Ildikó UNK
senior research associate

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Éva BÁLINT senior research associate
Miklós HALMAI research associate
Orsolya FRITTMANN Ph.D. student
Szilvia MINORITS laboratory assistant

REGULATION OF MUTAGENESIS IN YEAST

DNA, the genetic material of our cells is constantly exposed to environmental agents that can damage or modify the structure of the DNA and alter the information encoded in it. This can ultimately lead to changes in the behavior and function of the cell and initiate the formation of cancer. However, cells possess several DNA repair systems that act to preserve the structure of the DNA and to correct the changes inflicted upon it. Despite the repair systems, uncorrected DNA modifications and DNA damages can still persist, and during cell division they can block the replication machinery leading to cell death. To avoid the fatal consequences, cells have evolved mechanisms that can sustain DNA replication on damaged DNA. These so-called DNA damage tolerance processes allow replication to continue on damaged DNA without removing the damage, either in an error-free or an error-prone way. The error-prone way causes increased mutagenesis and a rise in the incidence of cancers in humans, whereas error-free replication of damaged DNA contributes to genetic stability.

The main interest of our group is DNA damage tolerance. We investigate how the different DNA damage tolerance mechanisms are regulated by aiming to identify the proteins and protein modifications important for regulation. Furthermore, we examine the possible connections between the different damage tolerance mechanisms, aiming to better understand how their activities are synchronized and balanced in the cellular response to DNA damaging treatments.

In our research, we employ the yeast Saccharomyces cerevisiae as a model organism, taking advantage of the high conservation of DNA damage bypass processes from yeasts to humans.



Selected publications

Gali VK, Balint E, Serbyn N, Frittmann O, Stutz F, Unk I. Translesion synthesis DNA polymerase η exhibits a specific RNA extension activity and a transcription-associated function. Sci Rep. 12;7(1):13055. doi: 10.1038/s41598-017-12915-1 (2017)

Halmai M, Frittmann O, Szabo Z, Daraba A, Gali VK, Balint E, Unk I. Mutations at the Subunit Interface of Yeast Proliferating Cell Nuclear Antigen Reveal a Versatile Regulatory Domain. PLoS One. 18;11(8):e0161307. doi: 10.1371/journal.pone.0161307. (2016)

Daraba A. Gali V.K., Halmai M., Haracska L., Unk I. Def1 Promotes the Degradation of Pol3 for Polymerase Exchange to Occur During DNA Damage Induced Mutagenesis in Saccharomyces cerevisiae. Plos Biol. 12: e1001771 (2014)

Unk I., Hajdú I., Blastyák A., Haracska L. Role of yeast Rad5 and its human orthologs, HLTF and SHPRH in DNA damage tolerance. DNA repair 9:257-267 (2010)

Unk I., Hajdú I., Fátyol K., Hurwitz J., Yoon JH., Prakash L., Prakash S., Haracska L. Human HLTF functions as a ubiquitin ligase for proliferating cell nuclear antigen polyubiquitination. Proc. Natl. Acad. Sci. USA. 105: 3768-3773 (2008)

Unk I., Hajdú I., Fátyol K., Szakál B., Blastyák A., Bermudez V., Hurwitz J., Prakash L., Prakash S., Haracska L. Human SHPRH is a ubiquitin ligase for Mms2-Ubc13-dependent polyubiquitylation of proliferating cell nuclear antigen. Proc. Natl. Acad. Sci. USA. 103: 18107-18112 (2006)

Unk I., Haracska L., Gomes X.V., Burgers P.M.J., Prakash L. and Prakash S. Stimulation of 3’->5’ exonuclease and 3’-phosphodiesterase activities of yeast Apn2 by PCNA. Mol. Cell. Biol. 22, 6480-6486 (2002)

Unk I., Haracska L., Prakash S. & Prakash L. 3’-Phosphodiesterase and 3’->5’ Exonuclease Activities of Yeast Apn2 Protein and Requirement of These Activities for Repair of Oxidative DNA Damage. Mol. Cell Biol. 21, 1656-1661 (2001)

Unk I., Haracska L., Johnson RE., Prakash S. & Prakash L. Apurinic endonuclease activity of yeast Apn2 protein. J. Biol. Chem. 275, 22427-34 (2000)