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51.
In the last decades, natural products from lichens have gained more interest for pharmaceutical application due to the broad range of their biological activity. However, isolation of the compounds of interest directly from the lichen is neither feasible nor sustainable due to slow growth of many lichens. In order to develop a pipeline for heterologous expression of lichen biosynthesis gene clusters and thus the sustainable production of their bioactive compounds we have identified and characterized the phosphopantheteinyl transferase (PPTase) EppA from the lichen Evernia prunastri. The Sfp-type PPTase EppA was functionally characterized through heterologous expression in E. coli using the production of the blue pigment indigoidine as readout and by complementation of a lys5 deletion in S. cerevisiae. 相似文献
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Skals Marianne Greve Anne-Sofie Fagerberg Steen K. Johnsen Nanna Christensen Mette G. Praetorius Helle A. 《Purinergic signalling》2019,15(2):265-276
Purinergic Signalling - Urosepsis is a severe condition often caused by Escherichia coli that spontaneously have ascended the urinary tract to the kidneys causing pyelonephritis and potentially... 相似文献
55.
Johnsen Bjarne Kaschubowski Klaus Eric Nader Sorush Schneider Enja Nicola Jan-Andrei Fliegert Ralf Wolf Insa M. A. Guse Andreas H. Nikolaev Viacheslav O. Koch-Nolte Friedrich Haag Friedrich 《Purinergic signalling》2019,15(2):155-166
Purinergic Signalling - ATP and its metabolites are important extracellular signal transmitters acting on purinergic P2 and P1 receptors. Most cells can actively secrete ATP in response to a... 相似文献
56.
Tobias Abzieher Somayeh Moghadamzadeh Fabian Schackmar Helge Eggers Florian Sutterlüti Amjad Farooq Danny Kojda Klaus Habicht Raphael Schmager Adrian Mertens Raheleh Azmi Lukas Klohr Jonas A. Schwenzer Michael Hetterich Uli Lemmer Bryce S. Richards Michael Powalla Ulrich W. Paetzold 《Liver Transplantation》2019,9(12)
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Samantha L. van der Beek Azul Zorzoli Ebru anak Robert N. Chapman Kieron Lucas Benjamin H. Meyer Dimitrios Evangelopoulos Luiz Pedro S. de Carvalho Geert‐Jan Boons Helge C. Dorfmueller Nina M. van Sorge 《Molecular microbiology》2019,111(4):951-964
Biosynthesis of the nucleotide sugar precursor dTDP‐L‐rhamnose is critical for the viability and virulence of many human pathogenic bacteria, including Streptococcus pyogenes (Group A Streptococcus; GAS), Streptococcus mutans and Mycobacterium tuberculosis. Streptococcal pathogens require dTDP‐L‐rhamnose for the production of structurally similar rhamnose polysaccharides in their cell wall. Via heterologous expression in S. mutans, we confirmed that GAS RmlB and RmlC are critical for dTDP‐L‐rhamnose biosynthesis through their action as dTDP‐glucose‐4,6‐dehydratase and dTDP‐4‐keto‐6‐deoxyglucose‐3,5‐epimerase enzymes respectively. Complementation with GAS RmlB and RmlC containing specific point mutations corroborated the conservation of previous identified catalytic residues. Bio‐layer interferometry was used to identify and confirm inhibitory lead compounds that bind to GAS dTDP‐rhamnose biosynthesis enzymes RmlB, RmlC and GacA. One of the identified compounds, Ri03, inhibited growth of GAS, other rhamnose‐dependent streptococcal pathogens as well as M. tuberculosis with an IC50 of 120–410 µM. Importantly, we confirmed that Ri03 inhibited dTDP‐L‐rhamnose formation in a concentration‐dependent manner through a biochemical assay with recombinant rhamnose biosynthesis enzymes. We therefore conclude that inhibitors of dTDP‐L‐rhamnose biosynthesis, such as Ri03, affect streptococcal and mycobacterial viability and can serve as lead compounds for the development of a new class of antibiotics that targets dTDP‐rhamnose biosynthesis in pathogenic bacteria. 相似文献
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Hanna N. Ststad Melissah Rowe Arild Johnsen Jan T. Lifjeld 《Journal of evolutionary biology》2019,32(7):666-674
