TSYMBAL N. Effect of virus infection on the nuclease activity of the cyanobacterium Plectonema boryanum

In the thesis the results of investigation the cyanobacterium Plectonema boryanum nuclease barrier and nucleases induced by cyanofage LPP-3 during its reproduction have been represented. Nuclease barrier of the cyanobacterium P. boryanum consists of a membrane associated nonspecific deoxyribonuclease with endonuclease activity and a restriction endonuclease PboI. The restriction endonuclease recognizes hexapalindromic sequence 5'-GGATCC-3'. During cyanophage LPP-3 reproduction in the cells of the cyanobacterium at an early stage of infection, induction of the nuclease complex occurs: a sitespecific nicase by molecular mass 34 kDa and a nonspecific exonuclease by molecular mass 28 kDa. It has been established the nicase is more sensitive to conditions of enzymatic hydrolysis relatively to the exonuclease. The maximal activity of the nicase appears in the buffer, that contains 10 mM Tris HCl, pH 8,0, 50 mM sodium acetate, 10 mM Mg-acetate and at a temperature of 370C, the exonuclease - 10 mM Tris HCl, pH 7,5, 50 mM sodium acetate, 10 mM Mg-acetate at a temperature of 370C.