Panshchina A. Genome's structural organization of the temperate bacteriophage ZF40 of Erwinia carotovora

It has been shown for the first time that thermal inactivation of Erwinia carotovora's bacteriophage ZF40 is of a double stage character. It is an evidence of phage ZF40 virions' heterogeneity. With the help of thermal inactivation a set of temperature resistant clear-type mutants has been obtained. In this research the problem of phage ZF40 virions' stabilization has been solved using ficoll based buffer. To obtain highly purified phage ZF40 virions' a method of double stage centrifugation in the metrizamid gradient with following cesium chloride density gradient purification has been proposed for the first time. Physical map of phage ZF40 genome's restriction sites for endonucleases of restriction HindIII, BglII, PstI and BamHI has been created and the main parameters of cyclic permutation have been determined. It has been shown for the first time that cyclic permutation of genome is a characteristic of virions' DNAs of wild-type phage and its temperature clear-mutants. Unstoppable character of wild-type phage' permutaion changes into discrete one of temperature resistant clear-type mutants. It has been established that phage ZF40's virion consists of three major proteins with molecular weights 39,2, 31,2 and 19,3 kDa, that have been classified as capside, sheath and core structure proteins respectively. According to structure and protein composition phage ZF40 is similar to phage P2 of Escherichia coli. Structural organization of phage ZF40's genome is mosaic. It combines cyclic permutated DNA packed into P2-type virion with headfull packing mechanism. An ability of phage ZF40 to general transduction of plasmid pKM101 is a ground for creation of vector system based on the transdusing phage particles. Results of this work concerning phage ZF40 DNA's structure are a base for detail study of molecular-genetic organization and discovery of genetic determinants of pathogenicity in the structure of bacterial and phage genomes of phytopathogenic bacterium E. carotovora.