[Integrase of lambda phage inhibits the activity of promotor Patt under in vivo and in vitro conditions].

In vitro and in vitro transcription of the region of lambda phage DNA containing promoter Patt has been studied. Active transcription was observed in the vicinity of the att site and at the promoter Patt in vivo during the first minutes after infection. This transcription considerably decreases at the 1th minute, and stops completely at the 15th minute after infection. Maximum synthesis of integrase also takes place at the 15th minute after infection. In vitro the partially purified int protein (integrase) completely inhibited transcription from the promoter Patt. Hence, integrase is most probably a repressor of Patt in vivo and in vitro.