Multiple sources of slow activity fluctuations in a bacterial chemosensory network.

Cellular networks are intrinsically subject to stochastic fluctuations, but analysis of the resulting noise remained largely limited to gene expression. The pathway controlling chemotaxis of provides one example where posttranslational signaling noise has been deduced from cellular behavior. This noise was proposed to result from stochasticity in chemoreceptor methylation, and it is believed to enhance environment exploration by bacteria.

The ultimate picture-the combination of live cell superresolution microscopy and single molecule tracking yields highest spatio-temporal resolution.

We are witnessing a breathtaking development in light (fluorescence) microscopy, where structures can be resolved down to the size of a ribosome within cells. This has already yielded surprising insight into the subcellular structure of cells, including the smallest cells, bacteria. Moreover, it has become possible to visualize and track single fluorescent protein fusions in real time, and quantify molecule numbers within individual cells.

Replacing the Ethylmalonyl-CoA Pathway with the Glyoxylate Shunt Provides Metabolic Flexibility in the Central Carbon Metabolism of Methylobacterium extorquens AM1.

The ethylmalonyl-CoA pathway (EMCP) is an anaplerotic reaction sequence in the central carbon metabolism of numerous Proteo- and Actinobacteria. The pathway features several CoA-bound mono- and dicarboxylic acids that are of interest as platform chemicals for the chemical industry. The EMCP, however, is essential for growth on C1 and C2 carbon substrates and therefore cannot be simply interrupted to drain these intermediates.

Osmosensing by the bacterial PhoQ/PhoP two-component system.

The PhoQ/PhoP two-component system plays an essential role in the response of enterobacteria to the environment of their mammalian hosts. It is known to sense several stimuli that are potentially associated with the host, including extracellular magnesium limitation, low pH, and the presence of cationic antimicrobial peptides. Here, we show that the PhoQ/PhoP two-component systems of and can also perceive an osmotic upshift, another key stimulus to which bacteria become exposed within the host.

Genomic and Proteomic Evidence for the Presence of a Peroxisome in the Apicomplexan Parasite Toxoplasma gondii and Other Coccidia.

Apicomplexans are successful parasites responsible for severe human diseases including malaria, toxoplasmosis, and cryptosporidiosis. For many years, it has been discussed whether these parasites are in possession of peroxisomes, highly variable eukaryotic organelles usually involved in fatty acid degradation and cellular detoxification. Conflicting experimental data has been published.

Drift and Behavior of E. coli Cells.

Chemotaxis of the bacterium Escherichia coli is well understood in shallow chemical gradients, but its swimming behavior remains difficult to interpret in steep gradients. By focusing on single-cell trajectories from simulations, we investigated the dependence of the chemotactic drift velocity on attractant concentration in an exponential gradient. Whereas maxima of the average drift velocity can be interpreted within analytical linear-response theory of chemotaxis in shallow gradients, limits in drift due to steep gradients and finite number of receptor-methylation sites for adaptation go beyond perturbation theory.

Exception to the Rule: Genomic Characterization of Naturally Occurring Unusual Strains with a Single Chromosome.

The genetic make-up of most bacteria is encoded in a single chromosome while about 10% have more than one chromosome. Among these, , with two chromosomes, has served as a model system to study various aspects of chromosome maintenance, mainly replication, and faithful partitioning of multipartite genomes. Here, we describe the genomic characterization of strains that are an exception to the two chromosome rules: naturally occurring single-chromosome .

Phenotypes of Mutant Cells Indicate that the Escherichia coli Clamp Loader Has a Role in the Restart of Stalled Replication Forks.

The mutation was discovered in connection with a screen for multicopy suppressors of the temperature-sensitive topoisomerase IV mutation The gene for the clamp loader subunits τ and γ, , but not the mutant , was found to suppress (Ts) when overexpressed. Purified mutant protein was found to be functional , and few phenotypes were found apart from problems with partitioning of DNA in rich medium. We show here that a large number of the replication forks that initiate at never reach the terminus in mutant cells.

Emergent properties of bacterial chemotaxis pathway.

