Kai Ostermann

Technische Universität Dresden | TUD · Faculty of Biology - Institute for Genetics

Saccharomyces cerevisiae is a commonly used microorganism in the biotechnological industry. For the industrial heterologous production of compounds, it is of great advantage to work with growth‐controllable yeast strains. In our work, we utilized the natural pheromone system of S. cerevisiae and generated a set of different strains possessing an α‐...

It is the intention of this study to elucidate the nested formation of calcium carbonate polymorphs or polyamorphs in the different nanosized compartments. With these observations, it can be concluded how the bacteria can survive in a harsh environment with high calcium carbonate supersaturation. The mechanisms of calcium carbonate precipitation at...

An increasing number of reports substantiate the link between emerging estrogenic pollutants and a variety of adverse effects including developmental disorders, infertility, cancer and neurological disorders, threatening public health as well as environment. The detection of the diverse classes of estrogenic and antiestrogenic substances is still c...

Accumulation of acetic acid indicates an imbalance of the process due to a disturbed composition of the microorganisms. Hence, monitoring the acetic acid concentration is an important parameter to control the biogas process. Here, we describe the generation and validation of a fluorescence‐based whole cell sensor for the detection of acetic acid ba...

The continually growing use of glyphosate and its critically discussed health and biodiversity risks ask for fast, low cost, on-site sensing technologies for food and water. To address this problem, we designed a highly sensitive sensor built on the remarkably specific recognition of glyphosate by its physiological target enzyme 5-enolpyruvyl-shiki...

Glyphosate, the most widely used pesticide worldwide, is under debate due to its potentially cancerogenic effects and harmful influence on biodiversity and environment. Therefore, the detection of glyphosate in water, food or environmental probes is of high interest. Currently detection of glyphosate usually requires specialized, costly instruments...

Whole-cell biosensors, based on genetically modified yeast cells, were employed to detect anthropogenic micropollutants (e.g. drugs). Specific stimuli, e.g. traces of drugs, lead to the induction of fluorescence in the respective cells. Receptors of the cells detect specific signal molecules and induce the formation of fluorescent proteins. In this...

Under adequate conditions, cavity polaritons form a macroscopic coherent quantum state, known as polariton condensate. Compared to Wannier-Mott excitons in inorganic semiconductors, the localized Frenkel excitons in organic emitter materials show weaker interaction with each other but stronger coupling to light, which recently enabled the first rea...

Microbial consortia can be used to catalyze complex biotransformations. Tools to control the behavior of these consortia in a technical environment are currently lacking. In the present study, a synthetic biology approach was used to build a model consortium of two Saccharomyces cerevisiae strains where growth and expression of the fluorescent mark...

Recently it has been proposed to use sensors based on genetically engineered reporter cells to perform continuous online water monitoring. Here we describe the design, assembly and performance of a novel flow-through device with immobilized genetically modified yeast cells that produce a fluorescent protein upon stimulation with diclofenac whose in...

Bioconversions in industrial processes are currently dominated by single‐strain approaches. With the growing complexity of tasks to be carried out, microbial consortia become increasingly advantageous and eventually may outperform single‐strain fermentations. Consortium approaches benefit from the combined metabolic capabilities of highly specializ...

Ziel des Vorhabens HIGS "Hochintegrierte Ganzzellsensoren für die Umwelt-und Medizintechnik" war die Entwicklung einer neuartigen Generation von Ganzzellsensoren, welche durch die Reaktion lebender Zellen die Bewertung der biologischen Wirkung von biomolekularen oder nichtbiologischen Analyten ermöglichen. Die innovative Lösung soll es weiterhin er...

The fission yeast Schizosaccharomyces pombe is an attractive host for heterologous gene expression. However, expression systems for industrially viable large-scale fermentations are scarce. Several inducible expression vectors for S. pombe have been reported, with the strong thiamine-repressible nmt1+ promoter or derivatives thereof most commonly e...

