scholarly journals Gating by ionic strength and safety check by cyclic-di-AMP in the ABC transporter OpuA

2020 ◽  
Vol 6 (47) ◽  
pp. eabd7697 ◽  
Author(s):  
Hendrik R. Sikkema ◽  
Marco van den Noort ◽  
Jan Rheinberger ◽  
Marijn de Boer ◽  
Sabrina T. Krepel ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Molecular Level ◽  
Compatible Solutes ◽  
Second Messenger ◽  
In Vitro Activity ◽  
Cellular Processes ◽  
Cryo Electron Microscopy ◽  
Micro Organisms

(Micro)organisms are exposed to fluctuating environmental conditions, and adaptation to stress is essential for survival. Increased osmolality (hypertonicity) causes outflow of water and loss of turgor and is dangerous if the cell is not capable of rapidly restoring its volume. The osmoregulatory adenosine triphosphate–binding cassette transporter OpuA restores the cell volume by accumulating large amounts of compatible solute. OpuA is gated by ionic strength and inhibited by the second messenger cyclic-di-AMP, a molecule recently shown to affect many cellular processes. Despite the master regulatory role of cyclic-di-AMP, structural and functional insights into how the second messenger regulates (transport) proteins on the molecular level are lacking. Here, we present high-resolution cryo–electron microscopy structures of OpuA and in vitro activity assays that show how the osmoregulator OpuA is activated by high ionic strength and how cyclic-di-AMP acts as a backstop to prevent unbridled uptake of compatible solutes.

scholarly journals A New MAP Kinase Protein Involved in Estradiol-Stimulated Reproduction of the Helminth ParasiteTaenia crassiceps

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
Galileo Escobedo ◽  
Gloria Soldevila ◽  
Guadalupe Ortega-Pierres ◽  
Jesús Ramsés Chávez-Ríos ◽  
Karen Nava ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Map Kinases ◽  
Host Cells ◽  
Cross Contamination ◽  
Flow Cytometry Analysis ◽  
Cellular Processes ◽  
17Β Estradiol ◽  
Activation Motif

MAP kinases (MAPK) are involved in the regulation of cellular processes such as reproduction and growth. In parasites, the role of MAPK has been scarcely studied. Here, we describe the participation of an ERK-like protein in estrogen-dependent reproduction of the helminth parasiteTaenia crassiceps. Our results show that 17β-estradiol induces a concentration-dependent increase in the bud number of in vitro cultured cysticerci. If parasites are also incubated in presence of an ERK-inhibitor, the stimulatory effect of estrogen is blocked. The expression of ERK-like mRNA and its corresponding protein was detected in the parasite. The ERK-like protein was over-expressed by all treatments. Nevertheless, a strong induction of phosphorylation of this protein was observed only in response to 17β-estradiol. Cross-contamination by host cells was discarded by flow cytometry analysis. Parasite cells expressing the ERK-like protein were exclusively located at the subtegument tissue by confocal microscopy. Finally, the ERK-like protein was separated by bidimensional electrophoresis and then sequenced, showing the conserved TEY activation motif, typical of all known ERK 1/2 proteins. Our results show that an ERK-like protein is involved in the molecular signalling during the interaction between the host andT. crassiceps, and may be considered as target for anti-helminth drugs design.

scholarly journals Subinhibitory Antimicrobial Concentrations: A Review of In Vitro and In Vivo Data

1992 ◽  
Vol 3 (4) ◽  
pp. 193-201 ◽  
Author(s):  
George G Zhanel ◽  
Daryl J Hoban ◽  
Godfrey KM Harding
Keyword(s):  
Antimicrobial Activity ◽  
Animal Studies ◽  
Molecular Level ◽  
Bacterial Virulence ◽  
Antibacterial Effects ◽  
Wide Range ◽  
Immune Defences

Antimicrobial activity is not an ‘all or none’ effect. An increase in the rate and extent of antimicrobial action is usually observed over a wide range of antimicrobial concentrations. Subinhibitory antimicrobial concentrations are well known to produce significant antibacterial effects, and various antimicrobials at subinhibitory concentrations have been reported to inhibit the rate of bacterial growth. Bacterial virulence may be increased or decreased by subinhibitory antimicrobial concentrations by changes in the ability of bacteria to adhere to epithelial cells or by alterations in bacterial susceptibility to host immune defences. Animal studies performed in rats, hamsters and rabbits demonstrate decreased bacterial adherence, reduced infectivity and increased survival of animals treated with subinhibitory antimicrobial concentrations compared to untreated controls. The major future role of investigation of subinhibitory antimicrobial concentrations will be to define more fully, at a molecular level, how antimicrobials exert their antibacterial effects.

