[DNA inside bacteriophage lambda forms a Z-form]

The site of the transition regions between the B- and Z-forms of the DNA duplex (B-Z junction) may serve as marker of the existence of Z-DNA in situ. The structure of (dC-dG)10 insert in the bacteriophage lambda gt10 has been studied in situ by modification of B-Z junction with O-beta-diethylaminoethylhydroxylamine (OHA). The latter is an analogue of hydroxylamine possessing specificity with respect to unpaired cytidine. This modification inhibited the process of restriction at BamHI site adjacent to the Z-insert. Judging by the extent of the inhibition about 5% of all inserts has been converted in Z-form. The certain role of Z-form at process of the packaging DNA into bacteriophage's capsid suggest.