The commonly used drug diclofenac is an important environmental anthropogenic pollutant. Currently, detection of diclofenac is mainly based on chemical and physical methods. Here we describe a yeast biosensor that drives the diclofenac-dependent expression of a recombinant fluorescent protein from the authentic promoter of the PDR5 gene. This key c...

In their natural habitats, microorganisms always live in consortia. Until now, such consortia are applied e.g. in wastewater treatment or for the production of traditional beverages and food (Jagmann and Philipp (2014) J Biotechnol 184: 209–218). After a long era of using single species in biotechnological production processes, recent research also...

Under adequate conditions, cavity polaritons form a macroscopic coherent quantum state, known as polariton condensate. Compared to Wannier-Mott excitons in inorganic semiconductors, the localized Frenkel excitons in organic emitter materials show weaker interaction with each other but stronger coupling to light, which recently enabled the first rea...

FRET forms the basis for energy transfer in biological systems and organisms and it has become an investigative tool in the analysis of protein-protein interactions and in the study of semiconductors (SC). Until now, FRET has been restricted to the simultaneous presence of both components in the same phase. Here, we report on the first successful p...

Detection and quantification of small peptides, such as yeast pheromones, are often challenging. We developed a highly sensitive and robust affinity-assay for the quantification of the α-factor pheromone of Saccharomyces cerevisiae based on recombinant hydrophobins. These small, amphipathic proteins self-assemble into highly stable monolayers at hy...

Cell-cell communication is a widespread phenomenon in nature, ranging from bacterial quorum sensing and fungal pheromone communication to cellular crosstalk in multicellular eukaryotes. These communication modes offer the possibility to control the behavior of an entire community by modifying the performance of individual cells in specific ways. Sy...

Self-assembling surface layer (SL) proteins of bacteria have been widely studied, in particular their use as molecularly defined, 2D coatings of technical surfaces. An important prerequisite is the availability of a sufficient amount of protein. However, a detailed and optimized protocol for the complete SL extraction is so far not available. Here,...

Membrane proteins are not homogeneously distributed throughout the membrane. One proposed localization mechanism is related to membrane curvature. In this work a sensor platform has been developed that uses carbon nanotubes to create curvature in a supported lipid bilayer. The specific binding of curvature sensitive proteins to the bent areas of th...

We report on a pheromone-based inter-species communication system, allowing for a controlled cell-cell communication between the two species Saccharomyces cerevisiae and Schizosaccharomyces pombe as a proof of principle. It exploits the mating response pathways of the two yeast species employing the pheromones, α- or P-factor, as signaling molecule...

Kit comprises yeast cells of different species comprising (a) a sensor-cell of a first type comprising a gene, which leads to the synthesis of a pheromone and is provided under transcriptional control of a primary signal-dependent promoter and (b) actuator-cells of at least one type comprising (i) at least one receptor for a pheromone, (ii) at leas...

We report on the spatial and temporal signaling properties of a yeast pheromone-based cell communication and amplifier system. It utilizes the Saccharomyces cerevisiae mating response pathway and relies on diffusion of the pheromone α-factor as key signaling molecule between two cell types. One cell type represents the α-factor secreting sensor par...

In an approach to generate Saccharomyces cerevisiae strains with increased intracellular copper amounts for technical applications we over-expressed the copper transporter CTR1 and a variant of CTR1 with a truncation in the C-terminus after the 300th amino acid (CTR1Δ300). We determined the copper sensitivity of the generated strains and used induc...

Hydrophobins are small surface-active proteins that have considerable potential for use in applications ranging from medical and technical coatings, separation technologies, biosensors, and personal care. Their wider use would be facilitated by the availability of recombinant tailor-made hydrophobins. We successfully expressed the class II hydropho...

In nanobiotechnology, the properties of surfaces are often key to sensor applications. If analytes possess a low tolerance or affinity regarding the sensory substrate (surface), then the setup of mediators may be indicated. Hydrophobins enable biocompatible surface functionalization without significant restrictions of the physicochemical substrate...