Attachment of the flagellate Giardia lamblia: role of reducing agents, serum, temperature, and ionic composition

1982 ◽  
Vol 2 (4) ◽  
pp. 369-377
Author(s):  
F D Gillin ◽  
D S Reiner
Keyword(s):  
Sodium Chloride ◽  
Ionic Strength ◽  
Oxygen Tension ◽  
Giardia Lamblia ◽  
Bovine Serum ◽  
Ionic Composition ◽  
Short Term ◽  
Reduced Temperature

The flagellated protozoan Giardia lamblia has been grown only in highly complex media under reduced oxygen tension. Therefore, the organic and physiological requirements for in vitro attachment and short-term (12-h) survival of this organism were determined. In defined maintenance media, a thiol reducing agent (e.g., cysteine) was absolutely required for attachment and survival of this aerotolerant anaerobe. The crude bovine serum Cohn III fraction greatly stimulated attachment and survival. Attachment was decreased at a reduced temperature (24 degrees C as compared with 35.5 degrees C) and absent at 12 degrees C or below. Attachment and survival were strongly dependent upon pH and ionic strength, with optima at pH 6.85 to 7.0 and 200 to 300 mosmol/kg. Sodium chloride was better tolerated than KC1. Reduction of Ca2+ and Mg2+ to below 10(-8) M did not significantly affect attachment.

scholarly journals Functional genetic encoding of sulfotyrosine in mammalian cells

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Xinyuan He ◽  
Yan Chen ◽  
Daisy Guiza Beltran ◽  
Maia Kelly ◽  
Bin Ma ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Biochemical Characterization ◽  
Trna Synthetase ◽  
Functional Verification ◽  
Cellular Processes ◽  
Genetic Encoding ◽  
Efficient Expression

Abstract Protein tyrosine O-sulfation (PTS) plays a crucial role in extracellular biomolecular interactions that dictate various cellular processes. It also involves in the development of many human diseases. Regardless of recent progress, our current understanding of PTS is still in its infancy. To promote and facilitate relevant studies, a generally applicable method is needed to enable efficient expression of sulfoproteins with defined sulfation sites in live mammalian cells. Here we report the engineering, in vitro biochemical characterization, structural study, and in vivo functional verification of a tyrosyl-tRNA synthetase mutant for the genetic encoding of sulfotyrosine in mammalian cells. We further apply this chemical biology tool to cell-based studies on the role of a sulfation site in the activation of chemokine receptor CXCR4 by its ligand. Our work will not only facilitate cellular studies of PTS, but also paves the way for economical production of sulfated proteins as therapeutic agents in mammalian systems.

scholarly journals The Ser/Thr kinase p90RSK promotes kidney fibrosis by modulating fibroblast–epithelial crosstalk

2019 ◽  
Vol 294 (25) ◽  
pp. 9901-9910 ◽  
Author(s):  
Ling Lin ◽  
Chaowen Shi ◽  
Zhaorui Sun ◽  
Nhat-Tu Le ◽  
Jun-Ichi Abe ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Nuclear Translocation ◽  
Disease Model ◽  
Kidney Fibrosis ◽  
Cellular Processes ◽  
Ribosomal Protein S6 ◽  
Forkhead Box

Healthy kidney structure and environment rely on epithelial integrity and interactions between epithelial cells and other kidney cells. The Ser/Thr kinase 90 kDa ribosomal protein S6 kinase 1 (p90RSK) belongs to a protein family that regulates many cellular processes, including cell motility and survival. p90RSK is predominantly expressed in the kidney, but its possible role in chronic kidney disease (CKD) remains largely unknown. Here, we found that p90RSK expression is dramatically activated in a classic mouse obstructive chronic kidney disease model, largely in the interstitial FSP-1–positive fibroblasts. We generated FSP-1–specific p90RSK transgenic mouse (RSK-Tg) and discovered that these mice, after obstructive injury, display significantly increased fibrosis and enhanced tubular epithelial damage compared with their wt littermates (RSK-wt), indicating a role of p90RSK in fibroblast–epithelial communication. We established an in vitro fibroblast–epithelial coculture system with primary kidney fibroblasts from RSK-Tg and RSK-wt mice and found that RSK-Tg fibroblasts consistently produce excessive H2O2 causing epithelial oxidative stress and inducing nuclear translocation of the signaling protein β-catenin. Epithelial accumulation of β-catenin, in turn, promoted epithelial apoptosis by activating the transcription factor forkhead box class O1 (FOXO1). Of note, blockade of reactive oxygen species (ROS) or β-catenin or FOXO1 activity abolished fibroblast p90RSK-mediated epithelial apoptosis. These results make it clear that p90RSK promotes kidney fibrosis by inducing fibroblast-mediated epithelial apoptosis through ROS-mediated activation of β-catenin/FOXO1 signaling pathway.

