingår i: Microbial Cell. - : Shared Science Publishers OG. - 2311-2638. ; 5:1, s. 42-55
-
Tidskriftsartikel (refereegranskat)abstract
- Microbial cell factories with the ability to maintain high productivity in the presence of weak organic acids, such as acetic acid, are required in many industrial processes. For example, fermentation media derived from lignocellulosic biomass are rich in acetic acid and other weak acids. The rate of diffusional entry of acetic acid is one parameter determining the ability of microorganisms to tolerance the acid. The present study demonstrates that the rate of acetic acid diffusion in S. cerevisiae is strongly affected by the alcohols ethanol and n-butanol. Ethanol of 40 g/L and n-butanol of 8 g/L both caused a 65% increase in the rate of acetic acid diffusion, and higher alcohol concentrations caused even greater increases. Molecular dynamics simulations of membrane dynamics in the presence of alcohols demonstrated that the partitioning of alcohols to the head group region of the lipid bilayer causes a considerable increase in the membrane area, together with reduced membrane thickness and lipid order. These changes in physiochemical membrane properties lead to an increased number of water molecules in the membrane interior, providing biophysical mechanisms for the alcohol-induced increase in acetic acid diffusion rate. nbutanol affected S. cerevisiae and the cell membrane properties at lower concentrations than ethanol, due to greater and deeper partitioning in the membrane. This study demonstrates that the rate of acetic acid diffusion can be strongly affected by compounds that partition into the cell membrane, and highlights the need for considering interaction effects between compounds in the design of microbial processes.
|
|
| 8. |
- Eriksson, Emma S. E., et al.
(författare)
-
Permeability of 5-aminolevulinic acid oxime derivatives in lipid membranes
- 2016
-
Ingår i: Theoretical Chemistry accounts. - : Springer Science and Business Media LLC. - 1432-881X .- 1432-2234. ; 135:1, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- The endogenous molecule 5-aminolevulinic acid (5ALA) and its methyl ester (Me-5ALA) have been used as prodrugs in photodynamic treatment of actinic keratosis and superficial non-melanoma skin cancers for over a decade. Recently, a novel set of 5ALA derivatives based on introducing a hydrolyzable oxime functionality was proposed and shown to generate considerably stronger onset of the photoactive molecule protoporphyrin IX (PpIX) in the cells. In the current work, we employ molecular dynamics simulation techniques to explore whether the higher intercellular concentration of PpIX caused by the oxime derivatives is related to enhanced membrane permeability, or whether other factors contribute to this. It is concluded that the oximes show overall similar accumulation at the membrane headgroup regions as the conventional derivatives and that the transmembrane permeabilities are in general close to that of 5ALA. The highest permeability of all compounds explored is found for Me-5ALA, which correlates with a considerably lower fee energy barrier at the hydrophobic bilayer center. The high PpIX concentration must hence be sought in other factors, where slow hydrolysis of the oxime functionality is a plausible reason, enabling stronger buildup of PpIX over time.
|
|
| 9. |
- Zeng, Jiao, et al.
(författare)
-
High-resolution structure of a fish aquaporin reveals a novel extracellular fold
- 2022
-
Ingår i: Life Science Alliance. - : Life Science Alliance, LLC. - 2575-1077. ; 5:12
-
Tidskriftsartikel (refereegranskat)abstract
- Aquaporins are protein channels embedded in the lipid bilayer in cells from all organisms on earth that are crucial for water homeostasis. In fish, aquaporins are believed to be important for osmoregulation; however, the molecular mechanism behind this is poorly understood. Here, we present the first structural and functional characterization of a fish aquaporin; cpAQP1aa from the fresh water fish climbing perch (Anabas testudineus), a species that is of high osmoregulatory interest because of its ability to spend time in seawater and on land. These studies show that cpAQP1aa is a water-specific aquaporin with a unique fold on the extracellular side that results in a constriction region. Functional analysis combined with molecular dynamic simulations suggests that phosphorylation at two sites causes structural perturbations in this region that may have implications for channel gating from the extracellular side.
|
|
| 10. |
- Bettiga, Maurizio, 1978, et al.
(författare)
-
Plasma membrane as a crucial player in acetic acid effect on yeast
- 2017
-
Ingår i: IMYA12- 12th International Meeting on Yeast Apoptosis, Bari, Italy • 14-18 May 2017.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Weak organic acids such as formic, acetic or lactic acid are known inhibitors of microbial growth and fermentation. Acetic acid toxicity to yeast cells has been explained by different theories, involving specific signaling effects triggering an active cell death program, reduction of intracellular pH and acetate anion accumulation. Regardless of the fact whether the actual effect of acetate involves one of these mechanisms or a combination thereof, acetic acid inhibits yeast metabolism and affects yeast viability. This has a high impact on the feasibility of the new generation of fermentation processes, based on the naturally acetic acid-rich lignocellulosic substrates. It is therefore highly desirable to obtain a strain with increased capacity of coping with high acetic acid concentrations in the fermentation medium. Acetic acid is thought to be internalized by yeast cells in its undissociated form, by crossing the hydrophobic barrier of plasma membrane. Thus, in our work we focused on the investigation of membrane properties and how these influence the tolerance of yeast to acetic acid. First, we demonstrated with lipidomics analysis of membrane lipids that the yeast Zygosaccharomyces bailii, showing extraordinary tolerance to acetic acid, has a plasma membrane which is rich in sphingolipids. Next, we combined membrane molecular dynamics and in vivo measurements to confirm the specific role of sphingolipids in altering the permeability of plasma membrane to acetic acid. Finally, we investigated the effect of alcohols on the acetic acid permeation rate through the membrane. Our ultimate goal is to engineer the membrane composition of an industrial yeast strain towards reduced permeability, in order to obtain higher acetic acid tolerance.
|
|