Zusammenfassung Eine Vielzahl von Prozessen in der Medizin, Biotechnologie, Verfahrenstechnik und Analytik erfordern die spezifische Detektion und Quantifizierung bestimmter Stoffe, wie zum Bespiel Schwermetalle, Antibiotika oder Stoffwechselintermediate. Zahlreiche Studien der letzten Jahre haben bewiesen, dass biologische Wandler grundsätzlich in...

A wide range of processes in the fields of medicine, biotechnology, process engineering, as well as chemical analyses require a specific detection and quantification of certain substances like heavy metals, antibiotics, or metabolic intermediates. Numerous recent studies have clearly demonstrated the ability of biological transducers to cope with s...

Based on experimental studies on tube formation during self-assembly of bacterial surface (S)-layers, a mechanistic model for describing the underlying basic mechanisms is proposed and the effect of process parameters on growth velocity and tube radius is investigated. The S-layer is modeled as a curved sheet with discrete binding sites for the ass...

Monomolecular crystalline bacterial cell surface layers (S-layers) have broad application potential in nanobiotechnology due to their ability to generate functional supramolecular structures. Here, we report that Bacillus megaterium is an excellent host organism for the heterologous expression and efficient secretion of hemagglutinin (HA) epitope-t...

In the present study, we demonstrate that the Escherichia coli–Bacillus megaterium shuttle vector pHIS1522 can be used as a versatile expression vector. Recombinant genes under the control of the xylA promoter are constitutively expressed at a high level in E. coli strains, whereas their expression is strongly induced by the addition of xylose in B...

Pichia pastoris is an important eukaryotic organism for the expression, processing, and secretion of recombinant proteins. Here, the secretion of enhanced green fluorescent protein (EGFP) in P. pastoris by using three novel secretion signals originating from the HFBI and HFBII class 2 hydrophobins of Trichoderma reesei was investigated. EGFP was fu...

The dimorphic yeasts Candida boidinii and Yarrowia lipolytica were applied as model organisms to study mycelial growth. A mathematical model of hybrid cellular automaton type was developed to analyze the impact of different biological assumptions on the predicted development of filamentous yeast colonies. The one-dimensional model described discret...

Based on the p426 series of expression vectors developed by Mumberg et al. (Gene 156, 119-122, 1995), we have generated a set of plasmids that allow the glucose-dependent expression of target genes in the yeast, Saccharomyces cerevisiae. The ADH1 promoter in plasmid p426-ADH1 was replaced by the 1-kb 5'-region from either of the following genes: HX...

Surface layer proteins have the appealing property to self-assemble in nanosized arrays in solution and on solid substrates. In this work, we characterize the formation of assembly structures of the recombinant surface layer protein SbsC of Geobacillus stearothermophilus ATTC 12980, which was tagged with enhanced green fluorescent protein and expre...

Most bacterial surface layers (SLs) are formed by self-assembly of a single type of protein. Native and recombinant surface layer monomers are capable to self-assemble on solid substrates and in solution to highly regular nanosized arrays which make them attractive for nanobiotechnological applications. In this study, we expressed the surface layer...

The aim of the work is to exploit the yeast pheromone system for controlled cell-cell communication and as an amplification circuit in technical applications, e.g. biosensors or sensor-actor systems. As a proof of principle, we developed recombinant Saccharomyces cerevisiae cells that express enhanced green fluorescent protein (EGFP) in response to...

Colony development of the dimorphic yeasts Yarrowia lipolytica and Candida boidinii on solid agar substrates under glucose limitation served as a model system for mycelial development of higher filamentous fungi. Strong differences were observed in the behaviour of both yeasts: C. boidinii colonies reached a final colony extension which was small c...

We describe the construction and validation of novel test systems for detecting androgenic activities using a combination of the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. By applying the reporter enhanced Green Fluorescent Protein (EGFP) the incubation time could be reduced to only 24h if compared to the classical β-galactosida...

