Utjecaj proteina DnaK na naivnu CRISPRCas adaptaciju u bakteriji Escherichia coli

undergraduate thesis

• Title (english): The effect of DnaK protein on naïve CRISPR-Cas adaptation in Escherichia coli
• Author: Mario Jurada
• Mentor: Ivana Ivančić Baće (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2023-09-07, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Adaptivni imunosni sustav, CRISPR-Cas, moćno je oružje u obrani protiv invazivnih genetičkih
elementa, poput bakteriofaga i plazmida. Efektivnost tog sustava uvelike ovisi o njegovoj
mogućnosti raspoznavanja vlastite i strane DNA. Nakon prepoznavanja strane DNA, u procesu
naivne adaptacije, kompleks Cas1–Cas2 iz strane DNA stvara razmaknice koje ugrađuje u Lokus
CRISPR. Dugo vremena nije bilo poznato na koji način Cas1–Cas2 raspoznaje stranu od vlastite
DNA. U nedavnim istraživanjima otkriveno je da protein DnaK, koji inače ima ulogu šaperona i
jedan je od najvažnijih proteina toplinskog šoka, igra važnu ulogu u prostornoj i vremenskoj
regulaciji naivne adaptacije. U ovom radu ponovljeni su neki od eksperimenata iz nedavnih
istraživanja koji su dokazali utjecaj DnaK na aktivnost naivne adaptacije. Praćenjem efikasnosti
naivne adaptacije u lizogenim sojevima E. coli pokazao sam da DnaK ima negativan utjecaj na
naivnu adaptaciju, tj. da smanjuje stopu ugradnje novih razmaknica. Ti rezultati su u skladu s
nedavnim istraživanjima koja sugeriraju da protein DnaK sprječava ugradnju vlastite DNA
inhibicijom kompleksa Cas1–Cas2 prilikom naivne adaptacije.

Abstract (english)

The adaptive immune system, CRISPR-Cas, is a powerful weapon in defense against invasive
genetic elements such as bacteriophages and plasmids. The effectiveness of this system greatly
depends on its ability to distinguish between self and foreign DNA. Upon recognizing foreign DNA,
in the process of naïve adaptation, the Cas1–Cas2 complex generates spacers from foreign DNA,
which are then incorporated into the CRISPR locus. For a long time, it was not known how Cas1–
Cas2 distinguishes between foreign and self-DNA. Recent research has revealed that the protein
DnaK, which normally acts as a chaperone and is one of the key heat shock proteins, plays an
important role in spatial and temporal regulation of naive adaptation. This study replicated some
of the experiments from recent research, which demonstrated the impact of DnaK on the activity
of naïve adaptation. By monitoring the efficiency of naive adaptation in lysogenic strains of E. coli,
I show that DnaK has a negative influence on naïve adaptation, i.e., it reduces the rate of
incorporating new spacers. These results are consistent with recent research, where it is suggested
that DnaK prevents acqusition of host DNA by inhibiting the Cas1–Cas2 complex during naive
adaptation.

• Keywords: E. coli; CRISPR-Cas; naivna adaptacija; Cas1–Cas2; DnaK; bakteriofagi
• Keywords (english): E. coli; CRISPR-Cas; naïve adaptation; Cas1–Cas2; DnaK; bakteriophages
• Language: croatian
• URN:NBN: urn:nbn:hr:217:117144
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-09-12 10:57:21