Chromatin Molecular Complexes - Jiří Fajkus

PhD Topics

1. Dynamics of the Structure Maintenance of Chromosome (SMC) complexes

Supervisor: assoc. prof. Jan Paleček

Annotation: The SMC (Structure Maintenance of Chromosome) complexes are the key components of higher-order chromatin fibers and play important roles in genome stability. Three SMC complexes are present in most eukaryotic cells: cohesin (SMC1/3), condensin (SMC2/4) and SMC5/6 complex. Cohesin can make internal loops or embrace two sister chromatids (feature essential for proper chromosome segregation); condensin interconnects loops to condense chromatin during mitosis. The SMC5/6 complex is involved in the homologous recombination-based DNA repair, in replication fork stability and processing, and in cohesin regulation. In our lab, we study assembly and functions of SMC5/6 complexes (http://www.ncbr.muni.cz/SPEC/). New student will use combination of genetic (fission yeast model), biochemical (mostly yeast two-hybrid system and other binding assays) and bioinformatics methods to get deep insights into SMC5/6 features.

RG: Jiří Fajkus Research Group

Keywords: Structure Maintenance of Chromosome, SMC complexes, SMC5/6; genome stability, chromatin fibers

 

2. Structure, function and evolution of plant telomere components

Supervisor: prof. Jiří Fajkus

Annotation: Telomeres are terminal, but nevertheless integral parts of chromosomes, and as such they are also formed and function as supramolecular nucleoprotein (chromatin) structures. Their DNA component is usually formed by repetitive DNA whose incomplete end-replication by the conventional replication machinery can be compensated by elongation via a specific ribonucleoprotein complex with RNA-dependent DNA polymerase activity – the telomerase. Besides preventing the replicative shortening, telomeres also protect chromosome ends from being mistaken for unrepaired chromosome breaks. For the latter function, protein components of telomeres are responsible. Our group has described evolutionary changes in plant telomere DNA repeats and some protein components of plant telomeres in typical telomeres in the model system of Arabidopsis thaliana. It will be important to follow-up these studies with description of further protein components of telomeres together with testing their functional importance for telomere maintenance and chromosome stability. In addition, the impact of the evolutionary change in telomere DNA sequence on its protein interactors will be examined. Background in molecular biology, biochemistry and bioinformatics will be an asset for selection of a suitable candidate. Literature: Fajkus, P., Peska, V., Sitova, Z., Fulneckova, J., Dvorackova, M., Gogela, R., Sykorova, E., Hapala, J. and Fajkus, J. (2016) Allium telomeres unmasked: the unusual telomeric sequence (CTCGGTTATGGG)n is synthesized by telomerase. Plant J, 85, 337-347. Prochazkova Schrumpfova, P., Schorova, S. and Fajkus, J. (2016) Telomere- and Telomerase-Associated Proteins and Their Functions in the Plant Cell. Front Plant Sci, 7, 851. Schrumpfova, P.P., Vychodilova, I., Dvorackova, M., Majerska, J., Dokladal, L., Schorova, S. and Fajkus, J. (2014) Telomere repeat binding proteins are functional components of Arabidopsis telomeres and interact with telomerase. Plant J, 77, 770-781.

RG: Jiří Fajkus Research Group

Keywords: plant telomere DNA repeats, telomere maintenance, telomerase