scholarly journals Overview of RNA G-quadruplex structures

2017 ◽  
Vol 63 (4) ◽  
Author(s):  
Magdalena Małgowska
Keyword(s):  
Three Dimensional ◽  
Telomere Maintenance ◽  
Structural Studies ◽  
Biological Functions ◽  
Cellular Processes ◽  
Novel Drugs ◽  
G Quadruplex ◽  
Conformational Diversity

G-quadruplexes are non-canonical secondary structures which may be formed by guanine rich sequences, both in vitro and in living cells. The number of biological functions assigned to these structural motifs has grown rapidly since the discovery of their involvement in the telomere maintenance. Knowledge of the three-dimensional structures of G-quadruplexes plays an important role in understanding their conformational diversity, physiological functions, and in the design of novel drugs targeting G-quadruplexes. For the last decades, structural studies have been mainly focused on the DNA G-quadruplexes. Their RNA counterparts gained an increased interest along with still-emerging recognition of the central role of RNA in multiple cellular processes. In this review we focus on structural properties of RNA G-quadruplexes, based on high-resolution structures, available in RCSB PDB data base and on structural models. In addition, we point out to the current challenges in this field of research.

scholarly journals Bacterial dynamin-like protein DynA mediates lipid and content mixing and shows phospholipid specificity

2018 ◽  
Author(s):  
Lijun Guo ◽  
Marc Bramkamp
Keyword(s):  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Membrane Stress ◽  
Gtp Hydrolysis ◽  
Cellular Processes ◽  
Organelle Division ◽  
Membrane Tethering ◽  
Hydrolysis Of

ABSTRACTThe dynamins family of GTPases is involved in key cellular processes in eukaryotes, including vesicle trafficking and organelle division. The GTP hydrolysis cycle of dynamin translates to a conformational change in the protein structure, which forces the underlying lipid layer into an energetically unstable conformation that promotes membrane rearrangements. Many bacterial genomes encode dynamin-like proteins, but the biological function of these proteins has remained largely enigmatic. In recent years, our group has reported that the dynamin-like protein DynA from Bacillus subtilis mediates nucleotide-independent membrane tethering in vitro and contributes to the innate immunity of bacteria against membrane stress and phage infection. However, so far the mechanism of membrane stress response and the role of GTP hydrolysis remain unclear. Here, we employed content mixing and lipid mixing assays in reconstituted systems to study if the dynamin-like protein DynA from B. subtilis induces membrane full fusion, and further test the possibility that GTP hydrolysis of DynA may act on the fusion-through-hemifusion pathway. Our results based on fluorescence resonance energy transfer (FRET) indicated that DynA could induce aqueous content mixing even in absence of GTP. Moreover, DynA-induced membrane fusion in vitro is a thermo-promoted slow response. Surprisingly, digestion of protein mediated an instantl rise of content exchange, supporting the assumption that disassembly of DynA is the fundamental power for fusion-through-hemifusion.

scholarly journals The bacterial chromatin protein HupA can remodel DNA and associates with the nucleoid in Clostridium difficile

2018 ◽  
Author(s):  
Ana M. Oliveira Paiva ◽  
Annemieke H. Friggen ◽  
Liang Qin ◽  
Roxanne Douwes ◽  
Remus T. Dame ◽  
...  
Keyword(s):  
Protein A ◽  
Chromatin Protein ◽  
Chromosomal Organization ◽  
Cellular Processes ◽  
Hu Proteins ◽  
Architectural Proteins ◽  
Chromatin Proteins

