Freimoser:Research: Difference between revisions

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==Research==


==Research==
The focus of the research in our group is a simple
molecule: <strong>inorganic
polyphosphate (poly P)</strong>. Poly P is a linear polymer that consists of a variable number of
phosphate residues
(from three to more than a thousand) that are
linked by energy-rich phosphoanhydride bonds. It has been detected
in all organisms and living cells and was found in many organelles.
In eukaryotes, poly P is particularly
prominent in fungi, algae and trypanosomatids.
Poly P serves as a phosphate and energy store and regulates
enzymes, chromatin condensation
and translation. Poly P is also involved in bacterial pathogenicity,
survival during stationary phase in
bacteria and yeast, or the adaptation to alkaline and osmotic stress.
In the slime mold <i>Dictyostelium discoideum</i>, poly P regulates
development and predation behaviour, and in humans blood coagulation is
accelerated and fibrinolysis is delayed by poly P.


Inorganic polyphosphate (poly P) occurs ubiquitously in all living cells and regulates many molecular and biological processes. Nevertheless, poly P is scarcely studied and little is known about poly P metabolism and its exact molecular functions; especially in eukaryotes. In our group we have developed methods to quantify poly P, to stain and localize poly P and to screen for poly P binding proteins. We are using these tools to investigate poly P metabolism and functions in fungi, plants and algae. However, at the moment our main efforts are devoted to the study of poly P metabolism in the yeast ''Saccharomyces cerevisiae'' and of poly P in fungal cell walls.
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<h3>Poly P in ''Saccharomyces cerevisiae'':</h3> We have developed a fast and easy method for the quantification of poly P in yeast, which is amenable for large-scale analyses. This allowed extraction and quantification of poly P in mutant strains of all non-essential yeast genes. From this screen we conclude that at least 5% of all yeast genes are required for the maintenance of normal poly P levels. We are now studying specific pathways to determine their link with poly P metabolism. In addition, we study phenotypical differences in poly P hypo- and hyper-accumulating strains in order to learn more about the biological significance of poly P accumulation in yeast.
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[[Image:yeast.jpg]]<h3>Poly P in ''Saccharomyces cerevisiae''<nowiki>:</nowiki></h3> We have developed a fast and easy method for the quantification of poly P in yeast, which is amenable for large-scale analyses. This allowed extraction and quantification of poly P in mutant strains of all non-essential yeast genes. From this screen we conclude that at least 5% of all yeast genes are required for the maintenance of normal poly P levels. We are now studying specific pathways to determine their link with poly P metabolism. In addition, we study phenotypical differences in poly P hypo- and hyper-accumulating strains in order to learn more about the biological significance of poly P accumulation in yeast.
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[[Image:cellwall_polyP.jpg]]<h3>Cell wall localized poly P:</h3> One of our major goals and a very difficult problem is the specific localization of poly P. We have developed a staining method that is based on poly P binding proteins and immunohistochemical detection that allows for highly sensitive localization of poly P in fungal cell walls. We have used this technique for a systematic study of poly P in fungi from all fungal phyla. In the future we will also define procedures to stain poly P intracellularly.
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<h3>Cell wall localized poly P:</h3> One of our major goals and a very difficult problem is the specific localization of poly P. We have developed a staining method that is based on poly P binding proteins and immunohistochemical detection that allows for highly sensitive localization of poly P in fungal cell walls. We have used this technique for a systematic study of poly P in fungi from all fungal phyla. In the future we will also define procedures to stain poly P intracellularly.
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Research

The focus of the research in our group is a simple molecule: inorganic polyphosphate (poly P). Poly P is a linear polymer that consists of a variable number of phosphate residues (from three to more than a thousand) that are linked by energy-rich phosphoanhydride bonds. It has been detected in all organisms and living cells and was found in many organelles. In eukaryotes, poly P is particularly prominent in fungi, algae and trypanosomatids. Poly P serves as a phosphate and energy store and regulates enzymes, chromatin condensation and translation. Poly P is also involved in bacterial pathogenicity, survival during stationary phase in bacteria and yeast, or the adaptation to alkaline and osmotic stress. In the slime mold Dictyostelium discoideum, poly P regulates development and predation behaviour, and in humans blood coagulation is accelerated and fibrinolysis is delayed by poly P.

Poly P in Saccharomyces cerevisiae:

We have developed a fast and easy method for the quantification of poly P in yeast, which is amenable for large-scale analyses. This allowed extraction and quantification of poly P in mutant strains of all non-essential yeast genes. From this screen we conclude that at least 5% of all yeast genes are required for the maintenance of normal poly P levels. We are now studying specific pathways to determine their link with poly P metabolism. In addition, we study phenotypical differences in poly P hypo- and hyper-accumulating strains in order to learn more about the biological significance of poly P accumulation in yeast.

Cell wall localized poly P:

One of our major goals and a very difficult problem is the specific localization of poly P. We have developed a staining method that is based on poly P binding proteins and immunohistochemical detection that allows for highly sensitive localization of poly P in fungal cell walls. We have used this technique for a systematic study of poly P in fungi from all fungal phyla. In the future we will also define procedures to stain poly P intracellularly.