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- Woitowich, N. C., et al.
(författare)
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Structural basis for light control of cell development revealed by crystal structures of a myxobacterial phytochrome
- 2018
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Ingår i: Iucrj. - : International Union of Crystallography (IUCr). - 2052-2525. ; 5:Part 5, s. 619-634
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes are red-light photoreceptors that were first characterized in plants, with homologs in photosynthetic and non-photosynthetic bacteria known as bacteriophytochromes (BphPs). Upon absorption of light, BphPs interconvert between two states denoted Pr and Pfr with distinct absorption spectra in the red and far-red. They have recently been engineered as enzymatic photoswitches for fluorescent-marker applications in non-invasive tissue imaging of mammals. This article presents cryo- and room-temperature crystal structures of the unusual phytochrome from the non-photosynthetic myxobacterium Stigmatella aurantiaca (SaBphP1) and reveals its role in the fruitingbody formation of this photomorphogenic bacterium. SaBphP1 lacks a conserved histidine (His) in the chromophore-binding domain that stabilizes the Pr state in the classical BphPs. Instead it contains a threonine (Thr), a feature that is restricted to several myxobacterial phytochromes and is not evolutionarily understood. SaBphP1 structures of the chromophore binding domain (CBD) and the complete photosensory core module (PCM) in wild-type and Thr-to-His mutant forms reveal details of the molecular mechanism of the Pr/Pfr transition associated with the physiological response of this myxobacterium to red light. Specifically, key structural differences in the CBD and PCM between the wild-type and the Thr-to-His mutant involve essential chromophore contacts with proximal amino acids, and point to how the photosignal is transduced through the rest of the protein, impacting the essential enzymatic activity in the photomorphogenic response of this myxobacterium.
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| 2. |
- Berg, S, et al.
(författare)
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Incidence and prognosis of meningitis due to Haemophilus influenzae, Streptococcus pneumoniae and Neisseria meningitidis in Sweden.
- 1996
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 28:3, s. 247-52
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Tidskriftsartikel (refereegranskat)abstract
- The incidence, concomitant conditions and case fatality rate of Haemophilus influenzae (Hi) and pneumococcal meningitis and of invasive meningococcal infections were studied retrospectively in Sweden (population 8.4 million) for the years 1987-89, the period before vaccination against Hi type b started. A total of 1,019 cases with culture-verified infection were found. The incidence rates per 100,000 per year were 1.8 for Hi meningitis, 1.2 for pneumococcal meningitis and 1.0 for invasive meningococcal infections. The age-specific incidence was highest in the 3-23 months age group for the 3 bacterial species. Pneumococcal meningitis was common in individuals > or = 60 years and meningococcal infections in the age-group 10-24 years. A serious concomitant condition was known in 57% of all patients with pneumococcal meningitis while this was uncommon for the other organisms. The case fatality rate was 2% for Hi meningitis, 24% for pneumococcal meningitis and 10% for meningococcal infections. All 81 pneumococcal isolates which had been serotyped belonged to serotypes in the 23-valent pneumococcal vaccine. Of the meningococcal isolates, 65% belonged to serogroup B. In conclusion, the high incidence of Hib meningitis justifies general Hib vaccination. Development of a vaccine against N. meningitidis group B should have high priority. Furthermore, improved pneumococcal vaccines are needed for patients with predisposing conditions. The currently available pneumococcal polysaccharide vaccine seems to be underused.
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| 3. |
- Edlund, Petra, et al.
(författare)
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The room temperature crystal structure of a bacterial phytochrome determined by serial femtosecond crystallography
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes are a family of photoreceptors that control light responses of plants, fungi and bacteria. A sequence of structural changes, which is not yet fully understood, leads to activation of an output domain. Time-resolved serial femtosecond crystallography (SFX) can potentially shine light on these conformational changes. Here we report the room temperature crystal structure of the chromophore-binding domains of the Deinococcus radiodurans phytochrome at 2.1 angstrom resolution. The structure was obtained by serial femtosecond X-ray crystallography from microcrystals at an X-ray free electron laser. We find overall good agreement compared to a crystal structure at 1.35 angstrom resolution derived from conventional crystallography at cryogenic temperatures, which we also report here. The thioether linkage between chromophore and protein is subject to positional ambiguity at the synchrotron, but is fully resolved with SFX. The study paves the way for time-resolved structural investigations of the phytochrome photocycle with time-resolved SFX.
