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AMMERER LAB


Gustav Ammerer
group leader

ammerer.jpg
tel. 43-1-4277 52816
 
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Members

Reiter Wolfgang
Postdoc
Ballarini Annalisa
PhD student
Dohnal Ilse
PhD student
Klug Helene
PhD student
Petrysmyn Andriy
PhD student
Salah Suhal Maria
PhD student
De Wever Veerle
PhD student
Veis Jirka
PhD student
 

EC-Grants:

Quantifying signal transduction
 - QUASI

 

 

Signal transduction and transcription in yeast

In signal transduction research, aims have shifted towards gaining a dynamic understanding of such processes. Current questions also concern how multiple signal pathways are integrated to elicit defined responses, how signal/response specificity is maintained when the same factors transmit multiple signals, and how cross talk between different signal systems is either established or avoided.
Our lab has tried to make progress towards such questions by studying the high osmolarity glycerol response in yeast. Upon exposure to osmotically imbalanced environments, yeast cells transiently activate a specific MAP kinase cascade. The transcriptional response coordinated by this MAP kinase, Hog1, has been well characterized. Apart from transcription factors Hog1 also becomes associated with stress induced promoters suggesting that it acts directly on the general transcription machinery. Hog1 is activated via two sensors linked to two separate signaling branches. One of the branches requires the function of signaling factors that are also active in mating and during starvation induced filamentous growth. Signal specificity seems to be maintained through Hog1 dependent feedback control and a scaffolding function of Pbs2, the activator of Hog1. Aims are to find Hog1 targets within this feedback system and to investigate how Pbs2 complexes are formed and disassembled during signaling.

 

Msn2 control

 


A defined set of genes is induced by a wide variety of stress situations via the zinc finger protein Msn2. Since this response is highly influenced by the nutrient supply, Msn2 can be viewed as integrator of growth and stress signals. Indeed, the principal growth regulator, protein kinase A inhibits directly the nuclear accumulation and DNA binding of Msn2. Since stresses have the opposite effect without changing PKA activity, Msn2 dephosphorylation has recently emerged as overarching theme in stress signal transduction.
Regulated expression of genes that contribute to stage specific functions are a key feature of eukaryotic cell cycles. In budding yeast, one set of genes is induced during the G2/M phase. Expression depends on the activity of the mitotic kinase Cdk1/Clb2. Promoter elements and factors regulating promoter function have been identified. Additionally, it has become clear that the periodic transcription is due to both positive and negative regulatory mechanisms. Apart from defining the interactions of transcriptional regulators, we have tried to determine how Cdk1/Clb2 could modulate their function.



Recent Publications

Durchschlag E, Reiter W, Ammerer G, Schuller C. 
Nuclear localization destabilizes the stress regulated transcription factor Msn2.J Biol Chem. 2004 Oct 22 [Epub ahead of print] 

Alepuz PM, de Nadal E, Zapater M, Ammerer G, Posas F. 
Osmostress-induced transcription by Hot1 depends on a Hog1-mediated recruitment of the RNA Pol II.
EMBO J. 2003 May 15;22(10):2433-42. 

Görner, W., Durchschlag, E., Wolf, J., Brown, E.L., Ammerer, G., Ruis, H., and Schüller, C. (2002). Acute glucose starvation activates the nuclear localization signal of a stress-specific yeast transcription factor. EMBO J. 21, 135-144.

Alepuz, P.M., Jovanovic, A., Reiser, V. and Ammerer, G. (2001). Stress induced MAP kinase Hog1 is part of transcription activation complexes. Molecular Cell 7, 767-777.

Teige, M., Scheikl, Reiser, V., Ruis, H., and Ammerer, G. (2001). Rck2, a member of the CaM- protein kinase family links protein synthesis to high osmolarity MAP kinase signaling in budding yeast. Proc. Natl. Acad. Sci. USA. 98, 5625-5630.

Reiser, V., Salah, S.M., and Ammerer, G. (2000). Polarized localization of yeast Pbs2 depends on osmostress, the membrane protein Sho1 and Cdc42. Nature Cell Biol. 2, 620-627.

Koranda, M., Schleiffer, A., Endler, L., and Ammerer, G. (2000). Forkhead like transcription factors recruit Ndd1 to the chromatin of G2/M-specific promoters. Nature 406, 94-98.

VanWuytswinkel, O., Reiser, V., Siderius, M., Kelders, M.C., Ammerer, G., Ruis, H., and Mager W.H. (2000). Response of Saccharomyces cerevisiae to severe osmotic stress: evidence for a novel activation mechanism of the HOG MAP kinase pathway. Mol. Microbiol. 37, 382-397.



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