AbstractThe maintenance and organization of the chromosome plays an important role in the development and survival of bacteria. Bacterial chromatin proteins are architectural proteins that bind DNA, modulate its conformation and by doing so affect a variety of cellular processes. No bacterial chromatin proteins of C. difficile have been characterized to date.Here, we investigate aspects of the C. difficile HupA protein, a homologue of the histone-like HU proteins of Escherichia coli. HupA is a 10 kDa protein that is present as a homodimer in vitro and self-interacts in vivo. HupA co-localizes with the nucleoid of C. difficile. It binds to the DNA without a preference for the DNA G+C content. Upon DNA binding, HupA induces a conformational change in the substrate DNA in vitro and leads to compaction of the chromosome in vivo.The present study is the first to characterize a bacterial chromatin protein in C. difficile and opens the way to study the role of chromosomal organization in DNA metabolism and on other cellular processes in this organism.

scholarly journals A search for the in trans role of GraL, an Escherichia coli small RNA*

2018 ◽  
Vol 65 (1) ◽  
pp. 141-149 ◽  
Author(s):  
Maciej Dylewski ◽  
Monika Ćwiklińska ◽  
Katarzyna Potrykus
Keyword(s):  
Small Rna ◽  
Enteric Bacteria ◽  
Clear Correlation ◽  
Synthetic Lethal ◽  
Cellular Processes ◽  
In Trans ◽  
Regulatory Loop

Small RNA are very important post-transcriptional regulators in both, bacteria and eukaryotes. One of such sRNA is GraL, encoded in the greA leader region and conserved among enteric bacteria. Here, we conducted a bioinformatics search for GraL’s targets in trans and validated our findings in vivo by constructing fusions of probable targets with lacZ and measuring their activity when GraL was overexpressed. Only one target's activity (nudE) decreased under those conditions and was thus selected for further analysis. In the absence of GraL and greA, the nudE::lacZ fusion's β-galactosidase activity was increased. However, a similar effect was also visible in the strain deleted only for greA. Furthermore, overproduction of GreA alone increased the nudE::lacZ fusion’s activity as well. This suggests existence of complex regulatory loop-like interactions between GreA, GraL and nudE mRNA. To further dissect this relationship, we performed in vitro EMSA experiments employing GraL and nudE mRNA. However, stable GraL-nudE complexes were not detected, even though the detectable amount of unbound GraL decreased as increasing amounts of nudE mRNA were added. Interestingly, GraL is being bound by Hfq, but nudE easily displaces it.  We also conducted a search for genes that are synthetic lethal when deleted along with GraL. This revealed 40 genes that are rendered essential by GraL deletion, however, they are involved in many different cellular processes and no clear correlation was found. The obtained data suggest that GraL's mechanism of action is non-canonical, unique and requires further research.

scholarly journals Mitogen Kinase Kinase (MKK7) controls cytokine production in vitro and in vivo in mice

2021 ◽  
Author(s):  
Amada D. Caliz ◽  
Hyung-Jin Yoo ◽  
Anastassiia Vertii ◽  
Cathy Tournier ◽  
Roger J. Davis ◽  
...  
Keyword(s):  
Cytokine Production ◽  
Cell Types ◽  
Minor Role ◽  
Cellular Processes ◽  
Mitogen Activated Protein ◽  
And Migration ◽  
Jnk Activation

Mitogen kinase kinase 4 (MKK4) and Mitogen kinase kinase 7 (MKK7) are members of the MAP2K family which can activate downstream mitogen-activated protein kinases (MAPKs). MKK4 has been implicated in the activation of both, c-Jun N-terminal Kinase (JNK) and p38 MAPK, whereas MKK7 only activates JNK in response to different stimuli. The stimuli as well as cell type determine the choice of MAP2K member that mediates the response. In a variety of cell types, the MKK7 contributes to the activation of downstream MAPKs, JNK, which is known to regulate essential cellular processes, such as cell death, differentiation, stress response, and cytokine secretion. Previous studies have implicated the role of MKK7 in stress signaling pathways and cytokine production. However, little is known about the degree to which MKK7 and MKK4 contributes to innate immune response in macrophages as well as during inflammation in vivo. To address this question and elucidate the role of MKK7 and MKK4 in macrophage and in vivo, we developed MKK7- and MKK4-deficient mouse models with tamoxifen-inducible Rosa26 CreERT. This study reports that MKK7 is required for JNK activation both in vitro and in vivo. Additionally, we demonstrated that MKK7 in macrophages is necessary for LPS induced cytokine production and migration which appears to be a major contributor to the inflammatory response in vivo. Whereas MKK4 plays a significant but minor role in cytokine production in vivo.

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