Two genes coding for proteins with a high degree of sequence similarity to glycerol-3-phosphate dehydrogenases have been isolated from the yeast Pichia jadinii. Fragments of the genes were PCR-amplified with degenerated primers from genomic DNA of P. jadinii. Clones containing the full-length genes PjGPD1 and PjGPD2 were isolated by screening genom...

The surface (S)-layer of Sporosarcina ureae strain ATCC 13881, a periodic ordered structure with p4 square type symmetry, was recently reported to be an excellent biotemplate for the formation of highly ordered metal clusters. The S-layer is formed by self-assembly of a single subunit, the 116 kDa SslA protein. Here we report on the isolation and s...

S-layer proteins are an issue of arising interest due to their ability to form periodical self-assembly nanopore structures. In this work we analyze the self-assembly potential of the recently characterized SslA S-layer protein of Sporosarcina ureae and of truncated SslA derivatives. The SslA protein with an estimated molecular weight of 116 kDa is...

Two genes coding for proteins with a high degree of sequence similarity to glycerol-3-phosphate dehydrogenases have been isolated from the yeast Pichiajadinii. Fragments of the genes were PCR-amplified with degenerated primers from genomic DNA of P. jadinii. Clones containing the full-length genes PjGPDI and PjGPD2 were isolated by screening genomi...

Artificial gene regulatory networks (AGRNs) are instrumental in elucidating basic principles that govern the dynamics and consequences of stochasticity in the gene expression of naturally occurring "gene regulatory networks". In contrast to state of the art computer engineering circuits, these AGRNs are evolutionarily highly optimized and fault tol...

The sequencing of the genome of Schizosaccharomyces pombe revealed the presence of a number of genes encoding tandem proteins, some of which are mitochondrial components. One of these proteins (pre-Rsm22-Cox11) consists of a fusion of Rsm22, a component of the mitochondrial ribosome, and Cox11, a factor required for copper insertion into cytochrome...

Cytochrome c oxidase is the terminal enzyme of the mitochondrial (mt) respiratory chain. It contains copper ions, which are organized in two centres, Cu(A) and Cu(B). The Cu(A) site of subunit Cox2p is exposed to the mt intermembrane space, while the Cu(B) site of subunit Cox1p is buried in the inner mt membrane. Incorporation of copper into the tw...

The development of yeast colonies on solid agar substrates served as a model system to investigate the growth of higher fungi in a heterogeneous environment. Applying a new analytical technique – which was based on the estimation of the intensity of transmitted light from microscopic images taken along the colony radius – cell-density distributions...

A mathematical model was developed which described the growth of yeast colonies based on the assumptions that (i) these populations were built up of single cells whose proliferation was (ii) exclusively controlled by nutrient availability in the environment. The model was of a hybrid cellular automaton type and described discrete cells residing on...

On Mar 1, 2005 this sequence version replaced gi:46309120.

On Feb 11, 2005 this sequence version replaced gi:45597910.

In the present study, yeast colony development serves as a model system to study growth of fungal populations with negligible nutrient and signal transport within the mycelium. Mathematical simulations address the question whether colony development is governed by diffusional limitation of nutrients. A hybrid one-dimensional cellular automaton mode...

The gene germ cell-less (gcl) plays an important role in the early differentiation of germ cells in Drosophila. We isolated the gcl homolog of the model teleost medaka (Oryzias latipes) using degenerated primers and an ovary cDNA bank. The predicted amino acid sequence of medaka gcl showed 92, 68 and 31% overall identity to mouse, human and Drosoph...

The genetic analysis of the Rubinstein-Taybi syndrome (RTS, OMIM 180849) may shed light on mechanisms of transcription, brain function, keloid formation, and cancer.1–6 RTS can be caused by heteroallelic mutations of CREBBP (the gene for cAMP responsive element binding (CREB) binding protein).2 Human CREBBP resides on chromosome 16p13.3,7–9 spans a...