The chemotaxis pathway of Escherichia coli is the most studied sensory system in prokaryotes. The highly conserved general architecture of this pathway consists of two modules which mediate signal transduction and adaptation. The signal transduction module detects and amplifies changes in environmental conditions and rapidly transmits these signals to control bacterial swimming behavior.

Response of Methylocystis sp. Strain SC2 to Salt Stress: Physiology, Global Transcriptome, and Amino Acid Profiles.

Soil microorganisms have to rapidly respond to salt-induced osmotic stress. Type II methanotrophs of the genus are widely distributed in upland soils but are known to have a low salt tolerance. Here, we tested the ability of sp.

Structural Variation of Type I-F CRISPR RNA Guided DNA Surveillance.

CRISPR-Cas systems are prokaryotic immune systems against invading nucleic acids. Type I CRISPR-Cas systems employ highly diverse, multi-subunit surveillance Cascade complexes that facilitate duplex formation between crRNA and complementary target DNA for R-loop formation, retention, and DNA degradation by the subsequently recruited nuclease Cas3. Typically, the large subunit recognizes bona fide targets through the PAM (protospacer adjacent motif), and the small subunit guides the non-target DNA strand.

From hybridomas to a robust microalgal-based production platform: molecular design of a diatom secreting monoclonal antibodies directed against the Marburg virus nucleoprotein.

Background: The ideal protein expression system should provide recombinant proteins in high quality and quantity involving low production costs only. However, especially for complex therapeutic proteins like monoclonal antibodies many challenges remain to meet this goal and up to now production of monoclonal antibodies is very costly and delicate. Particularly, emerging disease outbreaks like Ebola virus in Western Africa in 2014-2016 make it necessary to reevaluate existing production platforms and develop robust and cheap alternatives that are easy to handle.

Effects of P limitation and molecules from peanut root exudates on pqqE gene expression and pqq promoter activity in the phosphate-solubilizing strain Serratia sp. S119.

The mineral phosphate-solubilizing phenotype in bacteria is attributed predominantly to secretion of gluconic acid produced by oxidation of glucose by the glucose dehydrogenase enzyme and its cofactor, pyrroloquinoline quinone. This study analyzes pqqE gene expression and pqq promoter activity in the native phosphate-solubilizing bacterium Serratia sp S119 growing under P-limitation, and in the presence of root exudates obtained from peanut plants, also growing under P-limitation. Results indicated that Serratia sp.

Combining Primed Photoconversion and UV-Photoactivation for Aberration-Free, Live-Cell Compliant Multi-Color Single-Molecule Localization Microscopy Imaging.

Super-resolution fluorescence microscopy plays a major role in revealing the organization and dynamics of living cells. Nevertheless, single-molecule localization microscopy imaging of multiple targets is still limited by the availability of suitable fluorophore combinations. Here, we introduce a novel imaging strategy which combines primed photoconversion (PC) and UV-photoactivation for imaging different molecular species tagged by suitable fluorescent protein combinations.

A Complex Endomembrane System in the Archaeon Tapped by .

Based on serial sectioning, focused ion beam scanning electron microscopy (FIB/SEM), and electron tomography, we depict in detail the highly unusual anatomy of the marine hyperthermophilic crenarchaeon, . Our data support a complex and dynamic endomembrane system consisting of cytoplasmic protrusions, and with secretory function. Moreover, we reveal that the cytoplasm of the putative archaeal ectoparasite can get in direct contact with this endomembrane system, complementing and explaining recent proteomic, transcriptomic and metabolomic data on this inter-archaeal relationship.

Cellular compartmentation follows rules: The Schnepf theorem, its consequences and exceptions: A biological membrane separates a plasmatic from a non-plasmatic phase.

Is the spatial organization of membranes and compartments within cells subjected to any rules? Cellular compartmentation differs between prokaryotic and eukaryotic life, because it is present to a high degree only in eukaryotes. In 1964, Prof. Eberhard Schnepf formulated the compartmentation rule (Schnepf theorem), which posits that a biological membrane, the main physical structure responsible for cellular compartmentation, usually separates a plasmatic form a non-plasmatic phase.