Sperm morphology varies enormously across the animal kingdom. Whilst knowledge of the factors that drive the evolution of interspecific variation in sperm morphology is accumulating, we currently have little understanding of factors that may constrain evolutionary change in sperm traits. We investigated whether susceptibility to sperm abnormalities could represent such a constraint in songbirds, a group characterized by a distinctive helical sperm head shape. Specifically, using 36 songbird species and data from light and scanning electron microscopy, we examined among‐species correlations between the occurrence of sperm head abnormalities and sperm morphology, as well as the correlation between sperm head abnormalities and two indicators of sperm competition. We found that species with more helically shaped sperm heads (i.e., a wider helical membrane and more pronounced cell waveform) had a higher percentage of abnormal sperm heads than species with less helical sperm (i.e., relatively straight sperm) and that sperm head traits were better predictors of head abnormalities than total sperm length. In contrast, there was no correlation between sperm abnormalities and the level of sperm competition. Given that songbird species with more pronounced helical sperm have higher average sperm swimming speed, our results suggest an evolutionary trade‐off between sperm performance and the structural integrity of the sperm head. As such, susceptibility to morphological abnormalities may constrain the evolution of helical sperm morphology in songbirds. 相似文献
59.
The pelagic realm of the ocean is characterized by extremelyclear water and a lack of surfaces. Adaptations to the visualecology of this environment include transparency, fluorescence,bioluminescence, and deep red or black pigmentation. While thesignals that pelagic organisms send are increasingly well-understood,the optical capabilities of their viewers, especially for predatorswith camera-like vision such as fish and squid, are almost unknown.Aquatic camera-like vision is characterized by a spherical lensfocusing an image on the retina. Here, we measured the resolvingpower of the lenses of eight species of pelagic cephalopodsto obtain an approximation of their visual capabilities. Wedid this by focusing a standard resolution target through dissectedlenses and calculating their modulation transfer functions.The modulation transfer function (MTF) is the single most completeexpression of the resolving capabilities of a lens. Since theoptical and retinal capabilities of an eye are generally well-matched,we considered our measurements of cephalopod lens MTF to bea good proxy for their visual capabilities in vivo. In general,squid have optical capabilities comparable to other organismsgenerally assumed to have good vision, such as fish and birds.Surprisingly, the optical capability of the eye of Vampyroteuthisinfernalis rivals that of humans. 相似文献
60.
Tom Albrecht Kamila Opletalov Jií Reif Vclav Janouek Lubomír Pilek Emily R. A. Cramer Arild Johnsen Radka Reifov 《Evolution; international journal of organic evolution》2019,73(2):202-213
Postcopulatory sexual selection may promote evolutionary diversification in sperm form, but the contribution of between‐species divergence in sperm morphology to the origin of reproductive isolation and speciation remains little understood. To assess the possible role of sperm diversification in reproductive isolation, we studied sperm morphology in two closely related bird species, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (Luscinia luscinia), that hybridize in a secondary contact zone spanning Central and Eastern Europe. We found: (1) striking divergence between the species in total sperm length, accompanied by a difference in the length of the mitochondrial sperm component; (2) greater divergence between species in sperm morphology in sympatry than in allopatry, with evidence for character displacement in sperm head length detected in L. megarhynchos; (3) interspecific hybrids showing sperm with a length intermediate between the parental species, but no evidence for decreased sperm quality (the proportion of abnormal spermatozoa in ejaculates). Our results demonstrate that divergence in sperm morphology between the two nightingale species does not result in intrinsic postzygotic isolation, but may contribute to postcopulatory prezygotic isolation. This isolation could be strengthened in sympatry by reinforcement. 相似文献