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Zbog učestalih napada bakteriofaga, veliki udio bakterija razvilo je specifičan obrambeni sustav adaptivne imunosti koji se naziva CRISPR-Cas. Sustav se sastoji od seta gena cas i lokusa CRISPR koji se sastoji od kratkih ponavljajućih sljedova između kojih se ugrađuju razmaknice koje potječu od strane DNA. U bakteriji Escherichia coli efikasnost zaštite bakterija od faga sustavom CRISPR-Cas ovisi o aktivnosti proteina Cas3 koja pak ovisi o temperaturi inkubacije i šaperonu HtpG. U ovom radu istraženo je utječe li šaperon HtpG na količinu proteina Cas3 u ovisnosti o temperaturi i jačini promotora. Uz to, istraženo je da li promjene u konformaciji šaperona HtpG utječu na aktivnost proteina Cas3, odnosno na efikasnost zaštite od infekcije. Rezultati sugeriraju da šaperon HtpG utječe na funkcionalne količine proteina Cas3 u ovisnosti o temperaturi, dok točkaste mutacije u proteinu HtpG nemaju utjecaja na interakciju HtpG s proteinom Cas3. Jačina promotora za gen cas3 je ključna i analiza količina proteina Cas3 je moguća samo nakon ekspresije s inducibilnog promotora. Due to frequent bacteriophage attacks, a large group of bacteria have developed a specific adaptive immunity defense system called CRISPR-Cas. The system consists of a set of cas genes and CRISPR locus consisting of short repeats between which spacers derived from foreign DNA are inserted. In Escherichia coli, the effectiveness of immunity against phages depends on the activity of Cas3, which depends on the incubation temperature and HtpG chaperone. In this work, the influence of HtpG chaperone on the amount of Cas3 protein as a function of temperature and promoter strength was investigated. In addition, it was investigated whether conformational changes of HtpG affect the activity of Cas3, ie the effectiveness of the immunity against infections. The results suggest that chaperone HtpG affects functional amounts of Cas3 protein as a function of temperature, whereas point mutations in HtpG protein have no effect on the interaction of HtpG with Cas3. The strength of the promoter for the cas3 gene is critical and analysis of the amount of Cas3 is only possible from an inducible promoter.