ViCAR: An Adaptive and Landmark-Free Registration of Time Lapse Image Data from Microfluidics Experiments.

In order to understand gene function in bacterial life cycles, time lapse bioimaging is applied in combination with different marker protocols in so called microfluidics chambers (i.e., a multi-well plate).

A General Mechanism of Photoconversion of Green-to-Red Fluorescent Proteins Based on Blue and Infrared Light Reduces Phototoxicity in Live-Cell Single-Molecule Imaging.

Photoconversion of fluorescent proteins by blue and complementary near-infrared light, termed primed conversion (PC), is a mechanism recently discovered for Dendra2. We demonstrate that controlling the conformation of arginine at residue 66 by threonine at residue 69 of fluorescent proteins from Anthozoan families (Dendra2, mMaple, Eos, mKikGR, pcDronpa protein families) represents a general route to facilitate PC. Mutations of alanine 159 or serine 173, which are known to influence chromophore flexibility and allow for reversible photoswitching, prevent PC.

AraC-like transcriptional activator CuxR binds c-di-GMP by a PilZ-like mechanism to regulate extracellular polysaccharide production.

Cyclic dimeric GMP (c-di-GMP) has emerged as a key regulatory player in the transition between planktonic and sedentary biofilm-associated bacterial lifestyles. It controls a multitude of processes including production of extracellular polysaccharides (EPSs). The PilZ domain, consisting of an N-terminal "RxxxR" motif and a β-barrel domain, represents a prototype c-di-GMP receptor.

New Functions and Subcellular Localization Patterns of c-di-GMP Components (GGDEF Domain Proteins) in .

The universal and pleiotropic cyclic dinucleotide second messenger c-di-GMP is most prominently known to inversely regulate planktonic and sessile lifestyles of Gram-negative species. In the Gram-positive model organism , intracellular c-di-GMP levels are modulated by a concise set of three diguanylate cylases (DgcK, DgcP, DgcW) and one phosphodiesterase (PdeH). Two recent studies have reported the negative influence of the c-di-GMP receptor DgrA (PilZ domain protein) on swarming motility indicating a conserved role of this second messenger across the bacterial domain.

The Central Vacuole of the Diatom Phaeodactylum tricornutum: Identification of New Vacuolar Membrane Proteins and of a Functional Di-leucine-based Targeting Motif.

Diatoms are unicellular organisms evolved by secondary endosymbiosis. Although studied in many aspects, the functions of vacuolar-like structures of these organisms are rarely investigated. One of these structures is a dominant central vacuole-like compartment with a marbled phenotype, which is supposed to represent a chrysolaminarin-storing and carbohydrate mobilization compartment.

Structure of the hibernating 100S ribosome reveals the basis for 70S dimerization.

Under stress conditions, such as nutrient deprivation, bacteria enter into a hibernation stage, which is characterized by the appearance of 100S ribosomal particles. In , dimerization of 70S ribosomes into 100S requires the action of the ribosome modulation factor (RMF) and the hibernation-promoting factor (HPF). Most other bacteria lack RMF and instead contain a long form HPF (LHPF), which is necessary and sufficient for 100S formation.

The Mitotic Exit Network Regulates Spindle Pole Body Selection During Sporulation of .

Age-based inheritance of centrosomes in eukaryotic cells is associated with faithful chromosome distribution in asymmetric cell divisions. During ascospore formation, such an inheritance mechanism targets the yeast centrosome equivalents, the spindle pole bodies (SPBs) at meiosis II onset. Decreased nutrient availability causes initiation of spore formation at only the younger SPBs and their associated genomes.

BiFCROS: A Low-Background Fluorescence Repressor Operator System for Labeling of Genomic Loci.

Fluorescence-based methods are widely used to analyze elementary cell processes such as DNA replication or chromosomal folding and segregation. Labeling DNA with a fluorescent protein allows the visualization of its temporal and spatial organization. One popular approach is FROS (fluorescence repressor operator system).