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| 9. |
- Ragunathrao, Vijay Avin Balaji, et al.
(författare)
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Sphingosine-1-Phosphate Receptor 1 Activity Promotes Tumor Growth by Amplifying VEGF-VEGFR2 Angiogenic Signaling
- 2019
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Ingår i: Cell Reports. - : CELL PRESS. - 2211-1247. ; 29:11, s. 3472-3487
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Tidskriftsartikel (refereegranskat)abstract
- The vascular endothelial growth factor-A (VEGF-A)-VEGFR2 pathway drives tumor vascularization by activating proangiogenic signaling in endothelial cells (ECs). Here, we show that EC-sphingosine-1-phosphate receptor 1 (S1PR1) amplifies VEGFR2-mediated angiogenic signaling to enhance tumor growth. We show that cancer cells induce S1 PR1 activity in ECs, and thereby, conditional deletion of Si PR1 in ECs (EC-Slpr1(-/-) mice) impairs tumor vascularization and growth. Mechanistically, we show that S1 PR1 engages the heterotrimeric G-protein Gi, which amplifies VEGF-VEGFR2 signaling due to an increase in the activity of the tyrosine kinase c-Abl1. c-Abl1, by phosphorylating VEGFR2 at tyrosine-951, prolongs VEGFR2 retention on the plasmalemma to sustain Rac1 activity and EC migration. Thus, S1 PR1 or VEGFR2 antagonists, alone or in combination, reverse the tumor growth in control mice to the level seen in EC-Slpr1(-/-) mice. Our findings suggest that blocking S1 PR1 activity in ECs has the potential to suppress tumor growth by preventing amplification of VEGF-VEGFR2 signaling.
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| 10. |
- Screaton, E., et al.
(författare)
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Interactions between deformation and fluids in the frontal thrust region of the NanTroSEIZE transect offshore the Kii Peninsula, Japan : Results from IODP Expedition 316 Sites C0006 and C0007
- 2009
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Ingår i: Geochemistry Geophysics Geosystems. - 1525-2027. ; 10, s. Q0AD01-
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Tidskriftsartikel (refereegranskat)abstract
- Integrated Ocean Drilling Program (IODP) Expedition 316 Sites C0006 and C0007 examined the deformation front of the Nankai accretionary prism offshore the Kii Peninsula, Japan. In the drilling area, the frontal thrust shows unusual behavior as compared to other regions of the Nankai Trough. Drilling results, integrated with observations from seismic reflection profiles, suggest that the frontal thrust has been active since similar to 0.78-0.436 Ma and accommodated similar to 13 to 34% of the estimated plate convergence during that time. The remainder has likely been distributed among out-of-sequence thrusts further landward and/or accommodated through diffuse shortening. Unlike results of previous drilling on the Nankai margin, porosity data provide no indication of undercompaction beneath thrust faults. Furthermore, pore water geochemistry data lack clear indicators of fluid flow from depth. These differences may be related to coarser material with higher permeability or more complex patterns of faulting that could potentially provide more avenues for fluid escape. In turn, fluid pressures may affect deformation. Well-drained, sand-rich material under the frontal thrust could have increased fault strength and helped to maintain a large taper angle near the toe. Recent resumption of normal frontal imbrication is inferred from seismic reflection data. Associated decollement propagation into weaker sediments at depth may help explain evidence for recent slope failures within the frontal thrust region. This evidence consists of seafloor bathymetry, normal faults documented in cores, and low porosities in near surface sediments that suggest removal of overlying material. Overall, results provide insight into the complex interactions between incoming materials, deformation, and fluids in the frontal thrust region.
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