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TALIÁN, Csaba Gábor

TALIÁN, Csaba Gábor

PhD

senior lecturer

Department of Biophysics

Supervisor of the following TDK topics

Supervisor: TALIÁN, Csaba Gábor

Co-supervisor: VARNYUNÉ KIS-BICSKEI, Nikolett

The mechanical stability of eukaryote cells is provided by an internal scaffold, the cytoskeleton, whose one main component is the actin filament system. Also these structures are responsible for the majority of cell movements. The actin system is operated by hundreds of regulatory proteins that not only define the properties of the filaments but influence each other’s activities. The elongated tropomyosins bind the filaments longitudinally in a lateral way. They come in several isoforms even within the same cell type, but the significance of this is poorly understood. In the gelsolin family proteins share a similar molecular structure but differ in function.

Gelsolin is able to sever, nucleate (promote the formation) or cap (bind to one end) the filaments. It is also known that tropomyosin and gelsolin can bind not only actin but each other, as well. We aim to investigate the interactions of these two types of proteins (and, later on, some other members of the gelsolin family) and how they can mutually influence their regulatory effects on the actin filament. So we try to build a molecular model that can help us understand the functioning of this complex system. During our work we apply both molecular biology tools and fluorescence spectroscopy measurements or microscopy imaging.

Supervisor: TALIÁN, Csaba Gábor

Fluorescent amino acids that do not naturally occur can be a subject of site-specific incorporation into proteins. This way individual protein species can be labelled in live cells and they can then be investigated by spectroscopy or microscopy methods. The essential part of the technique is to replace the position of interest in the gene by a stop codon and to add such specific tRNAs, carrying the fluorescent non-conventional amino acid, that can recognise this ectopic stop codon. In that manner the labelled amino acid is incorporated only to the desired sites.

We aim to generate actin mutants containing fluorescent amino acids at sites that have been inappropriate to be labelled yet. This would make it possible to measure the intramolecular movements in the actin more precisely and to characterise them under different circumstances of investigation. On the other side, the labelled molecules could be good candidates to follow the changes of the actin morphology in live cell experiments. In our studies we plan to apply, beside the methods mentioned above, molecular biology and eukaryote protein expression techniques, as well.