| Abstract [eng] |
In this thesis was investigated the mechanism of action of restriction endonuclease CglI from Corynebacterium glutamicum strain. In the overview of dissertation literature was discussed about helicases, their structure and mechanisms, and also about distribution of helicase-like domains in other proteins. There was also discussed about antiviral defence systems in prokaryotes, concentrating into restriction-modification (RM) systems. In the results and discussion section was described structural and biochemical methods used to study CglI. CglI RM system is composed of three proteins: a putative restriction endonuclease (R.CglI), a methyltransferase (M.CglI) and a putative ATPase (H.CglI). There was showed that CglI forms a heterotetrameric R2H2.CglI complex, which hydrolyses ATP and cuts double stranded DNA. More detailed studies about H.CglI showed that it contains previously undescribed monomeric helicase-like motor responsible for ATP binding/hydrolysis and DNA translocation (movement on the DNA). There was also demonstrated that CglI displaces DNA triplex and tightly bound proteins from the DNA. This activity may be used in gene regulation, DNA metabolism studies or for other biomedical purposes. It was demonstrated that DNA translocation activity can be transferred from one DNA molecule to another, which is not typical for ATP-dependent motor enzymes. Summarizing the experimental data there was proposed mechanism of action of CglI restriction endonuclease. |
