The role of Cas3 protein in R-loop formation in Escherichia coli

Radovčić, Marin (2011) The role of Cas3 protein in R-loop formation in Escherichia coli. Diploma thesis, Faculty of Science > Department of Biology.

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The bacterial CRISPR/Cas system is a recently discovered new defense mechanism against foreign genetic elements. It comprises a CRISPR region (clustered regularly interspaced short palindromic repeat) and a few adjacent cas (CRISPRassociated) genes. The resistance is acquired by integration of short foreign DNA sequences within the CRISPR region. These sequences then serve for recognition and cleavage of target DNA during recurring infection by foreign DNA, similar to RNAi in eukaryotes. The stage in which recognition and cleavage of foreign DNA takes place is known as interference, and protein Cas3 is indispensable for this stage in Escherichia coli. The purpose of this research was to test if a structure similar to R-loop, i.e. an RNA molecule hybridized within the DNA duplex, forms during the interference stage. To test this, the efficiency of transformation and replication of ColE1 type plasmids, which require R-loop formation for initiation of replication, has been studied.Furthermore, the effects of overexpressed Cas3 protein on viability of mutants, which are known to affect the R-loop formation, has been studied. Obtained results suggest that Cas3 protein stabilizes R-loops or promotes their formation.

Item Type: Thesis (Diploma thesis)
Keywords: CRISPR, R-loop, E. coli, ColE1, Cas3
Supervisor: Ivančić Baće, Ivana
Date: 2011
Number of Pages: 44
Subjects: NATURAL SCIENCES > Biology
Divisions: Faculty of Science > Department of Biology
Depositing User: Grozdana Sirotic
Date Deposited: 07 Jul 2014 11:48
Last Modified: 07 Jul 2014 11:48

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