Translation of cytochrome b mRNA in yeast mitochondria requires activation by the nuclear-encoded Cbs1p. According to the current model, Cbs1p tethers cytochrome b mRNA to the inner mitochondrial membrane via interaction with the 5'-untranslated leader. Cbs1p is predicted to be a hydrophilic protein with two hydrophobic segments near the carboxyl-t...

Translation of cytochrome b mRNA in yeast mitochondria requires activation by the nuclear-encoded Cbs1p. According to the current model, Cbs1p tethers cytochrome b mRNA to the inner mitochondrial membrane via interaction with the 5′-untranslated leader. Cbs1p is predicted to be a hydrophilic protein with two hydrophobic segments near the carboxyl-t...

Cytochrome c oxidase is a multiprotein complex in the mitochondrial membrane whose biogenesis requires a number of proteins besides the structural subunits. Several yeast proteins as well as a human disease-related protein have been reported which are involved in cytochrome c oxidase assembly. The S. cerevisiae Sco1p protein has been implicated in...

Saccharomyces cerevisiae Sco1p is believed to be involved in the transfer of copper from the carrier Cox17p to the mitochondrial cytochrome c oxidase subunits 1 and 2. We here report on the results of a mutational analysis of Sco1p. The two cysteine residues of a potential metal-binding motif (CxxxC) are essential for protein function as shown by t...

The Schizosaccharomyces pombe rhp51 + , rad22 + and rhp54 + genes are homologous to RAD51, RAD52 and RAD54 respectively, which are indispensable in the recombinational repair of double-strand breaks (DSBs) in Saccharomyces cerevisiae. The rhp51Δ and rhp54Δ strains are extremely sensitive to ionizing radiation; the rad22Δ mutant turned out to be muc...

The RAD52 gene of Saccharomyces cerevisiae is required for recombinational repair of double-strand breaks. Using degenerate oligonucleotides based on conserved amino acid sequences of RAD52 and rad22, its counterpart from Schizosaccharomyces pombe, RAD52 homologs from man and mouse were cloned by the polymerase chain reaction. DNA sequence analysis...

In Schizosaccharomyces pombe, an intrachromosomal crossover between the mating type (MT) expression locus and one of the silent donor cassettes is lethal due to the loss of the intervening L region. The region contains one essential gene, let1. This gene was cloned and sequenced. The deduced amino acid (aa) sequence of let1 shows extensive homologi...

The switching gene swi6 of Schizosaccharomyces pombe is involved in the repression of the silent mating-type loci mat2 and mat3. We have cloned the gene by functional complementation of the switching defect of the swi6-115 mutation. DNA sequence analyses revealed an open reading frame of 984 bp coding for a putative protein of 328 amino acids (aa)....

Degenerate oligonucleotides encoding conserved regions of the Rad52 protein of S.cerevisiae and its homologue, the Rad22 protein of S.pombe, were used to clone a chicken RAD52 counterpart by the polymerase chain reaction. Sequence comparison of the chicken and yeast proteins reveals a strongly conserved region between positions 40 and 178 of the ch...

The gene rad22 of the fission yeast Schizosaccharomycespombe has a function in DNA repair and matingtype switching. We have cloned the rad22 gene from a genomic gene bank by functional complementation of the switching defect. An open reading frame coding for a putative protein of 469 amino acids was found by sequence analyses. The rad22 gene contai...

In Schizosaccharomyces pombe 11 different switching genes (swi1 to swi10 and rad22) are known which are involved in mating-type (MT) switching. Mutations in swi5, swi9, swi10 and rad22 also cause an increased radiation sensitivity. We tested whether the survival of these mutants after UV irradiation is influenced by caffeine. We included rad1 and r...

Nach dem heutigen Stand der Technik scheint eine ausreichende Energieversorgung der Gesellschaft stets mit Risiken verbunden zu sein. Wir gehen in dem Artikel der Frage nach, ob auch biologische Systeme bei der Nutzung von Energie Risiken in Kauf nehmen. Zur effizienten Energiegewinnung nutzen Organismen meist Sauerstoff zur Oxidation energiereiche...